Calf Coronavirus Enteritis

Calf coronavirus enteritis is a notable cause of neonatal diarrhea in bovines, leading to significant economic losses in the cattle industry. Below is a comprehensive overview tailored for veterinary professionals preparing for the NAVLE examination:

• Type of Agent: Virus

• Classification of the Agent:

  • Family: Coronaviridae

  • Genus: Betacoronavirus

  • Species: Bovine coronavirus (BCoV)

• Clinical History:

  • Affects neonatal calves, typically between 5 to 21 days of age

  • High morbidity with variable mortality rates

  • Rapid onset of clinical signs, often within 24–72 hours post-infection

• Transmission of the Disease:

  • Fecal-oral route

  • Respiratory secretions may also play a role in transmission

  • Highly contagious; virus shed in large quantities in feces

  • Environmental stability contributes to rapid spread among neonatal calves

• Causes:

  • Ingestion of BCoV-contaminated feed, water, or fomites

  • Exposure to infected animals or asymptomatic carriers

• Clinical Presentation:

  • Acute onset of profuse, watery to pasty diarrhea

  • Feces may contain mucus and, occasionally, blood

  • Dehydration

  • Depression and weakness

  • Anorexia

  • In severe cases, hypovolemic shock and death

• Changes in Clinical Pathology Tests:

  • Hemoconcentration due to dehydration

  • Electrolyte imbalances: hyponatremia, hypokalemia

  • Metabolic acidosis

• Differentials:

  • Enterotoxigenic Escherichia coli infection

  • Cryptosporidiosis

  • Rotavirus enteritis

  • Salmonellosis

  • Coccidiosis

• Diagnostic Tests to Confirm:

  • Antigen-capture ELISA on fecal samples

  • RT-PCR for BCoV RNA detection

  • Electron microscopy for viral particle visualization

  • Fluorescent antibody testing on intestinal tissues

• Changes in Other Tests (e.g., Imaging):

  • Typically, imaging is not utilized for diagnosis

• Possible Treatments:

  • Supportive Care:

    • Oral rehydration solutions containing electrolytes and glucose

    • Intravenous fluid therapy in cases of severe dehydration

    • Maintenance of acid-base balance

  • Antimicrobial Therapy:

    • Not indicated for viral infections; however, antibiotics may be administered to prevent or treat secondary bacterial infections

  • Other Medications:

    • Nonsteroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation management

• Zoonotic Risk:

  • Bovine coronaviruses are not considered zoonotic and do not pose a risk to human health

• Reportable Status:

  • Calf coronavirus enteritis is generally not a reportable disease; however, reporting requirements may vary by region

• Disease Control:

  • Prevention:

    • Ensure adequate colostrum intake to confer passive immunity

    • Implement strict biosecurity measures to prevent introduction and spread

    • Maintain proper sanitation and hygiene in calf-rearing areas

    • Vaccination of pregnant dams with coronavirus vaccines to enhance colostral antibodies

  • Management During Outbreaks:

    • Isolate affected animals to reduce transmission

    • Enhance supportive care to affected calves

    • Thoroughly clean and disinfect contaminated environments

• Prognosis:

  • Generally favorable with prompt and appropriate supportive care

  • Delayed or inadequate treatment can lead to increased mortality

References:

Veterinary Merck Manual: Intestinal Diseases in Cattle.

Veterinary Merck Manual: Diarrhea in Neonatal Ruminants.