canned cat food meal feeding

Diet is a key therapy for cats with chronic kidney disease (CKD). Diets for managing CKD in cats aim to (Reference 1):

  • lessen the clinical signs of CKD
  • slow the progression of the disease
  • provide adequate nutrition

Diets for managing ckd in cats


The goal of diets for managing CKD in cats is to reduce the amount of uremic waste products while providing adequate nutrition. There are a number of commercially available diets that are formulated to do this. These foods feature (Reference 1):

  • reduced phosphorus
  • restricted amounts of high-quality protein
  • higher calories
  • reduced sodium
  • potassium supplementation
  • B vitamins and fatty acids

Phosphorus


Phosphorus is needed for the growth, maintenance, and repair of all tissues and cells, and for the production of the genetic building blocks, DNA and RNA. Phosphorus is also needed to help balance and use other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc (Reference 2).

As kidney disease progresses, the ability of the kidneys to excrete phosphorus declines. To reduce stress on the kidneys, diets for managing CKD in cats aim to reduce the amount of phosphorus and balance the ratio of calcium to phosphorus. Too much phosphorus and not enough calcium can lead to kidney and bone damage (Reference 1). Commercial kidney diets are formulated to maintain an appropriate ratio of calcium to phosphorus.

protein in diets for managing cats with ckd


Since protein contributes significantly to phosphorus content, kidney diets restrict the amount of protein. Less protein means less uremic waste products. Emphasis is placed on formulating these diets with “high quality” protein. High quality proteins are a “complete package” and provide the cat with all the amino acids he or she needs. Thus, the protein used is highly bioavailable and generates less uremic waste products (Reference 1).

There are concerns that reduced protein diets predispose cats to weight loss and loss of lean muscle mass. Some recent studies suggest that senior cats may require more protein than younger cats to maintain lean body mass (LBM) (Reference 1).

Some practitioners advocate feeding higher protein diets to cats suffering with CKD to maintain the LBM. This may not be the answer to maintain LBM – increased protein in the cat’s diet means more uremic waste, making the cat feel nauseated and not inclined to eat. Ultimately, the cat will be eating less and calorie reduction will lead to muscle wasting as the cat’s body uses his own muscles for nutrition (Reference 3).

More on Lean Body Mass…


A recent study in 2019 (Reference 4) found a correlation between consumption of essential amino acids (essential amino acids must be consumed in the diet) and LBM. Cats with CKD Stages 1 and 2 were fed either a control kidney diet or a higher calorie “test” kidney diet that included higher amounts of essential amino acids and carnitine, an amino acid derivative that plays a role in energy production in the body.

The cats eating the lower calorie control diet lost LBM whereas the other group of cats eating the “test” diet maintained their LBM. Researchers observed that the cats on the control diet did not eat enough food to get adequate amounts of essential amino acids.  They found that essential amino acid intake, not total dietary protein, correlated with maintaining LBM.  

Although offering reduced protein, most commercial kidney diets make sure that more than sufficient amounts of the essential amino acids are available.  The challenge is to get cats with CKD to eat enough of the diets.

Other Supplements


Commercial diets for managing CKD in cats also supplement:

  • Potassium, an electrolyte essential to the function of muscles and nerves
  • B vitamins – these water soluble vitamins can be depleted as the cat drinks more water and urinates more
  • Fatty acids – fatty acids found in fish oils are thought to reduce inflammation and decrease protein in the urine

Starting a kidney Diet


Renal diets are typically recommended for cats in IRIS Stages 2, 3, and 4. Occasionally a reduced protein diet may be prescribed for a Stage 1 cat who has persistent protein in her urine. Many practitioners like to introduce therapeutic diets when the cat is in IRIS Stage 2, because the cat should still be feeling well and more likely to accept the new diet (Reference 3).

The best time to switch to a kidney diet is when your cat is eating her regular cat food well and is feeling well. Wait to introduce the new diet if…

  • Your cat has just come back from the hospital
  • You have visitors or are doing home remodeling
  • Your cat is not eating her regular food well
  • Your cat is vomiting or having diarrhea

Introduce the new diet gradually, over several weeks (Reference 1)

       

Week 1

Week 2

Week 3

Week 4

Offer 25% of the new diet and 75% of the current food

Offer 50% of the new diet and 50% of the current food

Offer 75% of new diet and 25% of the current food

Offer 100% of the new diet

Make sure to offer the appropriate amount of calories to your cat – the new renal diet will most likely be more caloric than the your cat’s current food and you will not need to feed as much.

tips for transitioning to a kidney diet


  • Choose a food similar to the one your cat is eating already – wet or dry? fish or chicken?
  • Offer the new food in a separate bowl alongside the regular food
  • Make sure to offer fresh food
  • Use a “topper” to encourage your cat to try the new food – fish flakes or a favorite treat
  • Try gently warming wet foods – the stronger smell may make the food more appealing
  • Meal feed your cat – small, frequent meals gives your cat more chances to try the new food
  • Avoid mixing medications into the new food – use a small amount of another food or pureed treat to give the medications

from “Helping Your Cat Transition to a Therapeutic Kidney Food”, Hill’s Pet Nutrition/Clinician’s Brief, Educational Concepts, LLC © 2022

If you are struggling with a finicky cat, talk to your vet. If your cat is healthy, ask if you can do a trial of mirataz to stimulate his appetite and facilitate the transition to the new food.

Alternatives to a commercial kidney diet


  • Use a phosphorus binder in the food your cat will eat. Consult your veterinarian for the appropriate dose.
  • Home cooked diets are an option but should be formulated by a veterinary nutritionist.  Nutritionists affiliated with websites such as balance.it  will work with your vet to formulate a recipe for your cat.

Studies have shown that diets for managing CKD in cats can increase longevity, help control uremia and maintain phosphorus concentrations. While some have concerns about the protein restriction in these diets, kidney diets have been shown to maintain LBM providing the cat eats enough food to get sufficient nutrition.

New research is focusing on the connection between the kidneys and the GI tract, particularly the uremic toxins that originate in the gut. Prebiotic and probiotic treatments in CKD cats are being investigated to see if improving the health of the microorganisms living in the gut can reduce blood concentrations of gut-derived uremic toxins. (Reference 5)

references

  1. Quimby, J. and Ross, S., Diets for Cats with Chronic Kidney Disease (CKD) [updated 2022]. http://www.iris-kidney.com/education/protein_restriction_feline_ckd.html [viewed 9/2023]
  2. Phosphorus: Fact Sheet for Health Professionals, https://ods.od.nih.gov/factsheets/Phosphorus-HealthProfessional/, viewed 9/2023.
  3. Cave, N. and Wall, M. Protein restriction for cats with chronic kidney disease, Vet Focus, Issue # 30.1, © 6/25/20
  4. Hall JA, Fritsch DA, Jewell DE, Burris PA, Gross KL. Cats with IRIS stage 1 and 2 chronic kidney disease maintain body weight and lean muscle mass when fed food having increased caloric density, and enhanced concentrations of carnitine and essential amino acids. Vet Rec. 2019 Feb 9;184(6):190. doi: 10.1136/vr.104865. Epub 2018 Dec 4. PMID: 30514741; PMCID: PMC6589452.
  5. Summers, S. and Quimby, J., The feline gut-kidney axis: food for thought, Veterinary Focus, Issue #33.1, 5/31/23, https://vetfocus.royalcanin.com/en/scientific/the-feline-gut-kidney-axis-food-for-thought, viewed 9/2023
HDO BP cat
A cat relaxes in his basket during a home blood pressure check. Regular blood pressure checks are essential to monitoring chronic kidney disease.

