BOVINE PASTEURELLOSIS

Causative Agent(s)

Pasteurella multocida serotype B: 2 or E:2 Pasteurella haemolytica biotype A Clinical Presentation and Epidemiology

Bovine Pasteurellosis is clinically divided into two forms: haemorrhagic septicaemia caused by P. multocida serotype B:2 and E: 2, and pneumonic pasteurellosis caused by P. haemolytica biotype A.

Haemorrhagic septicaemia been estimated that up to 5% of healthy cattle are colonized by small numbers of P. multocida serotype B: 2 or E:2, which can be shed during periods of stress. Common stressors associated with outbreaks of haemorrhagic septicaemia include high temperature and humidity, concurrent infection, poor nutrition, or work stress. Although outbreaks can occur at any time, disease is most prevalent during the rainy season. Increased outbreaks associated with high rainfall are most likely due to the multiple stressors present during this time and the moist conditions, which prolong the survival time of the organism in the environment.

Per acute cases of haemorrhagic septicaemia result in death within 8–24 hours, animals often have fever, hypersalivation, nasal discharge, and laboured respiration; however, because of the short duration of disease, these clinical signs may easily be overlooked. Acute disease can persist for up to 3 days, and less often up to 5 days, and is characterised by fever of 40°– 41.1°C, apathy or restlessness and reluctance to move, hypersalivation, lacrimation, nasal discharge that begins as serous and progresses to mucopurulent. Subcutaneous swelling in the pharyngeal region that extends to the ventral neck and brisket (and sometimes the forelimbs), progressive respiratory distress, cyanosis, terminal recumbency, and sometimes abdominal pain with diarrhoea are also seen.

Pneumonic pasteurellosis occurs commonly in young growing animals. Stress is an intrinsic condition that has consistently been reported to increase susceptibility to the infection. Clinical signs include high fever (40-41°C), respiratory distress, dullness, reduced appetite, marked depression. Others include anorexia, rapid shallow respiration followed by muco - purulent nasal discharge which is finally followed by productive cough.

Diagnostic Considerations

Blood and tissue samples should be collected for culture and isolation of P. multocida serotype B:2 or E:2 or P. haemolytica biotype A and other less common serotypes

Management and Treatment

Prevention is by the use of Killed vaccines which include bacterins, alum-precipitated and aluminium hydroxide gel vaccines, and oil-adjuvant vaccines. In patients >3 years old, an initial two doses, 1–3 months apart, are recommended, followed by booster vaccinations once or twice yearly. The oil-adjuvant vaccine provides protection for 9–12 months and is administered annually. The aluminium hydroxide gel vaccines have shorter durations of

immunity (approximately 4–5 months with variable protective efficacy), and twice-yearly booster vaccinations are recommended. It is most effective when administered 1 month before the monsoon or rainy season.

Treatment is by the use of any of the following antibiotics after culture and sensitivity tests have been conducted.

Streptomycin 10 mg/kg IM, q12h + penicillin G procaine 17,000-25,000 IU (10-15 mg)/kg IM or SC, q12-24h.
Oxytetracycline 5-10 mg/kg IM, q24h; 20 mg/kg IM; repeat after 2-4 days if depot form long acting (LA) is Calf, 10-20 mg/kg PO, q12h. Sheep, goat: 6-11 mg/kg IM or IV, daily 20 mg/kg PO, q6h.
Trimethoprim + sulphadiazine) 30 mg/kg PO, q24h 15-24 mg/kg IM or slow IV, q24h
Enrofloxacin 5-5 mg/kg IM, daily for 3-5 days for calves; 2.5-5 mg/kg SC once daily for 3-5 days or 7.5-12.5 mg/kg once for adult cattle.
Gentamicin 5 mg/kg IM
Ceftiofur 2 mg/kg PO, 3-5/7.