Acromegaly

Acromegaly (also known as hypersomatotropism) is a hormonal condition resulting from over-secretion of growth hormone, known as Somatotropin from the pituitary gland. This hormone is responsible for growth from birth to adulthood. At adulthood, secretions of the growth hormone slow dramatically and growth normally stops. In acromegaly, the bones continue to grow. Because the bone plates will still close upon entering adulthood, continuing growth is not in normal proportions.

The effect of excess growth hormone is similar to the effect of steroids in the respect that it causes insulin resistance. Animals with acromegaly often are diabetic. Since acromegaly is an endocrine disease, its sufferers can also be prone to neuropathy.

See Acromegaly cases for current and recent case studies of cats and dogs with acromegaly.

In cats

Cats and people usually have a pituitary tumor which is the cause of acromegaly. Over 90% of feline sufferers are male; there's no sexual predisposition in humans.

The clinical features of feline acromegaly include large head and paws, forward-jutting lower jaw, weight gain, and enlarged abdomen and organs, such as the heart, liver, and kidneys.

Acromegaly was thought to be a rare condition, but a recent UK study of diabetic cats with poor to adequate glycemic control showed that nearly a third of them showed signs of acromegaly. Testing confirmed acromegaly in over 90% of those. So as many as 1 in 3 hard-to-control diabetic cats may have acromegaly!

In dogs

In dogs, the condition often develops due to excess progestrone secretion (as happens with ovarian cysts). The usual canine sufferers of acromegaly are unspayed females. Spaying usually may cure the condition, depending on whether the pancreas is still able to secrete sufficient insulin. (Any type of diabetes may if unregulated eventually shut down the pancreas; see amyloidosis.) Using medication containing progesterones can also result in an excess of growth hormone.

Treatment

Diagnosis can be difficult, but the condition can be tested for using the IGF-1 (insulin-like growth factor-1) or somatotropin test. The present best treatment for cats with pituitary tumors is radiation.

There is also a chance that acromegaly is being caused by tumors on other organs, not the pituitary. This unusual case is hard to detect since the pituitary will often be enlarged from the acromegaly, appearing on a brain scan like a tumor. Of course in this case, radiation therapy to the brain will be ineffective.

Experiences

Add protocols, suggestions, treatment options here. If you see some here already and they look disorganized, please help organize them!

Further Reading

• Acromegaly in cats support forum
• The Merck Veterinary Manual article on feline acromegaly
• Feline Acromegaly-JAAHA 2005
• Introduction to Feline Acromegaly--Axiom Vet Laboratories-UK
• OSU Endocrinology Symposium 2006-Unusual Endocrine Disorders in Dogs & Cats-Nelson-Feline Acromegaly-Page 45
• Feline Acromegaly-University of Illinois-Veterinary Clinical Medicine-Page 1
• IGF-1 Concentration as an Acromegaly Screen for Diabetic Cats-Page 20, Abstract #57, ACVIM 2006

• Progesterone-Induced Canine Acromegaly--WSAVA 2005

• Transient Diabetes Insipidus in a Dog With Acromegaly--Journal of Small Animal Practice-1999

• Pancreatic Islet Ultrastructure, Serum & Pancreatic Immunoreactive Insulin in Somatotrophic and Metasomatotrophic Diabetes in Dogs-Journal of Submicroscopic Cytology-1981
• Acromegaly-North American Veterinary Conference-2006
• Treatment of Excess Growth Hormone in Dogs with Progesterone Receptor Antagonist Aglepristone Theriogenology 2006
• Primary Hypothyroidism in Dogs is Connected with Growth Hormone (GH) Release-Utrecht University-Article in English
  Can mimic acromegaly.
• Treatment of Growth Hormone Excess in Dogs with the Progesterone Receptor Antagonist Aglepristone-Universities of Utrecht & Ghent-2006-Article in English
• Dog ear infection
• Pancreatitis in dogs
• Ivermectin for dogs
• How long are dogs pregnant
• Why do dogs eat grass
• Purina dog chow coupons

• Metasomatotrophic Diabetes & Its Induction Diabetelogica-1980

• Pet Health Library article discussing acromegaly, among other topics
• Introduction to Somatostatin, a Naturally Occurring Hormone, Used in Treating Acromegaly