Clostridium difficile is the agent that causes pseudomembranous colitis associated with antibiotic use in humans. C. difficile forms heat-resistant spores that can persist in the environment for years. These spores can survive the acid environment of the stomach and convert to vegetative forms in the colon. When established in the colon, strains of C. difficile produce toxins that cause diarrhea and colitis. Clinical presentation can range from chronic signs of colic, lowgrade diarrhea to fulminating colitis (inflammation of the colon) with decreased gastrointestinal movements. Foals with severe colitis become anorexic and dehydrated. Electrolyte imbalances, dehydration, decreased serum protein, and low white blood cell count are usually present. The liver enzymes can be elevated due to toxic insult, as well as increased kidney parameters due to dehydration and decreased perfusion. Diagnosis can be made by culturing of the organisms, and/or detection of the toxins by PCR or ELISA. The ELISA can be performed in our laboratory with results in 24 hours.


Because C. difficile can cause diarrhea and illness in horses, other animals, and human beings (especially children, senior citizens, or those with a compromised immune system), we suggest a few measures to reduce the risk of infection to other animals or people in contact with infected horses.

  • Avoid subjecting the horse to stressful situations. Hard exercise, long distance transportation, competition of any sort, and elective veterinary procedures should all be avoided for the next 3-4 weeks.
  • Prevent other horses from coming into contact with manure from an infected horse. Maintain the horse in a separate paddock, clean stalls with separate or disinfected tools, and properly disposing of the manure for at least 2 weeks.
  • Always wear disposable gloves when working with an infected horse, and wash your hands thoroughly when finished. Prevention of this disease includes proper hygiene and the use of bleach disinfectants (8oz bleach per gallon of water)


Treatment may require hospitalization and intensive therapy. Mild cases may be treated at the farm with oral antibiotics such as Metronidazole if isolation is possible. Hospitalized horses should be isolated for 2 weeks after returning to the farm. Animals that have diarrhea should be tested for Clostridium difficile infection.


Hagyard Equine Medical Institute has one of the highest equine caseloads in the world. Because we run a state of the art hospital, we are dedicated to providing the best veterinary care possible for our patients. As part of our veterinary services, we run an infection control program to control and prevent infections in our patients during hospitalization. The main goal of this program is to develop an early warning system for detection of disease causing organisms and help prevent the potential spread of disease. This system includes monitoring temperatures several times daily and diligent isolation of horses having or suspected of having infectious diseases.