ISSN 2398-2977      

Diarrhea: neonate


Synonym(s): Neonatal diarrhea


  • Diarrhea is a common and ubiquitous problem in neonatal and young foals. 
  • Diarrhea is seen in up to 50% of foals up to 6 months of age.
  • Morbidity and mortality rates can be high, and the severity of clinical signs is variable depending on the etiological agent and other factors such as concurrent disease conditions, maternal and environmental factors, etc.
  • it is important to rule out infectious etiologies to reduce risk of herd outbreak.
  • Cause: infectious and non-infectious causes.
  • Signs: diarrhea, colic, pyrexia, anorexia, dehydration.
  • Diagnosis: clinical examination, blood and fecal samples, ultrasonography.
  • Treatment: oral adsorbents, fluids, etiology specific treatments.
  • Prognosis: varies from excellent to poor.
Print off the Owner factsheets on Diarrhoea and Rotavirus to give to your clients.



Predisposing factors


  • Poor stable hygiene. 
  • Overcrowding. 
  • Poor nutritional or health status of mare pre-partum. 
  • Previous or current conditions such as ruptured bladder Bladder: rupture, septicemia Foal: neonatal septicemia syndrome, congenital abnormalities.
  • Use of antibiotics.
  • Use of proton pump inhibitors (non-infectious diarrhea).



  • Varies with etiological agent. 
  • Foal heat diarrhea Foal heat diarrhea is still not fully understood. It appears to be associated with a stage of the development of the foal's intestinal tract involving the establishment of intestinal flora and/or hypersecretion by the small intestine which may overwhelm the absorptive ability if the immature colon. Frequently seen aged 5-15 d with no evidence of pyrexia and self resolves.
  • Rotavirus is very common and is primarily a malabsorptive disease but can induce a toxin-induced secretory component to the disease. The malabsorption is due to damage to the villi tips.
  • Primary lactose intolerance is caused by lack of lactase in brush border of small intestine cells but is rare in foals. Secondary lactose intolerance occurs in any condition that damages the brush border of these cells, eg Rotavirus infection. The resultant maldigestion and malabsorption induces an osmotic diarrhea.
  • Both C. perfringens Clostridium perfringens types A and C produce potent enterotoxins. Enteritis caused by C. perfringens type C is associated with extensive mucosal damage causing hemorrhagic diarrhea. Production of endotoxins and exotoxins, some of which are rapidly absorbed results in circulatory collapse and possible death. 90% of foals are carriers for C. perfringens, therefore testing should only be performed on animals exhibiting clinical signs.
  • C. difficile Clostridium difficile is one of the most important enteric diseases which causes an enterocolitis in very young foals. it causes an increased permeability of the mucosa as well as cell death. The resultant inflammation leads to a secretory diarrhea or pseudomembranous colitis.
  • Salmonella leads to massive mucosal damage of the ileum and colon due to invasion of the secretory system within the intestine.
  • Lawsonia intracellularis is an intracellular pathogen that leads to a proliferative enteropathy Intestine: enteropathy - proliferative in foals at weaning age. It is not found in animals <4 months.


  • Varies with etiological agent. C. perfringens Clostridium perfringens type C enteritis can be rapidly fatal following circulatory collapse and may occur before diarrhea is observed.
  • Rotavirus diarrhea can follow a prolonged course and may be complicated by the development of gastric and/or duodenal ulceration Stomach: gastric ulceration - foal.
  • In hot weather, any diarrhea can result in dehydration and circulatory failure if fluid intake is not maintained.


  • Mares are known to be carriers of rotavirus and Salmonella spp Salmonella spp and act as sources of infection for their foals, therefore should be tested in positive cases.
  • Rotavirus Rotavirus is highly contagious and affected foals shed large numbers of infectious particles. While mares can also confer a degree of immunity to their foals, disease occurs if the level of viral challenge overwhelms this immunity.
  • Due to the high rate of shedding isolation is imperative to reduce the spread of disease.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Oliver-Espinosa O (2018) Foal Diarrhea: Established and Postulated Causes, Prevention, Diagnostics, and Treatments. Vet Clin North Am Equine Pract 34 (1), 55-68 PubMed.
  • Furr M, Cohen N D, Axon J E et al (2012) Treatment with histamine-type 2 receptor antagonists and omeprazole increase the risk of diarrhoea in neonatal foals treated in intensive care units. Equine Vet J 44 (41), 80–86 PubMed.
  • Naylor R & McSloy A (2009) Common medical problems in the older foal Part 2: Diarrhoea. UK Vet 14 (3), 5-13 VetMedResource.
  • Weese J S & Rousseau J (2005) Evaluation ofLactobacillus pentosusWE7 for prevention of diarrhea in neonatal foals. JAVMA 226 (12), 2031-2034 PubMed.
  • Dunkel B & Wilkins P A (2004) Infectious foal diarrhoea: pathophysiology, prevalence and diagnosis. Equine Vet Educ 16 (2), 94-101 VetMedResource.
  • Weese J S, Parsons D A & Staempfli H R (1999) Association of Clostridium difficile with enterocolitis and lactose intolerance in a foal. JAVMA 214 (2), 229-232 & 205 PubMed.
  • Netherwood T, Wood J L, Townsend H G, Mumford J A & Chanter N (1996) Foal diarrhoea between 1991 and 1994 in the United Kingdom associated with Clostridium perfringens, Rotavirus, Strongyloides Westeri and Cryptosporidium spp. Epidemiol Infect 117 (2), 375-383 PubMed.
  • Watanabe T, Otah C, Shirahata T, Goto H, Tsunoda N, Tagami M & Akita H (1993) Preventative administration of bovine colostral immunoglobulin for foal diarrhoea with Rotavirus. J Vet Med Sci 55 (6), 1039-1040 PubMed.
  • Masri M D, Merritt A M, Gronwall R & Burrows C F (1986) Faecal composition in foal heat diarrhoea. Equine Vet J 18 (4), 301-306 PubMed.
  • Pearson E G, Hedstrom O R, Sonn R & Wedam J (1986) Haemorrhagic enteritis caused byClostridium perfringenstype C in a foal. JAVMA 188 (11), 1309-1310 PubMed.
  • Tzipori S, Makin T, Smith M & Krautil F (1982) Enteritis in foals induced by Rotavirus and enterotoxigenic Escherichia coliAust Vet J 58 (1), 20-23 PubMed.

Other sources of information

  • Pusterla N, Gebhart C J, Lavoie J P et al (2014) Lawsonia intracellularis. In: Equine infectious diseases. 2nd edn. Eds: Sellon D C, Long M T. Saunders Elsevier, USA. pp 316–21.
  • Lester G D (2003) Foal Diarrhoea. In: Current Therapy in Equine Medicine 5. Ed: Robinson N E. Saunders, USA.

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