The Silent Killer. 9 Toxic Substances That Wreck Havoc On Your Cat’s Kidneys


Kidney toxicity in cats occurs when toxins build up in the kidneys, damaging them and impairing their ability to filter waste products from the blood. This condition can be acute or chronic. Acute kidney toxicity comes on suddenly, while chronic kidney toxicity develops over time.

Some of the main toxins that can damage cats’ kidneys include:

  • Antifreeze (ethylene glycol) – a common toxin found in many households
  • Lilies – all parts of the lily plant are toxic to cats’ kidneys
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen
  • Grapes and raisins
  • Xylitol – an artificial sweetener

Kidney toxicity can be acute or chronic, and occurs when toxins damage the kidneys over time or suddenly. It impairs the kidneys’ ability to filter blood. This section provided an overview of kidney toxicity and some common household toxins.

Common Household Toxins

Some common household items and substances can be very toxic to cats’ kidneys if ingested. These include:

  • Lilies – Both true lilies (Lilium species) and daylilies (Hemerocallis species) contain toxins that can cause acute kidney injury in cats, even in small amounts. All parts of the plant are toxic. Common examples of true lilies include Tiger, Asiatic, Easter, Japanese Show, and Stargazer lilies (1).
  • Antifreeze – Ethylene glycol in antifreeze tastes sweet but is extremely toxic. Just a small amount can cause kidney failure in cats (2).
  • Household cleaners – Cleaning products like bleach, detergents, disinfectants, and tile/shower cleaners can contain corrosive chemicals that damage kidneys if ingested (3).
  • Medications – Human medications like NSAIDs (e.g. ibuprofen), acetaminophen, and antidepressants can be toxic to cats’ kidneys, even in small doses (1).

It’s important to keep lilies, antifreeze, household chemicals, and human medications safely out of reach of cats to prevent accidental poisoning.




Foods Toxic to Kidneys

Certain foods can be toxic to a cat’s kidneys. Some of the most dangerous foods for cats include:

Onions – Onions contain an ingredient called thiosulphate which is toxic to cats. It can cause oxidative damage to red blood cells and lead to anemia. Even small amounts of onions can be toxic over time. Source

Grapes and Raisins – Grapes and raisins contain an unknown toxin that can cause sudden kidney failure in cats. Even a small number of grapes or raisins can make a cat ill. The toxins are present in all parts of grapes, raisins, and currants. Source

Chocolate – Chocolate contains theobromine and caffeine, both of which are toxic to cats. If ingested, chocolate can cause vomiting, diarrhea, seizures, heart arrhythmias, and even death. Dark chocolate and baking chocolate are most toxic. Source

Toxic Plants

Certain plants contain toxins that can cause kidney damage or failure in cats. The most dangerous plant for cats in terms of kidney toxicity is the lily. All parts of the lily plant are toxic to cats – the leaves, flowers, pollen, and even the water in a vase containing lilies. According to the Cornell Feline Health Center, lilies can cause life-threatening kidney failure in cats when ingested even in tiny amounts (

Other toxic plants for cats’ kidneys include poinsettias, oleander, and azaleas. Poinsettias contain a toxic sap that can irritate the mouth and stomach when ingested. Oleander contains cardiac glycosides that affect the heart rate and can be fatal to cats. Azaleas and rhododendrons contain grayanotoxins which can cause vomiting, diarrhea, weakness, and potential kidney failure ( Keep these plants out of reach of cats to prevent accidental ingestion.


Some of the most common symptoms of kidney toxicity in cats include:

Excessive thirst and urination: As kidney function declines, the kidneys are less able to concentrate urine. This leads to increased thirst and urination as the cat tries to compensate.

Vomiting: Toxins building up in the blood can cause nausea and vomiting. Vomit may contain blood or appear brown and foul-smelling.

Diarrhea: Gastrointestinal irritation from toxins can lead to diarrhea, which may also contain blood.

Lethargy: Toxins in the blood make cats feel unwell and weak. They often have little energy or appetite.

Other symptoms may include bad breath, mouth ulcers, weight loss, poor coat condition, and ultimately seizures or coma in severe toxicity.


