Comparative Study of the Use of Doxycycline and Oxytetracycline to Treat Anaplasmosis in Fattening Lambs

SIMPLE SUMMARY: Ovine anaplasmosis has been causing relevant economic losses during the last years due to icteric lamb carcasses condemnation. They are apparently healthy lambs in good body condition that, after being slaughtered, show an icteric coloration of their carcasses. Anaplasmosis produces strong haemolysis that leads to an increase in bilirubin that stains the carcasses. The present work analyzes the therapeutic effect of oxytetracycline and doxycycline in Anaplasma ovis infected fattening lambs. ABSTRACT: Lamb icteric carcasses condemnation due to Anaplasma ovis is causing relevant economic losses. A comparative study was developed on the effects of different antibiotics to treat ovine anaplasmosis in fattening lambs. A total of 100 A. ovis naturally infected lambs were selected and randomly divided into four groups of 25 lambs: Group ID, treated with injectable doxycycline; Group OD, oral doxycycline; Group O, injectable oxytetracycline; and Group C, untreated animals for the control group. Clinical, haematological, and molecular analyses were performed before the treatment and 12 and 45 days after the beginning of the treatments, and carcass condemnation was followed after slaughter. The A. ovis bacterial load was high before the treatments in the four groups and decreased significantly 45 days after treatment in the ID and O Groups (p < 0.001). The parameters that were related to haemolysis showed similar results. At the abattoir, 15 out of the 47 examined carcasses were condemned; 7 of C Group, 6 of OD Group, 2 of O Group, and 0 of ID Group. It can be concluded that injectable doxycycline and oxytetracycline significantly reduce A. ovis bacterial load in blood and carcass condemnation at the abattoir. Further studies are needed in order to confirm these encouraging findings.