Congenital Hypothyroid Dwarfism in a Family of Giant Schnauzers

Abstract

Congenital hypothyroid dwarfism was diagnosed in a family of Giant Schnauzers. Three female and two male puppies from different litters were evaluated for dwarfism, lethargy, somnolence, gait abnormalities, and constipation. On physical examination, disproportionate dwarfism (n = S), macroglossia (n = 3), hypothermia (n = 3), delayed dental eruption (n = 3), ataxia (n = 2), and abdominal distension (n = 1) were identified. Results of initial laboratory tests showed anemia (n = 4), hypercholesterolemia (n = 4), hypercalcemia (n = 2), and transudative abdominal effusion (n = 1). Radiographic skeletal surveys disclosed epiphyseal dysgenesis and delayed skeletal maturation (n = 5). A diagnosis of hypothyroidism was established on the basis of low basal serum thyroxine concentrations that failed to increase following the administration of TSH (n = 5) and markedly reduced to absent thyroid image when evaluated with gamma camera imaging of the thyroid gland (n = 4). In the two dogs that were most thoroughly evaluated, the results of thyroid histology, prolonged TSH testing, and repeat thyroid imaging, after three daily injections of TSH, were all consistent with secondary or tertiary, rather than primary, hypothyroidism. When TSH was administered over a period of 3 consecutive days (5 IU/day, subcutaneously), serum thyroid hormone response became normal and resulted in a normal thyroid image in the two dogs re-evaluated with gamma camera imaging. Daily treatment with oral levothyroxine (20 ug/kg) resulted in complete remission in puppies (n = 4) treated prior to 4 months of age. The other puppy failed to attain normal breed standards for height. Pedigree analysis suggests an autosomal recessive mode of inheritance for the development of congenital hypothyroidism in this family of Giant Schnauzers. (Journal of Veterinary Internal Medicine 1991; 557-65) CONGENITAL CENTRAL hypothyroidism is a rare endocrine disorder of both man and animals resulting from deficiency of, or end-organ resistance to, thyrotropin (TSH) or thyrotropin releasing hormone (TRH) at birth.'-3 Because thyroid hormone secretion is essential From the

Hipotireoidismo congênito primário em cão: relato de caso

“…O hipotireoidismo congênito é de rara ocorrência e acomete mais comumente filhotes de até um ano de idade, sendo relatado em algumas raças de cães (Fyfe et al, 2003;Pettigrew et al, 2007;Greco et al, 1991;Mooney & Anderson, 1993).…”

“…Casos de disgenesia da tireóide em cães mestiços de Pastor alemão foram relatados por Greco et al (1985) e em Boxer relatado por Mooney & Anderson (1993). O hipotireoidismo congênito central foi relatado em Shnauzer gigante (Greco et al, 1991) e em um cão da raça Boxer (Mooney & Anderson, 1993).…”

Hypercalcaemia in a dog with primary hypothyroidism : clinical communication

“…In humans with adult-onset hypothyroidism serum concentrations of calcium and phosphorus are typically within normal limits 7 , whereas in congenital hypothyroidism up to 23 % of children exhibit hypercalcaemia with elevated concentrations of PTH and calcitriol 8 . Mild hypercalcaemia (up to 3.04 mmol/ ) has been reported in dogs with congenital hypothyroidism 4,5 , with untreated puppies continuing to show mildly elevated serum calcium levels during adulthood 4 . The proposed mechanism for the hypercalcaemia is decreased renal clearance and/or increased gastrointestinal absorption of calcium 5 .…”

“…Mild hypercalcaemia (up to 3.04 mmol/ ) has been reported in dogs with congenital hypothyroidism 4,5 , with untreated puppies continuing to show mildly elevated serum calcium levels during adulthood 4 . The proposed mechanism for the hypercalcaemia is decreased renal clearance and/or increased gastrointestinal absorption of calcium 5 . The dog in this report had markedly elevated serum calcium levels together with what would appear to be a compensatory low PTH.…”

“…Less common and less specific abnormalities are mild increases in alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activity, and creatine kinase 11 . Mild hypercalcaemia has only been reported in dogs with congenital hypothyroidism 4,5 , with the proposed mechanism being decreased renal clearance and/or increased gastrointestinal absorption of calcium 5 . Untreated hypothyroid puppies continue to show mildly elevated serum calcium levels during adulthood 4 .…”