Symptoms of hyperthyroid cats: a retrospective study

The clinical signs, ECG and sonographic findings were investigated in a ret rospective study with altogether 98 hyperthyroid cats of the years of 1974- 1998. The findings were only used as statistical data when clearly mentione d in the case records. The following signs were mentioned most frequently i n the history: polyphagia (72%), weight loss (71%), polydipsia (55%), vomit ing (53%), diarrhea (50%), dull haircoat and excitement teach (45%), dyspne a (40%), polyuria (37%), hyperactivity as well as general weakness teach (3 4%). The clinical examination revealed sonographically enlarged thyroid gla nds in 100% of the 21 examined cases, followed by palpably enlarged thyroid lobes on one or both sides (84%), tachycardia > 200/min (78%), and hypertr ophic cardiomyopathy (50%), investigated by echocardiography. In 26 cats an ECG examination was performed. A hyper-voltage of the R-wave was observed in 38%, an increased P-wave or a ST-segment elevation in 19% of the cases. In two cases pathologic arrhythmias could be diagnosed as AV-block II and i ll, respectively. A hypertrophic cardiomyopathy was found in one half of th e cases, but just one case developed a congestive heart failure. 53% had a systolic heart murmur or a gallop rhythm. The volumes of the thyroid lobes were sonographicaliy calculated by the formula pi/6 x length x width x heig ht. The enlarged thyroid lobes were egg shaped differing distinctly from th e spindle-like shape of the healthy organ. Of the laboratory results, serum alkaline phosphatase was - after serum-thyroxine - most frequently increas ed followed by ALT, total leukocyte number, and urea, A simultaneous increa se of serum creatinine was seen just in 4 of 84 examined cats (5 %) which h ad a kidney insufficiency besides the hyperthyroidism.