VN April 2022

Vetnews | April 2022 31 required to create better adhesion points for the epithelial cells in most cases. The rabbit cornea is significantly thinner than in a dog. Thus, performing a striate keratotomy with a needle is far more dangerous and would undoubtedly require good magnification. The safer and very effective option is an Algerbrush diamond head burr procedure. 3] Uveitis Besides corneal ulcers, Uveitis is probably the next most common reason for a rabbit with an ocular problem. As in other domestic animals, there are many possible causes, and very often, the definitive diagnosis cannot be found. Major concerns would be systemic Pasteurella or Staphylococcus infections [septicaemia], lens induced Uveitis, and post-traumatic or idiopathic causes. Symptoms include blepharospasm, scleral congestion, corneal oedema, aqueous flare, hypopyon, blood-tinged fibrin, secondary cataracts, miosis and posterior synechiae. The Staphylococcus infections usually result in a yellow–cream abscess filling a large proportion of the eye, whilst Pasteurella tends to forma sedimented hypopyon in the ventral anterior chamber. Besides these above causes of Uveitis, it is the lens-induced Uveitis as a result of intra-lenticular infection by Encephalitozoon cuniculi that is particularly important in rabbits. The lesion is generally a whiter colour unless neovascularization also occurs, in which case it can be pink/red. A unique situation occurs in rabbits where the obligate intracellular microsporidian generally infects rabbits by ingesting contaminated urine and may cause renal or neurological signs. Still, it is also possible that transmission can be transplacental and migrates to the lens where it is inoculated via a protoplasmic discharge tube into the embryonic lens. Once in the lens, it may lie dormant for many months before moving through the lens, causing cataract formation and then erupting through the anterior lens capsule to liberate antigenic lens material into the anterior chamber. It elicits lens-induced Uveitis, which, although it may cause the cardinal signs of intraocular inflammation, namely miosis, iridal redness and swelling, and hypopyon, is much more likely to result in a white or pink mass protruding into the anterior chamber of the eye [see photo] Any uveitis should be treated with topical anti-inflammatory medications that can include steroid drops such as prednisolone acetate (Pred Forte] or dexamethasone (Maxidex], or a topical nonsteroidal such as ketorolac (Acular, Kelopt]. Oral meloxicam (Metacam, Petcam) can be added to the regime. Uveitis caused by E. cuniculi should also be treated with oral fenbendazole [Panacur] to kill the parasites causing the cataract. Phacoemulsification of the cataract is a further treatment option. v Regulars I Ophthalmology Column