Keratoconjunctivitis vernalis (KCV) beim Pferd.

The advancement in veterinary medicine is driven by the specialisation of veterinarians. In the field of equine ophthalmology, this leads to a high number of patients referred to specialised veterinarians. The high number of patients, in turn, gives the opportunity to closely monitor certain diseases and develop targeted therapies. In the present work, based on human ophthalmology, a new eye disease in horses, vernal keratoconjunctivitis (keratoconjunctivitis vernalis-KCV), is described. The aim of the study is to define the disease which makes definitive diagnosis possible in the future, and to describe optimal therapy. The clinical presentation, differential diagnoses, histological findings, and the applied therapy are described on the basis of clinical data obtained from 22 patients (28 eyes). KCV is a chronic, immune-mediated conjunctival and corneal disease in horses. Affected patients show hyperaemia of the conjunctiva, signs of extreme ocular pain, blepharospasm and a thick, mucous epiphora. A varying degree of reflexive miosis is also visible in the eyes, depending on the severity of the disease. The clinical appearance is classified into a gigantopapillary type, a limbal type, and a mixed type. In the gigantopapillary type, typical changes are visible in the ventral conjunctiva. This appears through the pathognomonic, paving stone-like giant papillae. In the limbal type, in addition to the giant papillae, which look like a rosary in the limbus, cloudy, yellowish, round corneal changes, the so-called „Horner-Trantas dots" also appear. The changes can be further differentiated histologically. In one form, accumulated eosinophil cells are present. The other form is predominantly characterised by lymphocytes. Typical white, granular deposits are visible in cases with the eosinophilic type. In contrast, the surfaces appear smoother in the lymphocytic type. The disease can be diagnosed on the basis of the clinical appearance, with a supporting histological examination if necessary. In the differential diagnosis, neoplasms of the conjunctiva and cornea as well as inflammatory changes should be ruled out. The patients were examined and treated as inpatients between 2018 and 2020. The therapeutic plan included a combination of laser treatment with a diode laser, subconjunctival injections, local ointment therapy and systemic analgesic and anti-inflammatory treatment. Due to its immunological genesis, local treatment was based on cortisone. Dexamethasone was used for both subconjunctival injection, and eye ointment. All horses showed a clear improvement within 24 hours after the initiation of the therapy. Complete healing occurred between 7 and 14 days (on average, 9 days). Eight horses (9 eyes, 41%) exhibited corneal involvement as a complication, ranging from punctiform erosions to ulcerations of about 8mm in size. There was a relapse in two cases, and the therapy had to be repeated. In one horse, surgical excision of the altered tissue was also done. A regular check-up was carried out over a period of 10-36 months. No age dependency, breed or genetic predisposition was evident in the patients. This study has shown that it is necessary to observe, name and define new clinical entities in the eye to be able to carry out an adequate therapy. The multimodal therapy described appears to be very suitable for the treatment of KCV in horses. A critical examination of other patients is necessary to achieve better statistical evaluability due to a larger group and, if necessary, to obtain additional information on the aetiology [ABSTRACT FROM AUTHOR]