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Infectious diarrhea in foals is a significant health concern that can lead to dehydration, weight loss, and systemic illness. Without timely intervention, it can lead to severe complications and even be life-threatening.
Diarrhea in foals can be caused by a variety of pathogens including bacteria, viruses, and parasites. Signs of infectious diarrhea include watery feces, decreased appetite, lethargy and weakness.
Foals are particularly susceptible to infectious diarrhea because their immune system is not fully developed. Their gut microbiome, which plays a crucial role in fighting infections, is also not yet well-established.
Treatment must be administered promptly and may consist of fluid therapy, electrolyte supplementation and antibiotic medications. Through a combination of good management practices, vigilant observation, and prompt veterinary care, the risks associated with infectious diarrhea in foals can be significantly reduced.
Infectious Diarrhea in Foals
Diarrhea refers to an increased volume or fluidity of the feces, resulting in the passage of frequent, watery stool. Diarrhea is a common condition in foals, with one study reporting a prevalence of 48% in foals from birth up to the age of two months. [2]
Unfortunately, diarrhea frequently results in death of affected foals, particularly those under 7 days of age. [1] Early recognition of the signs of diarrhea by breeders is crucial to allow rapid medical intervention and reduce the risk of mortality. [1]
Treatment is primarily supportive in nature, and focuses on maintaining hydration, nutritional support, and protecting the gastrointestinal lining. Specific medications that target the cause of the diarrhea are added to these support measures to complete the treatment plan.
The most common causes of infectious foal diarrhea are: [1]
- Salmonella
- Clostridium
- Rotavirus
- Cryptosporidium
- Strongyloides
For all of these infections, early identification and treatment are essential for a good prognosis for the foal.
Risk Factors
Several studies have identified common environmental and management factors that contribute to a heightened risk of diarrhea in foals. Common risk factors include: [1][2][12]
- Mares that are not vaccinated against rotavirus prior to foaling
- Administering antibiotics to the foal
- Foaling in a stall
- Not receiving adequate colostrum (failure of passive transfer)
- Inadequate deworming of the mares prior to foaling
Symptoms of Infectious Diarrhea
The symptoms of foal diarrhea are typically related to severe dehydration. In addition to diarrhea, foals may exhibit signs such as: [1][2]
- Colic
- Distention of the abdomen
- Sunken in eyes
- Prolonged skin tent
- Lethargy
- Weakness
- Grinding teeth
- Fever or hypothermia
Systemic Inflammatory Response Syndrome
Some foals develop systemic inflammatory response syndrome (SIRS), in which the infection triggers an inflammatory response spread widely throughout the body. Symptoms of SIRS include: [2]
- Red gums
- Rapid heart rate
- Rapid breathing
- Cool extremities, including the ears
- Weak pulses
- Recumbency
Without treatment, foals affected by SIRS may become comatose or die.
Treatment for Diarrhea
Treatment protocols for foals with diarrhea generally follow a standard approach, focusing primarily on maintaining hydration, protecting the integrity of the intestinal tract, and providing nutritional support.
Once these priorities are addressed, the veterinarian may introduce additional treatments tailored to the specific cause of the foal’s diarrhea for a more comprehensive treatment plan.
Maintaining Hydration
Due to the large amount of fluid excreted in diarrhea, foals with diarrhea are prone to becoming dehydrated. Dehydration directly impacts the function of internal organs, particularly the kidneys, and may lead to organ failure if not corrected. [1][3]
To address dehydration, veterinarians provide intravenous fluids. The volume of intravenous fluids provided depends on: [3][4]
- The level of dehydration when treatment begins
- An estimation of how much fluid the foal is losing per day in diarrhea
- The amount of fluid required to sustain a healthy foal
Foals receiving intravenous fluids require close monitoring, as they are prone to developing overhydration from this treatment. [3] The amount of fluids requires constant recalculation by the veterinarian to prevent overhydration, particularly as the diarrhea resolves and the foal begins to feel better. [3]
Depending on the electrolyte balance of the foal, your veterinarian may also add extra electrolyte minerals to the intravenous fluids. Common electrolytes to add include sodium, bicarbonate, chloride, and potassium. [2]