Rovedar Journal of Veterinary Physiology and Pathology 2821-0328 2 2 2023 06 05 Pyelonephritis and Polycystic Kidneys in a Male Holstein Calf 9 11 10.58803/jvpp.v2i2.23 eng Akbar Nikkhah Chief Highly Distinguished Professor and Nutritional Scientist, National Elites Foundation, Tehran, Iran. anikkha@yahoo.com Masoud Alimirzaei Behroozi Dairy CO., Tehran, Iran. rovedarpub@gmail.com 2023 06 05 2023 06 05 Introduction: Pyelonephritis and cystitis in cattle are urinary tract bacterial infections that can ascend to the kidneys and cause inflammation. This study presented a rarely-seen clinical kidney complication in a male Holstein calf. This problem was accompanied by respiratory tract infections. Bacterial infection caused bovine pyelonephritis and cystitis and consequently, there was an inflammation in the kidneys. A wide range of bacteria were responsible for such infections.   Case report: A 5-day-old male Holstein calf was initially diagnosed with high body temperature (> 40˚C), followed by respiratory signs. Treatment with antibiotics and anti-inflammatory drugs (dexamethasone and gentamicin) began immediately after diagnosis of the high body temperature, but the clinical signs, such as appetite loss and cough did not fully disappear. The calf’s growth was hindered and finally, died at the age of 90 days. Post-mortem necropsy findings included inflamed and cystic kidneys that coexisted with severe lung infections. Conclusion: The present uncommon renal complication may provide further information about the physiology and pathology of such rare kidney disorders in newborn Holstein calves.