Refractive state of the Spanish Thoroughbred horse: a comparison with the Crossbred horse.

OBJECTIVE: To assess the refractive state of the equine eye utilizing retinoscopy. To compare the refractive state of Spanish Thoroughbred horses with the refractive state of Crossbred horses. PROCEDURES: The refractive state of 135 horses (264 eyes) was assessed utilizing streak retinoscopy. Two perpendicular meridians were examined in order to assess astigmatism at a working distance of approximately 67 cm. A group of 81 Spanish Thoroughbred horses was compared with a group of 54 Crossbred horses. Cyclopentolate ophthalmic solution was instilled in the eyes of a group of 18 horses to determine if accommodation has any influence on the assessment of the refractive state. RESULTS: Mean ± SE refractive state of all horses examined was -0.17 ± 0.04 D. The mean refractive state of the Spanish Thoroughbred was -0.28 ± 0.06 D while that of the Crossbred was -0.01 ± 0.05 D. The refractive state of the Spanish Thoroughbred was found to be statistically different to that of the Crossbred. The most prevalent refractive state was emmetropia in all cases, followed by hyperopia for the Crossbred, and myopia for the Spanish Thoroughbred. Astigmatism ≥0.50 D present in both eyes from the same individual was found in 21.7% of all horses examined. Anisometropia ≥1.00 D was diagnosed in 4 out of 129 horses with both visual eyes. Cycloplegia did not statistically affect the refractive state of the evaluated eyes. CONCLUSIONS: The equine eye has a refractive state close to emmetropia. Myopia is higher among Spanish Thoroughbred horses than among Crossbred horses.

Fluorangiographic study of the ocular fundus in normal horses.

PURPOSE: To describe the protocol and appearance of fluorescein angiography (FA) in normal horses. ANIMALS: A total of 25 healthy horses aged between 5 and 15 years. MATERIALS AND METHODS: The horses were sedated with 15 microg/kg detomidine and 50 microg/kg butorphanol and dilated with topical tropicamide 1%. All angiograms were recorded after intravenous bolus injection of 10 mg/kg of fluorescein sodium solution. RESULTS: Two successive angiographic phases could be discerned: the choriopapillary phase, starting at 46.95 +/- 9.48 s, and the retinal vascular phase, starting at 47.79 +/- 10.38 s. The retinal vascular phase was divided in three parts: filling phase, maximum fluorescence point, and fading phase. During the filling phase, the dye progressed into the retinal vessels, obtaining maximum fluorescence at 59.79 +/- 10.39 s, termed the maximum fluorescence point. The fading phase started immediately following the maximum fluorescence point. During this phase, vascular fluorescence decreased to complete reduction at 74.76 +/- 9.81 s. Also, areas of delayed choroidal filling, the presence of short retinal vessels in the ventral region of the optic disc, and a particular filling of the optic disc were also observed. CONCLUSIONS: The normal angiographic sequence was described in horses. FA may be a useful method for studying the integrity of the blood-retinal barriers in horses.

The ocular effects of intravitreal triamcinolone acetonide in dogs.

The aim of the study was to determine the ocular safety of a single intravitreal dose of triamcinolone acetonide (IVTA) in dogs. Eleven healthy dogs received a single IVTA injection (8 mg) through the mid-temporal pars-plana of the left eye (OS) using a 27G needle. The dogs were re-evaluated immediately post-IVTA, every 5 min until pre-IVTA values had returned, then daily for 3 days, weekly for 1 month and monthly for 3 months. Immediately post-IVTA, all the treated eyes showed a rise in intraocular pressure (IOP) with a mean value of 41.8+/-8.9 mm Hg. The IOP values then decreased progressively to 14.5+/-2.1 mm Hg at 12.2+/-3.8 min post-IVTA. From then on, normal IOP values were maintained throughout the 3-month monitoring period. The most frequently observed clinical sign post-IVTA was conjunctival hyperaemia. The presence of triamcinolone acetonide in the vitreous was observed in all subsequent examinations of 10/11 eyes and there were still triamcinolone crystals in 5/11 eyes after 90 days. It was concluded that intravitreal injection of triamcinolone acetonide in dogs is feasible under sedation. The immediate increase in IOP post-IVTA is short-lived and pressure quickly returns to pre-IVTA levels.

Comparative fluorescein angiography of the normal sheep and goat ocular fundi.

Fluorescein angiography without sedative or anesthetic agents was evaluated in 20 normal goats and 20 normal sheep. All of the angiographic phases were observed using 20 mg/kg fluorescein IV in both species. Fundus fluorescein angiography results revealed wide stars of Winslow in the tapetal fundus, central or marginal flow during the first part of the arterial phase, delayed filling of the focal areas in the choroid near the optic disc that often coincided with others in the disc, and lack of evidence of the 'striate area' in the tapetal fundi. In goats, the angiographic times were 6.54+/-1.25 s for the arterial phase (TA), 7.80+/-1.37 s for the arterio-venous phase (TAV), and 14.13+/-2.01 s for the venous phase (TV). I1: 1.30+/-0.30 s (time elapsing between TA and TAV), and I2: 6.20+/-1.60 s (time elapsing between TAV and TV). In sheep, times were 9.54+/-2.18 s TA, 11.73+/-2.10 s TAV, and 20.86+/-2.74 s TV. I1: 2.04+/-0.75 s and I2: 8.98+/-2.47 s, respectively. Due to the large size of the fundic vessels in sheep and goats, fluorescein angiography of the retinal vasculature can facilitate the study of the different vascular diseases in these species.

A Clinical, Pathological and I mmunopathological Study of Vitiligo in a Siamese Cat.

Abstract- The clinical, histopathological and ultrastructural features of a spayed female Siamese cat with a three-and-a-half year history of progressive cutaneous depigmentation are described. Clinically the condition was characterised by progressive leukoderma of the nose, pinna and footpad skin, and multifocal leukotrichia involving the whole body. Histopathological and ultrastructural studies confirmed the absence of melanocytes and melanin in the epidermis and hair follicles of affected areas. Immunohistochemical study revealed areas with absence of immune response to anti-vimentin antiserum, which was interpreted as a loss of dendritic cells, especially melanocytes. Diagnosis of vitiligo was based on the clinical signs and pathological features. This study adds a new case of this uncommon condition in the cat, and documents some previously non-reported features of feline vitiligo, such as the chronic progressive and generalised nature of the skin lesions, and its reversible character with partial lentiginous repigmentation on the pinna.