Cushings or Hyperadrenocorticism

29 05 2011

Cushings or Hyperadrenocorticism






Typical clinical signs of Cushing’s includes:  Polyuria (increase in urination), polydipsia (increase in thirst), polyphagia (increase in appetite and food consumption), panting, pendulous abdomen and dermatologic changes such as alopecia (bilateral symmetrical hair loss) and comedone formation.  Not every clinical sign will be seen in each individual patient.


With PDH it is estimated that 10% to 30% of the dogs will develop neurologic signs of disease.  These clinical signs may be specific to the central nervous system and include walking in circles, seizures and blindness or they may be vague and nonspecific such as mental dullness, lethargy, poor appetite and aimless pacing.


There is no apparent relationship between the size of a pituitary tumor and the development of neurologic signs in dogs with PDH.  In dogs with a pituitary tumor, adenocarcinomas grow more rapidly than adenomas and may therefore result in more profound neurologic signs.


FDA recently gave marketing approval to Dechra Veterinary Products to manufacture trilostane or Vetoryl®.  Trilostane is a competitive inhibitor of 3ß-hydroxysteroid dehydrogenase an enzyme necessary in the body’s manufacture of cholesterol to cortisol.

Vetoryl® offers effective treatment for both pituitary-dependent hyperadrenocorticism (PDH) and adrenal-dependent hyperadrenocorticism (ADH).


In a study involving 28 dogs with naturally occurring hyperadrenocorticism trilostane at low doses every 12 hours was found to be an effective treatment.  Two dogs became ill during treatment and it was suggested that a lower dose may decrease potential adverse side effects.  The drug effectiveness was also seen to decrease within 8 to 9 hours following administration.
















Retinoic Acid has been shown to decrease corticotroph secretion.  Dogs treated with retinoic acid were found to have significantly reduced plasma ACTH, α-MSH, and urine cortisol/creatinine ratio. Pituitary adenomas were also shown to decrease significantly in size.  All clinical signs of disease improved and survival time was increased in all treated animals.  There were neither adverse events detected nor signs of Hepatotoxicity.  The use of retinoic acid is not only effective but appears to be extremely safe. Retinoic acid controls ACTH and cortisol hyperactivity and tumor size in dogs with ACTH-secreting tumors, leading to resolution of the clinical disease.  The one disadvantage of using retinoic acid is the price of the drug which is quite expensive at the current time.


Ketaconazole has also been used as a treatment for Cushing’s.  Ketaconazole interferes with steroid biosynthetic pathways.








“New Therapies for Canine Cushing’s Disease.”  Antech Diagnostic News.  December 2008. P. 1.


Rosenthal, Marie.  “FDA Grants Marketing Approval for Cushing’s Syndrome Drug.”  Veterinary Forum. January 2009. P 10.


Wood, Farica and Rachel Pollard.  “Diagnostic Imaging Findings and Endocrine Test Results in Dogs with Pituitary-Dependent Hyperadrenocorticism that did or did not have Neurologic Abnormalities:  157 cases (1989-2005).  JAVMA, Vol 231, No. 7, October 1, 2007. Pp. 1081-1085.




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