This is a subject we’ve written about in previous years but in the last month we’ve had one confirmed case that presented in an unusual way, along with a few other suspect cases. We have seen a noticeable increase in the occurrence of tick-borne diseases in both sheep and cattle across the last five years here. This would appear to be as a consequence of climate change leading to milder winters and wetter springs, though other factors such as increased re-wilding may have an impact in certain areas. We see these diseases mostly during the spring and autumn, periods of higher tick activity, though these periods are becoming less defined, especially during warm, wet summers. 

The bacteria at the root of Tick Born Fever is called Anaplasma and is transmitted to both sheep and cattle through the bites and feeding of ticks. Once in the blood stream, this bacteria attacks white blood cells and can severely damage an animal’s immune defences, leaving them vulnerable to further disease and infections. Particularly in lambs (Tick Pyaemia), a secondary bacteria, Staphylococcus, that lives on the skin, is introduced into the bloodstream as the tick bites it. In a normal animal with a healthy immune system, this may not be a big deal – however with the immunosuppression from Anaplasma, this bacteria can easily multiply in the bloodstream and progress to a form of septicaemia. As these bacteria are carried around the bloodstream, they begin to form small abscesses all around the body.  

Joints, muscles and tendon sheaths are a common place for these abscesses to form and can result in crippled lambs with moderate to severe lameness, despite no obvious cause in the feet. Sometimes, however, you may be able to see swollen joints. Symptoms typically appear at around 2-12 weeks old in lambs. Abscesses may also pop up in any of a lamb’s major organs: liver, lungs, kidneys, brain and spinal cord – causing ill thrift, respiratory issues, neurological symptoms (such as paralysis, wobbly gait etc) and even sudden death.  

Prevention is primarily through tick control. Sprays and pour-on products containing Cypermethrin can be applied to lambs from 7 days old and provide protection for up to 10 weeks, so where possible either wait until then to treat ewes and lambs before turnout or try to keep ewes and lambs in low-risk paddocks until they can be treated and moved away to problem pastures. In addition, administering a one-off double dose of long-acting oxytetracycline (eg 3ml for a 15kg lamb) from 3 weeks of age can offer up to 3 weeks of protection against Anaplasma. This again can be useful to do before turning ewes and lambs away to more marginal grazing, helping to protect against disease or at least defer it to an older age when the lambs may be less susceptible. Mortality and ill thrift can be reduced significantly using these two preventative measures together. Long acting oxytetracycline or amoxicillin, together with anti-inflammatories, can be used to treat affected individuals (multiple treatments may be needed at 2 day intervals) though often recovery can be poor once obvious symptoms have started.