A beef cattle producer, located near Ballina NSW, also has a herd of Boer goats used for household meat consumption. The goats are kept on 43 hectares of low lying unimproved pasture and weeds near the banks of the Richmond River. Prior to the disease investigation the goats were not vaccinated. The herd was established in 2007 with approximately 50 does and three bucks but by October 2012 herd numbers had steadily declined to about 30 due to ongoing, undiagnosed mortalities. Deaths also occurred in young kids. In September 2012 at least eight goats, including a number of kids, had been found dead with no obvious signs of disease prior to their death. In early October two live goat kids of approximately eight weeks of age were found in lateral recumbency, unable to stand. The farmer suspected that her neighbor was poisoning the goats. Four days after the live kids had been found a District Veterinarian from the North Coast Livestock Health and Pest Authority was tasked by both the RSPCA and the farmer to establish the cause of the most recent mortalities.
The two live goats were both laterally recumbent with a "sawhorse" posture and a dorsal curve in the spine. The tails were deviated to one side. It was not possible to open the mouth of either kid and saliva was drooling from the mouths. One of the kids had a prolapsed third eyelid. The kids could not be made to stand and did not respond to stimuli. When carried the kids were as "stiff as a board" with no flexing or extension of any muscle groups. The kids were both euthanized.
No gross abnormalities were identified with detailed necropsy of both kids. On the basis of clinical history, examination and necropsy a field diagnosis of tetanus was made. The farmer requested testing to be done for strychnine poisoning.
Stomach contents from both kids were sampled and sent to Elizabeth Macarthur Agricultural Institute at Menangle, NSW for strychnine testing. Both samples were negative in a strychnine qualitative analysis. The brain of each kid was also submitted for histopathology with no abnormalities detected.
Tetanus is caused by the spore-forming bacterium Clostridum tetani that is present in the faeces of animals and can survive in the soil for many years (Radostits et al 1994). Disease is caused by the production of a powerful neurotoxin. The bacterium usually enters through puncture wounds but "idiopathic tetanus", where toxin is presumed to be produced within the gastrointestinal tract, is also described (Radostits et al 1994). Tetanus is considered particularly common in the goat (Hungerford, 2007).
In this case the lack of vaccination, the classic clinical signs and the lack of gross pathology at necropsy were highly suggestive of tetanus. Strychnine poisoning can cause similar signs of diseases but the duration of illness would normally be more rapid compared to tetanus (Radostits, 1994). No obvious wounds were found on the kids so this may have been a case of "idiopathic tetanus" or perhaps the rough feed in the paddock had caused entry of infection through small mouth wounds. The farmer was recommended to introduce a vaccination program to the herd.