Ethylene Glycol Toxicosis in Cats

Ethylene Glycol Toxicosis in Cats

By: Dr. Anne Marie Manning

Section: Veterinary Care In-depth

Veterinary care should include diagnostic tests and subsequent treatment recommendations.

Diagnosis In-depth

Diagnostic tests are needed to recognize ethylene glycol toxicosis. These include:

  • A complete medical history and physical examination to determine if exposure to ethylene glycol or other toxins has occurred. Unfortunately, in many cases the owner is not aware that the pet has consumed ethylene glycol and first recognizes the non-specific signs of severe acute kidney failure such as lethargy, loss of appetite, vomiting.

  • An chemical test to detect ethylene glycol in the blood. The test is only accurate if performed within 6 to 12 hours of ingestion.

  • Urinalysis to evaluate for dilute urine, casts, and calcium oxalate crystals, which appear in the urine within 3 to 5 hours of ethylene glycol ingestion.
    Failure to identify calcium oxalate crystals in the urine does not rule out the possibility of ethylene glycol poisoning because crystal formation may cease within a few days of poisoning.

  • Venous blood gas analysis to identify severe acidosis (low blood pH) characteristic of early ethylene glycol poisoning.

  • Serum biochemistry tests to evaluate for low blood calcium concentration (hypocalcemia) that may occur soon after ethylene glycol ingestion. Abnormal kidney function tests, like high blood urea nitrogen, serum creatinine, and serum phosphorus, will be observed if acute kidney failure has developed between 12 and 72 hours after ingestion of ethylene glycol. Serum biochemistry tests also help identify electrolyte disturbances, like abnormal blood sodium, potassium, and chloride concentrations, and help evaluate other organ systems, for example liver function and pancreas function, which will help your veterinarian eliminate other diagnostic possibilities.

  • A calculation called the "osmolal gap," if your veterinarian suspects recent ethylene glycol poisoning. A high osmolal gap raises suspicion that a large amount of ethylene glycol metabolites are present in the blood.

  • An ultrasound examination and ultrasound-guided kidney biopsy for diagnosis if the pet is presented in kidney failure. The ultrasound examination typically shows very bright kidneys with ethylene glycol poisoning. A biopsy is recommended to confirm the diagnosis of acute kidney failure due to ethylene glycol poisoning because of the extensive treatment required and the poor prognosis.

    Treatment In-depth

    Therapy is often successful if the pet is seen by the veterinarian within a few hours after ingestion of ethylene glycol and before kidney damage has occurred. Such pets never develop kidney failure and are discharged from the hospital after a few days of treatment and observation. If kidney failure already is present (based on observation of high kidney function test results and lack of urine production) the prognosis for recovery is very poor. Treatment is difficult and hospitalization may extend for weeks. More than 80 percent of pets with severe acute kidney failure due to ethylene glycol poisoning die despite intensive treatment.

    Your veterinarian may recommend any of the following treatments for ethylene glycol poisoning:

  • Induction of vomiting is indicated if your pet is seen within a few hours of ethylene glycol ingestion. Induced vomiting eliminates poison that had not yet been absorbed from the stomach. Call your veterinarian immediately if your pet has consumed ethylene glycol. Your veterinarian may recommend you give your pet hydrogen peroxide by mouth to induce vomiting before you transport the animal to the hospital.

  • Gastric lavage (pumping the stomach) also is indicated if your pet is seen within a few hours of ethylene glycol ingestion.

  • Activated charcoal is administered via a stomach tube or by syringe to the animal to prevent further absorption of ethylene glycol from the digestive tract. Activated charcoal binds ethylene glycol in the stomach and allows it to pass through the digestive tract to be eliminated in the stool. A cathartic may be given with the activated charcoal to speed its movement through the digestive tract.

  • In cats, only 20 percnt ethanol (ethyl alcohol) is used to prevent the breakdown of ethylene glycol to its toxic end-products. Twenty percent ethanol produces nervous system signs of "drunkenness" but can be used both in dogs and cats. 4-methylpyrazole (4-MP or Antizol®) does not produce "drunkenness," but at this time, it is not recommended for use in cats. Ethanol must be used within 6 to 8 hours after ingestion of ethylene glycol. Treatment requires 2 to 3 days.

  • Treatment with sodium bicarbonate may be required if the pet has severe acidosis (low blood pH).

  • Fluids are administered intravenously to correct dehydration resulting from vomiting and to help prevent damage to the kidneys. Intravenous fluids often are continued 24 to 48 hours after treatment with 20 percent ethanol has been completed.

  • Thiamine (vitamin B1) may be administered to aid in the conversion of the toxic by-products to non-toxic metabolites. This treatment is adjunctive only.

  • Furosemide (a diuretic) and dopamine (a blood vessel-dilating drug) are used to try and increase urine production when kidney failure is present. Often it is impossible to increase urine production despite intensive treatment.

  • Peritoneal dialysis and hemodialysis are available for animals that have developed severe kidney failure and are not producing urine despite intravenous fluid, furosemide and dopamine administration. This treatment is very expensive and is only available at selected specialty referral hospitals. Some animals with severe kidney failure due to ethylene glycol poisoning die despite dialysis support.

  • Metoclopramide and the antihistaminic drugs cimetidine, ranitidine, and famotidine are examples of drugs that may be used to treat the gastrointestinal complications of severe kidney failure such as vomiting and gastric hyperacidity, respectively.

  • Phosphorus binding drugs such as aluminum hydroxide may be given to bind phosphorus in the digestive tract.

  • Blood transfusions and intravenous nutritional support, called "total parenteral nutrition," may be required from animals that survive yet have prolonged hospitalization times.

     
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