No abstract

Haemorrhagic septicaemia (HS) is an acute disease of cattle and buffaloes caused by Pasteurella multocida 6:B. Outbreaks of the disease have been closely associated with carrier animals that transmit the organism to susceptible animals during stressful condition. This study was conducted to determine whether goats exposed intranasally to P. multocida 6:B can transmit the organism to contact goats. Thirty-six healthy local Katjang goats were divided into four groups and goats of groups 1 and 3 were each inoculated intranasally with a 1-ml inoculum that contained 1 x 10(9) CFU/ml of live P. multocida 6:B. Following the exposure, all goats of groups 3 and 4 were injected with dexamethasone at the rate of 1 mg/kg for three consecutive days. At the end of the dexamethasone treatment, goats of groups 1 and 2 were commingled but kept separate from goats of groups 3 and 4, which were commingled in another pen. Three surviving goats from each group were killed on days 7, 14 and 21 post-exposure for postmortem examination. Naso-pharyngeal mucus and heart blood were collected on swabs. Tissues from lungs, lymph nodes and tonsils were collected for bacteriological isolation and identification. Only one goat of group 3 died 6 days post-exposure showing clinical signs and lesions typical of HS. Other goats showed mild signs of upper respiratory tract infection. Goats of all groups developed acute mild pneumonic lesions, however, those treated with dexamethasone had significantly (P < 0.05) more extensive lesion scoring based on the lesion scoring system. P. multocida 6:B was isolated from the nasal mucosa and lung lesions of exposed and contact goats not treated with dexamethasone. Exposed and contact goats treated with dexamethasone carried the organism for 21 days. P. multocida isolation from heart blood was made only from exposed and contact goats treated with dexamethasone. P. multocida was isolated from the lymph node of the goat that died during the experiment.

This report describes the proliferation and transmission patterns of Pasteurella multocida B:2 among stressful goats, created through dexamethasone injections. Thirty seven clinically healthy adult goats were divided into three groups consisted of 15 goats in group A, 11 goats in group B and the remaining 11 in group C. At the start of the study, all goats of group A were exposed intranasally to 1.97 x 10(10) CFU/ml of live P multocida B:2. Dexamethasone was immediately administered intramuscularly for 3 consecutive days at a dosage rate of 1 mg/kg. The exposed goats were observed for signs of HS for a period of 1 month. At the end of the 1-month period, 11 goats from group B were introduced into and commingled with the surviving goats of group A before all goats from both groups were immediately injected intramuscularly with dexamethasone for 3 consecutive days. The treatment with dexamethasone was then carried out at monthly interval throughout the 3-month study period. Goats of group C were kept separately as negative control. Three surviving goats from each group were killed at 2-week interval for a complete post-mortem examination. Two (13%) goats of group A were killed within 24 hours after intranasal exposure to P multocida B:2 while another two (13%) goats from the same group were killed on day 40, approximately 10 days after the second dexamethasone injection. All four goats showed signs and lesions typical of haemorrhagic septicaemia. Bacteraemia was detected in 3 goats of group A that were having rectal temperature higher than 41degrees C. The P. multocida B:2 isolation pattern was closely associated with dexamethasone injections when significantly (p < 0.05) higher rate of isolations from both groups were observed after each dexamethasone injection. Transmission of P multocida B:2 from goats of group A to group B was successful when P multocida B:2 was isolated from goats of group B for a period of 28 days. There was a strong correlation between dexamethasone injections, rate of bacterial isolation and serum cortisol level. The IgG level showed an increasing trend 2 weeks after exposure to P multocida B:2 and remained high throughout the study period.