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

Blood tests: Blood tests check levels of blood urea nitrogen (BUN) and creatinine to measure kidney function. Increased levels indicate reduced kidney function. Blood tests also check electrolyte levels and complete blood count.[1]

Urine tests: A urine test checks for specific gravity, pH, protein, glucose, and the presence of casts or crystals, which indicate kidney problems. Increased protein in the urine points to kidney damage.[2]

Ultrasound: An ultrasound uses sound waves to create images of the kidneys. This allows vets to visualize kidney size, shape, and check for masses, stones, or structural problems.[1]

Biopsy: A kidney biopsy involves removing a small sample of kidney tissue for examination under a microscope. This helps identify the cause and severity of kidney toxicity.[2]

These diagnostic tests help vets determine the extent of kidney toxicity and dysfunction in order to plan appropriate treatment.




Treatment for kidney toxicity focuses on flushing toxins out of the cat’s system and restoring normal kidney function. The main treatments include:

IV Fluids – Cats with kidney toxicity are often dehydrated and have electrolyte imbalances. Vets will administer intravenous (IV) fluids to rehydrate the cat and restore normal electrolyte levels. IV fluids help flush toxins out of the kidneys. According to the VCA Animal Hospitals, “This is usually accomplished by administering intravenous fluids and appropriate electrolyte supplementation” (source).

Medications – Certain medications can help protect kidney cells, control vomiting, and reduce blood pressure. Antioxidants like vitamin E may help reduce damage to kidneys. Anti-nausea medication can relieve vomiting. ACE inhibitors can help control high blood pressure.

Dialysis – In severe cases of toxicity, vets may recommend dialysis. This involves filtering the cat’s blood through a machine to remove waste products and excess fluids. Peritoneal dialysis, where fluid is injected into the abdomen to absorb toxins, is sometimes done. Hemodialysis, filtering blood through an external machine, is rare in cats.


The key to preventing kidney disease is to limit your cat’s exposure to toxins and monitor their diet. Here are some tips:

Keep medications, chemicals, antifreeze, and other household toxins safely out of your cat’s reach. Cats can be tempted to ingest toxic substances, so storing them in locked cabinets is safest. Never give your cat medication without consulting your vet first (Source).

Choose cat-safe plants for your home and yard. Common houseplants like lilies, orchids, azaleas, and oleander are toxic to cats. Opt for pet-friendly options like bamboo, Boston ferns, roses, and hibiscus instead (Source).

Monitor your cat’s diet and avoid overfeeding. Obesity can put additional strain on the kidneys. Feed an age-appropriate cat food and avoid human foods high in salt, fat, and sugar (Source).


The prognosis for kidney toxicity in cats depends on several factors, including the specific toxin ingested, the amount ingested, how quickly treatment is received, and how much kidney damage has already occurred.

For example, a small ingestion of antifreeze that is promptly treated has a good prognosis, while a large ingestion that goes untreated can quickly lead to acute kidney failure and death. With aggressive treatment, the prognosis for acute kidney injury is fair to good if treated promptly. However, if acute failure leads to chronic kidney disease, the prognosis is generally poor.

According to VCA Animal Hospitals, “The long-term prognosis for recovery depends on the amount of kidney damage that has occurred. The kidney has very little capacity to regenerate or heal itself, therefore, the damage is generally permanent.”

Overall, the earlier kidney toxicity is caught and treated, the better the prognosis. Any cat showing symptoms of possible kidney toxicity should be evaluated by a veterinarian immediately to determine the prognosis and initiate potentially life-saving treatment.

When to See a Vet

If you suspect your cat has ingested something toxic to their kidneys, immediately contact your veterinarian or visit an emergency veterinary clinic. Time is critical when treating toxin ingestions, as clinical signs often progress quickly. The sooner the toxins can be identified and treated, the better the chances of recovery.

Do not wait for symptoms to appear before seeking veterinary care for a suspected toxin ingestion. However, if your cat does display any symptoms that may indicate kidney issues, such as increased thirst, increased urination, vomiting, diarrhea, lethargy, or loss of appetite, seek veterinary care right away. Early treatment greatly improves the prognosis when kidney toxicity is involved.

Contact your vet without delay if toxin exposure is known or suspected. Also call your vet immediately if any symptom associated with kidney disease is observed. Quick action is essential for the best outcome when feline kidney health may be compromised.

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