1. Department of Animal-, Wildlife- and Grassland Sciences, Bloemfontein 9301, South Africa
2. Kroonstad Dierehospitaal, Kroonstad 9500, South Africa
3. Department of Anatomical Pathology and National Health Laboratory Services, Bloemfontein 9301, South Africa
4. Department of Mathematical Statistics and Actuarial Science, Bloemfontein 9301, South Africa