Bara at 18:43, 27 February 2011

2011-02-27T18:43:39Z

Bara: Created 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..."

2011-02-21T13:47:16Z

Created 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..."

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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]]

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 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>]]
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 [[Category:Pituitary Gland - Pathology]]

Congenital Panhypopituitarism - Revision history

Bara at 18:43, 27 February 2011

Bara: Created 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..."