Diagnosis and treatment
The most reliable test for EPI in dogs and cats is serum trypsin-like immunoreactivity (TLI);  a low value indicates EPI. Fecal elastase levels may also be used for diagnosis in dogs.In dogs, the best treatment is to supplement the animals food with dried pancreatic extracts. There are commercial preparations available, but chopped bovine pancreas from the butcher can also be used. (Pork pancreas should not be used because of the rare transmission of pseudorabies). Symptoms usually improve within a few days, but lifelong treatment is required to manage the condition. A rare side-effect of use of dried pancreatic extracts is oral ulceration and bleeding.Because of malabsorption, serum levels of cyanocobalamin (vitamin B12) and tocopherol (vitamin E) may be low. These may be supplemented, although since cyanocobalamin contains the toxic chemical cyanide, dogs that have serious cobalamin issues should instead be treated with hydroxocobalamin or methylcobalamin.Cyanocobalamin deficiency is very common in cats with EPI because about 99 percent of intrinsic factor (which is required for cyanocobalamin absorption from the intestine) is secreted by the pancreas. In dogs, this figure is about 90 percent, and only about 50 percent of dogs have this deficiency.Cats may suffer from Vitamin K deficiencies. If there is bacterial overgrowth in the intestine, antibiotics should be used, especially if treatment is not working. In dogs failing to gain weight or continuing to show symptoms, modifying the diet to make it low-fiber and highly digestible may help.
Nelsons syndrome is a disorder that occurs in about one in four patients who have had both adrenal glands removed to treat Cushings disease. In patients with pre-existing adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, loss of adrenal feedback following bilateral adrenalectomy can trigger the rapid growth of the tumor, leading to visual symptoms (e.g. bitemporal hemianopsia) and hyperpigmentation. The severity of the disease is dependent upon the effect of ACTH release on the skin, pituitary hormone loss from mass compression, as well as invasion into surrounding structures around the pituitary gland.The first case of Nelsons syndrome was reported in 1958 by Dr. Don Nelson. Within the past ten to twenty years, improvements have been made with identification and care for patients with Cushings disease. Techniques such as pituitary radiation therapy, ACTH assay, transsphenoidal pituitary surgery, higher resolution MRIs, and sampling of the inferior petrosal sinus have allowed physicians to pursue routes for Cushings syndrome therapy prior to consideration of bilateral adrenalectomy.Nelsons syndrome is also referred to as post adrenalectomy syndrome, a possible result of adrenalectomy performed for Cushings disease. Symptoms and signs
The common symptoms include:
hyper-pigmentation of the skin
visual disturbances
headaches
abnormally high levels of beta-MSH and ACTH
abnormal enlargements of the pituitary gland,
interruption of menstrual cycles in women

Cause
Common causes include bilateral adrenalectomy for the treatment of Cushings disease, and hypopituitarism. The onset of the disease can occur up to 24 years after a bilateral adrenalectomy has been performed, with an average of up to 15 years after.