Chronic Kidney Disease (CKD) in cats is progressive and not curable but there are strategies we can undertake to improve the quality of life of our “kidney” cats and possibly give them some more time with us. Here is a checklist for managing the cat with chronic kidney disease:

  1. Keep Kitty hydrated
  2. Feed a diet that will lessen the stress on the kidneys
  3. Maintain appetite
  4. Manage high blood pressure
  5. Treat anemia if necessary
  6. Treat urinary tract infections

Managing the cat with chronic kidney disease


hydration


Kidney failure is tied to the “death” of nephrons that filter the blood. The remaining nephrons compensate by increasing filtration. Dehydration decreases renal blood flow putting more stress on the remaining nephrons. Keeping the “kidney” cat hydrated helps maintain electrolyte concentrations and dilute the waste products the kidneys are struggling to filter out.

Increasing Voluntary Water Intake

  • Have a variety of water sources and fountains in the home to encourage water intake.
  • Consider feeding a wet diet – many canned foods contain about 80% water.
  • Try water from tuna, water used to poach chicken or fish (offer alone, add to the water bowl, or try frozen in an ice cube tray and added to the water bowl). 

Hydration supplements like Purina’s Hydra Care are designed to maximize the amount of water cats take in while drinking. Nutrient enriched water is more viscous, clings to the cat’s barbed tongue, and increases the water consumed with each lap of the tongue.

Subcutaneous Fluids

This refers to giving fluids under the skin, not in a vein. It is done using a bag of sterile fluids, an IV line and a needle. This is a strategy often employed in IRIS stages 3 and 4 of kidney disease.  This can be done in the veterinary clinic or at home, once you and your cat are comfortable with the process.

Kidney-friendly diets


As the kidneys fail, they are no longer as efficient at filtering the waste products of protein metabolism. Phosphorus in the form of phosphates tends to build up in the body while potassium levels may drop.

Commercial renal diets for kidney cats feature reduced phosphorus and restricted amounts of high-quality protein, an increased calorie density, sodium restriction, potassium supplementation, supplementation with B vitamins, anti oxidants and omega-3 fatty acids (Reference 1). There have been a number of studies done addressing the effectiveness of these diets – the results show that cats suffering from CKD lived longer when fed a renal diet (Reference 2).

Phosphorus Binders

For some cats in advanced stages of CKD, a renal diet may not reduce phosphorus enough; other cats simply refuse to consume a renal diet. For these cats, adding a “binding agent” to the food can help reduce the amount of phosphorus that is available for the cat to metabolize. Supplements that “bind” with the phosphates in the food form a nonabsorbable compound eliminated in the stool.   “Phosphorus binders” include (Reference 1):

  • Aluminum hydroxide
  • Calcium carbonate
  • Calcium acetate
  • Sevalamer (a hydrogel of poly-allylamine, free of aluminum and calcium)

 appetite and nausea


A “kidney” cat can suffer from nausea and vomiting due to the buildup of uremic toxins in the bloodstream. The cat consequently doesn’t eat well resulting in dehydration and weight loss. Reduced potassium levels and anemia due to CKD also contribute to a reduced appetite (Reference 1).

Medical Management

Managing the cat with chronic kidney disease also includes managing nausea and vomiting. Drugs that target nausea and vomiting include maropitant (Cerenia) and ondansetron. These are typically available in oral tablets.

There is another drug that is often the first choice of many practitioners. Mirtazapine is an antidepressant drug that not only controls nausea and vomiting, it also stimulates appetite.

  • available in a transdermal gel (Mirataz) as well as tablets
  • the transdermal form is FDA approved for use in cats
  • the transdermal gel is applied once daily and the dose is easily adjusted
  • side effects are vocalizing and increased activity.

If a cat is too nauseous or unwell to maintain food intake, a feeding tube should be considered.

high blood pressure


Increased filtration rate in the remaining nephrons and activation of the renin-angiotensin system can lead to high blood pressure in cats with CKD. Systolic blood pressures over 160 mm Hg require treatment to prevent damage to the cat’s eyes, heart and kidneys. In particular, the leakage of proteins into the urine (proteinuria) can be reduced once high blood pressure is managed (Reference 1).

Amlodipine is the most commonly used drug to reduce cats’ blood pressure. It is a calcium channel blocker that is available in tablets that can be taken once or twice daily. Amlodipine typically reaches therapeutic levels in 7-10 days.  Managing the cat with chronic kidney disease should include a blood pressure check every 3-6 months.

anemia


One of the kidney’s functions is to produce the hormone erythropoietin. Erythropoietin triggers cells in the bone marrow to make more red blood cells. Failing kidneys may not generate enough erythropoietin and anemia (low levels of red blood cells) can result.

Fewer red blood cells means less hemoglobin. Less hemoglobin means less oxygen is getting moved around the body. Anemia can result in weakness and tiredness. 

If the fraction of red blood cells in the blood drops below 20%, many practitioners will supplement the cat with a man-made analog of erythropoietin. The most commonly used drug is darbepoetin; it is given as an injection under the skin. Injections of iron supplements often accompany the darbepoetin injections in the initial stages of therapy (Reference 1).

A new treatment (2023) is available for anemia in cats with CKD.  Varenzin -CA1 is a once daily oral liquid medication made specifically for cats.  Varenzin-CA1 is designed to stimulate the cat’s body to make its own erythropoetin.

Urinary tract infections (UTI)


With increasingly dilute urine seen in cats with CKD, UTI’s are more common. Most of these UTI’s do not have clinical signs such as frequent urination or blood in the urine. Urinalysis should be part of the CKD cat’s checkup. White blood cells found in a centrifuged urine sample are indications for a bacterial culture and treatment. Treatment can be based on sensitivity testing and a kidney friendly antibiotic chosen.

Managing the cat with chronic kidney disease requires attention to multiple factors. Treating dehydration, nausea, high blood pressure and anemia can keep the “kidney” cat comfortable and slow the progression of the disease. A critical part of managing the cat with chronic kidney disease is feeding an appropriate diet. The next post will look at the science behind the commercial renal diets and alternatives to them.

references

  1. Sparkes, A. (panel chair), ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease, Journal of Feline Medicine and Surgery (2016) 18, 219–239.
  2. Quimby, J. and Ross, S., Diets for Cats with Chronic Kidney Disease (CKD) [updated 2022]. http://www.iris-kidney.com/education/protein_restriction_feline_ckd.html [viewed 9/2023]

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Cat on Baby Scale
Weight loss is a symptom of kidney disease.

