Table 1.

Disease categories for 1016 horses from a survey of veterinary practitioners’ primary assessment of colic

Disease category	Definition/inclusion criteria for disease category and sub-category	Number of cases
No definitive diagnosis	Defined as cases in which a definitive diagnosis was not determined at the primary or any subsequent assessments	580
Sub category: spasmodic	Inclusion criteria: described by veterinary surgeon as spasmodic, no abnormalities on rectal examination, and resolved with medical treatment Exclusion criteria: cases subsequently found to have other lesions were excluded and categorised according to the final diagnosis/outcome	254
Sub category: gas	Inclusion criteria: with gas distension of intestines on rectal examination, with no underlying cause of distension identified Exclusion criteria: cases with gas distension associated with another lesion were excluded and categorised according to the primary lesion	68
Sub category: unknown	Inclusion criteria: diagnosis undetermined by veterinary surgeon, or where proposed diagnosis could not be confirmed from diagnostic work up (including cases where there were no clinical or diagnostic findings to support the veterinary surgeon’s proposed diagnosis (e.g. cases reported as ‘impactions’ where no rectal examination was performed, recurrent or geriatric cases euthanased for colic with mild signs of pain, no rectal findings and no post mortem results)	258
SCOD (impaction or simple displacement)	Defined as simple obstruction with subsequent distension of the large colon [2] diagnosed on the basis of positive findings on rectal examination either at the primary or any subsequent assessments, and resolved with medical treatment	155
Sub category: large colon impaction	Inclusion criteria: positive rectal finding of a primary large colon impaction Exclusion criteria: impactions with a positive sand test were categorised as a separate category under category 4 Cases which required surgical intervention, euthanasia or died were excluded and categorised as category 3. Surgical/strangulating lesion	121
Sub category: large colon displacement	Inclusion criteria: positive rectal finding of a large colon displacement on rectal examination (including palpation of a LDD displacement, RDD displacement, Pelvic flexure retroflexion or abnormal taenial bands) Exclusion criteria: cases which required surgical intervention, euthanasia or died were excluded and categorised as category 3. Surgical/strangulating lesion	34
Surgical/strangulating lesion	Defined as cases that required surgical treatment, were euthanased or died due to surgical or strangulating lesions either at the primary or any subsequent assessments	178
Sub category of SI lesion	Inclusion criteria: identification of small intestinal lesion at surgery or post mortem, or where these were not available, positive rectal findings of small intestinal distension	72
Sub category of LI lesion	Inclusion criteria: identification of large intestinal lesion at surgery or post mortem, or where these were not available, positive rectal findings of large intestinal distension. This sub category includes large colon displacements which had surgical treatment or were euthanased	36
Sub category of other location	Inclusion criteria: identification of other intestinal lesion (gastric obstruction n = 1 and small colon strangulation n = 1) at surgery or post mortem	2
Sub category of no lesion site identified	Inclusion criteria: cases where the site of the surgical lesion was not determined, including surgical cases where the data could not be obtained, and horses that were euthanased or died with no rectal examination, or no findings on rectal examination and no post mortem	68
Other	Defined as cases where a definitive diagnosis was obtained either at the primary assessment or subsequent investigations, and which did not have either SCOD or a surgical/strangulating lesion	103
Gastric diseases (EGUS)	Inclusion criteria: EGUS diagnosed by endoscopy	2
Simple SI obstruction	Inclusion criteria: distended small intestine on rectal or ultrasound examination of thickened small intestine, and resolved with medical treatment	7
Caecal disease	Inclusion criteria: abnormalities of the caecum identified on rectal examination, including caecal tympany (n = 4), caecal impaction (n = 2), and typhlitis (n = 1) which resolved with medical treatment	7
Small colon obstruction	Inclusion criteria: positive rectal finding of impaction of the small colon, which resolved with medical treatment	6
Rectal impaction	Inclusion criteria: positive rectal finding of impaction of the rectum (n = 5), or meconium impaction (n = 1), which resolved with medical treatment	6
Grass sickness	Inclusion criteria: euthanased with a diagnosis of grass sickness confirmed by biopsy, post mortem or clinical signs (ptosis, dysphagia, sweating)	13
Neoplasia	Inclusion criteria: neoplasia confirmed on surgery or post mortem	2
Parasitic	Inclusion criteria: worms seen in faeces, high faecal egg count (>800 eggs per gram), positive surgical or post mortem findings, clinical history and laboratory results consistent with cyathastomiasis	9
Peritonitis/PUO	Inclusion criteria: pyrexic, with no underlying cause identified (PUO) (n = 3) or peritonitis confirmed on abdominocentesis (n = 4)	7
Enteritis, colitis or enterocolitis	Inclusion criteria: presence of diarrhoea, or ultrasound or surgical findings consistent with colitis or enteritis	13
Sand colic	Inclusion criteria: positive sand test (faecal sand test or on radiography)	14
Rupture of the gastro-intestinal (GI) tract	Inclusion criteria: rupture or tear of GI tract identified at surgery or post mortem, regardless of location Lesion location: 1 large colon, 1 small colon, 1 rectal, 1 unrecorded	4
Non-GI causes	Inclusion criteria: non-gastrointestinal problem confirmed by other clinical findings or diagnostic tests. This included cardiac disease diagnosed on auscultation and clinical signs of cardiac failure (n = 1), choke (n = 2), haematuria (n = 1), hepatic disease diagnosed based on blood biochemistry (n = 5) and ‘maggots in sheath’, diagnosed on physical examination (n = 2), urticarial/allergic reaction (n = 1), muscle abscess (n = 1)	13

Disease categories were determined retrospectively by reviewing the veterinary surgeon’s diagnosis, presenting signs, physical examination findings, diagnostic test findings, further information provided by the veterinary surgeon and final outcomes recorded