Xylazine

Xylazine In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Agonist at peripheral and central alpha-2 adrenoreceptors, producing dose-dependent sedation, muscle relaxation and analgesia.

Uses of Xylazine

• Licensed to provide sedation and premedication when used alone or in combination with opioid analgesics.
• Xylazine combined with ketamine is used to provide a short duration (20–30 min) of surgical anaesthesia.
• Xylazine stimulates growth hormone production and may be used to assess the pituitary’s ability to produce this hormone (xylazine stimulation test).
• Has been used to induce self-limiting emesis in cats where vomiting is desirable (e.g. following the ingestion of toxic, non-caustic foreign material). Emesis generally occurs rapidly and within a maximum of 10 min. Further doses depress the vomiting centre and may not result in any further vomiting.

Dose of Xylazine in Dogs and Cats

Dogs:

• Growth hormone response test: 100 μg (micrograms)/kg i.v.

Cats:

• Emesis: 0.6 mg/kg i.m. or 1 mg/kg s.c. once (effective in >75% of cats).
• Growth hormone suppression test: 100 μg (micrograms)/kg i.v.

Side Effects of Xylazine in Dogs and Cats

• Xylazine impacts various organ systems, including the cardiovascular system.
• It induces diuresis by suppressing ADH secretion.
• Xylazine causes a temporary increase in blood glucose levels by decreasing endogenous insulin secretion.
• It also results in pupil dilation and reduces intraocular pressure.
• Vomiting is a common side effect after xylazine administration, especially in cats.

Contraindications of Xylazine in Dogs and Cats

• Avoid using xylazine in animals with cardiovascular or systemic diseases, as well as geriatric patients.
• It increases uterine motility and should not be administered to pregnant animals or those likely to need or receiving sympathomimetic amines.
• Due to its effects on blood glucose, it is not recommended for diabetic animals.
• Do not use xylazine when vomiting is contraindicated, such as in cases of foreign body ingestion or elevated intraocular pressure.
• Inducing vomiting is not advisable if a strong acid or alkali has been ingested to prevent further damage to the oesophagus.
• Avoid inducing vomiting if the animal is unconscious, experiencing seizures, has a reduced cough reflex, or if more than 2 hours have passed since ingestion of the toxin.
• Do not use xylazine for inducing vomiting in species other than dogs or cats.

Some Notes:

• When used for premedication, xylazine will significantly reduce the dose of all other anaesthetic agents required to maintain anaesthesia.
• In cats and dogs, xylazine has largely been replaced by medetomidine or dexmedetomidine and is no longer recommended for sedation.
• Unlike medetomidine and dexmedetomidine, xylazine is less specific for the alpha-2 adrenoreceptor and exhibits significant effects on alpha-1 adrenoreceptors.
• This lack of specificity contributes to the poorer safety profile of xylazine compared to medetomidine and dexmedetomidine.
• Xylazine sensitizes the myocardium to catecholamine-induced arrhythmias, increasing the risk of cardiovascular complications.
• Due to its potent effects on the cardiovascular system, xylazine should not be used in animals with cardiovascular or systemic diseases affecting cardiovascular function.
• Although atipamezole is not officially approved as a reversal agent for xylazine, it is effective in reversing its effects in case of overdose.
• Animals sedated with xylazine may spontaneously become alert after stimulation, so caution should be exercised, especially with aggressive animals.