Why Your Cat Eats Less When Sick. The Kidney Disease Connection


Kidney disease is one of the most common health issues affecting cats, especially as they age. According to the IRIS Kidney Education website, the prevalence of chronic kidney disease (CKD) in cats is estimated to be between 1-3%, but this number rises significantly in older cats [1]. For cat owners, changes in their feline companion’s appetite can be one of the most noticeable symptoms of underlying kidney dysfunction. This raises important questions – do cats eat less when they have kidney disease? What causes appetite changes with CKD? And what can be done to encourage fussy eaters? This article provides an overview of kidney disease in cats, explores reasons behind appetite changes, and offers tips for enticing picky eaters to eat [2]. We’ll also look at the prognosis for cats with CKD and what cat owners can expect. Understanding the link between appetite and kidney health is key for proactively monitoring cats and providing optimal veterinary care.

[1] http://www.iris-kidney.com/education/risk_factors.html
[2] https://pubmed.ncbi.nlm.nih.gov/31023949/

Kidney Disease in Cats

Kidney disease is a common condition in cats, especially as they age. It occurs when the kidneys are damaged and can no longer function properly to filter waste from the blood. This results in the buildup of toxins and wastes in the body that can make cats very sick.

Chronic kidney disease (CKD) is the most common type seen in cats. It develops slowly over months to years. CKD has multiple causes including congenital defects, infections, toxins, and aging. Older cats are at higher risk, with more than half over 15 years old affected. Kidney disease is not curable but treatment can help manage symptoms and slow progression.

Acute kidney disease develops suddenly, over days to weeks, typically from toxins, infections, or blocked urine flow. It may be reversible if treated early. Chronic kidney disease is not reversible but progression can be slowed with supportive care and diet changes.

Signs of kidney disease in cats include increased thirst and urination, weight loss, poor appetite, vomiting, diarrhea, and lethargy. As the kidneys fail toxins build up leading to ulcers, blindness, seizures and eventually death. Regular vet exams and bloodwork can detect kidney issues early.

Treatment focuses on keeping the cat hydrated, controlling vomiting and acid buildup, regulating electrolytes, and feeding a kidney friendly diet. Medications may help control blood pressure and anemia. Depending on the stage of disease, hospitalization for IV fluids and other support may be needed. With treatment, cats may live months to years with good quality of life.

While kidney disease shortens lifespan, early detection and dedicated owners providing attentive homecare can help cats live happily with the condition for some time. Work closely with your vet for the best care plan for your cat. Provide extra fluids, tempting foods, and litterbox access. Monitor for any new symptoms and ensure your cat stays comfortable.



As kidney disease progresses in cats, it leads to some notable symptoms. One of the most common is a loss of appetite and weight loss. Cats with kidney disease often experience a decreased appetite and start losing weight as their kidney function declines (Chronic Kidney Disease in Cats – VCA Animal Hospitals). The kidneys help regulate appetite hormones, so when they are damaged, this can suppress a cat’s appetite.

Increased thirst and vomiting are also common symptoms of kidney disease. Cats will become very thirsty as their kidneys lose the ability to concentrate urine properly. This leads to increased water intake and urination (Kidney Disease in Cats – PetMD). Vomiting may occur as waste products build up in the blood due to decreased kidney function. Toxins that would normally be filtered out by the kidneys can also cause nausea and vomiting.

If kidney disease is caught early, treatment may help slow the progression and manage symptoms like appetite loss. But in advanced stages, encouraging eating can become very difficult as the cat’s condition deteriorates.


There are several common causes of kidney disease in cats:

Chronic kidney disease is a gradual loss of kidney function over time. It can be caused by aging, chronic infections, high blood pressure, or diabetes. As the kidneys fail, toxins build up in the body.

Acute kidney injury is a sudden episode of kidney failure, usually caused by ingesting toxins, some medications, or obstruction of urine flow. It needs prompt veterinary treatment.

Cancer in the kidneys, like lymphosarcoma or renal cell carcinoma, can spread to other organs. Symptoms may include blood in the urine.

Infections like pyelonephritis are inflammation and infection of the kidney tissue itself. It is often caused by bacterial infections that ascend from the bladder.


