In a clinical context the difference between acute colitis and chronic colitis is, in many respects, only a difference in the duration of time the condition has been present. As with all forms of colitis, the inflammation leads to disruption of colonic function; namely disruption in the absorption of water and electrolytes. In addition there may be reduced colonic segmented contractions.
Acute colitis is relatively common in dogs but is much more unusual in cats. The aetiology is rarely detected although dietary influences may be important. In particular the effects of scavenging and ingestion of abrasive foods such as bone may be important causes. Bacterial infection especially involving Salmonella and Campylobacter spp. should be considered together with heavy infestations of Trichuris vulpis.
The onset of clinical signs is usually sudden with profuse watery diarrhoea often containing mucus and occasionally blood. Vomiting may be present as may pyrexia and abdominal pain. Dehydration occurs most frequently when vomiting and diarrhoea are both present, and is unusual with diarrhoea alone. Tenesmus and urgency are often reported by the owner as is nocturnal defaecation.
It is important to examine the faeces for evidence of bacterial infection and for parasites. Occasionally and especially when there is pyrexia, a neutrophilia will be observed. Assuming there is no evidence of infection or parasitism, endoscopy usually reveals the mucosa to be inflamed, with a ‘granular’ appearance and loss of visualization of submucosal blood vessels. Ulceration may be observed,
Histopathological examination of affected gut reveals varying levels of acute mucosal and submucosal inflammation characterized in the early stages by oedema and polymorphonucleocyte infiltration. Increasing numbers of plasma cells and lymphocytes occur in more advanced or longer standing cases. Goblet cell hyperplasia may also occur ().
Treatment should be based on eliminating the underlying cause if this can be found. Where evidence of endoparasites such as Trichuris spp. is detected the patient should receive 5 days’ treatment with fenbendazole (Panacur; Hoechst Animal Health) at a dose rate of 20 mg/kg/day. Where Salmonella spp. are detected and the patient is pyrexic, then antibiotic sensitivity should be obtained and a suitable antibiotic administered systemically. Campylobacter spp. may often be isolated from cases of acute colitis but this is usually an opportunist organism, which should still be eliminated using either erythromycin at 40 mg/kg/day or tylosin 40 mg/kg/day for 5 days ().
Correction of fluid balance must be considered in the initial stages of treatment if there is any evidence of dehydration. Otherwise with the idiopathic form, treatment should involve the use of sulphasalazine (Salazopyrin; Pharmacia) at 20 to 40mg/kg/day in divided doses (). This drug is only activated in the colon by action of bacteria producing sulphapyridiiie and 5-aminosalicylic acid. The latter component is considered to be responsible for the improvement in colitis.
Selections from the book: “Digestive Disease in the Dog and Cat” (1991)