Regional and zonal variations in the sulfation patterns of chondroitin sulfate in normal equine corneal stroma

Aqueous humor and plasma concentrations of a compounded 0.2% solution of terbinafine following topical ocular administration to normal equine eyes

OBJECTIVE

To determine the transcorneal penetration and systemic absorption of a compounded 0.2% terbinafine solution following repeated topical administration to normal equine eyes. Sample population  Six healthy adult horses with normal ocular examinations.

PROCEDURES

One eye of each horse received 0.2 mL of a compounded 0.2% terbinafine solution every 4 h for seven doses. During the 1 h following administration of the final dose, multiple peripheral blood samples were obtained, and a single aqueous humor (AH) sample was collected at the end of the hour. AH and plasma concentrations of terbinafine were determined using high pressure liquid chromatography (HPLC). Stability of the formulation was assessed with HPLC analysis over a 14-day time period.

RESULTS

Terbinafine was not detected in the AH or plasma of any horse at any time point. No signs of ocular irritation or systemic toxicity were noted in any horse at any time point. The solution was stable over 14 days.

CONCLUSION

Topical ocular administration of compounded 0.2% terbinafine solution does not result in detectable AH or plasma levels following administration to normal equine eyes, suggesting its use for deep corneal or intraocular fungal infections in equine ophthalmology may be limited.

Immune-mediated keratitis in horses: 19 cases (1998-2004)

OBJECTIVE

The purpose of this study is to describe clinical and histologic findings, treatment, and outcome of horses with suspected immune-mediated keratitis (IMMK).

DESIGN

Retrospective study.

ANIMALS

Nineteen horses that presented to NCSU-VTH from 1998 to 2004 with IMMK. Procedures Information retrieved from the medical records included signalment, duration of clinical signs, therapy prior to initial examination, ophthalmic abnormalities, diagnostics performed, therapy instituted, and long-term vision.

RESULTS

Nineteen horses (22 eyes) were diagnosed with IMMK. Three distinct clinical groups were identified based on the depth of the lesion in the cornea: superficial stromal (n = 11 eyes), midstromal (n = 6 eyes), or endothelial (n = 5 eyes). Horses ranged from 5 to 19 years of age, with a mean age +/- SD of 11.9 +/- 3.6 years. Eleven horses had 12 months or greater duration of clinical signs of corneal disease prior to referral. Overall there was a mean duration of 11.8 +/- SD 8.3 months. Superficial stromal keratitis appeared as a superficial stromal cellular infiltrate with diffuse vascularization. Midstromal keratitis appeared as midstromal cellular infiltrate with mild, surrounding corneal edema and vascularization. Endothelial disease appeared as endothelial cellular infiltrate with diffuse corneal edema. In all types of IMMK, signs of uveitis or severe discomfort were not observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses with superficial IMMK responded to topical medical therapy, but responded best to surgical removal of the lesion. Horses with midstromal keratitis responded to topical cyclosporine therapy. Endothelial disease was the least amenable to therapy.

Ophthalmic findings in the geriatric horse

Ophthalmic conditions of the older horse are becoming increasingly common as geriatric care advances. The close relation between the eye and other structures of the head exposes the globe to direct expansion of clinical disease and raises management issues. Integrating an ophthalmic and fundic examination into the annual evaluation should reward the investment, permit enhanced patient care, and potentially provide early identification of systemic conditions. Surgical and medical management of neoplastic conditions is most successful with early identification and therapy. It is hoped that this article prompts the further identification and description of ophthalmic conditions as equine geriatric care increases in importance.