Glaucoma with Descemet's membrane detachment in five horses.

PURPOSE: To describe the clinical and histopathologic features of glaucoma associated with Descemet's membrane (DM) detachment in five horses without prior history of intraocular surgery. ANIMALS STUDIED: Three Appaloosa horses and two Thoroughbreds were included in this study. The affected horses ranged in age from 16 to 27 years and presented with severe diffuse corneal edema. PROCEDURE: Five eyes were enucleated due to intraocular hypertension and/or chronic corneal ulceration. The enucleated globes were evaluated by the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). Each globe was routinely processed for histopathology and analyzed by light microscopy. A histologic diagnosis of glaucoma was reached by demonstrating a loss of optic nerve axonal tissue by measuring neurofilament-immunopositive axons with automated image analysis software. RESULTS: All five horses presented with unilateral severe diffuse corneal edema that had developed between 2 and 16 weeks prior to enucleation. Intraocular pressures for the affected eyes were between 9 and 87 mmHg prior to enucleation. Descemet's membrane detachment was identified histopathologically in all five globes (5/5, 100%). All five eyes had an avascular spindle cell proliferation filling the space between the displaced peripheral DM and the corneal stroma. Neurofilament immunostaining revealed axonal loss consistent with glaucoma. CONCLUSION: Equine glaucoma may be associated with Descemet's membrane detachment. This detachment and glaucoma is a possible differential diagnosis for severe equine corneal edema. In this case series, an eye with a DM detachment had a poor prognosis for retention.

Characterization and outcome following excision of masses in the nictitating membranes of horses: 50 cases (1998-2012).

OBJECTIVE: To determine the histologic findings associated with masses in the nictitating membranes (third eyelids) of horses and to identify prognostic factors associated with recurrence and the outcome. DESIGN: Retrospective case series. ANIMALS: 50 horses with masses in a third eyelid. PROCEDURES: Medical records of horses with partial or complete excision of a third eyelid and submission for histologic evaluation between September 1998 and November 2012 were reviewed. Horses were included if follow-up information for at least 1 year after surgery was available. Information regarding signalment and treatment was obtained from the medical records. Histopathology reports were examined to determine surgical margins and vascular invasion. Data were analyzed by means of a χ(2) test to determine the association between recurrence and type of excision (partial or complete), surgical margins, vascular invasion, and use of chemotherapy as well as the association between partial excision of a third eyelid prior to referral and outcome. RESULTS: Squamous cell carcinoma was the predominant tumor type of the third eyelid. There was recurrence in 10 of 50 (20%) horses; recurrence was at a mean of 2.25 years and median of 1.5 years after excision. Partial excision prior to referral was associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: In horses with masses in a third eyelid, recurrence and mortality rates were high, which suggested that long-term monitoring is important for all patients in which partial or complete third eyelid excision is performed.

Corneal dystrophy in Friesian horses may represent a variant of pellucid marginal degeneration.

OBJECTIVE: To describe the clinical presentation, treatment, and outcome of a corneal dystrophy in Friesian horses and to analyze affected horses' pedigrees to investigate its heritability. ANIMALS: Nine Friesians with bilateral disease were identified. PROCEDURE: Retrospective medical record review was used to identify Friesian horses exhibiting bilateral symmetric corneal lesions. Variables identified from medical records included patient sex and age at diagnosis; location, depth and size of corneal lesions; medical and surgical therapy instituted; and visual outcome. A four-generation pedigree for each included horse was used to construct a combined pedigree. RESULTS: The nine included horses had an average age at diagnosis of the first eye of 10.7 years, with males (8/9) significantly more frequently affected than females (1/9), P = 0.012. Lesions were inferior and averaged 5 mm in diameter. Depth ranged from superficial facets to perforations, which developed in nine of 18 eyes. Eight of nine perforations were surgically repaired, with seven of eight repaired eyes visual at last follow-up. All nine eyes that had not perforated remained visual. All affected horses shared a common ancestor within six generations. CONCLUSIONS: This form of corneal dystrophy in Friesian horses, characterized by bilateral symmetric stromal loss, appears to be progressive but responds well to surgical repair, occurs more frequently in males, may have a genetic component in Friesian horses, and may be a variant of pellucid marginal degeneration.

