STILLBIRTH PERINATAL WEAK CALF SYNDROME - A STUDY OF CALVES WITH AN ABNORMAL THYROID-GLAND/

Data collected from 365 calves dead from stillbirth/perinatal weak cal f syndrome were analysed to determine the predictive value of thyroid gland weight as an indicator of abnormality of the thyroid gland, and to examine the relationships between abnormality of the thyroid gland and other findings in the calves and also the parity of the dam. There was a significant relationship (P<0.001) between the thyroid gland we ight and bodyweight for the calves with a histologically normal thyroi d gland, but there was no such relationship for calves with an abnorma l thyroid gland, Only 1.1 per cent of the histologically normal thyroi d glands weighed more than 30 g, indicating that there is a very high probability that glands weighing more than 30 g are abnormal, However, 76.0 per cent of moderately to severely affected glands weighed less than 30 g, The following significant differences between calves with a n abnormal and those with a normal thyroid gland were established. Abn ormal thyroid glands were significantly heavier (P<0.01), constituted a significantly greater percentage of the calf's bodyweight (P<0.01) a nd had a significantly lower iodine concentration (P<0.001). A signifi cantly higher proportion of calves with an abnormal thyroid gland had uninflated lungs (P<0.01), and a significantly higher proportion had p neumonia (P<0.01). Abnormal thyroid glands were associated with a low selenium concentration in the kidneys, There were no associations betw een abnormalities of the thyroid gland and the parity of the dam, the presence of skeletal fractures, the weight or sex of the calf, infecti on with leptospira, Salmonella dublin, Bacillus species, Actinomyces p yogenes or Aspergillus species, the quantities of hepatic iron pigment , liver vitamin E concentration or serum cholesterol concentration.