Definition or overview
There is a high incidence of cataracts in diabetic dogs, with many cataracts apparently developing rapidly over days to weeks. Most diabetic dogs form cataracts within 2.5years after diagnosis.

Etiology
In dog inciting factor include obesity, immune mediated insulitis, pancreatitis, infection, genetic predisposition and insulin antagonistic disease. In cats obesity induced carbohydrate intolerance and amyloid deposition in islet cells are factors.

 

Pathophysiology
The cataracts form during periods of hyperglycemia when glucose enters the lens and is converted by the enzyme aldose reductase (AR) to sorbitols as the glycolytic enzyme hexokinase is saturated. Sorbitol dehidrogenase (SD) activity is also reduced, wich allows sorbitols to accumulate. The sorbitol draws water into the lens and the lens fibers swell and rupture to result in cataracts. The cats lens has less activity of both enzymes than that of dogs but the ratio of aldose reductase (AR) to Sorbitol dehidrogenase (SD) is higher in cats. Sorbitol should accumulate more quickly in diabetic cat lenses than in diabetic dogs lenses but incidence of cataract is actually lower clinically in diabetic cats.
Clinical presentation
The most common ocular manifestation of diabetes mellitus in small animals is acute formations of cataracts, often associated with sudden blindness.

Deferential diagnosis
Cataract may be hereditary in specific breeds and may be caused by diabetes mellitus, aging, advanced retinal degeneration, anterior uveitis, disease causing hypocalcemia, radiation therapy and milk replacers in puppies and kittens. Atopy is also associated with cataract development in humans and may also associated with cataract development in humans and may also play an important role in cataract formation in dogs living in subtropical environments.

Diagnosis
Early cataractous changes diabetic change diabetic dogs and cats appear as vacuoles in the sub epithelial equatorials cortex which progress to mature, intumescent cataractous lenses with prominent Y structure clefting. Anterior uveitis is also found in some canine diabetics. Diabetic retinopathy is slow develop in diabetic dogs and cats.

Management and Treatment
Treatment can divided into acute management of diabetic ketoacidosis and the stabilization of the uncomplicated diabetic. The ketoacidotic dog can be stabilized as for the uncomplicated case, once it has started to feed normally. Surgery is necessary to treat the cataracts.