Monita Vereecken

Adenovirus infections in pigeons: A review

In the present article, a review is given on adenovirosis in pigeons. Aetiology, pathogenesis, clinical signs, lesions, diagnosis and control of two clinical types of pigeon adenovirus infections are described.

The effect of vaccination on the course of an experimental Salmonella typhimurium infection in racing pigeons.

Two killed adjuvanted vaccines were evaluated for their efficacy against salmonellosis in pigeons. Both vaccines contained whole-cell formaldehyde-inactivated Salmonella typhimurium var. Copenhagen bacteria. Two groups of 10 pigeons were inoculated twice with a 3-week interval with one of the vaccines. Ten weeks after the second vaccination, all vaccinated pigeons as well as 10 non-vaccinated birds were challenged by crop inoculation of 109 colony-forming units of a Salmonella serotype Typhimurium var. Copenhagen strain. Ten pigeons that were not vaccinated or challenged served as negative controls. As determined by clinical examination, plasma chemistry and necropsy, neither vaccine induced protection against challenge. The only significant effects observed were a reduction in the level of faecal shedding and a less severe polydipsia in the pigeons treated with one of the two vaccines. Results of this study indicate that vaccination against salmonellosis in pigeons with killed vaccines may not be very useful. However, the ability of certain vaccines to reduce shedding may contribute to the control of salmonellosis in infected pigeon lofts.

Plasma biochemistry in pigeons experimentally infected with Salmonella.

Ten pigeons were crop inoculated with 1 x 10(9) colony-forming units of Salmonella typhimurium var. Copenhagen and observed during 28 days. Ten sham-inoculated pigeons served as noninfected controls. Clinical signs after Salmonella infection consisted of polydipsia, polyuria, and diarrhea. Morbidity was 90%, but there was no mortality. All inoculated pigeons showed fecal excretion of Salmonella for at least 7 days. Biochemical analysis of plasma samples taken at 3-day intervals indicated decreased concentrations of creatine kinase (CK)-MM and CK-MB isoenzymes and elevated total protein and alpha- and gamma-globulin values. No consistent changes in the level of 17 other blood parameters were observed. After 28 days, all pigeons were necropsied. Gross lesions and bacteriologic and histologic examination indicated septicemia in all Salmonella-inoculated pigeons. Results indicate that Salmonella septicemia in pigeons induces only limited changes in biochemical blood parameters. Decreased CK concentration was a consistent finding, however, and may therefore be a useful aid in the diagnosis of salmonellosis in pigeons.

Efficacy of tiamulin alone or in combination with chlortetracycline against experimental Mycoplasma gallisepticum infection in chickens

ABSTRACT Mycoplasma gallisepticum (M. gallisepticum) remains one of the most important diseases in poultry production. Controlling the impact of the disease is done by eradication of positive breeder flocks or by vaccination and medication. A widely used molecule in medication programs is tiamulin, a pleuromutilin antibiotic. Since recent data on the in vivo efficacy of this molecule are scarce, 2 challenge studies were conducted using a recently isolated M. gallisepticum strain belonging to the wildtype population with regard to its tiamulin and tetracycline minimum inhibitory concentration (MIC). In the first challenge study, the dose rate of tiamulin was tested. For this, broilers were infected with M. gallisepticum and treated with 10 mg or 25 mg tiamulin hydrogen fumarate (hf)/kg body weight (BW) for 5 successive days. In a second challenge study, the dose rate of tiamulin combined with chlortetracycline was tested. For this, broilers were infected with M. gallisepticum and treated with 6.25 mg tiamulin hf/18.75 mg chlortetracycline hydrochloride (hcl)/kg BW or 12.5 mg tiamulin hf/37.5 mg chlortetracycline hcl/kg BW for 5 successive days. Clinical scoring of respiratory signs, macroscopic scoring of respiratory tract lesions, M. gallisepticum isolation from the respiratory organs, weight gain, and mortality were the monitored efficacy parameters. The first study demonstrated that a 5‐day 10 mg/kg BW tiamulin hf treatment provided significant protection against the M. gallisepticum infection. However, since the 5‐day 25 mg/kg BW group was significantly better than the 10 mg/kg BW for reducing the post‐treatment clinical signs and the M. gallisepticum numbers in the respiratory organs, the 25 mg/kg BW treatment is recommended for clinical M. gallisepticum infections. In the second study, the combined 12.5 mg tiamulin hf/37.5 mg chlortetracycline hcl/kg BW resulted in a significant reduction of the severity of clinical respiratory disease post treatment and a significant reduction of the M. gallisepticum numbers in the respiratory tract.