Effects of levamisole on pregnancy in ewes

The effects of levamisole, as an anthelmintic or immunomodulator, on pregnancy were investigated in ewes. Immunomodulatory and anthelmintic doses of levamisole and physiologic saline were injected on days 0 (oestrus), 7, 14, and 21 in group I (immunomodulatory dose; n=7), group II (anthelmintic dose; n=6), and group III (control; n=6), respectively. The first service pregnancy rate, tended to be lower (P<0.06) in group I (28.6%) compared to that of groups II (83.3%) and III (83.3%). Plasma progesterone (P-4) concentration was significantly higher (P<0.05) in group II compared to that of group III on day 3, and there was a treatment x day interaction (P<0.05). No effect of levamisole treatments on plasma P-4 concentrations was detected once pregnancy was established. There was a numeric decline in plasma cholesterol concentrations in group II, compared to group I or III on day 3. In conclusion, levamisole as an immunomodulator is detrimental for the establishment of pregnancy, possibly by stimulating general and intrauterine immunity.