Two years ago a new calf disease was reported in NZ. This was first seen on several farms in the Canterbury area and then more latterly in the Manawatu. To date there have been around 15 properties that have had a confirmed diagnosis in NZ.
The disease is caused by the bacterium Chlamydia pecorum (which was first found in NZ in the goat population about 30 years ago).
Affected calves develop neurological symptoms which include seizures and hind limb ataxia (wobbly in back legs), depression and an inability to stand. The progression of the disease is quite rapid - within 24-48 hours healthy calves may no longer be able to stand or want to suckle. The spread of infection through a mob of calves seems to be quite rapid - a high percentage of calves in the mob may have high temperatures without displaying significant illness.
The brain, heart and abdominal organs can all be affected. The pathology to the heart when viewed at post-mortem can be very dramatic (see below). The pericardium (sack around the heart) is thickened and full of fibrin (see arrow).
In September we diagnosed the first case in our practice. The affected farm has lost around 20 calves out of 350 reared, but it is probable that many more would have died had treatment not been provided. Early treatment is required to be successful. The rearer’s commented that they had not realised how sick the whole mob was until they started playing again a few days post-treatment.