Warning Signs. How Your Cat’s Behavior Changes With Kidney Disease


Kidney infections, also known as pyelonephritis, occur when bacteria enter a cat’s urinary tract and kidneys. This causes inflammation and infection of the kidneys and surrounding structures. Kidney infections in cats can be acute or chronic. Acute kidney infections come on suddenly while chronic kidney infections develop slowly over time.

Kidney infections in cats often cause noticeable changes in behavior and symptoms. Common symptoms include increased thirst and urination, vomiting, lethargy, loss of appetite, and bad breath. Cats may strain or have difficulty urinating and produce little urine. They may also vocalize while urinating if they experience pain. Overall, cats with a kidney infection tend to act very sick.

If a kidney infection is left untreated, it can lead to kidney failure, uremic poisoning, and even death. That’s why it’s important to get veterinary care right away if a kidney infection is suspected. With prompt treatment, many cats fully recover from kidney infections.

Loss of Appetite

One of the most common symptoms of a kidney infection in cats is a loss of appetite. Cats with kidney disease often experience a decreased desire to eat or drink. According to the Ohio State University Veterinary Medical Center, cats with chronic kidney disease (CKD) frequently lose their appetite due to buildup of toxins in their bloodstream that make them feel nauseous.

A cat with a kidney infection may start refusing food, even their favorite treats. This leads to weight loss as the cat is not getting enough calories. According to AVIM, cats with kidney issues will not feel like eating very much. The decreased appetite combined with other symptoms like increased thirst and lethargy are clear signs a kidney problem could be present.

If your cat stops eating for more than a day or two, it’s important to contact your veterinarian, as a loss of appetite can quickly lead to dangerous weight loss and malnutrition. Getting treatment for the underlying kidney infection is key to bringing back your cat’s normal appetite.

Increased Thirst and Urination

When cats have a kidney infection, they will often experience an increase in thirst and need to urinate more frequently. The kidney infection causes inflammation in the kidneys, which interferes with their ability to concentrate urine. The cat’s body attempts to flush out the infection by producing more dilute urine, which requires the cat to drink more water. According to PetMD, increased thirst and urination are common symptoms of kidney infections in cats.

As the veterinarians at VCA Hospitals explain, kidney disorders like infections cause the kidneys to be less efficient at removing wastes from the bloodstream. This builds up toxins in the cat’s body, leading the kidneys to draw more water from the body in an attempt to dilute the toxins. To replace this lost fluid, the cat drinks more water. With more fluid intake, the cat also urinates more frequently and in larger amounts to excrete the excess water.

Pet owners may notice their cat spending more time at the water bowl throughout the day and drinking larger amounts than usual. The litter box will also require more frequent cleaning, as the cat has an increased urge to urinate. According to Hampton Veterinary Hospital, increased thirst and urination can be one of the earliest signs of a kidney problem like infection in cats.


One of the most common symptoms of a kidney infection in cats is lethargy, or being less active and playful than normal (Source 1). Cats with a kidney infection tend to sleep more and have less energy for their usual activities like playing, jumping, and exploring.

Kidney infections can cause cats to appear tired, weak, and generally unwell. Where a healthy cat would be alert and active, a cat with a kidney problem may sleep for hours and be difficult to engage in play. They tend to spend more time resting and conserving their diminished energy reserves.

This lethargy and tendency to sleep more is often accompanied by muscle weakness and stiffness. The kidneys help regulate electrolyte balances, so kidney problems can result in low potassium levels that sap a cat’s strength (Source 2). Between the infection itself and these resulting imbalances, cats understandably become very low energy.

If cat owners notice their normally lively cat sleeping more often and not wanting to play or exercise, lethargy could signal a potential kidney problem. It’s important to contact a vet promptly when a previously energetic cat becomes inactive and sleepy.


One of the most common symptoms of a kidney infection in cats is vomiting. As the kidneys become damaged and struggle to filter toxins from the bloodstream, this can lead to nausea and vomiting. Cats may vomit undigested food, yellow bile, or foam.

Vomiting is often one of the first noticeable signs of kidney problems in cats. It may start sporadically at first but become more frequent over time. Throwing up food or liquid is a clear indication that something is wrong with the digestive system and the cat is unable to keep food down.

According to the Ormond Cat Clinic, increased stomach acid is a common effect of chronic kidney disease. The excess acid leads to stomach ulcers and nausea, resulting in vomiting and loss of appetite [1]. As kidney function declines, the buildup of toxins in the blood can also directly cause nausea and vomiting.

