Acute Equine Diarrhoea: Focus on Stabilisation Before Identification

Acute diarrhoea associated with colitis or typhlocolitis is a life-threatening emergency in horses. While clinicians often focus on identifying the causative pathogen, the immediate threat is usually hypovolaemia, endotoxaemia, electrolyte derangements, and systemic inflammation resulting from intestinal mucosal damage¹. 

One of the greatest challenges is that infectious and non-infectious causes of acute diarrhoea often present with similar clinical signs¹. As a result, definitive diagnosis is frequently delayed or never achieved. Therefore, early recognition of disease severity and prompt supportive care remain the most important determinants of outcome. 

Prognostic Clues Every Practitioner Should Monitor^1,2,3,4 

Rather than relying on a single laboratory value, serial monitoring of hydration status, renal parameters, acid-base balance, and lactate trends provides a more accurate picture of patient progression. 

Common Infectious Causes of Acute Diarrhoea^1,5,6,7,8,9 

Treatment Priorities 

1. Aggressive Fluid Therapy 

Fluid resuscitation remains the cornerstone of therapy. Treatment should focus on correcting dehydration, restoring circulating volume, addressing electrolyte abnormalities, and improving tissue perfusion¹. 

2. Judicious Antimicrobial Use 

Antimicrobial therapy should not be routine. Previous antimicrobial administration was associated with a 4.5-fold lower likelihood of survival in horses with colitis. Targeted therapy remains appropriate for conditions such as Potomac Horse Fever and cases with severe neutropenia or documented septic foci^1,10. 

3. Endotoxaemia and Laminitis Prevention 

Low-dose flunixin meglumine remains a mainstay of anti-endotoxic therapy. Polymyxin B may provide additional endotoxin neutralisation but should be used cautiously in hypovolaemic or azotaemic horses¹¹. 

Importantly, distal limb cryotherapy remains the only validated method for preventing sepsis-associated laminitis in horses with systemic inflammation¹. 

Clinical Take-Home Message 

In acute equine diarrhoea, survival is often determined within the first few hours of presentation. While identifying the pathogen is important, early assessment of disease severity, aggressive fluid therapy, careful antimicrobial stewardship, and prevention of complications such as endotoxaemia and laminitis remain the cornerstones of successful management.  

References  

1. Shaw SD, Stämpfli H. Diagnosis and treatment of undifferentiated and infectious acute diarrhea in the adult horse. The Veterinary clinics of North America. Equine practice. 2018 Feb 14;34(1):39. https://pmc.ncbi.nlm.nih.gov/articles/PMC7134835/pdf/main.pdf  

2. Cohen ND, Woods AM. Characteristics and risk factors for failure of horses with acute diarrhea to survive: 122 cases (1990–1996). Journal of the American Veterinary Medical Association. 1999 Feb 1;214(3):382-90. https://avmajournals.avma.org/view/journals/javma/214/3/javma.1999.214.03.382.xml  

3. Staempfli HR, Townsend HG, Prescott JF. Prognostic features and clinical presentation of acute idiopathic enterocolitis in horses. The Canadian Veterinary Journal. 1991 Apr;32(4):232. https://pmc.ncbi.nlm.nih.gov/articles/PMC1481315/pdf/canvetj00065-0042.pdf  

4. Hashimoto-Hill S, Magdesian KG, Kass PH. Serial measurement of lactate concentration in horses with acute colitis. Journal of Veterinary Internal Medicine. 2011 Nov;25(6):1414-9. https://doi.org/10.1111/j.1939-1676.2011.00808.x  

5. Kurowski PB, Traub-Dargatz JL, Morley PS, Gentry-Weeks CR. Detection of Salmonella spp in fecal specimens by use of real-time polymerase chain reaction assay. American journal of veterinary research. 2002 Sep 1;63(9):1265-8. https://www.academia.edu/download/123174509/ajvr.2002.63.1265.pdf  

6. Cohen ND, Martin LJ, Simpson RB, Wallis DE, Neibergs HL. Comparison of polymerase chain reaction and microbiological culture for detection of salmonellae in equine feces and environmental samples. American journal of veterinary research. 1996 Jun 1;57(6):780-6. https://avmajournals.avma.org/view/journals/ajvr/57/6/ajvr.1996.57.06.780.xml  

7. Schoster A, Staempfli H. Epidemiology and antimicrobial resistance in Clostridium difficile with special reference to the horse. Current Clinical Microbiology Reports. 2016 Mar;3(1):32-41. https://link.springer.com/article/10.1007/s40588-016-0029-3  

8. Magdesian KG, Dujowich M, Madigan JE, Hansen LM, Hirsh DC, Jang SS. Molecular characterization of Clostridium difficile isolates from horses in an intensive care unit and association of disease severity with strain type. Journal of the American Veterinary Medical Association. 2006 Mar 1;228(5):751-5. https://avmajournals.avma.org/view/journals/javma/228/5/javma.228.5.751.xml  

9. Gohari IM, Arroyo L, MacInnes JI, Timoney JF, Parreira VR, Prescott JF. Characterization of Clostridium perfringens in the feces of adult horses and foals with acute enterocolitis. Canadian journal of veterinary research. 2014 Jan 1;78(1):1-7. https://pmc.ncbi.nlm.nih.gov/articles/PMC3878003/pdf/cjvr_01_1.pdf  

10. Bertin FR, Reising A, Slovis NM, Constable PD, Taylor SD. Clinical and clinicopathological factors associated with survival in 44 horses with equine neorickettsiosis (Potomac horse Fever). Journal of veterinary internal medicine. 2013 Nov;27(6):1528-34. https://doi.org/10.1111/jvim.12209  
11. Morresey PR, MacKay RJ. Endotoxin-neutralizing activity of polymyxin B in blood after IV administration in horses. American journal of veterinary research. 2006 Apr 1;67(4):642-7. https://avmajournals.avma.org/view/journals/ajvr/67/4/ajvr.67.4.642.xml