 

Chronic kidney disease (CKD) is common in older cats. A 2014 study found that 30-40% of cats over age 10 years had CKD. (Reference 1).

chronic kidney disease in cats


Let’s take a closer look at what the kidneys do for our cats.

  • regulate fluid volume in the body
  • maintain the pH and electrolyte composition of the body.
  • make renin, an enzyme that helps maintain blood pressure
  • make erythropoietin, a hormone that stimulates production of red blood cells
  • filter the blood removing waste products

Nephrons are the tubular structures in the kidney that filter the blood and produce urine. A cat’s kidney has about 200,000 nephrons (Reference 2).

Over time, nephrons become damaged and are replaced by scar tissue. Renal failure occurs when less than 25% of the nephrons are functional and the remaining nephrons can’t maintain adequate function. The most common cause is an inflammatory process called tubulointerstital nephritis (Reference 3).

The remaining nephrons compensate by increasing filtration rate. The result of this “hyper filtration” is scarring of the tubes in the nephrons and loss of protein into the urine. The “hyperactive” nephrons also release the enzyme renin. Renin triggers the production of the hormone, angiotensin II, that makes heart beat more forcefully and raises the cat’s blood pressure. (Reference 3).

Diagnosing Chronic Kidney Disease in Cats


Clinical Signs of Chronic Kidney Disease

Some clinical signs are similar to those of other chronic diseases such as hyperthyroidism and diabetes.  Like those disorders, these signs are usually not present until later in the disease process.

  • weight loss
  • increased thirst and urination
  • rapid pulse and breathing
  • unkempt hair coat

In addition the “kidney cat” may have

  • lethargy
  • weakness
  • poor appetite
  • bad breath or ulcers in the mouth (occasionally)

Diagnosing Chronic Kidney Disease in Cats

CKD is typically diagnosed by measuring creatinine and SDMA in the blood and measuring the urine concentration (Reference 1).

Creatinine

Creatinine is a by-product of energy-producing processes in the muscles. A healthy cat’s kidneys filter out most of the creatinine.  As kidney disease progresses, the remaining nephrons filter out less creatinine and values of creatinine in the blood rise.

SDMA

SDMA (symmetric dimethylarginine) is a metabolite of arginine, one of the essential amino acids for cats. SDMA is produced from metabolism of proteins and, like creatinine, is filtered out by the kidneys. Unlike creatinine, SDMA is not influenced by the change in muscle mass. SDMA is more sensitive to the increase in the filtration rate as kidney disease progresses. It will increase earlier than creatinine.

Urine Concentration

As remaining nephrons increase filtration to compensate for the loss of nephrons, the cat drinks more fluid and the urine he produces becomes more dilute.   As CKD progresses, urine concentration decreases.

the stages of chronic kidney disease


The International Renal Interest Society (IRIS) has formulated a guide to staging CKD in cats, as well as in other animals. There are 4 stages of CKD.  The table below summarizes the values for creatine and SDMA seen for cats in the stages of CKD.

Stage Creatinine (mg/dL) SDMA (mcg/dL) Comments
Stage 1 <1.6 <18   Blood values are normal but urine is dilute or kidneys are abnormal on examination or imaging
Stage 2 1.6 – 2.8 18 – 25 Clinical signs are mild or absent
Stage 3 2.9 – 5.0 26 – 38 Clinical signs are present but vary in severity
Stage 4 >5.0 >38 Risk of uremic crisis

 

Signs of Uremic crisis (end stage kidney failure):

Refusal to eat, vomiting, lethargy, confusion (possibly pacing and restlessness), withdrawn, uncontrolled urination or defecation, ammonia-like odor to the breath, seizures (from https://www.petmd.com/cat/conditions/urinary/kidney-failure-cats). Emergency treatment is needed.

other signs of chronic kidney disease in cats


Even if creatinine and SDMA are within normal limits, high blood pressure and protein in the urine may indicate that a cat has kidney disease.   Recall that as nephrons “die”, the remaining nephrons increase filtration to compensate and blood pressure rises. The higher pressure damages the walls of the tubes in the nephrons and protein can leak out into the urine.

High Blood Pressure

Systolic blood pressures under 140 mm Hg are considered normal; SBP 140- 159 is prehypertensive; over 160 is hypertensive and treatment is recommended. (see “Measuring Your Cat’s Blood Pressure: Why and How”)

Protein in the Urine

Protein in the urine can be associated with disease processes such as urinary tract infection.  Persistent protein in the urine warrants a closer look and the veterinarian will often choose to run a test to measure the urine protein creatinine ratio (UPCR). UPCR < 0.2 are normal; ratios of 0.2-0.4 are borderline; ratios over 0.4 support a diagnosis of CKD.

Diagnosis of chronic kidney disease can be challenging. Clinical signs are non specific and shared by other chronic diseases such as hyperthyroidism and diabetes. Because the kidneys have so much reserve capacity and our markers do not detect it until nephron death approaches 70-80%, it can be easy to miss some of the more subtle indicators of kidney dysfunction. It is important for our cats to have regular exams to assess their overall condition, lab work, and blood pressure measurement. Kidney disease is progressive and not curable, however, early intervention can slow down the process. In the next post, we discuss treatment of Stage 1 through Stage 4 of chronic kidney disease in cats.

references

  1. Sparkes, A. et al. ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease,  Journal of Feline Medicine and Surgery (2016) 18, 219–239, https://journals.sagepub.com/doi/pdf/10.1177/1098612×16631234
  2. Sadeghinezhad, J. and Nyegaard, J. Cat Kidney Glomeruli and Tubules Evaluated by Design-Based Stereology. The Anatomical Record, Volume 302, Issue 10, 18-46-1854, 14 May 2019, https://doi.org/10.1002/ar.24144
  3. Grauer, Gregory, Feline Chronic Kidney Disease, Today’s Veterinary Practice, February 6, 2015, Issue March/April 2015, https://todaysveterinarypractice.com/urology-renal-medicine/feline-chronic-kidney-disease/

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Over 10% of cats over 8 years old will be diagnosed with hyperthyroidism in their lives.  Although evidence points to thyroid disrupting chemicals in the cats’ food and environment, we don’t really know why these cats will become hyperthyroid.  Prompt diagnosis and treatment will help these cats live long and healthy lives.

Diagnosing and Treating Hyperthyroidism in Cats


Diagnosing


Clinical signs of hyperthyroidism include increased appetite and weight loss. These signs progress slowly and it may be months to years before the cat owner realizes that something is wrong.

