by Stuart Nelson, Jr., DVM
Pannus or Uberreiter’s disease refers to a corneal abnormality most prevalent in German Shepherds, Border Collies, Siberian Huskies and Australian Shepherds. Alaskan Huskies often include these breeds in their lineage, and although infrequent, they are also affected by Pannus.
There are several definitions of the disease process, but the condition in dogs is best described as a chronic superficial corneal inflammation (keratitis). It is first noticed as a slight cloudiness or haze along the margin of the cornea on the lateral surface (towards the side of the head). Eventually, both eyes become affected, although only one side may be initially noticed. The film gradually (usually months) increases with size and becomes infiltrated with small blood vessels (neovascularization). As the abnormalities progress, affected areas may become darkly pigmented, with resulting vision impairment. In worst-case scenarios, the cornea may become sufficiently damaged to result in blindness. In spite of the fact that a true cure does not exist, the good news is that this disorder can be satisfactorily controlled with various medications.
Other conditions can cause somewhat similar signs, including eyelid conformational defects such as entropion (eyelids turned in) and ectropion (eyelids turned out), the presence of abnormally located eyelashes, keratoconjunctivitis sicca (dry eye from lack of tear production) and primary infectious agents. If only one eye is involved, other considerations include the presence of a foreign body behind the third eyelid or within the cornea itself, and trauma induced corneal abrasions (ulcers). A veterinary examination is needed for confirmation of the disease process.
The chronic inflammation characteristic of Pannus is believed to be immune-mediated (allergic?) in nature. Secondary infections may be present, but are not the actual cause. Ultraviolet light exposure may make the condition more difficult to control. Many treatments have been tried, including radiation, cryotherapy and topical immunosuppressive agents, but the most successful protocols involve the use of corticosteroids. An initial injection of ten milligrams of a long acting preparation, such as Depo Medrol, into the conjunctiva of the affected eye(s), is followed by daily topical applications of an antibiotic/corticosteroid ophthalmic ointment. Repeated injections are administered as needed every few months. In advanced cases, surgical intervention may be necessary to remove damaged areas. This entails excision of the affected superficial layers of the cornea. Following regeneration of the corneal epithelium, corticosteroids need to be administered to prevent relapses. Ultimately, detecting the early signs of Pannus and initiating prompt medical treatment are the keys to minimizing the severity of corneal damage.