Inherited primary hypothyroidism with thyrotrophin resistance in Japanese cats

Abstract

Mutant cats were developed with non-goitrous primary hypothyroidism. They were clinically characterized by severely retarded growth, mild anaemia and high mortality in the young. They responded markedly to thyroid hormone replacement. Thyroid glands in the mutants were normal in position but slightly reduced in size. Laboratory studies revealed low serum concentrations of thyroxine (T4) and tri-iodothyronine (T3), and increased serum concentrations of TSH. Administration of TRH induced no further increase in TSH. Administration of exogenous TSH after suppression of endogenous TSH by T3 did not increase the serum concentration of T4 in the mutants, in sharp contrast with the threefold increase in serum T4 observed in the normal litter-mates. These findings suggest that the underlying pathogenesis of this disorder is unresponsive to TSH. Moreover, we found that the mutants were transmitted in an autosomal recessive manner.

Responses of the Thyroid Gland to TSH and Other Thyroid Stimulators in the Growth-Retarded (grt) Mouse

“…The development of goiter in cog/cog mice is due to a defect in thyroglobulin synthesis (Kim et al, 1998). On the other hand, non-goitrous animal models have been reported for several animals, such as hyt/hyt mice (Beamer et al, 1980), dfc/dfc cats (Tanase et al, 1991), and rdw/rdw rats (Umezu et al, 1998). The hypothyroidism in the hyt/hyt mice reflects the hyporesponsiveness of the thyroid gland to TSH (Stein et al, 1991).…”

Hypothyroidism

“…An inherited defect in iodine organification was documented in a family of Abyssinian cats with congenital hypothyroidism and goiter (Jones et al, 1992); an autosomal recessive mode of inheritance was suspected. TSH resistance was proposed to be the cause of inherited primary hypothyroidism in a colony of Japanese cats (Tanase et al, 1991). A colony of cats with hypothyroidism and thyroiditis with severe signs of hypothyroidism developing 40 to 60 days after birth has also been reported (Schumm-Draeger et al, 1996).…”

Primary goitrous hypothyroidism in a young adult domestic longhair cat: diagnosis and treatment monitoring

“…1–3 However, congenital hypothyroidism (cretinism) is also rare but is one of the most common causes of disproportionate dwarfism in kittens and is much better characterized than the adult-onset form. 4,5 Of the 60 or so cats with congenital hypothyroidism that have been reported, 6–20 only two were older than 12 months of age at time of diagnosis, 16,17 whereas another two cats were diagnosed at 7 and 8 months of age, respectively. 12,19 All of the remaining cases were diagnosed as kittens, generally at 2–4 months of age.…”