Cats are considered seniors at the age of seven. Regular lab work is recommended for senior cats and most senior feline blood panels include a thyroid hormone (T4) measurement. Persistently elevated T4 concentrations coupled with one or more of the classic clinical signs (below) at the same time often confirms the diagnosis of hyperthyroidism. (Reference 1)

  • weight loss
  • increased thirst and urination
  • increased vocalization
  • hyperactivity
  • rapid pulse and breathing
  • vomiting, diarrhea
  • unkempt hair coat

This list of clinical signs is also shared with other feline diseases, such as diabetes, kidney disease, and GI disorders. These diseases can lower the T4 measurement, so that it is in the reference range, making diagnosis of hyperthyroidism challenging.

a challenging diagnosis


Cats that may have kidney disease as well as hyperthyroidism are particularly challenging to diagnose. Thyroid hormone increases the blood flow through the kidneys, often lowering kidney values to within the reference ranges. At the same time, kidney disease impairs the binding of T4 to proteins, reducing the T4 concentration. One disease masks the other and vice versa (Reference 2).

Cats with borderline T4 values and those suspected of having another chronic disease will need additional testing before a definitive diagnosis of hyperthyroidism is made. The veterinarian may request a more sensitive test called a “free T4 by equilibrium dialysis” in addition to remeasuring total T4. “Free T4” measures a form of T4 that is not bound to proteins in the blood. (Reference 3)

Routine thyroid monitoring in humans and dogs measures levels of  TSH or thyroid stimulating hormone. Unfortunately, levels of  TSH in hyperthyroid cats are often too low to be detected using canine tests. Zomedica has recently developed a feline TSH assay capable of measuring the low levels of TSH in cats which may aid in diagnosing feline hyperthyroidism. (Reference 3)

treating hyperthyroidism in cats


At the present time, there are 4 treatments available to cats with hyperthyroidism (Reference 1).

  • radioactive iodine (I-131)
  • medical management with a drug called methimazole
  • surgical removal of abnormal thyroid tissue
  • dietary therapy using iodine-restricted food

1. Radioactive Iodine (I-131)

Treating hyperthyroidism in cats with radiation must be done at a licensed facility. An injection of radioactive iodine is given under the skin, like a vaccine. The cat stays at the facility until radiation levels drop enough to send cat home (about 3-4 days) (Reference 1, 4)

  • 95% cure rate
  • side effects are rare
  • small risk of hypothyroidism (too much tissue is destroyed and the cat will need thyroid supplements)
  • owner must store wastes and soiled litter for 2 weeks
  • cannot cuddle kitty for extended times for 2 weeks post discharge (e.g. cat cannot sleep on bed)

2. Medical Management with Methimazole (Reference 1)

  • not a cure and the cat must receive daily medication to manage his hyperthyroidism
  • methimazole is available in pills and transdermal gel
  • frequent monitoring of T4 values is necessary
  • side effects: vomiting, facial itching, liver failure
  • tumor may continue to grow and become cancerous

3. Surgical Removal of Thyroid Gland (Reference 1)

The abnormal thyroid tissue is removed surgically, leaving the normal tissue alone. It is a procedure most surgeons can perform.

  • up to 90% cure rate
  • if not all the abnormal tissue is removed, hyperthyroidism can return
  • general anesthesia can be risky in cats with cardiac issues and kidney disease
  • there is a risk of damaging the adjacent parathyroid glands (regulate calcium in the body)
  • risk of hypothyroidism if too much normal tissue is removed

4. Dietary therapy (Reference 1)

Hills y/d diet reduces the amount of thyroid hormone in the body by decreasing the amount of iodine in the cat’s food.

  • response is 82% when on the diet
  • safe for cats with kidney disease
  • the cat cannot eat other foods
  • only low-iodine treats and water can be used
  • the cat will become hyperthyroid if he stops eating the diet

Both I-131 and thyroid surgery offer a cure for hyperthyroidism. However, both have a low risk of too much normal tissue being destroyed and the cat developing “hypothyroidism” as a consequence. The “hypothyroid” cat does not produce enough thyroid hormone and must be supplemented with daily oral medication for the rest of his/her life.

Both I-131 and surgery run the risk of unmasking more advanced kidney disease. Unlike medication or diet which can be adjusted or stopped, I-131 and surgery are permanent. Before recommending I-131 or surgery, some practitioners will conduct a trial with methimazole to assess kidney function when the hyperthyroidism is managed. However, some clinicians will opt to treat with I-131 even in the face of advanced kidney disease – persistent hyperthyroidism will further damage the kidneys if left untreated (Reference 5).

Diagnosing and treating hyperthyroidism in cats can be challenging. The presence of other diseases can mask hyperthyroidism and interfere with testing.  I-131 is considered the gold standard for treating hyperthyroidism in cats. It does not carry the risks of surgery, avoids the side effects of methimazole and the difficulties of maintaining a strict prescription diet with a cat. Whichever treatment you choose, you have taken a step toward giving your hyperthyroid cat a healthier and longer life.

 

references

  1. Carney HC, Ward CR, Bailey SJ, et al. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. Journal of Feline Medicine and Surgery. 2016;18(5):400-416. doi:10.1177/1098612X16643252
  2. Geddes R, Aguiar J. Feline Comorbidities: Balancing hyperthyroidism and concurrent chronic kidney disease. Journal of Feline Medicine and Surgery. 2022;24(7):641-650. doi:10.1177/1098612X221090390
  3. Kvitko-White, Heather. Recognizing and confirming feline hyperthyroidism. dvm360 March 2021 Volume 53, Feb 9, 2021. https://www.dvm360.com/view/recognizing-and-confirming-feline-hyperthyroidism (viewed 9/2023)
  4. Brooks, Wendy. Thyroid Treatment Using Radiotherapy for Cats. Veterinary Partner:VIN. Date Published: 01/01/2001
    Date Reviewed/Revised: 09/05/2023. https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951399 (viewed 9/2023)
  5. Vaughan, F. and Wackerbarth, D. “Methimazole Trials: What Are They Good For?”, https://www.felinehtc.com/documents/Methimazole-Trials.pdf (viewed 9/2023)
Thyroid Disruptors have a similar structure to the thyroid hormone T4

About 10% of senior cats will develop a condition called hyperthyroidism in their lives. Hyperthyroidism can affect a cat’s quality of life and potentially shorten it.

What is hyperthyroidism?
A cat has two thyroid glands, one on each side of the throat below the larynx or voice box. In a healthy cat, these glands are small and difficult to feel. In a cat with hyperthyroidism, these glands are enlarged due to an overgrowth of tissue. This tissue is functional and produces thyroid hormones. Chemical assay of an affected cat’s blood will show an excess of thyroxine (T4).

Most of these growths are benign – only 2% of hyperthyroid cats have cancerous tumors at the time of diagnosis (Reference 1).

Hyperthyroidism in Cats – what you may notice


  • Weight loss
  • Increase in vocalizing
  • Hyperactivity
  • Increased thirst and urination
  • Unthrifty haircoat
  • Vomiting
  • Diarrhea

Hyperthyroidism in cats – causes?