If your cat is frequently throwing up their food, it is vital to get them checked by a vet for possible kidney problems. Persistent vomiting will lead to dehydration and weight loss, which further exacerbates kidney disease.

Bad Breath

One of the most common symptoms of kidney disease in cats is bad breath. Kidney infections or kidney failure can cause toxins like urea to build up in a cat’s bloodstream. This buildup of toxins leads to an unpleasant ammonia-like odor coming from your cat’s mouth (AVIM). The bad breath may have a urine-like or rotten smell that seems especially strong when the cat yawns or exhales (PetAssure).

Some describe the bad breath of kidney disease as smelling sickeningly sweet, while others equate it to the smell of ammonia, depending on the severity of kidney dysfunction. In any case, it will be a very unwelcome and unpleasant odor for both you and your cat (Bottletree Animal Hospital).

Checking for bad breath can help alert you to potential kidney problems so you can get your cat veterinary care as soon as possible. Work with your vet to determine the cause and get treatment to manage your cat’s kidney disease and minimize the ammonia smell coming from their mouth.


One of the most common symptoms of kidney disease in cats is dehydration. This occurs because the kidneys are no longer able to concentrate urine efficiently or maintain the body’s fluid balance. According to AVIM&O, dehydration can also happen from excessive vomiting or diarrhea that comes with kidney issues. There are several signs that indicate a cat is dehydrated, including dry gums and sunken eyes.

When a cat is dehydrated, the gums will feel dry and tacky instead of moist when touched. The gums may also appear pale or white instead of a healthy pink color. According to WebMD, gently pinching and releasing the cat’s skin can check for dehydration. If the skin is slow to fall back down, it means the cat is dehydrated.

Dehydration also causes a cat’s eyes to appear sunken in and the third eyelid to show. The eyes may seem dull instead of bright and alert. According to Guilford Jamestown Veterinary Clinic, the eyes may also have a blue tint to the sclera, which is normally white. These eye changes indicate the dehydration is severe enough to require immediate veterinary attention.


Cats with a kidney infection often experience pain or tenderness in their abdomen, especially around the kidney area. This is because the inflammation from the infection puts pressure on the kidney tissue and surrounding organs. According to Merck Veterinary Manual, one of the most common signs of pyelonephritis is “pain in the sides (especially in the area around the kidneys)”.

You may notice your cat crying out or showing signs of discomfort when you touch their belly or back. They may avoid laying on that side of their body or shy away when you try to pet them there. The abdominal pain can range from mild soreness to more severe or acute pain depending on the severity of the infection.

PetMD notes that your cat may demonstrate pain by changing their normal posture – arching their back, stretching out, or holding their stomach off the ground. Other signs can include lack of appetite, lethargy, fever, and vomiting.

If your cat shows any indications of abdominal pain or discomfort, especially paired with urinary issues, it’s important to get them veterinary care right away as it could signal a kidney infection or other serious medical problem.


Kidney infections in cats require aggressive treatment with antibiotics. The antibiotics are typically given for 4-8 weeks to fully clear the infection (Source A). Common antibiotics used include amoxicillin, ampicillin, enrofloxacin, and trimethoprim-sulfa. IV fluids may also be administered to flush the kidneys and prevent dehydration (Source C).

Severe kidney infections often require hospitalization so the cat can receive injectable antibiotics and IV fluids. Hospitalization allows close monitoring of kidney values, hydration status, and response to medications. Cats with uncontrolled vomiting or kidney failure may need hospitalization to manage these issues. The prognosis is generally good if treatment starts before the infection causes lasting kidney damage (Source B).


There are some steps cat owners can take to help prevent kidney infections in their feline companions:

Get your cat an annual veterinary exam. Annual exams allow vets to check your cat’s kidney values and catch any potential issues early before they become problematic. Early detection and treatment is key for kidney disease management.

Feed your cat a high-quality diet and avoid foods with excessive minerals that can stress the kidneys. Cats with kidney issues may benefit from prescription kidney diets. Always provide your cat with access to fresh, clean water. Dehydration stresses the kidneys.

Keep the litter box clean and have multiple boxes available. Cats don’t like dirty boxes and may hold their urine. Holding urine allows bacterial growth.

Avoid toxins like lilies, antifreeze, etc. that are poisonous to cats and harmful to kidneys.

Monitor for any signs of issues like increased thirst/urination, weight loss, vomiting, bad breath, lethargy. Catching problems early is key.

Routine veterinary care, proper nutrition, hydration and safe home environment are the best ways to support kidney health in cats.

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