Chronic kidney disease in dogs and cats: signs

The water bowl empties sooner. Litter clumps get larger, or the dog asks to go outside more often. Weight loss and an uneven appetite may come later. Chronic kidney disease can progress before it causes one obvious sign, so comparing a pet with their own normal pattern is more useful than waiting for them to look ill.

Early signs can hide inside an ordinary routine

The kidneys filter waste from the blood, help balance water and minerals, take part in blood pressure control, and produce hormonal signals involved in red blood cell production. When some kidney tissue stops working, the remaining tissue can compensate for a while. That reserve helps explain why a dog or cat may look well even when test results have started to show a trend.

Increased thirst and urine volume are often among the first changes families notice. Reduced appetite, weight and muscle loss, nausea, vomiting, dehydration, weakness, and a change in breath odor may follow. Mouth ulcers and pale gums tend to appear with more advanced disease. The Merck Veterinary Manual describes how signs develop and why serial testing matters.

None of these signs belongs only to kidney disease. Diabetes can also increase thirst and urination, for example. The guide to diabetes in dogs and cats explains that overlap. A veterinarian needs the history, physical examination, and diagnostic tests to separate chronic kidney disease from dehydration, infection, urinary obstruction, acute kidney injury, and other illnesses.

Dogs and cats reveal changes in different ways

The same broad disease process affects both species, but their routines leave different clues. Test interpretation and treatment recommendations also contain species-specific differences. A plan designed for a dog should not be transferred to a cat, or the other way around.

What to watch	In cats	In dogs
Water and urine	Larger litter clumps, a wetter box, or new interest in taps and other bowls	A bowl that empties sooner, extra requests to go out, or accidents indoors
Weight and muscle	The spine and hips may become easier to feel under the coat	The chest, thighs, and stamina on walks may change gradually
Appetite	Refusing a new diet or eating less calls for a conversation with the veterinary team; withholding food to force acceptance of a kidney diet is unsafe	Reduced appetite, weight loss, and muscle loss also need close follow-up
Problems to investigate	High blood pressure, low potassium, and hyperthyroidism can affect assessment and management	Urinary protein loss and glomerular disease may carry particular weight in the investigation

Chronic kidney disease is especially common in older cats. Cornell explains that many cats have no obvious signs early in the disease. In cats, high blood pressure can cause sudden vision changes, disorientation, or weakness. These changes need immediate care even when thirst and appetite seemed stable.

In dogs, urinary protein needs careful evaluation because disease of the glomeruli, structures involved in filtration, may cause substantial protein loss. The 2026 IRIS recommendations for dogs use canine criteria for proteinuria, blood pressure, staging, and management. The recommendations for cats set out feline criteria and species-specific choices.

Diagnosis comes from tests that answer different questions

Blood urea nitrogen, creatinine, and SDMA help estimate how well the kidneys are filtering, but no single marker establishes the diagnosis. Dehydration can raise some results. Creatinine is also affected by muscle mass, which matters in thin or older animals. SDMA may identify reduced filtration before creatinine moves beyond its reference interval, yet it still has to be read with the rest of the case.

Urinalysis shows whether the kidneys are concentrating urine and checks for blood, cells, sediment, and other findings. A urine protein:creatinine ratio quantifies protein loss when the sample can be interpreted reliably. A culture may be appropriate when infection is suspected. A complete blood count, phosphorus, electrolytes, and protein values help find anemia and imbalances that change the plan.

Blood pressure belongs in the evaluation because hypertension can accompany kidney disease and damage the eyes, brain, heart, and kidneys themselves. Ultrasound or other imaging may look for changes in kidney size or structure, stones, obstruction, or evidence of a treatable cause. Imaging adds another piece; a normal-looking ultrasound does not cancel persistent abnormalities in blood and urine.

IRIS recommends diagnosing CKD before assigning a stage. One high creatinine or SDMA result is not enough. When the animal’s condition allows, the veterinarian confirms persistence, assesses hydration, and interprets results over time.

Staging gives the care plan a structure

After chronic kidney disease is confirmed, the team may use the four IRIS stages. Creatinine and SDMA help determine the stage in a stable, hydrated patient. Urinary protein loss and blood pressure define substages. Together, these findings guide which complications to seek, what to treat, and how to follow the response.

A stage is not a score that can be calculated at home. Dehydration, muscle loss, food intake, medications, and another illness can shift a value. Comparing a result with the pet’s previous results often says more than checking whether it sits inside or outside the laboratory’s printed reference range.

