Evaluation of haematological parameters in haemolytic anaemia caused by tick‐borne pathogens in grazing cattle
Youngjun Kim, Ji‐Young Ku, Youngwoo Jung, Young‐Hwan Lim, Min‐Jeong Ji, Yu‐Jin Park, Hyung‐Chul Cho, Kyoung‐Seong Choi, Jinho Park- General Veterinary
Abstract
Background
No tick‐borne pathogens (TBPs) causing haemolytic anaemia in cattle have been reported, except Theileria orientalis and complete blood count (CBC) profile is the only haematological parameter to determine the severity of regenerative haemolytic anaemia.
Objectives
To identify the causative agents of TBP‐induced haemolytic anaemia and determine haematological parameters that indicate haemolytic anaemia in grazing cattle.
Methods
Eighty‐two Korean indigenous cattle (Hanwoo) were divided into two groups: grazing (n = 67) and indoor (n = 15) groups. CBC and serum biochemistry were performed. PCR was conducted using whole blood‐extracted DNA to investigate the prevalence of TBPs.
Results
TBP‐induced haemolytic anaemia was observed in the grazing group. In grazing cattle, co‐infection (43.3%, 29/67) was most frequently detected, followed by T. orientalis (37.6%, 25/67) and Anaplasma phagocytophilum infections (1.5%, 1/67). In indoor cattle, only co‐infection (20%, 3/15) was identified. Grazing cattle exhibited regenerative haemolytic anaemia with marked monocytosis, mild neutropenia, and thrombocytopenia. According to grazing frequency, the 1st‐time grazing group had more severe anaemia than the 2nd‐time grazing group. Elevations in indirect bilirubin and L‐lactate due to haemolytic anaemia were identified, and correlations with the respective markers were determined in co‐infected grazing cattle.
Conclusions
Quantitative evaluation of haematocrit, mean corpuscular volume, and reticulocytes (markers of regenerative haemolytic anaemia in cattle) was performed for the first time. Our results show that, in addition to T. orientalis, A. phagocytophilum is strongly associated with anaemia. The correlation between haemolytic anaemia severity and haematological parameters (indirect bilirubin, reticulocytes, and L‐lactate) was confirmed.