Pasteurellosis is a disease seen in wildlife, particularly at this time of the year when animals are under stress due to body condition deterioration as a result of drought, high dust levels and cold spells at the end of July and August.
The main bacteria involved are Mannheimia haemolytica and Pasteurella multocida. These bacteria can account for syndromes ranging from acute mortalities (called haemorrhagic septicaemia) to more chronic forms of pneumonia (bronchopneumonia). Vaccination by drop out darts are quite effective in the case of an outbreak. In smaller herds the administration of antibiotics like tilmicosin or draxxin can be used effectively. Common vaccines used as preventative measures are Onderstepoort's Leukopast or pasteurella vaccine, respiravax, Multivax P,rhinovax etc.
Animals are less likely to develop this disease when nutrition is optimal and other stressors are kept to a minimum e.g. parasite burdens, population overload, rearrangement of social hierarchy, early weaning etc.
It is crucial if this disease is suspected that a veterinarian with experience be contacted to make a quick and accurate diagnosis to prevent further mortalities.
The first sign that indicates that you might be dealing with pasteurella is if you lose one or two animals very acutely (rapidly) and close together. With haemorrhagic septicaemia cases this can be less than 24 hours. With primary pneumonia cases it can take slightly longer and coughing animals with nasal discharge can be seen, this is more common in feedlot situations with cattle when overcrowding and dusty conditions predispose animals to irritation of airways, which lead to a raw surface in the soft palate, windpipe (trachea) and lower airways where bacteria can have an entry point.
These organisms are commensal bacteria (in the airways under normal circumstances) but they cause disease when stress factors mentioned previously are at play.
Preventative vaccination during risk periods remains the best method along with proper planning of nutritional requirements and stocking densities of farms and camps. Buffalo tend to be particularly susceptible to pastuerellosis this time of year.
It is very important that a thorough post mortem examination be done on a fresh carcass to ensure accurate diagnosis through sampling of the right organs, tissues and fluids. A cold room on farms dedicated to incidents like these or any other mortalities are invaluable for managerial purposes.