Adverse reactions of α₂-adrenoceptor agonists in cats reported in 2003-2013 in Finland

Objective: To describe suspected adverse drug reactions in cats associated with use of α₂-adrenoceptor agonists.

Study design: Retrospective study.

Animals: A total of 90 cats.

Methods: Data were collected from reports on adverse reactions to veterinary medicines sent to the Finnish Medicines Agency during 2003-2013. All reports of suspected adverse reactions associated with use of α₂-adrenoceptor agonists in cats were included. Probable pulmonary oedema was diagnosed based on post mortem or radiological examination, or presence of frothy or excess fluid from the nostrils or trachea. If only dyspnoea and crackles on auscultation were reported, possible pulmonary oedema was presumed.

Results: Pulmonary oedema was suspected in 61 cases. Of these cats, 37 were categorised as probable and 24 as possible pulmonary oedema. The first clinical signs had been noted between 1 minute and 2 days (median, 15 minutes) after α₂-adrenoceptor agonist administration. Many cats probably had no intravenous overhydration when the first clinical signs were detected, as either they presumably had no intravenous cannula or the signs appeared before, during or immediately after cannulation. Of the 61 cats, 43 survived, 14 died and for four the outcome was not clearly stated.

Conclusions and clinical relevance: Pulmonary oedema is a perilous condition that may appear within minutes of an intramuscular administration of sedative or anaesthetic agent in cats. The symptoms were not caused by intravenous overhydration, at least in cats having no venous cannula when the first clinical signs were detected.