Abstract
Background:
For sheep in tropical/subtropical areas of the world, the reported mortality and morbidity rate regarding cardiomyopathies is quite less (1-2%), yet it has been elucidated that many sheep slaughtered for meat purposes in Pakistan have enlarged hearts with underlying cardiac abnormalities.

Aim:
The present preliminary work is the first record of deducing normal reference intervals (RIs) for various serum cardiac biomarkers namely cardiac troponin I (cTnI), alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase-myocardial band (CK-MB), sodium (Na+), potassium (K+) and total protein (TP), and their interrelationship in apparently healthy indigenous Sipli breed of sheep (n=141) from Pakistan.

Methods:
Apropos to aseptic blood collection and serum extraction, the attributes were deduced using commercially available kits. For the sake of analyses, the studied biomarkers were attributed as independent (Na+, K+, and TP) and dependent (LDH, ALT, AST, cTnI and CK-MB) variables. The RIs were determined through Reference Value Advisor Version 2.1 as per gender and age keeping in view the guidelines provided by American Society of Veterinary Pathology (ASVCP).

Results:
The RIs for cardiac serum biomarkers included in the present study were generally within the reference range provided for sheep with slight variations which might be attributed to physiological adaptation to harsh desert climate. The Na+ significantly (P≤0.05) predicted AST (adj. r-square= 0.976, 97% probability) and CK-MB (adj. r-square= 0.477, 47% probability). Similarly, K+ significantly (P≤0.05) predicted LDH (adj. r-square= 0.626, 62% probability) and ALT (adj. r-square= 0.897, 89% probability). The TP had highest adjusted r-square of 0.770 (77% probability) with AST however it was statistically non-significant (P≥0.05).

Conclusion:
The results of the study present a baseline data about these cardiac biomarkers which may be utilized for cardiac assessment of the sheep. It is recommended that the serum cardiac biomarkers ascertained in this study may be studied in perspective to electrophysiology and ultrasonography of sheep heart for confirmed diagnosis/prognosis of cardiomyopathies.

Key words: Sipli sheep, Cardiac troponins, Reference intervals