Multicenter evaluation of the administration of crotalid antivenom in cats: 115 cases (2000–2011)

Abstract

To evaluate use of crotalid antivenom, frequency of hypersensitivity reactions, and risk factors for hypersensitivity reactions and death in envenomed cats. Retrospective multicenter case series. 115 envenomed cats treated with antivenom and 177 envenomed cats treated without antivenom. Procedures-Medical records from 5 institutions were searched by means of a multiple-choice survey with standardized answers for patient data including signalment, diagnosis, antivenom administration criteria, premedication, product, dose, administration rate, hypersensitivity reactions, and mortality rate. 95 of 115 (82.6%) cats received whole IgG antivenom, 11 (9.57%) received F(ab')2 antivenom, and 4 (3.48%) received Fab antivenom. The majority (101/115 [878%]) of cats received 1 vial of antivenom. In all cats, the median dilution of antivenom was 1:60 (range, 1:10 to 1:250) administered over a median period of 2.0 hours (range, 0.3 to 9.0 hours). There was no mortality rate difference between cats that did (6.67%) or did not (5.08%) receive antivenom. A type I hypersensitivity reaction was diagnosed in 26 of 115 (22.6%) cats. The use of premedications did not decrease type I hypersensitivity or improve mortality rate. Cats that had a type I hypersensitivity reaction were 10 times as likely to die as were those that did not have such a reaction. The mortality rate of cats treated with antivenom was low. The administration of premedications did not improve mortality rate or prevent hypersensitivity reactions. The only variable associated with mortality rate was development of a type I hypersensitivity reaction. The rate of antivenom administration should be further evaluated as a possible risk factor for type I hypersensitivity reactions.