Abstract
Winter coccidiosis is an economically important protozoan disease of calves, largely caused by Eimeria zuernii and Eimeria bovis. Due to environmental stress, overcrowding, malnutrition, and immunosuppression brought on by the cold in young calves, the disease worsens over the winter. Clinically, affected animals display watery to bloody diarrhoea, anorexia, weight loss, dehydration, anemia, tenesmus and increasing weakening, with outbreaks commonly occurring 16–23 days post-infection. Pathogenesis entails the parasite's quick intracellular growth in the intestinal mucosa, which causes significant tissue damage. Hypoglycemia, hyperproteinemia, increased differential leukocyte counts and reduced hemoglobin, TEC and PCV values are typical laboratory results. The identification of Eimeria oocysts in faecal samples provides confirmation. In addition to anticoccidial treatments such amprolium, sulfadimidine, decoquinate, diclazuril, toltrazuril, and ionophores like monensin, effective therapeutic care focuses on treating electrolyte imbalance and dehydration by intravenous crystalloid therapy. Supportive therapy, including multivitamin supplementation and antipyretics, promotes recovery, but corticosteroids are contraindicated due to their involvement in increasing oocyst shedding. To lower morbidity, avoid serious intestinal damage, and minimize financial losses related to winter coccidiosis in calves, strategic treatment, early diagnosis, and suitable management techniques are crucial.

Key words: Bovine coccidiosis; Eimeria spp.; Calves; Economic impact; Disease management