Changes

Megacolon may be managed medically, or surgically if the condition is severe or recurrent. Medical therapy aims to restore the patient's hydration and then clear the faecal impaction. Under anaethesia, the colon is manulally evacuated using warm water enemas, lubrication and gentle extraction of faeces with forceps or a finger. Care must be taken not to damage the colonic mucsoa during this procedure, and prophylactic antibiotics are recommended before commencement. Once the patient's colon is clear, the focus is shifted to preventing recurrence. Dogs and cats must have adequate access to litter or the outdoors to encourage regular defaecation, and regular exercise may be beneficial. Diets containing bulk-forming fibre may contribute to the recurrence of impaction, but a high-fibre diet may occasionally be useful in prevention. Stool softeners such as lactulose, and prokinetic drugs such as cisapride can promote motility and defaecation. Medical management is usually an ongoing, life-long committment which may be frustrating for the owner, and relapse is common.

Megacolon may be managed medically, or surgically if the condition is severe or recurrent. Medical therapy aims to restore the patient's hydration and then clear the faecal impaction. Under anaethesia, the colon is manulally evacuated using warm water enemas, lubrication and gentle extraction of faeces with forceps or a finger. Care must be taken not to damage the colonic mucsoa during this procedure, and prophylactic antibiotics are recommended before commencement. Once the patient's colon is clear, the focus is shifted to preventing recurrence. Dogs and cats must have adequate access to litter or the outdoors to encourage regular defaecation, and regular exercise may be beneficial. Diets containing bulk-forming fibre may contribute to the recurrence of impaction, but a high-fibre diet may occasionally be useful in prevention. Stool softeners such as lactulose, and prokinetic drugs such as cisapride can promote motility and defaecation. Medical management is usually an ongoing, life-long committment which may be frustrating for the owner, and relapse is common.

Sub-total colectomy can be used to correct megacolon in the cat. However, this technique is very poorly tolerated in the dog. The term refers to the removal of the majority of the colon, and the ileocaecocolic valve may be preserved or removed. The ileocaecocolic valve prevents reflux of colonic contents into the small intestine and so some surgeons believe that removing this structure can predispose to small intestinal bacterial overgrowth,steatorrhoea and deconjugation of bile salts,sup>. The rationale for excision of the

Sub-total colectomy can be used to correct megacolon in the cat. However, this technique is very poorly tolerated in the dog. The term refers to the removal of the majority of the colon, and the ileocaecocolic valve may be preserved or removed. The ileocaecocolic valve prevents reflux of colonic contents into the small intestine and so some surgeons believe that removing this structure can predispose to small intestinal bacterial overgrowth,steatorrhoea and deconjugation of bile salts². However, removing the ileocaecocolic valve minimises the recurrence of megacolon.

valve is that it minimises the recurrence of segmental megacolon

 

Although sub-total colectomy is an effective way of correcting megacolon, removal of majority of the colon does have adverse effects on the animal. For example, the colon normally functions to absorb water. This is achieved by the creation of an osmotic gradient by active sodium absorbtion. Additionally, extracellular potassium is lost and bicarbonate ions are exchanged for chloride ions in the colon. It could therefore be implied that sub-total colectomy disrupts water and electrolyte homeostasis. However, cats undergoing sub-total colectomy have been found to show no clinical evidence of abnormal bowel function⁶.

is that differentiation between diseased and normal tissue

Removing the majority of the colon

will undoubtedly have certain metabolic

effects on the animal. The colon

normally acts to absorb water along

an osmotic gradient created by active

sodium absorption. Bicarbonate ions

are secreted in exchange for chloride

are secreted in exchange for chloride

ions, and potassium is lost from extracellular

ions, and potassium is lost from extracellular