Treatment of nonhealing corneal ulcers in 60 horses with diamond burr debridement (2010-2013).

OBJECTIVE: To review the signalment, clinical characteristics, and outcome of horses with nonhealing corneal ulcers treated with diamond burr debridement (DBD); and to evaluate the role of ulcer duration, size and location, and bandage contact lens (BCL) placement on healing. ANIMALS: From January 2012-April 2013, 60 horses were diagnosed with ulcers classified as nonhealing based on the presence of raised epithelial margins and duration of at least 7 days. PROCEDURE: Retrospective record review. RESULTS: Average age of included horses was 14.68 years, SD 8.17 years. There were three times as many males (45) as females (15), (χ12 = 15, P = 0.001). Forty-eight horses (80%) had nonhealing ulcers uncomplicated by associated corneal disease. In the remaining horses, associated corneal disease included esinophilic keratitis (10%), calcific band keratopathy (5%), endothelial decompensation (1.67%), habronemiasis(1.67%), and lid suture abrasion (1.67%). Average corneal ulcer duration prior to diamond burr debridement (DBD) was 29.0 days (n = 56). Ulcers occurred most commonly in the axial cornea (41%). Fifty-five of 60 horses (92%) healed with DBD. Healing time, defined as time to epithelialization following DBD, averaged 15.5 days, SD 9.32 days, and was not correlated with patient age or ulcer duration, location, or size prior to or following DBD. Healing time was significantly longer for eyes in which a BCL had been placed (n = 28, 19.0 days) than for eyes without a BCL (n = 32, 12.9 days), F(1,58) = 5.543, P = 0.02. DBD was considered a failure for five horses (8%). CONCLUSIONS: DBD may be an effective treatment for nonhealing corneal ulcers in horses.

Eosinophilic keratitis in 46 eyes of 27 horses in the Mid-Atlantic United States (2008-2012).

OBJECTIVE: To review the signalment, clinical characteristics, treatment, and outcome of equine EK cases in the Mid-Atlantic United States; to evaluate the effects of topical or systemic corticosteroid treatment, oral cetirizine treatment and secondary corneal infection on disease duration; and to evaluate the association between corticosteroid and cetirizine treatment and likelihood of recurrence. ANIMALS: Twenty-seven horses (47 eyes) diagnosed with EK from 2008 to 2012. PROCEDURE: Retrospective medical record review followed by phone interview to obtain recurrence data. RESULTS: Average age of affected horses was 8.2 years, SD 5.8 years. Eleven of 27 horses (41%) were diagnosed with EK in July. Twelve horses (44%) had been affected in previous years. Time to resolution averaged 3.7 months, SD 2.3 months. Ten horses (18 eyes) were treated with systemic dexamethasone, with a significantly shorter time to resolution, P = 0.03, averaging 2.23 months, SD 1.13 months, relative to horses not so treated, averaging 4.20 months, SD 1.47 months. Secondary infection led to a significant increase in time to resolution, P = 0.03, average 4.1 months, SD 1.7 months, relative to horses without secondary infection, average 3.0 months, SD 1.5 months. All eyes were visual at resolution. Horses treated with cetirizine were less likely to have recurrence during the follow-up period (1/13, or 8%) relative to horses not so treated (8/14, or 57%). CONCLUSIONS: Eosinophilic keratitis has a seasonal occurrence in summer in the Mid-Atlantic United States. Systemic but not topical corticosteroid treatment may decrease therapy duration. Treatment with cetirizine may be associated with a decreased risk of recurrence.