There are several diagnostic tests vets use to diagnose kidney disease in cats:

Bloodwork – Blood tests check levels of blood urea nitrogen (BUN) and serum creatinine to measure kidney function. Elevated levels indicate poor kidney function.[1]

Urinalysis – A urine test checks for elevated levels of protein, glucose, and blood, which signal kidney damage. It also looks at urine concentration to see if the kidneys are diluting urine properly.[2]

Imaging – X-rays, ultrasound, or CT scans of the kidneys look for abnormalities in size, shape, and structure. It helps identify causes like kidney stones or tumors.[1]

Biopsy – Taking a kidney tissue sample and examining it under a microscope can determine the type and extent of damage. This is not commonly done.[2]

Measuring blood pressure is also important, as high blood pressure can damage kidneys.Overall, vets use a combination of these tests to get a full picture of kidney function.[1]


Treatment for kidney disease in cats focuses on maintaining kidney function and managing symptoms. The main treatments include subcutaneous fluids, diet modifications, and medications.

Fluids help flush toxins from the body and prevent dehydration. Vets often recommend administering subcutaneous fluids at home. This involves injecting fluid under the skin with a small needle to hydrate the cat.[1]

Specialized kidney diets are lower in phosphorus and protein to reduce strain on the kidneys. These diets often contain increased omega-3 fatty acids and antioxidants as well. Changing to a kidney diet is one of the most important treatments.[2]

Medications help manage anemia, high blood pressure, vomiting, and other issues. Medications may include ACE inhibitors, anti-nausea drugs, phosphorus binders, and erythropoietin injections.[3]

Appetite Changes

Appetite changes are very common in cats with kidney disease. According to the Ohio State University Veterinary Medical Center, unfortunately cats with Chronic Kidney Disease (CKD) often lose their appetite. Lack of appetite can happen for a few reasons:

First, toxins can build up in the blood when the kidneys aren’t working properly. This causes cats to feel nauseous, making them not want to eat. Vomiting may also occur.

Second, anemia is common in kidney disease. Anemia causes lethargy and weakness, making cats not want to eat because they lack energy and motivation.

Third, secondary hyperparathyroidism happens in CKD, where the parathyroid glands secrete too much parathyroid hormone. This can contribute to mouth ulcers and poor oral health, making eating uncomfortable.

As a result of poor appetite, cats with kidney disease often lose weight. They may eat less food, but aren’t getting the proper nutrition and calories they need. Monitoring appetite and weight changes are important to properly diagnose and manage kidney disease.

Encouraging Eating

Cats with kidney disease often experience a decreased appetite and lose interest in food. However, it’s important for cats with kidney disease to maintain good nutrition to support kidney health and function. Here are some tips for encouraging a cat with kidney disease to eat:

Offer smelly, aromatic foods like tuna, salmon, or beef. The strong smell can stimulate appetite. Warming canned food can also increase its aroma and appeal. According to experts, eggs are a great source of high-quality protein for cats with kidney disease.

Try different food textures like adding some water to dry kibble to soften it or mixing in a meat baby food. Cats may prefer canned or homemade foods over dry. Consider adding nutritional gel supplements to increase calorie intake.

Feed smaller, frequent meals rather than one or two large meals per day. Leave food out for cats to graze as wanted. Hand feeding or treating with human foods like plain chicken can also entice cats.

Use shallow dishes and place food in different locations to spark interest. Providing plenty of fresh water sources can also help increase appetite.

Work closely with your veterinarian, as they may prescribe medications or recommend a kidney support cat food to address nutritional needs. Persistence and creativity in offering appetizing foods is key to supporting kidney health.


With treatment, cats with chronic kidney disease can often live a good quality of life for months to years. However, kidney disease is progressive and there is no cure. The prognosis depends on how quickly the disease progresses and how well the cat responds to therapy. According to the Cornell Feline Health Center, the prognosis is highly variable – some cats respond extremely well to treatment and have minimal clinical signs, while others progress more rapidly. Cats with acute kidney injury have a better prognosis if the underlying cause can be treated. With aggressive therapy, up to 50% of cats with acute renal failure may recover partial to normal kidney function (VCA Hospitals[1]). Overall, the prognosis is worse for cats with chronic renal failure versus acute renal failure.


In conclusion, kidney disease is a common condition in older cats that affects kidney function and causes symptoms like increased thirst and urination, weight loss, poor coat condition, and vomiting. It’s usually diagnosed through bloodwork and urinalysis. Treatment focuses on managing symptoms through diet changes, intravenous fluids, and medications. One of the most notable symptoms is a decreased appetite, since toxins build up in the bloodstream and affect the tastebuds. There are ways to encourage eating in cats with kidney disease through warming up food, trying different textures and flavors, adding flavor enhancers, and using appetite stimulants if recommended by your vet. While kidney disease is chronic and progressive, early diagnosis and careful management can help cats live comfortably for months or years.

The key takeaways are that kidney disease often causes appetite changes in cats, but various strategies can help encourage eating. Work closely with your vet to provide the best care and nutrition for your cat. With treatment tailored to your pet’s needs, cats with kidney disease can continue enjoying a good quality of life.

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