Vetnuus | Desember 2023 40 « BACK TO CONTENTS Feline herpes virus infection is an extremely common problem in cats with up to 80 % of cats worldwide being lifelong carriers with the possibility of developing recrudescent ocular disease. FHV may manifest in cats in several ways but one of the genuinely frustrating manifestations is Feline geographic corneal ulcers. Feline herpes keratitis usually starts as small dendritic ulcers. The presence of dendritic corneal ulcers is considered pathognomonic for FHV-1 infection. These lesions can be very fine in appearance and can be missed unless the cornea is examined with magnification. In the very early stages, these lesions may be fluorescein negative becoming positive as the lesion progresses but are lissamine green positive in the very early stages. It is therefore recommended to stain these corneas with fluorescein first, if staining is negative, it should be followed with lissamine green staining for the detection of very early lesions. Dendritic lesions coalesce leading to larger areas of geographic corneal ulceration. These may be single or multiple in appearance. In recrudescent infections, either dendritic or geographic corneal ulceration may be a clinical feature. A characteristic sign of these lesions is a lip of unattached epithelial cells and fluorescein undermining. [Figure 1]. Clinically these lesions are very similar to spontaneous chronic corneal epithelial defects [SCCED] in dogs, however, the underlying pathogenesis and treatment differ. Geographic ulcers can be extremely frustrating to deal with in practice as they typically take a lot longer to heal compared to common uncomplicated ulcers that should heal in less than a week. The treatment of FHV infections is discussed later but one of the crucial elements in treating these ulcers is the proper debridement [cotton bud or burr keratotomy] of the unattached epithelial cells. A grid / striate keratotomy as usually indicated for dogs with SCCED is contraindicated in FHV geographic ulcers as this procedure often leads to corneal sequestrums. Recommended treatment includes debriding the cornea under topical anaesthesia. Complete removal of all unattached epithelial cells is essential for healing and the most common reason for delayed healing is improper debriding of the lesion. Prophylactic antibiotic drops are prescribed as well as antiviral eyedrops. The product of choice is Cidofovir as this only requires a twice-daily application. The author prefers to use the compounded Cidofovir hyaluronic acid product as most cats with FHV keratitis will have a degree of tearfilm instability. Atropine or morphine may be used topically for 3 days as an analgesic if indicated. v Dr Izak Venter, Digital Veterinary Ophthalmology Services (DVOS) Feline Herpes Virus geographic ulcers in cats Technical I Ophthalmology Column The first mission of DVOS is to create a platform for the general practitioner veterinary surgeon to improve their ophthalmological knowledge and enable them to deal with ocular cases with more confidence. This will be done with online courses allowing participants to download course material that will include written notes as well as narrated PowerPoint presentations. The first small animal course comprises of 240 pages and the PowerPoint lectures are 20 hours in total excluding a guest lecture on SARDS. I shall also make surgical videos available covering some common surgical procedures. The course is CPD accredited with the South African Veterinary council for a total of 23 CPD points. The second mission is to provide a service to the practicing veterinarian offering specialist advice regarding problematic cases. More information regarding both of these aims are available on the website: www.dvos.co.za Figure 1. Typical appearance of the cat with a geographic corneal ulcer. Note the clear area of fluorescein undermining surrounding the lesion.
RkJQdWJsaXNoZXIy OTc5MDU=