Pannus, or chronic superficial keratitis, is a painful autoimmune disease of the cornea and conjunctiva of both eyes. This condition results from a misdirected immune response that manifests itself as blood vessel ingrowth, pigmentation, and scar tissue development in the cornea, conjunctiva, and 3rd eyelid. With time, the normally clear corneas become opaque, and some dogs eventually go blind.
Pannus is not caused by infection, and currently the stimulus for the immune reaction is not known. However, given the strong breed predisposition seen in German Shepherds, a hereditary component is very likely. Other affected breeds include Belgian Tervuerens, Siberian Huskies, Border Collies and Greyhounds.
Ultraviolet radiation is also known to contribute to the condition, thus dogs that live at higher altitudes are predisposed. A connection to other immune factors, such as reactions to environmental stimuli outside the body or against the corneal tissue itself has also been proposed as a cause of pannus.
Whenever your pet is showing signs of a health issue, your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from pannus or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.
Pannus usually develops in young to middle-age adult dogs, emerging first as redness to conjunctiva near the outer margins of the cornea. Often dogs develop a thick discharge from the eyes in the early stages. As the disease progresses, the inflammation progresses across the surface of the eye and white infiltrates made up of inflammatory cells invade the cornea. This is often seen as a film on the eye’s surface. Corneal ulcers can develop which are painful and require treatment to prevent infection.
With chronic, untreated pannus, the inflammation progresses to pigmentation, or brown tissue on the cornea, and can affect vision. The 3rd eyelid may also become affected by thickening, redness, depigmentation and lumpiness, which is known as atypical pannus, or plasmoma. Some dogs may only have atypical pannus, and the dog’s vision is less likely to become impaired. Pannus always affects both eyes, usually to a similar degree.