Calf cryptosporidiosis is a protozoal gastrointestinal disease caused by Cryptosporidium parvum, affecting calves most commonly between 5 and 15 days of age. It leads to profuse, watery diarrhea, dehydration, and weight loss, often persisting despite treatment.

Calf coccidiosis is a protozoal enteropathy caused by pathogenic Eimeria species—especially E. bovis and E. zuernii—affecting calves typically between 3 weeks and 6 months of age. It presents with tenesmus, mucous or hemorrhagic diarrhea, weight loss, and dehydration, often triggered by stressors like weaning or overcrowding.

Clostridial enteritis in calves, primarily caused by Clostridium perfringens type C, is a peracute, necrohemorrhagic disease affecting neonates, often under 10 days of age. This anaerobic, spore-forming bacterium produces potent β-toxins that cause rapid mucosal destruction, abdominal distension, hemorrhagic diarrhea, and sudden death.

Calf rotavirus enteritis is a leading cause of neonatal diarrhea in bovines, particularly affecting calves within the first week of life. This highly contagious viral disease, caused by group A Rotavirus (Reoviridae), results in rapid onset of watery diarrhea, dehydration, and electrolyte imbalance, often requiring aggressive fluid therapy.

Calf coronavirus enteritis is an important differential in neonatal calf diarrhea, typically affecting calves between 5 and 21 days of age. Caused by Bovine coronavirus (Betacoronavirus, Coronaviridae), this enteric disease leads to profuse, mucoid to hemorrhagic diarrhea, dehydration, and anorexia. Transmission is fecal-oral, with high environmental persistence and rapid herd spread.

Enterotoxigenic Escherichia coli (ETEC) is a primary bacterial cause of diarrhea in neonatal calves, especially within the first 3–5 days of life. This pathogen adheres to enterocytes via fimbrial adhesins (e.g., F5/K99) and secretes heat-stable enterotoxins (Sta), leading to secretory diarrhea, dehydration, and rapid deterioration.

Salmonellosis in calves is a severe enteric and systemic disease caused by Salmonella enterica serovars, most commonly S. Typhimurium and S. Dublin. Affecting calves of any age, this zoonotic infection presents with fever, foul-smelling or hemorrhagic diarrhea, and may progress to septicemia, polyarthritis, or pneumonia.