HISTOMORPHOLOGICAL CHANGES OF THE STRUCTURAL ELEMENTS OF THE ANTERIOR CHAMBER OF THE EYE IN KERATOUVEITIS IN DOGS AND CATS
Abstract
Corneal diseases of inflammatory genesis in dogs and cats are quite common and, therefore, continue to be an actual problem in scientific and clinical aspects, as they are the leading complication in the structure of general eye diseases among animals, which leads to loss of visual ability. Among the pathologies of the cornea in dogs and cats, the most common are various forms of keratitis, spontaneous defects of the corneal epithelium, post-traumatic ulcers, degenerative pannus, which are often complicated by the development of concomitant complications from the vascular membranes and, in particular, iritis, which is clinically manifested in the form of keratouveitis. The purpose of our research was to determine the features of the pathomorphological changes of the cornea, iris, and lens during keratoveitis in dogs and cats. The operative material was fixed in a 10% solution of neutral buffered formaldehyde for 24 hours, followed by dehydration and impregnation with paraffin in the ATM-4M carousel type apparatus (Ukraine). 10 parts of fixative were used for 1 part of the volume of the eyeball (approximately 0.15–0.3 ml of fixative). The fixative was injected into the eyeball using a small needle. The fixator was inserted behind the limbus of the cornea in the direction of the thick part of the eyeball so as not to damage the lens. Subsequently, fragments of the cornea, iris, and lens were washed in water, dehydrated, clarified in an alcohol-xylene solution, embedded in celloidin blocks, and a series of histological sections were performed. Serial histological preparations of 4 μm thickness were performed on a Shandon Finnesse 325 rotary microtome (Thermo Scientific). Obtaining and storing images of drugs was carried out using the digital image system "ZEN" for microscopes "Саrl Zeis" (Germany) on the basis of the Ukrainian-Swedish research center SUMEYA (Medical Institute of Sumy State University). After selection, the tissue material was fixed in a 10% neutral formalin solution. For inspection microscopy, staining of histological preparations was carried out with hematoxylin-eosin, and for the study of histochemical properties - with picrofuchsin mixture according to Van Gieson and the Malory method It was found that keratouveitis in dogs and cats shows erosive areas of the cornea with pronounced epithelial desquamation, hydropic dystrophy of the epithelium with local destructive-degenerative changes, along with the formation of coarse-fibrous connective tissue in Bowman's membrane, Descemet's membrane, and the cornea's own substance. It has been established that pathomorphological changes in the iris in keratouveitis are characterized by dyscirculatory disorders, vascular congestion, vasodilatation with areas of hemorrhage, significant edema with matrix fibrillation phenomena, and the formation of lacunae filled with exudate. In cases of intense inflammation, the spread of the inflammatory infiltrate from the cornea to the iris tissue is noted, with subsequent dystrophic and necrotic changes in the latter. During the long course of keratouveitis, in the structural elements of the lens, morphological changes are revealed in the germinal zone, according to the type of hydropic dystrophy of epitheliocytes, the structure of the nuclear mass, thickening of fibers, with a violation of their architecture.
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