Under the skin, inside the heart: Prevalence of arrhythmias triggered by bovine tick-borne diseases

Introduction

Tick-borne diseases continue to be among the most widespread health challenges affecting cattle in tropical and subtropical regions, where they significantly reduce productivity, weaken overall health and impair reproductive efficiency. Conditions such as theileriosis, anaplasmosis and babesiosis are primarily recognized for the systemic and haematological disturbances they produce, yet recent findings point to a broader impact, particularly on the heart. The combined effects of anaemia, inflammatory stress and altered physiological balance can interfere with normal cardiac conduction, making infected animals susceptible to various rhythm abnormalities. According to Gupta et al., (2018) [4] , calves suffering from tick-borne infections frequently show electrocardiographic deviations, including increased heart rate, Ist-degree AV block, atrial premature complex, left atrial hypertrophy and right atrial hypertrophy changes suggestive of considerable myocardial strain. Hasanpour et al., (2008) [6] similarly noted that ECG alterations are commonly overlooked in tick-affected buffalo, implying that cardiac involvement may be more widespread than earlier believed. However, information on the actual prevalence and types of arrhythmias associated with these infections is still limited, especially in state like Himachal Pradesh where tick pressure remains high throughout the year. To address this gap, the present study investigates the prevalence of tick-borne infections in cattle and documents the electrocardiographic changes observed in affected animals, highlighting the need to integrate routine ECG monitoring into clinical evaluation of suspected cases.

Materials and Methods

Study area and duration

The investigation was carried out at the Department of Veterinary Medicine, Dr. G.C. Negi College of Veterinary and Animal Sciences, CSK Himachal Pradesh Agricultural University, Palampur, situated in the mid-Himalayan region. This area is endemic for tick-borne diseases in cattle. The study was conducted over a period of 17 months, from April 2024 to August 2025.

Study population

A total of 616 cattle of varying breeds, ages and sexes presented to the Department of Veterinary Medicine were examined. Animals showing clinical signs suggestive of tick-borne infections were further investigated and only those confirmed positive were included for cardiac assessment.

Diagnosis of tick-borne infections

Blood samples were collected aseptically from the jugular vein into EDTA-containing tubes. Thin blood smears were prepared, fixed in methanol, stained with Giemsa and examined under a light microscope for the presence of haemoparasites. Animals were classified according to infection type as Theileriosis, Anaplasmosis, Babesiosis or mixed infections based on the parasitological findings (Harrison et al., 2010) [5] .

Electrocardiographic Evaluation

All positive animals underwent electrocardiographic examination using base apex limb lead II (Devadevi et al., 2022) [1] . ECG recordings were taken while the animals were in a standing position. Parameters such as heart rate, rhythm, P-wave, PR interval, QRS complex, ST segment and QT interval were assessed. ECG was performed using the RMS Vesta 301i machine.

Data analysis

The prevalence of cardiac alterations was calculated for each infection type as a percentage of total positive animals.

Descriptive statistics were used to summarize the data and associations between infection type and ECG abnormalities were evaluated.

Results

Incidence of tick-borne diseases

A total of 616 cattle were presented, among which 158 (25.64%) tested positive for one or more tick-borne pathogens (Table 1).

Month and Season wise incidence of Tick-borne diseases in cattle

The monthly prevalence of tick-borne infections from May 2024 to August 2025 showed a distinct seasonal pattern (

Incidence of Tick-borne affected cattle with cardiac alterations in relation to age, sex and breed

Table 5 summarizes the distribution of cardiac changes in cattle infected with ticks. ECG-based evidence of cardiac involvement was found in nearly half of the affected population (47.46%). Female cattle accounted for 98.66% of all recorded cases, indicating a significantly higher predisposition than male cattle, demonstrating a clear sex bias. Age-wise, cardiac alterations were concentrated predominantly in the 1-5-year category, which constituted the major proportion of cases across all tick-borne pathogens, whereas cattle over 9 years and those below 1 year contributed minimally. The largest affected group, according to breed-related trends, was Jersey crossbred cattle, followed by HF crossbreds and non-descript animals. Indigenous breeds, like Red Sindhi, were only occasionally involved. The overall pattern shows that younger female Jersey crossbreds are more susceptible to tick-borne infections linked to cardiac alterations.

