title: Central Hypothyroidism in Miniature Schnauzers.
abstract: BACKGROUND
  Primary hypothyroidism is a common endocrinopathy in dogs. In contrast, central hypothyroidism is rare in this species.
  
  
  OBJECTIVE
  The objective of this article is to describe the occurrence and clinical presentation of central hypothyroidism in Miniature Schnauzers. Additionally, the possible role of the thyroid-stimulating hormone (TSH)-releasing hormone receptor (TRHR) gene and the TSHβ (TSHB) gene was investigated.
  
  
  METHODS
  Miniature Schnauzers with proven central hypothyroidism, based on scintigraphy, and the results of a 3-day-TSH-stimulation test, or a TSH-releasing hormone (TRH)-stimulation test or both, presented to the Department of Clinical Sciences of Companion Animals at Utrecht University or the Department of Medicine and Clinical Biology of Small Animals at Ghent University from 2008 to 2012.
  
  
  METHODS
  Retrospective study. Pituitary function tests, thyroid scintigraphy, and computed tomography (CT) of the pituitary area were performed. Gene fragments of affected dogs and controls were amplified by polymerase chain reaction (PCR). Subsequently, the deoxyribonucleic acid (DNA) sequences of the products were analyzed.
  
  
  RESULTS
  Central hypothyroidism was diagnosed in 7 Miniature Schnauzers. Three dogs had disproportionate dwarfism and at least one of them had a combined deficiency of TSH and prolactin. No disease-causing mutations were found in the TSHB gene and the exons of the TRHR gene of these Schnauzers.
  
  
  CONCLUSIONS
  Central hypothyroidism could be underdiagnosed in Miniature Schnauzers with hypothyroidism, especially in those of normal stature. The fact that this rare disorder occurred in 7 dogs from the same breed suggests that central hypothyroidism could have a genetic background in Miniature Schnauzers.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Annemarie M W Y
authors.initials: AM
authors.lastname: Voorbij
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Peter A J
authors.initials: PA
authors.lastname: Leegwater
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Jenny J C W M
authors.initials: JJ
authors.lastname: Buijtels
authors.affiliation: Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Daminet
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Hans S
authors.initials: HS
authors.lastname: Kooistra
mesh_terms: D000818:Animals; D001483:Base Sequence; D016022:Case-Control Studies; D004247:DNA / Q000235:genetics; D004283:Dog Diseases / Q000188:drug therapy / Q000235:genetics*; D004285:Dogs; D004392:Dwarfism; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000235:genetics / Q000662:veterinary*; D008297:Male; D010375:Pedigree; D011994:Recombinant Proteins; D013961:Thyroid Gland / Q000473:pathology; D013972:Thyrotropin / Q000008:administration & dosage / Q000494:pharmacology; D037322:Thyrotropin, beta Subunit / Q000235:genetics / Q000378:metabolism; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use
chemical_list: D011994:Recombinant Proteins; D037322:Thyrotropin, beta Subunit; D013972:Thyrotropin; D004247:DNA; D013974:Thyroxine
keywords: Canine; Disproportionate dwarfism; Pituitary; TRHR gene; TSHB gene