When a cow started lagging behind the mob during mustering and experienced a sudden drop in production, our team was called to investigate. On arrival, the cow was weak, unsteady on her feet, and extremely reluctant to move. Clinical examination revealed a rapid heart rate and very pale mucous membranes, both signs pointing towards severe anaemia.
A blood sample was collected and examined under the microscope. The diagnosis became immediately clear: Theileriosis.
Theileriosis is a disease caused by a protozoal parasite that is spread by ticks. It is commonly seen throughout the northern half of New Zealand's North Island and can have a significant impact on cattle health and productivity.
Common signs of Theileriosis include:
Clinical outbreaks are often triggered during stressful periods such as transport, drying off, or calving.
The affected cow was showing signs consistent with life-threatening anaemia. After discussing treatment options with the farmer, including medication and supportive care, the decision was made to perform a blood transfusion.
A healthy donor cow was selected and screened to ensure no evidence of Theileria infection. Blood was carefully collected and transferred to the sick animal while closely monitoring for any adverse reactions.
Fortunately, the transfusion was successful, and the cow made an excellent recovery. Several months later, she was still performing well in the herd.
The next step was determining how the infection had been introduced to the farm.
Following further investigation, it was found that cattle had recently been brought onto the property from a Bay of Plenty run-off block. These animals had not received external parasite treatment before arrival, creating an opportunity for infected ticks to establish themselves.
This case highlights how easily Theileria can be introduced through stock movements and the importance of biosecurity when bringing new animals onto the farm.
To help protect your herd:
If you have concerns about Theileria, tick control, or protecting your herd from disease risk, talk to your local Vetora team. We can help develop a practical parasite management plan that suits your farming operation.
Based on a case study by Rory Speirs from Tokoroa.
