Therapeutic efficacy of doxycycline against experimental Pasteurella multocida infection in broiler chickens
1998
Semjen, G. (Univ. of Vet. Sci., Budapest (Hungary). Dep. of Pharmacology and Toxicology) | Magyar, T. (Hungarian Academy of Sci., Budapest (Hungary). Vet. Med. Res. Inst.) | Laczay, P. (Univ. of Vet. Sci., Budapest (Hungary). Dep. of Pharmacology and Toxicology)
The efficacy of doxycycline was investigated in two sets of experiments. In the first experiment 40, in the second experiment 60, hence altogether 100 five-week-old Ross broilers of both sexes were used. The birds were randomly allocated into groups (A and B in experiment 1; A, B and C in experiment 2) of 20 birds in each. All birds were infected intramuscularly with approx. 2 x 1000 colony forming units of Pasteurella multocida strain X-73 (serotype A:1). Birds in groups A were non-medicated controls. Chickens in groups B were given doxycycline via the drinking water at a dose of 10 mg/kg body weight for 5 days, while group C was treated with chlortetracycline at a dose of 20 mg/kg body weight for 5 days. The trial lasted for 9 days, then the surviving chickens were sacrificed. Clinical symptoms, number of deaths, post mortem lesions and bacteriological findings were recorded using a special score system. Acute fowl cholera developed in broilers within a few hours after infection, as evidenced by the clinical symptoms the high mortality rate (90 percent of the birds died within 4 days after infection), the pathological lesions and the recovery of P. multocida from the challenged birds. Doxycycline reduced the number of deaths (30 percent and 5 percent of birds died in experiments 1 and 2, respectively) and the severity of the clinical symptoms, and P. multocida could be re-isolated only from one of the survivors. In contrast, chlortetracycline slightly influenced the mortality; however, it delayed death and reduced the severity of clinical symptoms. These data indicate that doxycycline is highly effective for the treatment of experimental pasteurellosis in chickens
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