Pituitary dwarfism

What is ... ?: 

 This rare disorder is a result of reduced function of the pituitary gland, which is located at the base of the brain.  This small gland secretes hormones necessary for normal growth and development. Signs are apparent at a young age and are associated with slowed development and growth.

How is ... inherited?: 

In German shepherds and Carnelian bear dogs the disorder is inherited as a simple autosomal recessive trait. The mode of inheritance has not been demonstrated for other affected breeds.

What does ... mean to your dog & you?: 

 Breeders or owners will usually notice abnormalities by 2 or 3 months of age. The signs caused by a deficiency of pituitary growth hormone (somatotropin) include slow growth rate, retained puppy coat and eventual hairlessness, darkening of the skin, delayed eruption of permanent teeth, suppressed immune responses, and an altered mental state. These pups are proportionate dwarves - that is,  they are of small stature but normal proportions - and they often have a shrill bark.

Other hormones produced by the pituitary gland are also decreased and this causes abnormalities in thyroid, adrenal, and gonadal function.
Most dogs affected with this condition will have shortened lifespans.

How is ... diagnosed?: 

 The diagnosis is usually made based on the history and characteristic clinical signs in a young dog. Your veterinarian will want to rule out other possible causes of delayed growth.

How is ... treated?: 

 Dogs are treated with replacement growth hormone (GH), which is expensive and difficult to obtain. Treated dogs must be monitored for the development of diabetes mellitus which is a potential side effect of GH therapy. Secondary hypothyroidism and hypoadrenocorticism can also be treated if indicated.

For the veterinarian: 

 

  1.      CLINICAL PATHOLOGY: may see a mild normochromic, normocytic anemia, hypoglycemia (secondary to ACTH deficiency), and hypophosphatemia (secondary to GH deficiency); often routine clinicopathologic tests show no significant abnormalities
  2.      GROWTH HORMONE CONCENTRATIONS: Growth hormone assays or serum insulin-like growth factor (IGF) assays may be  available in some laboratories [check with your diagnostic laboratory].
Breeding advice: 

 This condition is generally apparent before dogs are sold. Breeders should avoid breeding parents of affected dogs.

FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources: 

 Nichols, R., Thompson, L. 1995. Pituitary-hypothalmic disease. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine. p. 1422-1436. W.B. Saunders Co., Toronto.


What breeds are affected by ... ?
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