The “tick disease “ Theileria has again this spring continued its insidious spread through dairy cattle herds of the upper North Island including the Bay of Plenty, as well as further down the country. Nationwide cases have been reported since September 2012 with the rate of new farms being infected each week showing that in due course virtually every cattle farm (both dairy and beef) will become infected at some point in the short to medium term.
The distribution generally follows the known distribution of the cattle tick, but there have been confirmed cases on the West Coast of the South Island and other random occurrences’ outside the tick zone. Many cows are infected without becoming clinically ill, while others are devastated by the infection and do not survive. September is the peak month for new infections, associated with the stress of calving and weather. Young stock are also vulnerable especially over the New Year period when other post weaning stresses start to figure and again in the late autumn.
The main effect of the blood borne parasite is to cause anaemia in cattle cow due to destruction of red blood cells.
What to look out for
- lethargy, weakness, depression, inappetance, poor milk production, mortality
- pale or yellow mucous membranes ie. gums, vulva and white of the eyes
- increased respiration and heart rates, raised temperature
- bloody urine
There is a treatment (Buparvaquone) available which improves the chance of survival, however the drug comes with a very long milk withholding period and an 18 month meat withholding period and some other conditions of use which have limited its use considerably. An additional option is to give a blood transfusion which does give an immediate response in the worst affected cows when done early in the disease course. Some cows will recover with supportive treatments, plus vitamin injections and tonics.
The most important preventative measure you can take is to control ticks on your cattle with Flumethrin or Bayticol. Over summer and into the autumn is a good time for this with the aim of reducing the number of ticks before risk periods. If you already see ticks on your cattle or you have cattle sick with Theileria unfortunately the best time to treat ticks was yesterday so to speak. All the same the impact of disease on your cattle may be mitigated if tick control is done at the next available opportunity. Don’t forget stock movement including bulls – ideally all stock should be treated coming on to or leaving the farm.
If you suspect any of your animals have anaemia feel free to contact your local large animal vet for advice.
Phil Rennie: BVSc, MACVSc