CYSTIC OVARIAN FOLLICLES AND THYROID ACTIVITY IN THE DAIRY COW

Thyroid activity affects the functionality of the reproductive axis and thyroid dysfunction has been associated with ovarian hyperstimulation syndrome and polycystic ovarian syndrome, in human medicine. This study investigates serum17- < beta> estradiol, progesterone, thyrotropic and thyroid hormone levels, in cyclic dairy cows on heat (Group H) and in dairy cows with ovarian follicular cysts (Group FC). Both 17- < beta> estradiol and progesterone serum concentrations were statistically higher in cystic than in cyclic cows (estradiol: 8.51 ± 1.91 vs 6.32 ± 1 pg/mL) (progesterone: 0.49 ± 0.17 vs 0.13 ± 0.03 ng/mL), whereas TSH and fT4 serum concentrations were statistically lower in cows with cystic ovarian follicles (COF), compared to cyclic ones (TSH: 2.48 ± 1.31 vs 3.56 ± 1.03 ng/mL) (fT4: 5,86 ± 1.69 vs 8.63 ± 1.08). fT3 serum levels were similar, in both cystic and cyclic subjects (2.94 ± 0.65 vs 3.02 ± 0.9, respectively). Standing on these results, a look to the functioning of thyrotropic axis should be given in dairy cows with COF, just like it is routinely performed in human gynaecology, in case of ovarian diseases. If severe hypothyroidism should be found, a hormone replacement therapy could be attempted in cystic cows refractory to “ordinary” therapies