Abstract
Purpose: :
To determine if there is a benefit to combining topical and systemic carbonic anhydrase inhibitors (CAI) to treat primary glaucoma in dogs.
Methods: :
The medical records of the UGA-VTH were searched from 2005-2010 for dogs with primary glaucoma (narrowed or closed angle). Patients were divided into three groups: topical 2% dorzolamide alone; oral methazolamide alone; or combination therapy. Eyes were categorized as initially affected (increased IOP) or contralateral (predisposed to increased IOP). Significance was defined as p<0.05. Changes in IOP over time were compared by repeated measures analysis. Systemic and ocular side effects were compared by chi-square test.
Results: :
30 medical records met the search criteria: topical CAI alone (patients N=20; eyes N=34); oral CAI alone (patients N=6; eyes N=6) and combination (patients N=10; eyes N=15). The average follow up was 168 days. The probability of disease control was not significantly different between groups. The average time to treatment failure in the initial eye was 37 days. The average time to the onset of glaucoma in the contralateral eye was 196 days. The addition of prostaglandin analogs and/or timolol to the treatment scheme was not associated with the overall treatment success between groups. When both eyes are considered, the addition of prostaglandin analogs significantly (travoprost p<0.01, latanoprost p<0.002) lowered the IOP in all three groups. There was no significant difference in the incidence of systemic or ocular side effects between groups.
Conclusions: :
Combination therapy of oral and topical CAI is not associated with increased side effects but has no benefit when compared to oral or topical use alone for the treatment of primary glaucoma in dogs.
Keywords: carbonic anhydrase • drug toxicity/drug effects