Equis ISSN 2398-2977

Abdomen: abscess

Contributor(s): Graham Munroe, Prof Jonathon Naylor, Carla Sommardahl


  • Cause: infrequently occur as a sequel to strangles, respiratory infections, septicemia or umbilical infections. Infection often localizes in mesenteric lymph nodes where it may or may not lead to adhesions and bowel obstruction.
  • Signs: commonly presents with 3 syndromes:
    • Chronic loss of weight.
    • Chronic low-grade colic.
    • Acute severe colic is occasionally seen.
  • Diagnosis: rectal palpation, +/- ultrasonography, clinicopathological data, peritoneal fluid collection and examination are all helpful, but laparoscopy/laparotomy may be required for definitive diagnosis.
  • Treatment: long-term antimicrobial therapy, often with penicillin, for a minimum of 30 days, supportive care and in selected cases surgical intervention.
  • Prognosis: varies according to size, location, causative agent and secondary involvement but guarded to poor.



  • Primary abdominal abscesses originate from a systemic bacterial infection and include sequelae to infectious diseases of the respiratory tract such asRhodococcus equiin foals and strangles in adults.
  • Secondary abscesses may be caused by trauma, ulceration or perforation of the gastrointestinal tract, or post-abdominal surgery.
  • Many cases result from systemic spread of strangles (bastard strangles)    Strangles (Streptococcus equi infection)  , respiratory infections or septicemias.
  • Organisms commonly isolated from abdominal abscesses include:
  • Mixed populations are common but anaerobes are more common than originally thought.
  • Other possible causes include foreign body penetration of the small intestine, post-abdominal surgery (particularly as a consequence of an anastomosis leakage or surgical contamination) umbilical infections, ascarid infestation in foals, other migrating larvae in heavily parasitized animals, gastric granulomas and parturition accidents.


  • Most internal abdominal abscesses affect the mesenteric lymph nodes.
  • Many are the result of systemic spread of strangles   Strangles (Streptococcus equi infection)  , respiratory infections or septicemia.
  • Streptococcus zooepidemicus var equiis the most commonly isolated bacteria.
  • Abscess enlargement, peritonitis and adhesions may   →   obstruction of the small intestine.
  • Infectious agents localize in abdominal or, most commonly, mesenteric lymph nodes.
  • Abscesses can occur in a variety of abdominal organs (liver, spleen, kidney, uterus, bladder and abdominal wall) but are usually located in or around the mesentery.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Berlin D et al (2013) Successful medical management of intra-abdominal abscesses in 4 adult horses. Can Vet J 54 (2), 157-161 PubMed.
  • Arnold C E & Chaffin M K (2012) Abdominal abscesses in adult horses: 61 cases (1993-2008). JAVMA 241 (12), 1659-1665 PubMed.
  • Mair T S & Sherlock C E (2011) Surgical drainage and post operative lavage of large abdominal abscesses in six mature horses. Equine Vet J Suppl Aug (39), 123-127 PubMed.
  • Reuss S M et al (2011) Sonographic characteristics of intraabdominal abscessation and lymphadenopathy attributable to Rhodococcus equi infections in foals. Vet Radiol Ultrasound 52 (4), 462-465 PubMed.
  • Pusterla N, Whitcomb M B & Wilson W D (2007) Internal abdominal abscesses caused by Streptococcus equi subspecies equi in 10 horses in California between 1989 and 2004. Vet Rec 160 (17), 589-592 PubMed.
  • Elce Y A (2006) Infections in the equine abdomen and pelvis: perirectal abscesses, umbilical infections, and peritonitis. Vet Clin North Am Equine Pract 22 (2), 419-436 PubMed.
  • Aleman M, Spier S J, Wilson W D & Doherr M (1996) Corynebacterium pseudotuberculosis infection in horses: 538 cases (1982-1993). JAVMA 209, 804-809 PubMed.
  • Zicker S C, Wilson W D & Medearies I (1990) Differentiation between intra-abdominal neoplasms and abscesses in horses, using clinical and laboratory data: 40 cases (1973-1988). JAVMA 196, 1130-1134 PubMed.
  • Prades M et al (1989) Surgical treatment of an abdominal abscess by marsupialisation in the horse: a report of two cases. Equine Vet J 21 (6), 459-461 PubMed.
  • Rumbaugh G E, Smith B P & Carlson G P (1978) Internal abdominal abscesses in the horse: a study of 25 cases. JAVMA 172, 304-309 PubMed.