Description
Caecal impaction in horses occurs in two forms. In primary impactions the caecum contains dry, relatively solid ingesta which may be localised to the crainial part of the caecal base, or extend to fill the whole visera. The onset of clinical signs is typically 5-7 days and the associated signs are of low grade intermittent colic.
Secondary impactions are a result of caecal dysfunction; the caecal content is fluid and the vicera is distended and imotile. This syndrome usually occurs in the post-operative period and early signs may be missed, being attributed to discomfort following surgery or the concurrent condition. The delayed diagnosis results in a serious situation where the caecum can become so distended that rupture is imminent.
Signalment
Hospitalised horses are at greater risk, especially those with musculoskeletal conditions, often due to the reduction in activity and treatment with non-steroidal anti-inflammatory drugs.
Diagnosis
Clinical signs
- Mild to moderate intermmitant colic signs
- Marginal increase in heart rate
- Reduced gut sounds
- Dehydration
Diagnosis can be made on rectal examintion, the caecum is firmer and filled with ingesta and can be indented digitally. The caecal mass will be palpated in the right paralumbar area, identified by the taut ventral caecal band and the fat and blood vessels overlying the medial caecal band.
Dehydration develops as the impaction becomes estabilised; in most cases the impaction is not sufficiently severe or prolonged to cause cardiovascular compromise or changes in peritoneal fluid, but if the case is chronic or progresses to rupture then the condition is serious and the horse should be closely monitored for worsening clinical signs. There will be an increase in the protein content of peritoneal fluid as well as cardiovascular signs of shock as the caecum becomes grossly distended, ischaemia of the visera occurs and toxaemia develops as the caecum eventually ruptures.
Treatment
Treatment depends on the severity and cause of the impaction. Mild impactions which are diagnosed early can be treated effectively with IV fluid therapy, oral fluid therapy with added magnesium sulphate by stomach tube and flunixin meglumate as analgesia. Food should be witheld and the horse should be monitored very closely to avoid the caecal distension progressing. Impactions which do not improve should be refered for surgical management.
Caecal impactions can be corected under general anaesthesia by laporotomy. The caecum is decompressed and the ingesta is removed. In cases where the emptying function of the caecum as been lost, a by-pass surgery must be performed.
The risk of secondary impactions developing post-operatively can be minimised by administering adequate analgesia and close monitoring of the patient. Feed intake, faecal output and gut sounds should be recorded while the patient is hospitalised, if they become reduced the rectal palpation is indicated to make an early diagnosis.
Prognosis
References
- Blood, D.C. and Studdert, V. P. (1999) Saunders Comprehensive Veterinary Dictionary (2nd Edition) Elsevier Science
- Edward Robinson, N and Sprayberry, K. A. (2009) Current Therapy In Equine Medicine Sixth edition Saunders Elsevier
- Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
- White, N.A., Edwards, G.B. (1999) Handbook of Equine Colic Reed Educational and Professional Publishing Ltd