This Basset hound comes to you with a two day history of a red painful eye and the owner’s suspicion that vision on that side may not be all it should be. What’s the diagnosis, how would you confirm that and what emergency treatment would you give to improve the condition?
This is glaucoma, caused because of dysplasia of the pectinate ligament of the iridocorneal angle in both eyes confirmed by tonometry showing an elevated intraocular pressure (iop) and gonioscopy of the angle in the still healthy fellow eye showing an abnormal pectinate ligament. Professor Gelatt has recently shown that over 5% of Bassets in the USA have glaucoma (Prevalence of the breed-related glaucomas in pure-bred dogs in North America.
Vet Ophthalmol. 2004 7:97-11) making it one of the worst affected breeds there and I guess here in the UK too. In the old days we would have given mannitol as an iv drip, but these days topical prostaglandin, in the form of Latanaprost or a similar agent, constricts the pupil, as you can see here and lowers the pressure in minutes. Here the iop was 37mmHg, lowered to 24mmHg in twelve minutes and under 20 over the next hour, by the drug opening up the unconventinal drainage route through the choroid which bypasses the iridocorneal angle altogether. Magic! Doctor Wilis and colleagues have produced a useful review of new topical anti-glaucoma agents in their 2002 paper ‘Advances in topical glaucoma therapy’ appearing in Veterinary Ophthalmology 5:9-17.