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Congenital Panhypopituitarism (view source)
Revision as of 13:47, 21 February 2011
, 13:47, 21 February 2011Created page with "Also known as ''Pituitary Dwarfism'', Congenital Panhypopituitarism is defined by failure of differentiation of oesophageal ectoderm from which the pituitary is derived. The pit..."
Also known as ''Pituitary Dwarfism'', Congenital Panhypopituitarism is defined by failure of differentiation of oesophageal ectoderm from which the pituitary is derived. The pituitary is replaced by a cystic dilatation of ''Rathke's Cleft'' which replaces normal tissue with multilocular cysts- lined with non-secretory cuboidal epithelium.
[[Image:Pituitary dwarfism.jpg|right|thumb|125px|<small><center>'''Cystic Rathke's Pouch'''. Courtesy of A. Jefferies</center></small>]]
''Incidence:''
*Seen in German Shepherd Dog. Inherited as a simple autosomal recessive trait in affected dogs.
*Congenital hypoplasia of the pituitary in the cat has also been reported.
''Clinical signs:''
Variable with degree of involvement of the pituitary. Most obvious signs are due to the lack of [[Pituitary Growth Hormone - Anatomy & Physiology|GH]] during the growing phase of the puppy's life:
*Pups appear normal at birth as the placenta supplies the foetus' need for GH.
*Retarded growth and proportionate dwarfism.
*Delayed growth plate closure; long bone physes normally close at 7-12 months but those of a pituitary dwarf will remain open until 3-4 years.
*Delayed dental eruption.
*Prognathism; undershot lower jaw as GH needed for mandible length.
*Pups are quieter, more nervous and perhaps slower to learn.
*Retention of puppy coat; wooly. Adult coat does not develop and a bilaterally symmetric, non-pruritic alopecia occurs over areas of friction E.g. neck and trunk.
*Hyperpigmentation with '''comedomes'''.
*Reproductive signs E.g. failure to cycle, testicular atrophy.
May also see signs of
*Secondary hypothyroidism
*Secondary hypoadrenocorticism
''Diagnosis'':
*Presumptive diagnosis based on signalment and clinical signs.
*Radiography to detect growth plate closure.
*'''GH stimulation test'''; Use alpha-2 agonist E.g. ''Xylazine'' which inhibit somatostatin and so induce GH production and release. Normal dogs will have 2-4X increased GH after 20 mins while a pituitary dwarf will show little change in GH upon stimulation.
*'''Somatomedin Assay'''; Also called '''insulin-like growth factors'''. GH mediates its effects by stimulating the production of IGFs which can be more easily measured. Low levels will be found in pituitary dwarfs.
*May also need to consider TSH and ACTH stimulation tests.
''Treatment:''
Need to treat early or will remain dwarfs.
*Sub-cut bovine/human GH can induce the growth of an adult haircoat. <br>Nb. GH is '''diabetogenic''' so overdose will induce Diabetes Mellitus.
*Progestagens may induce GH production from the mammary gland.
*May need to replace thyroid hormones and/or glucocorticoids.
[[Category:Pituitary Gland - Pathology]]
[[Image:Pituitary dwarfism.jpg|right|thumb|125px|<small><center>'''Cystic Rathke's Pouch'''. Courtesy of A. Jefferies</center></small>]]
''Incidence:''
*Seen in German Shepherd Dog. Inherited as a simple autosomal recessive trait in affected dogs.
*Congenital hypoplasia of the pituitary in the cat has also been reported.
''Clinical signs:''
Variable with degree of involvement of the pituitary. Most obvious signs are due to the lack of [[Pituitary Growth Hormone - Anatomy & Physiology|GH]] during the growing phase of the puppy's life:
*Pups appear normal at birth as the placenta supplies the foetus' need for GH.
*Retarded growth and proportionate dwarfism.
*Delayed growth plate closure; long bone physes normally close at 7-12 months but those of a pituitary dwarf will remain open until 3-4 years.
*Delayed dental eruption.
*Prognathism; undershot lower jaw as GH needed for mandible length.
*Pups are quieter, more nervous and perhaps slower to learn.
*Retention of puppy coat; wooly. Adult coat does not develop and a bilaterally symmetric, non-pruritic alopecia occurs over areas of friction E.g. neck and trunk.
*Hyperpigmentation with '''comedomes'''.
*Reproductive signs E.g. failure to cycle, testicular atrophy.
May also see signs of
*Secondary hypothyroidism
*Secondary hypoadrenocorticism
''Diagnosis'':
*Presumptive diagnosis based on signalment and clinical signs.
*Radiography to detect growth plate closure.
*'''GH stimulation test'''; Use alpha-2 agonist E.g. ''Xylazine'' which inhibit somatostatin and so induce GH production and release. Normal dogs will have 2-4X increased GH after 20 mins while a pituitary dwarf will show little change in GH upon stimulation.
*'''Somatomedin Assay'''; Also called '''insulin-like growth factors'''. GH mediates its effects by stimulating the production of IGFs which can be more easily measured. Low levels will be found in pituitary dwarfs.
*May also need to consider TSH and ACTH stimulation tests.
''Treatment:''
Need to treat early or will remain dwarfs.
*Sub-cut bovine/human GH can induce the growth of an adult haircoat. <br>Nb. GH is '''diabetogenic''' so overdose will induce Diabetes Mellitus.
*Progestagens may induce GH production from the mammary gland.
*May need to replace thyroid hormones and/or glucocorticoids.
[[Category:Pituitary Gland - Pathology]]