Bilateral femoral capital physeal fractures in an adult cat with suspected congenital primary hypothyroidism

Abstract

A 4-year-old, neutered male European shorthair was presented for evaluation of right hind limb lameness. Radiographs revealed bilateral femoral capital physeal fractures, widened vertebral growth plates and constipation. Physical findings included lethargy, mental dullness, mild hypothermia, retarded growth, pharyngeal stridor, moderate muscle atrophy of pelvic limbs, hair coat abnormalities, and lack of defecation and urination. A thyroid panel revealed thyroid hormone values below detection limits and high thyroid stimulation hormone values. A presumptive diagnosis of congenital primary hypothyroidism was made, however also an early onset acquired primary hypothyroidism could not be ruled out. Results of the insulin-like growth factor (IGF-1) and the parathyroid hormone as well as an adrenocorticotropic hormone stimulating test were normal. A bilateral femoral head and neck excision was performed. Levothyroxine supplementation was started at a dosage of 50 µg (11 µg/kg) BID and later adjusted to 100 µg (22 µg/kg) BID based on total thyroxine concentrations. The tomcat showed full clinical recovery and normal clinical behaviour. The case shows that primary hypothyroidism may be considered in cats presented with femoral capital physeal fractures.

Zusammenfassung

Ein 4 Jahre alter, kastrierter Europäisch-Kurzhaar-Kater wurde aufgrund einer Lahmheit der rechten Hintergliedmaße vorgestellt. Die röntgenologische Untersuchung zeigte eine beidseitige Fraktur der proximalen Epiphysenfuge des Femurs, verbreiterte offene Wachstumsfugen der Wirbelkörper und eine Koprostase. In der Allgemeinuntersuchung fielen Lethargie, Abgestumpftheit, geringgradige Hypothermie, Wachstumsverzögerung, pharyngealer Stridor, mittelgradige Muskelatrophie der Hinterextremitäten, Haarkleidveränderungen sowie fehlender Kot- und Urinabsatz auf. Die Konzentration der Schilddrüsenhormone war deutlich erniedrigt, die Thyreotropinkonzentration dagegen erhöht. Es wurde die Verdachtsdiagnose primäre kongenitale Hypothyreose gestellt, wobei differenzialdiagnostisch eine sehr früh vor dem Schluss der Wachstumsfuge erworbene primäre Hypothyreose nicht ausgeschlossen werden konnte. Sowohl der Wert des Insulin-Like Growth Factor (IGF-1) als auch die Parathormonkonzentration lag im Referenzbereich. Der ACTH-Stimulationstest verlief negativ. Es wurde eine bilaterale Femurkopfhalsresektion durchgeführt und eine Therapie mit Levothyroxin eingeleitet. Die initiale Dosis von 50 µg (11 µg/kg) zweimal täglich wurde nach Kontrolle der Thyroxinkonzentration auf 100 µg (22 µg/kg) zweimal täglich erhöht. Die klinischen Symptome des Katers bildeten sich unter der Substitutionstherapie vollständig zurück. Der Fall zeigt, dass bei Katzen mit Fraktur der proximalen Femurepiphysenfuge eine primäre Hypothyreose als Ursache berücksichtigt werden muss.

Key words

Femur - feline - thyroid gland - thyroxine - TSH

Schlüsselwörter

Oberschenkelknochen - felin - Schilddrüse - Thyroxin - TSH

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