Thyroidal and Progesterone Hormones in Cows with Ovarian Cysts and Effects of Therapy with Levothyroxine, KI, GnRH and Progesterone or Ovsynch

The plasma T3, T4, TSH and progesterone concentrations in cows with ovarian cysts (OC) (n=40) before and after treatment were compared with cows without ovarian cysts (n=8). Blood was collected from all affected cows before and 10 days after last treatment and plasma was separated and stored at -200 C till assay by enzyme immunoassay. Cows with OC were randomly treated with either SC injection of 2.5mg Levothyroxine (LV)every 48 hours for 4 occasions, oral feeding (10gm daily for 5 days) of potassium iodide (KI), GnRH (40 µg, IM injection Day 0) + Progesterone (750 mg, IM injection Day 0) + KI (GPI), or Ov-Synch protocol +Progesterone (OVP). The plasma progesterone concentrations before treatment were significantly higher in cows with OC compared to normal cows. Plasma progesterone concentration increased in GPI treated cows where as it decreased in the OVP treated cows significantly. The plasma triiodothyronine (T3) and plasma thyroxine (T4) were significantly lower (before treatment) in all treated cows with OC compared to normal control cows, whereas the thyroid stimulating hormone (TSH) was significantly higher (before treatment) in cows with OC. After treatment the plasma T3 and T4 increased significantly (P<0.01) and TSH decreased significantly (P<0.01) in levothyroxine treated cows. In cows treated with other treatments there were no changes in T3, T4, and TSH concentration. Out of 40 treated cows,50%,40%,10%, 0% cows conceived in the group OVP,GPI,LV and KI respectively. It was concluded that the treatment with levothyroxine resulted in positive alteration in thyroidal hormone without affecting pregnancy rates.