Abstract
Background:
Haemoparasitic infections significantly threaten cattle health globally, leading to economic losses and welfare issues for farmers.

Aim:
This retrospective study aimed to investigate the prevalence and associated factors of haemoparasitic infections in fighting bulls in southern Thailand over an eight-year period.

Methods:
Laboratory records of 5,518 bulls from the Livestock Animal Hospital, Faculty of Veterinary Science, Rajamangala University of Technology Srivijaya, were reviewed for the period January 2016 to December 2023. Blood samples were analyzed using thin blood smear methods to identify haemoparasites, and packed cell volume was measured using the microhematocrit method. Detailed profiles and demographic data for each animal were recorded.

Results:
Among the fighting bulls, 323 (5.85%) tested positive for haemoparasitic infections, with five haemoparasites identified: Trypanosoma spp. (TP), Microfilariae, Anaplasma spp. (AP), Babesia spp. (BB), and Theileria spp. (TR). TP was the most prevalent at 2.90%. Bulls aged 1–5 years showed the highest infection rates at 7.04%, with a decline in infections as age increased. Annual trends peaked in 2018 at 8.80%, with significant yearly fluctuations for most parasites (P < 0.05) except AP and BB. Monthly analyses revealed the highest infection rates in March, particularly for TP, with significant monthly variations for TR (P < 0.05). Geographical differences in infection rates between the East and West coasts were minor and not statistically significant. However, seasonal variations were significant for BB and TR on the east coast during summer (P < 0.05). Bulls with PCV below 30% had a higher prevalence of haemoparasitic infections (8.06%) compared to those with PCV above 30% (5.87%), with significant differences in the prevalence of AP and TR infections (P < 0.05).

Conclusion:
This study adds to the understanding of haemoparasite infections in bulls, informing the development of educational materials for farmers and ultimately empowering them to make better herd health decisions.

Key words: Blood parasite, Prevalence, Indigenous cattle, Bull, Epidemiological factors