Hyperthyroidism was rare in cats prior to 1970 – the first case was officially reported in 1979 (Reference 2). What has changed since the ’70’s?

  • cats are living longer
  • more cats are eating commercial cat food
  • many cats live exclusively indoors

Longer Lifespan
Humans are more at risk to form small growths on their thyroid glands as they age (Reference 1). It is likely that older cats are also more predisposed to thyroid tumors.

Diet
Soy can be found in many cat foods, particularly dry formulations. Soy inhibits some of the key enzymes in the production of the thyroid hormones.  The pituitary gland responds to the lower levels of thyroid hormones by producing TSH (thyroid stimulating hormone).  More thyroid tissue grows to meet the need for thyroid hormones.

Studies with rats have linked eating soy with thyroid tumors, but only when consuming diets deficient in iodine (Reference 2). Could iodine supplementation help?  More research is needed to determine how large a role iodine plays in feline hyperthyroidism.  Most cats are exposed to other chemicals in their environment, drinking water, and diet that also affect thyroid function. How much do these chemicals contribute to the development of feline thyroid tumors?

Cat food can linings and Bisphenol A

Most canned cat foods have a plastic coating to extend the shelf life of the food inside and guard against contamination. Many of these canned linings contain a chemical called bisphenol A or BPA.

BPA has a chemical structure that is similar to the thyroid hormones and can possibly interfere with thyroid hormone function. (Even though most of the linings are PVC, BPA can be an additive in the processing of PVC). Although the FDA says the level of BPA in cans is very low and does not present health risks to humans, the agency did ban the use of BPA in baby bottles, sippy cups and infant formula packaging in July of 2012.

Hyperthyroidism in cats – the environment


Poly brominated diphenyl ethers (PBDE) are another class of compounds that have a chemical structure similar to the thyroid hormones and are known to disrupt thyroid metabolism. PBDE’s are used as flame retardants in electronics, furniture and textiles as well as construction materials (Reference 2).

In 2004, manufacturers in the US voluntarily stopped making many of the PDBE flame retardants. However, these chemicals accumulate in the environment and have been detected in significant amounts in animals as well as humans.

Multiple studies have found that house cats have serum levels of PBDE that are about 50 times higher than that in humans (Reference 2). A study at the University of Illinois found that feral cats had a lower level of PBDE’s in their blood than house cats. This indicates that house cats are exposed to PBDE in their homes.

Further work analyzed dust samples and found higher concentrations of PBDE’s in dust from the homes of hyperthyroid cats compared with those of healthy cats (Reference 2). As cats groom, they can ingest dust and possibly PBDE.

At this time, there are not any studies that have conclusively linked exposure to a specific chemical compound to hyperthyroidism in cats. Soy, iodine, BPA and PBDE’s may or may not play a significant role in cats becoming hyperthyroid (Reference 1).

Preventing Hyperthyroidism in cats


The suggestions below will certainly not hurt your cat and may limit his exposure to chemicals that can disrupt thyroid function (Reference 2).

  • Avoid cat food products containing soy products.
  • Limit fish-flavored foods: fish contain high levels of iodine and may be contaminated with PCB, PBDE, etc.
  • Feed wet foods in foil pouches in preference to using canned food possibly lined with coatings containing BPA
  • Home cooked diets can help help avoid contamination with chemicals but consult with a veterinary nutritionist so that the diet is balanced and complete.
  • Use ceramic or glass containers for feeding and storage to reduce exposure to chemicals like BPA.
  • Use filtered water from the tap to limit exposure to chemicals.
  • Vacuum regularly to limit the dust your cat ingests.
  • Avoid cat litters with deodorizers or odor neutralizers.

Thyroxine (T4) levels are routinely checked on most senior feline blood panels. Annual or bi-annual labwork will let you know if your cat is developing hyperthyroidism. This way, you can plan for appropriate treatment before your feline friend starts to show outward symptoms.

What are the treatment options for hyperthyroidism in cats? We will look at these in the next post.

references

  1. Carney HC, Ward CR, Bailey SJ, et al. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. Journal of Feline Medicine and Surgery. 2016;18(5):400-416. doi:10.1177/1098612X16643252
  2. Peterson M. Hyperthyroidism in cats: what’s causing this epidemic of thyroid disease and can we prevent it? J Feline Med Surg. 2012 Nov;14(11):804-18. doi: 10.1177/1098612X12464462

 

Cat hunting treat ball

Your cat went in for her annual exam and your vet suggests that she lose some weight. Most likely, you were also given some daily calorie estimates and food amounts. Perhaps your vet recommended a weight loss food. What’s next?

Three ways to help your cat lose weight:

  1. portion control
  2. feeding multiple small meals
  3. keeping your cat moving

Portion Control


If you have not done this already, measure how much your cat is eating. Make sure to include treats and table scraps. If your cat is a grazer, put out a measured amount of food in the morning and measure what remains the next morning, 24 hours later.

Gradual weight loss is best. The rule of thumb is to cut your cat’s food portion by no more than 10-20% at a time. Drastic food reduction can lead to a cat who is frantic for food, begging and sometimes biting you in his quest for food. It may take some time to reach the calorie allowance recommended by your vet.

The Behavior of Feeding: Multiple small meals daily


Now that you know how much to feed, let’s look at how you feed. Cats have small stomachs; in the wild, they follow a nocturnal schedule, hunting and feeding about 4 times, starting in the late afternoon and finishing in the morning.  In between hunts, the cats nap and groom; sometimes they play with the kittens.

Your cat is designed to eat multiple small meals a day. If your cat is a grazer, this is what she is doing and she may be fine with her portion set out in a bowl for the day. Other cats may want to eat everything at once, which can lead to GI upset and boredom. To help your cat lose weight, portion control can be done by using a timed feeder or you can follow a feeding schedule. Here is a sample schedule for a working owner feeding 4 meals a day.

  1. AM before leaving for work – meal feed: canned or dry food
  2. Day Time: food puzzles or feeders with dry or canned food
  3. PM arrive home from work – meal feed: canned or dry food
  4. Bedtime Snack: Treat Time – treat toss or training

Strategies for the Multi-Cat Household


Life is rarely simple – often you have one cat who needs to lose weight and a “skinny” one who is a “grazer”.

Technology to the Rescue: Microchip feeders

SureFeed Microchip Pet Feeder:

Surefeeder for Cat
Athena’s Surefeeder opens only for her. Note the bubble on the back to keep the other cats out.

This plain vanilla feeder is ideal for grazers who tend limit themselves. The feeder is programmed to sense an individual cat’s microchip and only opens for the particular cat. Put the “skinny” cat’s food in the Surefeeder and the “fat” cat’s food in a timed feeder or in bowls spread out through the house. The Surefeeder can also accommodate canned food.

 

 

 

Timed Microchip Feeders:

These feeders sense the tag on the pet’s collar and allow a pet a certain amount of time to eat. Many of these feeders can accommodate more than one pet if they are eating the same food. However, some reviews note that a persistent pet will refuse to leave when the doors try to shut, keeping his head in the bowl and continuing to eat.

