And It's About Time There Was Some Support For Cushing's!
From http://www.freeweb.pdq.net/pbarbe/Cushing.htm
Cushing's Disease (Cushing's Syndrome), named after a Boston surgeon who first described the disease in people, is caused by elevated concentrations of circulating cortisol. It usually occurs in middle aged to older dogs, however, exceptions may occur. Normally, the pituitary gland produces a hormone, adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal gland to produce cortisol, a glucocorticoid. But if things get out of whack in either the pituitary or adrenal gland, too much cortisol may be produced causing Cushing's Disease.
These will vary greatly depending on the amount of excess cortisol and the length of the illness.
Lack of suppression--Cortisol production is not suppressed and levels remain above 1 ug/dl is consistent with Cushing's Disease.
Suppression--Cortisol values that drop at 4 hrs and then increase to above 1 ug/dl at 8 hrs is consistent with PDH.
Escape from suppression--Levels of cortisol < 1 ug/dl at both the 4 and 8 hr testing suggests that Cushing's Disease is not the problem.
Lack of suppression--Cortisol production is not suppressed and levels remain above 1.5 ug/dl is diagnostic for an adrenal tumor.
Suppression--If any cortisol value during the 8 hr testing falls below 1.5 ug/dl. This is consistent with PDH in 75% of dogs tested.
Normal to high--PDH
Low-adrenal tumor
Exaggerated plama cortisol response--PDH
No change in plasma cortisol level-adrenal tumor
Surgery: Not an option for pituitary tumors, but is a possibility for adrenocortico adenoma and small carcinoma if the dog is in otherwise good health and the tumor is benign. Malignant adrenal tumors that have already spread are poor surgical risks and medical management may be preferred. For pituitary tumors, radiation therapy has been used with success when the tumor is less than 15 mm in diameter. However, the radiation therapy will not be available at all clinics.
Medical management of Cushing's due to adrenal tumors uses a higher dose Lysodren than what is administered for PDH. The higher dosage usually causes more side effects.
Medical treatment of PDH: For a more complete description of Cushing's Disease treatments/options, please see the Cushing’s Syndrome Informational Website on the Mar Vista Animal Medical Center site.
