Panhypopituitarism (Pituitary Dwarfism)

By | March 6, 2016
  • hereditary, thought to be autosomal recessive
  • German shepherd dog and carnelian bear dog are predisposed
  • most dogs have a cyst (Rathke’s cyst) in the pituitary gland
  • signs are principally related to lack of growth hormone, but there are others if the thyroid, adrenal or gonadal releasing hormones are deficient

Clinical features

  • pups are normal until approximately 3 months of age, but subsequently fail to grow
  • the puppy coat is retained and no primary hairs develop; hair is easily epilated
  • bilaterally symmetrical alopecia gradually develops during the first year of life
  • although short of stature, affected pups have virtually normal body proportions
  • hyperpigmentation usually develops in the alopecic areas
  • there may be other signs attributable to hypothyroidism or hypoadrenocorticism
  • other abnormalities which may be noted include aggression (fear biting), short mandible, delayed dental eruption, cardiac disorders, megalooesophagus and gonadal abnormalities
  • lifespan is often reduced

Diagnosis

  • history
  • physical examination and comparison with litter mates
  • rule out other endocrine disorders
  • biopsy: histopathology is that of a typical endocrinopathy — hyperkeratosis, follicular atrophy of the sebaceous glands, melanosis and thinning of the dermis; there is usually a decrease in the amount of dermal elastin
  • radiography may reveal failure of the epiphyseal lines to close by the time the dog is adult
  • growth stimulation tests show failure of growth hormone response

Differential diagnosis

  1. congenital hypothyroidism
  2. other congenital disease — renal, heart, gonadal defects
  3. juvenile diabetes mellitus
  4. malnutrition/malabsorption
  5. portal caval shunts

Treatment

  • specific treatment for thyroid, adrenocortical or gonadal abnormalities if present
  • growth hormone (difficult to obtain, expensive, may induce diabetes)
  • response may take up to 3 months
  • growth plates close rapidly and there is no appreciable increase in size

 

Selections from the book: “Skin Diseases in the Dog and Cat”. D. I. Grant, BVetMed (1991)