Frequência e aspectos patológicos das doenças oculares em animais

Abstract

Clinical assessment of eyes from animals in Brazil is significant; however, histopathological examination for diagnosis and research is still incipient. In this study, eyes and annexes of different animal species were analyzed from February 2012 to September 2015. The proposed study aims to expand knowledge in ocular pathology, and to establish a diagnosis for the various changes that have occurred in ocular bulbs and annexes. The samples were examined using gross pathology and histopathology. In some samples, histochemistry and immunohistochemistry were also used. The frequency of changes was determined and the most affected animal species were identified, as well as the type of changes at the affected intraocular or periocular tissue. One hundred and eighty eight eyes and annexes were collected, and these were obtained from 125 dogs, 26 cats, 13 birds, 11 equines, five bovines, two wild felines, a wild canine, a rodent, a llama, a caprine, an equidae (donkey) and a non-human primate (Callithrix spp.). Of these, nine animals had two concurrent changes, bring it to a total of 197 eyes and annexes changes. There were 92 tumors, 43 traumas, of which 21 had a history of trauma and 22 were only suggestive of trauma, 37 inflammatory lesions, of which 20 had confirmed causes and 17 not determined, 18 degenerative diseases, four developmental changes and three vascular diseases. Of the 197 changes, 112 were in the eyeball, 52 in the eyelids, 17 in the third eyelid, 14 in the bulbar conjunctiva and two retrobulbar tumors. Of the tumors, 58 were found in annexes, 32 in eyes and two retrobulbars, and 57 were malignant, 31 benign and four were tumor-likes. The most frequent neoplasm in annexes was the Meibomian gland epithelioma; meanwhile, anterior uveal melanoma was the most common in the eyes. Among traumatic changes, lesions in the anterior uvea and cornea were the most frequent. In relation to inflammatory diseases, found in 37 cases, it was possible to determine the etiology in 20 ocular bulbs and annexes and, Leishmania sp., Escherichia coli and Streptococcus zooepidemicus were identified as infectious agents in these cases. Chalazion, a non-infectious inflammatory condition, was also found. In two bovines there were suggestive lesions by Moraxella spp. infection. In a dog, there were lesions suggestive of infection by canine distemper virus, while, in a cat, there were lesions suggestive of infection by feline infectious peritonitis virus. Degenerative diseases occurred mainly in chickens, seven of which presented clinic-pathological changes suggestive of progressive retinal atrophy. In the developmental diseases, the most frequent was microphthalmia, diagnosed in a foal and a cat. Ocular hyperemia was found in a case compatible with, and other suggestive of, poisoning by carbamate. A dog diagnosed with chronic renal failure presented alterations that were associated with fibrinoid necrosis of ocular and systemic blood vessels. Annexes neoplasms were the most frequent changes, possibly related to higher frequency of surgery and histopathological examination requested by clinicians and surgeons. However, the low frequency of eyes sent for histopathological examination may underestimate the results, and contribute to the ocular pathology remains an unknown field for some pathologists. Also, there is the anatomical specificity and the specific vocabulary for the alterations found, which require more time and training in order that the pathologist becomes able to perform this analysis. The results of the histopathological ocular evaluation in surgical enucleation cases can provide better recognition of clinical and pathological conditions, and help clinicians in taking steps that can prevent the animals death.