7 Apr 2020
Karin Kruger
Job Title
Image: Kseniya Abramova / Adobe Stock
Acute colic is the most common equine veterinary emergency and the most common gastrointestinal disorder. Thankfully, the vast majority of cases will be amenable to medical management.
To provide the best service to our clients and patients, we should be able to communicate the likely potential outcomes, complication risks and potential costs involved in treating various types of colic. These facts should ideally be established before emotive emergencies arise.
Importantly, if addressed in a timely fashion by a competent team, most types of colic and colic surgery should have an excellent prognosis.
If your practice does not provide the full range of medical and surgical colic treatments required by your patients, the author would encourage you to contact nearby referral facilities for cost estimates, as well as survival and complication rate data for each hospital, to select the optimal facility for referral.
History – including management, medications and recent changes – signalment and colic examination can reveal many clues to assist the practitioner.
A first opinion colic examination may comprise a full physical examination, rectal examination, nasogastric intubation and abdominocentesis. This can be complemented by abdominal ultrasound, haematology and serum biochemistry.
To guide selection of the most appropriate treatment, the author finds it helpful to classify colic horses into one of the following categories:
Any horse with severe or persistent pain (even mild persistent pain) where a specific diagnosis is not established, horses with no gut sounds, a horse with haemodynamic deterioration despite treatment, and those with suspected strangulating intestinal lesions should immediately be referred for further diagnostic evaluation and/or surgical exploration of the abdomen.
The single most important determination of outcome for a surgical colic patient is the time from the onset of clinical signs to surgical correction. Taking a “wait and see” approach when uncertainty exists about whether surgery is necessary will waste valuable time in patients where owners are amenable to referral.
Horses with acute, simple intestinal disturbances will often have unremarkable physical examination parameters. Gut sounds may be slightly decreased, normal, slightly increased or “gassy”, but are usually not absent – especially not after administration of flunixin. Horses are haemodynamically normal, and respond very well to small doses of hyoscine butylbromide and/or flunixin.
Non-strangulating large intestinal obstructions can have characteristic rectal findings. Pelvic flexure impactions are readily palpable. Unless gas distention is severe, left dorsal displacement can be palpated by following a colonic taenial band towards, or into, the nephrosplenic space. The spleen is displaced medially and ventrally, and access to the left kidney may be obstructed by the colon.
Right dorsal displacements may have a horizontal taenial band running left to right across the abdomen. They also frequently have elevated gamma‑glutamyltransferase on serum biochemistry.
Retroflexion of the pelvic flexure should be suspected when the pelvic flexure cannot be palpated, but the horse is showing signs consistent with a non‑strangulating large intestinal obstruction.
Gas distention associated with intestinal obstructions can be so severe as to preclude detailed rectal evaluation.
It is important to differentiate a large colon impaction, which is relatively easier to treat, from a caecal impaction, which is both more difficult to resolve and may rupture without much warning. If accessible, identifying the medial caecal band – which runs cranioventrally from the dorsal body wall – can help identify the caecum.
If the author is unsure whether a viscus is colon or caecum, she will try to run her hand over the top of it. If it is separate from the dorsal body wall then it is the colon. If she can’t get over the top of it because it is attached to the dorsal body wall then it is the caecum.
Both strangulating and non‑strangulating obstructions of the small intestine are associated with severe colic signs, small intestinal distention and varying amounts of reflux. Non‑strangulating small intestinal obstructions can be physical (for example, ileal impaction) or functional (for example, enteritis).
Enteritis cases also fit into the inflammatory gastrointestinal disorder category. Horses with enteritis tend to have larger volumes of reflux and are usually more depressed than painful after gastric distention is relieved. Their inflammatory markers (serum amyloid A and fibrinogen) are elevated. Ultrasound is extremely useful to detect subtle changes in small intestinal motility, content and wall thickness.
Horses with a strangulated bowel initially exhibit severe colic signs, but will have a period where owners may mistake an apparent improvement in comfort with overall improvement, when the affected bowel wall becomes necrotic. Examination will, however, show rapid haemodynamic deterioration.
Colon torsions may produce the most violently painful and rapidly deteriorating group of patients. Cases with acute colitis (before breaking with diarrhoea) can mimic a colon torsion, especially when the bowel wall becomes infarcted. Both conditions may cause severe abdominal gas distention and thickened colon wall on abdominal ultrasound.
Haematology and serum biochemistry may assist in differentiation, as horses with acute colon torsion have normal haematology and albumin, while colitis cases are often neutropenic and hypoalbuminaemic.
Colitis cases may also have a fever and signs of toxaemia earlier in the disease process.
The three pillars of successful medical colic management are:
Treatments may include enteral and/or IV fluids, analgesics and drugs, and procedures to prevent and manage complications such as laminitis and systemic inflammatory response syndrome.
A comprehensive review of treatment for inflammatory and infectious gastrointestinal disorders is beyond the scope of this article, but the author will comment on a few aspects of common treatments.
