Theileria Case Study

Theileria Case Study
Theileria Case Study
Theileria Case Study
Theileria Case Study
By Jemma Guyton, Veterinarian, Anexa Vets Matamata

In September, the farmer noticed that “Secrecy”, an 8-year-old Ayrshire cow had slowed down and become hollow. She had calved uneventfully, 2 weeks earlier. Her milk production had also crashed from 40L to 25L in three days. Secrecy’s membrane colour in her vulva was also extremely pale. Theileria was suspected based on a history of this on-farm - even though a case of Theileria hadn’t been seen for a couple of seasons.

Secrecy was examined by one of our vets and a presumptive diagnosis was made - suspected theileria. There are many reasons why a cow could be pale (anaemic) so a thorough examination had to be done to determine if anything else could be causing the signs that Secrecy was displaying. Nothing to indicate any other diseases was found on examination. A blood sample was taken to test the red blood cell level (also called PCV – packed cell volume). The result came back at 10%! Normal cows sit between 25-35+%!
When a PCV is 15% or less, there is cause for concern! When 12% or less, a blood transfusion may be the only thing that can save them.

So, the farmer agreed to a blood transfusion. The farmer then arranged for a couple of cows from the herd as options to be the blood donor – two middle aged cows, BCS 5, happy and healthy. One of the cows was dry, so she was selected as the first choice. A blood sample was taken to make sure she had a normal PCV – to make sure she was a suitable donor and could cope with donation. Her PCV was 34% so she was selected to donate the 5L of blood required.

The blood transfusion went well. Now it was touch and go. Secrecy was very unwell, so the farmer paid very special attention to her post-transfusion, giving her molasses and meal to try to encourage her to eat. She even got a cover to keep her protected from the horrible weather. Eventually, Secrecy started to eat and become livelier, but it wasn’t until a week later the vet and farmer were confident that Secrecy was going to make it.
She continued to improve, and 4 weeks post-transfusion was producing 30L/day.

Currently Secrecy is doing well, and her attitude has returned. She is now doing 35L/day!

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Theileria is a parasite that causes destruction of red blood cells (anemia). It is carried and spread by ticks.

Classic symptoms: dairy cow during a stressful period (esp around calving time) or a beef calf around 4-12 weeks of age. Off-colour and runs out of breath when walking. The vulva is a pale/yellow in colour instead of pink (see the Field Anaemia Nearest Indicator (FANI) card (pic 4)

Call a vet if you notice these symptoms.




Pic 1: 4 days post transfusion
Pic 2: 2.5 weeks post transfusion
Pic 3: 6.5 weeks post transfusion
Pic 4: FANI card

Date Added: Tuesday, 1st December 2020


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