The Meowspace:

This is a ventilated transparent “box” with an access door. Some models have a microchip flap while others have a magnetic flap. The Meowspace also has a timed access option, allowing the cat to access the “space” only at certain times of the day.

The DIY version: You can make a “meow space” out of a closet by installing a microchip cat flap in the closet door. To add a “timed” option, place an inexpensive automatic feeder in the closet.

Low Tech Solutions to help your cat lose weight:

Some cats prefer to be up high while others are “ground dwellers”. If this is the case, you can feed the cats who climb up high on a shelf, top of a bookcase, or on the upper level of a cat tree while the other cat eats at ground level. Another option is to meal feed and separate the cats in different rooms when feeding.

keeping your cat moving


In the wild, cats prowl around looking for food. You can mimic this behavior by placing portions of food in different places around the house. Your cat has to go look for it. This is the idea behind Doc & Phoebe’s indoor hunting system.

Puzzle feeders also can also stimulate and engage your cat while feeding. Make sure to introduce your cat to his puzzle feeder gradually, increasing the food in the puzzle and decreasing his food in the bowl as he learns to use the puzzle feeder.

Using the indoor hunting system or puzzle feeders can be challenging in the multi-cat home: some cats will catch on more quickly than others, getting more to eat in the process. Indoor hunting and food puzzles may not be appropriate. In that case, help your cat lose weight by engaging him in a daily play session or taking him for a leash walk outside.

Treat Toss
If you are feeding dry food, you can make one of the meals a tossing game. Dental treats or dental kibbles are large and can be tossed for your cats to hunt down. Space the cats out so each cat has his own “territory” to hunt in and make the rounds, tossing the kibbles. This is also a great way for the cats to interact with guests, who usually enjoy tossing the treats to the eager felines!

Help your cat lose weightreduce his risk of medical problems such as diabetes and arthritis, and form a closer relationship with your cat through daily play and exercise activities.

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If you search for “monoclonal antibodies”, most of the search results are about COVID-19 and its variants. But did you know that monoclonal antibodies form the basis of the newest treatment for arthritis in cats? This new treatment is called Solensia.  Solensia is a monthly injection for arthritic cats that won FDA approval this  month. It should be available through your veterinarian later this year.

arthritis in cats: a tale of biotech and a chinese hamster


what are monoclonal antibodies?


  • Monoclonal: refers to a cell or organism that comes from a single individual or cell.
  • Antibodies are proteins in the blood that our immune system produces to counteract a foreign substance such as a bacteria or virus (think COVID-19).

antibodies and the immune system


Immune cells in our bodies called B-lymphocytes mount a response to a foreign substance or antigen (e.g. a virus), binding to it and deactivating it. The presence of the antigen and immune cells called T cells activate the B-cells. The B cells then propagate and release antibodies that are able to bind to and deactivate the specific antigen that stimulated their formation!

Monoclonal antibodies are derived from clones or copies of activated B cells. They can be harvested and grown in the laboratory and used to fight infections caused by the antigen they were developed to target.

Where do monoclonal antibodies come from?


  • Blood cells from convalescing patients: Due to the large numbers of convalescing COVID patients, there was a ready source of blood cells containing B-cells with antibodies to COVD 19 that could be used to make monoclonal antibodies to treat newly infected patients.
  • Transgenic mice: Mice that have been genetically altered to carry human antibody genes instead of mouse antibody genes are the usual source for monoclonal antibodies. These mice can be injected with a specific antigen and produce fully human antibodies that can be used by human patients to combat that antigen.  Being human antibodies, they are less likely to be rejected by the human immune system.

Arthritis in cats: using monoclonal antibodies


Nerve growth factor (NGF) is a protein that is key to the development and survival of nerve cells or neurons, particularly sensory neurons that transmit pain, temperature, and touch sensations.

When NGF binds to pain receptors inside the sensory neuron, a series of events is triggered that ultimately sends a “pain” signal to the brain.

Instead of binding to a structure on a virus, monoclonal antibodies can be developed to recognize and attach to NGF, preventing NGF from binding to the pain receptors on the sensory neruron, blocking the pain signal.

Motion is Medicine

A reduction in pain means our arthritic cats will be more likely to move around more. Increased mobility will strengthen the cat’s muscles, so they can better support and assist the deteriorating joints.  Increased activity and reduced pain result in a better quality of life.

Biotech Magic

The active ingredient in Solensia is frunevetmab, a monoclonal antibody that targets NGF. The antibodies are sourced from Chinese hamster ovary cells. Like the mice that have human antibodies instead of mouse antibodies, the hamster cells are “felinised”using recombinant biotechnology. Sections of the hamster antibodies are replaced with their feline counterparts. “Felinization” ensures that the cat’s immune system will not reject the monoclonal antibodies but allow them to function as part of the cat’s immune system.

Of cats and hamsters: no hamsters harmed


Frunevetmab is sourced from the cells of Chinese hamster ovaries. In fact, cells from an individual Chinese hamster, harvested back in the 1950s, produced the cell line which dominates biotechnology today. These cells are easy to propagate and maintain in the lab, providing a ready source of monoclonal antibodies.

multimodal therapy for arthritis in cats


Solensia is a pain medication and does not directly aid in preserving the synovial tissues. Most likely, Solensia will be part of a multimodal treatment that will include drugs and supplements like Adequan or glucosamine that are thought to help maintain synovial tissues in addition to weight loss and exercise.

Unlike other arthritis pain treatments such as NSAID’s, monoclonal antibodies are eliminated in the same way other proteins are, with minimal effect on the kidneys and liver, a concern for our cats with Chronic Kidney Disease.

Treatment using Solensia will consist of monthly injections under the skin. Most cat owners can become proficient in giving subcutaneous injections and treatment can be done in the safety and comfort of the cat’s home.

Thanks to a Chinese hamster years ago and advances in biotechnology, our cats may be able to spend their “ golden years” without pain from osteoarthritis!

 

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cat in carrier with removable topMany of us (cat owners) dread taking our cat to the vet. There is the ordeal of the carrier and car trip; once there, your cat seems miserable. However, regular veterinary care is the key to a happy and longer life for your cat. Can medication before your cat’s vet visit help?

Not every cat needs medication at the vet.  Some cats are fine just having some familiar things with them.  Familiarity can help reduce situational anxiety – the anxiety you experience when you are in a strange place. Things we can do to increase familiarity for your cat at the vet visit include:

  • Training her to be comfortable in her carrier
  • Choosing a carrier with a removable top to allow examination in her carrier
  • Getting her used to the car and taking her on some drives that don’t end up at the vet
  • Bringing your cat’s favorite treats
  • Spraying the carrier with pheromones (Feliway) before the visit

For some cats, this may not be enough. Your usually nice kitty becomes a raging demon or just freezes like a rock and doesn’t move – both reactions can be the result of anxiety and fear.

