Feline post-sterilization hyphema.

OBJECTIVE

To determine incidence and risk factors of post-sterilization hyphema in shelter cats.

ANIMALS STUDIED: Retrospective medical record review of 1204 cats and prospective screening of 195 cats.

PROCEDURES: The study consisted of three parts: (a) Survey responses were collected from 20 veterinarians, who perform high-quality high-volume spay-neuter (HQHVSN) in both shelter and public clinic settings; (b) medical records of 1204 cats were analyzed retrospectively over a 14-month time period; and (c) ophthalmic examinations, including tonometry, were performed prospectively on 195 cats before and after sterilization surgery over 8 weeks.

RESULTS

Nine of 20 surveyed veterinarians reported having witnessed hyphema in cats following sterilization surgery. Retrospective review of 1204 medical record and prospective screening of 195 cats showed that three juvenile (<1 year of age) male cats (<2 kg) developed hyphema within 1 hour following surgery (0.2% incidence). In all three affected cats, anesthesia was induced with tiletamine/zolazepam (3 of 523 cats induced with this drug combination; 0.6% incidence), and hyphema resolved within 20 hours. Mean intraocular pressures as measured by Icare® TonoVet were (mean ± standard deviation) 11.5 ± 3.8 mm Hg and 21.7 ± 4.6 mm Hg for juvenile (<1 year of age) and adult (>1 year of age) cats, respectively.

CONCLUSIONS

Survey responses and three observed cases confirm the existence of feline post-sterilization hyphema with an estimated incidence of 0.2%. The underlying mechanism for this occurrence remains unknown.