Division of Zoological Medicine, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
Gut stasis, a term that is commonly used to describe a slowing down or cessation of the peristalsis of the gastrointestinal (GI) tract in rabbits, is among one of the most common reasons for this species to be presented to veterinarians. This clinical syndrome has many aetiological causes, of which a number can be addressed preventively. Knowledge on the aetiological factors may therefore help decrease the amount of rabbits suffering from gut stasis thereby increasing their welfare.
Identifying the underlying cause of gut stasis is often found challenging. This not necessarily poses a problem as supportive therapy will, in the majority of cases, result in a positive outcome. However, when a rabbit keeps coming back to the practice with recurrent signs of gut stasis, a more extensive work-up to identify potential underlying causes will be warranted.
Aetiological considerations for (recurrent) gut stasis, which is also referred to as “rabbit gastrointestinal syndrome” or “gastrointestinal hypomotility”, include gastrointestinal impaction, gastric and/or intestinal bloat, intestinal obstruction due to mechanical causes (obstructive ileus) or absence of bowel movements (paralytic ileus), gastritis, pancreatitis and hepatic disease. Of these, paralytic ileus is the most common cause for gut stasis, often also leading to secondary impaction of the gut content.
Recurrent gut stasis is often found to be related to suboptimal housing and nutrition, whereby stress, pain, inadequate nutrition and dehydration play an important role in inducing paralytic ileus. Aside from management aspects, a further understanding of the gastrointestinal anatomy of physiology may also be helpful to identify potential underlying causes. Considering the various small mammalian hind gut fermenters, rabbits have with the most elaborate gastrointestinal system whereby GI motility may be disrupted at various levels. For example, small pellets of hair may be found to cause recurrent obstructions in the small intestines. Particularly the jejunum and ileum junction are locations where such pellets may get stuck. Patients often present with acute anorexia, lethargy and shock. In case of inconclusive radiographs, measurement of blood glucose concentrations may be considered a useful screening tool, as described by Harcourt-Brown, whereby plasma glucose concentrations of >20 mmol/l often indicate that surgical intervention is warranted. If possible, the obstruction is gently massaged further along the GI tract rather than removed via an enterotomy.
Aside from the small intestines, the caecum is also considered an important location where disruption of normal gut motility may occur. One of the factors thought to disrupt normal GI function is a change in the bacterial and protozoal flora, which may occur in response to inadequate nutrition and/or sudden dietary changes. Particularly Bacteroides spp. (not Lactobacillus!) are deemed essential for a proper fermentation of caecal content. Aside from a change in microbial flora that alters the functionality of the caecum, recurrent gut stasis may also result from a change in caecal and/or colonic motility. The regulation of this motility is predominantly controlled by the fusus coli. The action of this structure, which is also responsible for the colonic separation mechanism, is influenced by various hormones, including adrenaline and cortisol, which may be released in response to environmental stressors or pain.
Prevention of Gut Stasis
In order to prevent gut stasis, it is important diminish the above described numerous causes of stress or pain that may be responsible for the reduced functionality of the fusus coli. In addition, providing an optimal diet is essential. The diet should consist predominantly of leafy vegetables/grass, hay and only a limited amount of high grade pellets. Muesli mixes are considered poor nutrition for rabbits and are therefore considered obsolete. Providing regular exercise will also enhance GI motility thereby contributing to the prevention of gut stasis.
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