I recently took my youngest cat in a for a rabies vaccine and to have a tooth evaluated. Gus accepted handling and food but had a whopping heart rate of 230 beats per minute! He was anxious even though I was there with him.

We would like our cats to associate good things with going to the vet but they may not be feeling well when they are there or they anticipate getting poked with a needle for vaccinations or blood tests.  So, when the carrier comes out, your cat may associate it with negative emotions and understandably becomes anxious.

Anxiety actually has a function in our lives – worrying about something in the bushes pouncing on you probably saved a lot of cavemen and feral cats; anxiety can improve your physical and mental performance. But anxiety at the vet clinic does not benefit your cat and can actually make things worse. An unpleasant visit can become an unpleasant memory.

Medication before your cat’s vet visit


Have you ever had elevated blood pressure at a doctor visit?  Anxiety before medical appointments is common for people as well as cats.  Because cats don’t speak human language, we can’t reassure them and let them know exactly what is happening. It is worth considering medication before your cat’s vet visit to help reduce his anxiety.

Gabapentin and trazodone are two medications commonly used to reduce the stress of the vet visit.  These medications must be prescribed by your veterinarian.

Gabapentin


  • Developed as an anti-convulsant
  • Has anti-anxiety properties – reduces the release of excitatory neurotransmitters
  • Is a pain reliever

Gabapentin is commonly used in the veterinary practice to reduce anxiety in cats.  There have been a few studies evaluating fear and stress in cats having taken gabapentin – these studies found a reduced CSS (cat stress score) after administration of gabapentin.

The typical dose is 100 mg given 1.5 – 2 hours prior to the vet visit. Frequently, a dose is also given the night before. Doses can vary for individual cats – some cats may do well with a 50 mg dose while others may need 150 mg.

Gabapentin is available in capsules, liquid and small tablets.

  • Capsules: The capsule is opened and the powder is mixed in a small amount of tuna fish or canned cat food. Gabapentin is bitter and some cats may not eat it in food. The capsules may also be given using a pet piller or a squeeze up treat.
  • Liquid: The liquid may result in foaming at the mouth.
  • Tablets: Gabapentin can also be compounded into small, flavored tablets – these can be given in pill treats.

Your cat may be a little sleepy or wobbly after taking gabapentin. You may want to watch kitty near the stairs or jumping up on things!

Gabapentin is a pain reliever for cats – reducing pain may be one of the ways it helps reduce anxiety and fear

 

Trazodone


  • Antidepressant that is commonly prescribed for insomnia and depression in humans
  • One of its side effects is drowsiness

There have been a few studies looking at cats receiving trazodone. One study in particular found that the CSS (cat stress score) was the same in the treated group as the group receiving the placebo. So, trazodone appears to be more of a sedative (makes you sleepy) than an anti-anxiety drug.

Typical dose is 50 mg given by mouth 90 minutes before the stressful event.

  • Can result in lower blood pressure in cats
  • There is a risk of serotonin syndrome if used with other anti-depressant medication such as fluoxetine (Reconcile).
  • Available as a tablet or can be compounded into a liquid or capsule form.

 

There is increased interest in identifying medications to reduce stress and anxiety in cats at veterinary visits. We should expect to see more medications becoming available in the near future.

Medication before your cat’s vet visit can be part of a low-stress veterinary visit.  However, it will be most effective  when combined with training to reduce situational anxiety and low-stress handling techniques.

As for Gus, I will make sure to give him some gabapentin before vet visits.

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A cat receives an injection of polysulfonated glycosaminoglycans.

It is thought that almost 40% of all cats have clinical signs of arthritis and 90% of cats over age 12 have damage to the joints that you can see on x-rays. Cats are such masters at hiding pain that we are now thinking that arthritis is there earlier, pain is happening and we may not be able to see it on x-rays yet.

What if we could be proactive and start some kind of treatment before our cats even seem painful? Could we slow the deterioration of the joints? What arthritis supplements for cats are available and do they work?

The motivation behind writing this post was to help my youngest cat,  5 year old Gus, who showed some indications of spinal arthritis in his x-rays. Should I begin a supplement with him? I was astounded by the sheer numbers of arthritis supplements for cats on the market and the astounding claims they made.

arthritis supplements for cats – do they work?


Arthritis supplements for cats on the market now range from supplements used by humans to homeopathic remedies. Clinical trials are rare to non-existent on many of these products. This post addresses the more common products and ones that have had some double-blinded clinical studies done.

  • glucosamine/chondroitin,
  • omega fatty acids/ green lipped mussel extract
  • polysulfated glycosaminoglycans

Glucosamine/chondroitin


Glucosamine occurs naturally in cartilage, the flexible connective tissue found throughout the body – for example, in the external ears and the surfaces of joints. The supplement can be made synthetically in the lab or harvested from the shells of shellfish.

Some human studies have shown oral glucosamine may help with pain relief and slowing of joint degeneration in people suffering from osteoarthritis. However, in general, the results from these studies are not conclusive.

Dasuquin is a commercially available formulation of glucosamine/chondroitin for cats. It is a dietary supplement in a capsule that is sprinkled on food. The product has been evaluated for safety.

A recent double-blinded study of Dasuquin enrolled 59 cats with Degenerative Joint Disease.

  • All 59 cats were given a placebo for 2 weeks.
  • Then 29 cats received the supplement for 6 weeks while another 30 continued to receive the placebo.
  • The cats were evaluated by using an at-home accelerometer (like a kitty “fit bit”), owner observations and vet exams through out the study.
  • The study showed a strong placebo effect – 78% of the cats were more active while on the placebo.
  • Cats on the supplement did not show any statistically significant improvement over cats on the placebo.

However, the study did raise some questions:

  • The “kitty fit-bits” showed that the least active cats at the start of the study became more active on the supplement. Were these cat more painful to begin with?
  • The placebo was given in the first two weeks of the study when owner enthusiasm would have understandably been highest and owners would have been looking for improvement.

More research is needed – perhaps a different study design?

Omega Fatty acids (fish oils)


Supplementation with fish oils has shown some benefit for arthritic cats. A double-blinded study showed that cats supplemented with fish oil for 10 weeks were more active, going up and down the stairs more, jumping higher, not walking as stiffly and were more interactive with their people. This study used owner evaluation to assess the cats’ improvement.

Fish oil can be given as a dietary supplement (Welactin) or fed as a therapeutic diet, such as  Hill’s j/d.

Side effects of fatty acid supplementation include GI upset and reduced blood clotting. There is some controversy over how much fish oil is enough. Additionally, fish oil can add quite a bit of calories to your cat’s diet and could result in weight gain, taxing your cat’s joints further.

Merial’s Antinol for Cats supplement is based on fatty acids from green-lipped mussel extract. There are a number of case studies where the supplement has been given to cats with good results for cardiac and dermatological issues, in addition to joint and mobility problems.