Discussion

According to previous epidemiological reports, Theileria annulata predominates in cattle throughout India (Ganguly et al., 2017; Krishnamoorthy et al., 2021) [3,7] . This is consistent with the incidence pattern found in this study, where Theileriosis accounted for the majority of infections, followed by Anaplasmosis. In a similar vein, the low detection of Babesiosis supports earlier research showing that Babesia bigemina circulates relatively less in Indian herds (Singh et al., 2022) [9] . The observed seasonal pattern, with lower prevalence in winter and early summer and peaks during the monsoon (July-September), is consistent with earlier reports from India. Similar seasonal trends, with Theileria annulata peaking during rainy and summer months and Babesia and Anaplasma remaining low, have been reported by (Ganguly et al., 2017; Shit et al., 2023 and Devi et al., 2025) [3,8,2] , reflecting the influence of temperature, humidity, and rainfall on tick activity and disease transmission. The results in relation to incidence of tick-borne diseases in relation to age, sex and breed supports previous research showing that crossbred and exotic cattle are more vulnerable to haemoparasitic infections (Singh et al., 2022) [9] . There was a clear sex predisposition, with males making up only a small percentage of cases (5.69%) and females making up the majority of the affected population (94.30%). Similar to the results of Shit et al., (2023) [8] and Ganguly et al., (2017) [3] , the predominance of females is probably due to herd management techniques and possible hormonal effects on immunity. The current study's prevalence of P mitrale, tachycardia, and arrhythmias is consistent with earlier reports showing abnormalities in electrocardiograms in cattle infected with Theileria and Anaplasma (Devadevi et al., 2022; Hasanpour et al., 2008) [1, 6] . With a variety of ECG abnormalities seen in infected animals, these results bolster the idea that tick-borne infections can seriously impair cardiac conduction and highlight the importance of ECG monitoring in the treatment of disease. The findings of this study clearly indicate that cardiac alterations represent an important clinical dimension of bovine tick-borne infections, with nearly half of the infected animals exhibiting measurable electrocardiographic disturbances. Theileriosis and Anaplasmosis were the principal contributors to myocardial involvement, with the highest susceptibility noted in females, Jersey crossbreds and cattle aged 1-5 years. P mitrale, tachycardia, conduction delays and rhythm disturbances emerged as the dominant ECG abnormalities, reflecting significant atrial and ventricular functional stress. The evidence highlights that tick-borne diseases impose substantial cardiovascular strain that may not be apparent through routine clinical examination alone. Incorporating ECG assessment into diagnostic workflows can improve early detection of cardiac compromise. Overall, the study emphasizes the need for enhanced monitoring and timely intervention to mitigate cardiac risks in endemic bovine populations.

Conclusion

The present study highlights that tick-borne diseases constitute a major health challenge in cattle and are frequently accompanied by significant disturbances in cardiac electrical activity. A considerable proportion of infected animals exhibited electrocardiographic abnormalities, confirming that cardiac involvement is a common and clinically relevant consequence of these infections. Among the haemoparasitic diseases identified, theileriosis and anaplasmosis were the principal contributors, with affected cattle showing a wide range of rhythm and conduction disturbances indicative of myocardial stress and altered cardiac function. The higher occurrence of infection and associated cardiac alterations in young, crossbred and female cattle suggests increased vulnerability in these groups, possibly due to differences in immunity, physiological demands and management practices. The diversity and frequency of ECG changes observed in this study indicate that cardiac dysfunction may develop even in the absence of obvious clinical signs, thereby increasing the risk of overlooked cardiac compromise. These findings underscore the importance of incorporating electrocardiographic evaluation into the routine diagnostic approach for cattle suspected of tick-borne diseases. Early identification of cardiac involvement can improve clinical assessment, support timely therapeutic intervention and enhance disease outcome. In addition, effective tick control and regular health monitoring are essential to minimize the impact of these infections. Overall, this study provides valuable evidence that tick-borne diseases have a measurable effect on cardiac function and reinforces the need for integrated diagnostic and preventive strategies in endemic cattle populations.

Acknowledgement

AcknowledgmentsI express my sincere gratitude to my advisor for their invaluable guidance and constant encouragement throughout this work. I am also thankful to my colleagues for their continuous support and helpful suggestions. Special thanks are extended to the Department of Veterinary Medicine for providing the necessary funds, facilities, and an excellent academic environment for conducting the present study.

References

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