The AAHA senior care guidelines include regular complete blood counts, chemistry panels, urinalysis, and blood pressure measurement. A screening interval for a healthy senior pet does not become a universal calendar after diagnosis. Stage, complications, treatment, and changes at home determine when the next assessment is due.

Keep laboratory reports in date order. A simple table with weight, appetite, creatinine, SDMA, urine specific gravity, urine protein:creatinine ratio, phosphorus, and blood pressure makes trends easier to see. Record the fields the team asks for, and do not change treatment on your own to “fix” one number.

Living with kidney disease takes an individual plan

Chronic kidney disease is usually irreversible and progressive, but pets do not all decline at the same rate. Management aims to slow progression where possible, treat complications, and protect comfort, nutrition, and hydration. The individual animal’s response guides each adjustment.

Therapeutic kidney diets contain reduced phosphorus and a planned amount of high-quality protein, along with other modifications. They are different from simply feeding less meat or improvising a homemade recipe. The Merck Veterinary Manual links kidney diets with longer survival and more time before a uremic crisis, with use based on the disease stage and veterinary assessment.

For cats, the transition has to account for acceptance, texture, and calorie intake. If a cat stops eating because they reject the new food, contact the team. Do not extend a fast in the hope that the cat will give in. Weight and muscle condition remain important in both cats and dogs, even when kidney values appear stable.

Fresh water should stay available. Some pets benefit from wet food, water added to meals, or more drinking stations when the team approves the approach. Subcutaneous fluids at home are not necessary for every animal with azotemia. When prescribed, they require training and reassessment because an inappropriate volume can also cause harm.

High blood pressure, proteinuria, nausea, altered potassium or phosphorus, anemia, and infection all call for different decisions. Do not give an anti-inflammatory drug, human pain medicine, supplement, or product marketed for kidney support without discussing it with the veterinarian. A useful drug for another condition may need adjustment when kidney filtration changes.

Changes that need action and details worth recording

Seek immediate veterinary care for breathing difficulty, collapse, a seizure, severe disorientation, sudden loss of vision, inability to stand, repeated attempts to urinate without producing urine, or an abrupt decline. Repeated vomiting, refusal of both water and food, marked weakness, and signs of dehydration also require prompt contact with the veterinary team. Do not wait for the next scheduled visit.

Little or no urine may point to an obstruction or acute kidney injury, which differs from the usual course of chronic disease. Do not try to solve it by giving extra water or fluids on your own. Arrange transport and tell the clinic what you are seeing.

For gradual changes, record observable facts:

• How much the pet usually drinks and what changed in bowl refills.
• Litter clump size, urinary accidents, or extra requests to go outside.
• How much of each food the pet ate and whether one texture was refused.
• Vomiting episodes, with date, time, and appearance when recording does not delay care.
• Weight and muscle condition using the method agreed with the team.
• Energy, interaction, coat care, and tolerance for walks.
• Medications actually given and any difficulty administering them.
• Changes in vision, balance, behavior, gum color, or breath.

This record reveals trends. It does not diagnose kidney disease, determine the stage, or replace testing.

Frequently asked questions

Can chronic kidney disease in dogs and cats be cured?

Chronic kidney loss is generally irreversible. Treatment can manage complications, reduce signs, and slow progression in some patients. The response depends on the cause, stage, and other health conditions.

Does a high SDMA result confirm chronic kidney disease?

Not by itself. The veterinarian reads SDMA with creatinine, urinalysis, hydration, muscle mass, history, and trends. IRIS recommends confirming CKD before assigning a stage.

Should a pet with kidney disease drink less water?

Do not restrict water. Dogs and cats with kidney disease may struggle to concentrate urine and face a greater risk of dehydration. Any change to hydration support needs veterinary direction.

Do dogs and cats receive the same kidney treatment?

Not necessarily. The broad goals are similar, but proteinuria criteria, common complications, and treatment choices differ by species and by patient.

Can I switch to a kidney diet all at once?

The transition should follow the team’s plan and account for acceptance. A cat that stops eating during the change faces a separate health risk. Report refusal or a drop in food intake.

Does every pet with kidney disease need fluids at home?

No. The need depends on hydration, stage, food and water intake, and other conditions. When home fluid therapy is prescribed, the family needs training and clear instructions about which changes to report.

How can I tell whether kidney disease has worsened?

Changes in appetite, weight, thirst, urine, vomiting, and energy provide clues, but assessment also depends on the physical examination, blood, urine, and blood pressure. Contact the team before a scheduled follow-up if the pet declines suddenly.

Bring your notes and previous test results to the appointment. The guide on what to note before a veterinary visit can help you organize the conversation. If the pet declines abruptly or shows any warning sign above, review when to seek veterinary care and prioritize professional help.