Polysulfated Glycosaminoglycans (PSGAGs)


This product is available under the brand name Adequan.  It is the veterinary version of Arteparon, used in humans.

  • Decreases the breakdown in cartilage. The PSGAG’s allows the cartilage to hold more water, making it resistant to degradation.
  • Adequan has been extensively studied in dogs and horses for over 20 years and is FDA-approved for these species
  • Available by prescription.
  • Given by subcutaneous injection in cats with generally good results.

The jury is still out on most of the arthritis supplements for cats. Given at the manufacturer’s recommended dose, these products are safe and may be effective. Considering the individual nature of pain, some cats may respond favorably while others do not. Once again supplements are basically unapproved drugs so there is not the rigorous evaluation that accompanies FDA approval.

Your vet is your best resource on arthritis supplements for cats. He or she will be able to recommend a supplement or diet that is appropriate for your cat and is compatible with other medications or medical conditions your cat may have. In particular, combining supplements should be done with care – glucosamine, fatty acids and Adequan all effect how your cat’s blood clots.

So, what will I do for Gus?


My vets recommended the Adequan injection, citing the robustness of the canine studies and the fact that it is an injection – there is a greater confidence that the cat will get the supplement. We are not depending on him to eat something.

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HDO BP cat
A cat relaxes in his basket during a blood pressure reading at home using an HDO unit. The cuff is on his tail. The blood pressure wave is on the computer screen.

You’ve brought your senior cat in for her regular checkup and the technician asks you if you would like to have her blood pressure checked. Although your blood pressure is routinely checked when you go to the doctor, it has not occurred to you to ask to have your cat’s blood pressure checked. Should you have your cat’s blood pressure measured? How is it done – will it be uncomfortable? Frightening?

Why measure your cat’s blood pressure


As cats age, many develop hyperthyroidism and kidney disease. Other cats may develop diabetes. All of these conditions can result in the heart pumping harder to compensate for the changes. As the heart pumps harder, blood pressure increases and arteries, the eyes, the kidneys, the brain and heart can be damaged.

Left untreated, high blood pressure can result in:

  • blindness
  • increasing loss of protein through the kidneys >> shortened life span
  • disorientation, lack of balance, seizures, altered mentation or behavior, or weakness in the limbs

The best way to avoid these consequences is to monitor your cat’s blood pressure and start treatment if his blood pressure is high.

So how do we measure your cat’s blood pressure?


When measuring blood pressure in humans, we typically place a pressure cuff on the upper arm, inflate the cuff until the flow of blood to the artery is shut off . The cuff is then released, and a wave of blood fills the artery, turbulent at first, then subsiding to a smooth flow.

The human practitioner can use a stethoscope to listen to the sounds made as the blood rushes back into the artery.

  • The first sound is heard at the systolic blood pressure (the higher number in 120/80)
  • The final sound is heard at the diastolic pressure (the lower number in 120/80).

We will also use a blood pressure cuff to measure your cat’s blood pressure. This cuff can be put:

  • on the front leg
  • on the hind limb, above or below the hock (ankle)
  • on the tail

Cats’ arteries are much smaller than humans’ and it is difficult to hear the sounds of the blood flow using a stethoscope, so we turn to other methods: Doppler and oscillometric.

Doppler


 

Doppler blood pressure cat
A cat has her blood pressure measured using a doppler unit. The cuff is on the hind leg and the sensor is held right above the paw pad.

A Doppler unit measures blood flow.

  • After placing the cuff on your cat, the Doppler sensor is placed over the target artery.
  • Piezoelectric crystals in the sensor detect changes in the flow of blood in the arteries and convert these to sound.
  • Acoustic gel on the sensor ensures good contact so that the practitioner can hear the heartbeat.
  • The cuff is inflated until the heartbeat is no longer heard.
  • The cuff is then released and the pressure at which the heartbeat can be heard again is the systolic blood pressure.
  • Headphones are usually used when measuring blood pressure with a Doppler.

 

Doppler units give us a measurement of the systolic blood pressure, the larger number in the 120/80.

Oscillometric


Only a cuff needs to be placed to measure your cat’s blood pressure with an oscillometric unit.

  • A sensor in the cuff detects the pressure pulses in the artery.
  • As the cuff is inflated, the pulses decrease as flow to the artery is cut off.
  • The cuff is then deflated and the pressure wave that results as the blood rushes back into the artery is analyzed.

Oscillometric units typically only measure the peak of this wave, the average blood pressure, and calculate the systolic and diastolic pressures.

A High Definition Oscillometric unit records the entire pressure wave, directly measuring the systolic and diastolic pressures. An HDO unit is usually connected to a computer to view the pressure wave and determine if the measurement was accurate.

How accurate is a blood pressure if my cat is nervous at the vet clinic?


Just like people, cats get anxious and nervous when visiting the vet clinic. Blood pressure is sensitive to this and it can be a challenge to measure your cat’s blood pressure.

Putting the odds in our favor:

  • Most of the time, you should be with your cat during a blood pressure measurement. Your cat knows you and trusts you. Your presence is reassuring and calming.
  • Allow your cat to settle in for 5-10 minutes – the measurement should be done in a quiet room.
  • If your cat likes to snuggle in your lap, see if the measurement can be done there. If your cat prefers to sit on his stomach, perhaps a tail measurement is best. If he is comfortable laying on his side, a hind leg may be better.
  • Using the front leg to measure blood pressure puts the practitioner in front of the cat; curious cats may want to take a nibble at the blood pressure cuff. I prefer that your cat be facing you, her person, who can reassure her. I feel the tail and hind leg work better.
  • The artery being measured, tail or hind leg, should be at the same level as the heart – so kitty should not be sitting up, but laying comfortably on his stomach or side.

What do the numbers mean?


  • Again, like people, the systolic pressure is ideally around 120.
  • Pressures 150 and over can indicate the need for medication.
  • Your vet may also do an eye exam, looking at the eye with an ophthalmoscope or lens. In some instances of high blood pressure, the vessels in the eye dilate and become twisted; sometimes the retina may be detached, resulting in blindness. If high blood pressure is caught early enough, blindness may resolve with treatment.

My cat’s blood pressure is high but her eyes looked OK. What next?


High blood pressure can be treated with drugs – the most common drug used is oral amlodipine. Amlodipine takes effect fairly quickly and a blood pressure can be repeated in about 10 days and the dose adjusted if needed.
Other medications such as benazepril or telmisartan may be used alongside or in place of amlodipine.

I don’t think the reading was accurate – my cat was too nervous


It is worth investing in a home blood pressure visit. A practitioner can come to your home and get a measurement where your cat feels safe and secure.

 

Measuring your cat’s blood pressure especially as she gets older will help keep her healthy and comfortable. Without treatment, high blood pressure can have serious side effects, including blindness, seizures, and cardiac damage.

Have your cat examined regularly by your veterinarian, as changes to the eyes or a heart murmur might warrant a blood pressure check.

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