AAFP 2018: Decontamination of Toxicoses in Cats

Veterinarians treating cats with toxicoses should consider decontamination early, said Adesola Odunayo, DVM, MS, DACVECC, at the 2018 meeting of the American Association of Feline Practitioners. Supportive care is key to treatment because specific antidotes are not available for most toxins, she added.

Common toxicants in cats are lilies, permethrin, rodenticides, and certain medications, said Dr. Odunayo, a clinical associate professor at the University of Tennessee College of Veterinary Medicine. She recommended that veterinarians consult an animal poison control helpline if they are unfamiliar with the toxin or if the toxin has a narrow safety margin.

Determining the Appropriate Treatment

Dr. Odunayo recommended checking the product label of a potential toxicant if the packaging is available. Identifying the active ingredient and dose may be crucial for treatment. For example, different rodenticides have different mechanisms of action requiring different treatment approaches.

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When a cat with possible toxin exposure arrives at the clinic, treat it as a medical emergency, Dr. Odunayo advised. Obtain a history quickly during triage. Important points to cover include the type and amount of toxin ingested, time of exposure, signs observed before arrival at the clinic, and remedies given at home (such as peroxide, which can be harmful to cats).

Inducing Emesis

Emesis induction is best performed within 1 to 3 hours of toxin ingestion, she said. She reminded the audience to ensure that the patient is stable (eg, not in respiratory distress) before initiating decontamination. Emesis induction is contraindicated for corrosive toxicants, cats with signs such as seizures or tremors, cats at risk for aspiration (such as those with megaesophagus), and cats that are already vomiting.

Advise clients not to induce emesis in cats at home, she warned. Substances used for home emesis induction are risky for cats. Hydrogen peroxide, for example, can cause hemorrhagic gastroenteritis, gastric necrosis, gastric rupture, and esophagitis. It is also not particularly effective for cats. Peroxide, table salt, dishwashing detergent, and syrup of ipecac should also not be given to cats in an attempt to induce vomiting.

Xylazine and dexmedetomidine can be used to induce emesis in cats, Dr. Odunayo said. These α₂-adrenergic receptor agonists are reversible. Hydromorphone may also be effective and is less sedating than dexmedetomidine, she added. Cats are relatively insensitive to the emetic effect of apomorphine, and its use in cats is controversial.

Activated charcoal can be administered after emesis to prevent drug adsorption within the gut. It is most effective if given within 1 hour of toxin ingestion. Multiple doses given every 4 to 6 hours may be helpful for toxins that undergo enterohepatic circulation, Dr. Odunayo noted. However, activated charcoal does not adsorb ethylene glycol and is contraindicated with some types of toxins (such as corrosives). Activated charcoal is usually easier to administer to cats via nasogastric tube than via oral syringe, she said. A single dose of a cathartic (sorbitol) can be given with the first dose of activated charcoal, but cats should not receive multiple doses of a cathartic. Cats receiving activated charcoal should be monitored for hypernatremia.

Gastric Lavage and Lipid Emulsion

Gastric lavage is not used commonly in veterinary patients, Dr. Odunayo said. It may be indicated in patients that have ingested a substance with a narrow safety margin or patients that are showing clinical signs (such as seizures) but still need gastric decontamination. The procedure is performed with the patient under general anesthesia. The cuff of the endotracheal tube should be inflated fully to help prevent aspiration.

Dr. Odunayo discussed using intravenous lipid emulsion as an antidote for lipid-soluble toxins such as ivermectin and permethrin. Topical permethrin is a common toxicant in cats, she said, and intravenous lipid emulsion therapy can improve the clinical signs rapidly.

Dr. Walden received her doctorate in veterinary medicine from North Carolina State University. She is a practicing companion animal veterinarian and a certified editor in the life sciences (ELS). She owns Walden Medical Writing, LLC, and writes and edits materials for health care professionals and the general public.