Xylazine for Emesis Induction in Cats

Several drugs used in veterinary medicine induce emesis in cats, including cefazolin, dexmedetomidine, and a combination of hydromorphone and midazolam. Agents commonly used for emesis induction in dogs, including apomorphine and hydrogen peroxide, are not recommended for use in cats due to either low effectiveness or risk of adverse effects.

Xylazine hydrochloride, an α₂-adrenergic agonist known for its sedative and analgesic effects, is noted to induce vomiting in cats, particularly when administered via subcutaneous or intramuscular routes; however, the drug’s effects can be reversed effectively with an α-adrenoreceptor antagonist such as yohimbine.

Until recently, the use of xylazine as an emetic in cats was investigated primarily in pharmacologic studies that examined doses higher than those typically used in clinical medicine. Researchers at Angell Animal Medical Center in Boston recently performed a retrospective study to investigate the effectiveness and adverse effects associated with administering xylazine for emesis induction in cats. Their results were published in the Journal of Veterinary Emergency and Critical Care.

RELATED:

• IVECCS 2017: Advances in Companion Animal Toxicology
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Study Design

Veterinary records were examined for cats that were administered xylazine for emesis induction after ingestion of a toxic substance or foreign material. The investigators recorded patient signalment; dose, route, and adverse effects of xylazine administration; use of any reversal agents; whether emesis occurred; and vomitus contents. Due to the retrospective nature of the study, additional factors such as the effect of xylazine on heart rate and blood pressure were not examined.

Cases were divided into 2 categories based on whether emesis did or did not occur. Multiple variables were then compared between the 2 groups to evaluate possible influences on the effectiveness of xylazine.

Results

Complete records were available from 48 cats aged 1 to 8 years. Most (45) cats were administered 1 intramuscular dose of xylazine, while 3 cats received 2 doses of the drug either on the same day or 3 days apart. The median dose of xylazine administered was 0.49 mg/kg, which is within the recommended dose range of 0.44 to 1.0 mg/kg. A reversal agent (yohimbine or atipamezole) was administered to all but 2 cats.

Major findings:

• Xylazine administration caused emesis in 60% (29/48) of cats.
• Signalment and xylazine dose did not significantly influence whether a cat vomited.
• The most common adverse effect from xylazine administration was sedation (31%), while 2% of cats experienced ptyalism or bradycardia.
• A foreign object or toxicant was recovered from the vomitus of 72% of the cats that vomited, suggesting a high rate of treatment success.

Take-home Message

While xylazine was associated with a high prevalence of adverse effects (namely sedation) in the study, the investigators noted that the drug’s effects can be blocked with a reversal agent once emesis is successful. Therefore, the study concluded that xylazine is a relatively safe and reasonable option for emesis induction in cats.

Dr. Stilwell received her DVM from Auburn University, followed by a MS in Fisheries and Aquatic Sciences and a PhD in Veterinary Medical Sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.