GI stasis
Really interesting lecture, I learnt so much about the rabbit GI tract and the way it functions – fascinating and complex!
One thing I just noticed from the notes is that Anna highlights that rabbits presenting with stasis often try and chew cardboard/wood/paper to obtain fibre. Thinking back to the number of times I’ve seen on here ‘my rabbit has eaten part of a cardboard box, could this have caused a blockage?’ my interpretation of these notes is that maybe the chewing is an indication that the rabbit’s guts are already slowing down rather than the cause of it.
Many causes of GI stasis – common ones include poor diet not high enough in fibre or containing too much carbohydrates, pain, anorexia, dehydration, stress, post-surgical adhesions, etc etc.
I didn’t know that carbohydrate actually inhibits a bunny hormone called motilin which, as its name suggests, stimulates gut motility. So it’s another reason that it’s important that starchy/sugary treats are fed only sparingly as a treat.
Also, while the pH of an adult rabbit gut is from 1-2, it’s 5-6.5 in youngsters, which is why they are so sensitive to changes in diet/surroundings/stress etc as their guts aren’t acidic enough to kill off anything infectious that gets into their gut.
Blockage v GI stasis – the vast majority of cases of ‘hairballs’ or stomach blockages are actually not true blockages. It’s perfectly normal for there to be a lot of hair in rabbit stomachs and it usually only becomes a true blockage in long-haired rabbits like angoras or in matted rabbits where a bunny pulls off the matt and swallows it whole. In severe GI stasis the solid stomach mass can resemble a very solid hairball but aggressive medical intervention should normally be attempted and even very solid lumps will usually disperse.
Treatment: fluid therapy, from oral through to IV depending on severity of condition. Gut stimulants (if not blockage): metaclopromide and ranitidine. Metaclop stimulates the hind gut and ranitidine stimulates stomach emptying so they use both to work on the whole system. Also they are finding high incidence of stomach ulcers on post mortem so ranitidine has the added benefit of being anti-ulcer. If this is an additional source of pain to the rabbit, it again can help treat the stasis. They are also now just starting to use domperidone (sp?) and are finding that it can really give a boost where other drugs haven’t had the effect. If they think it’s a true blockage then they deal with the blockage first and then use stimulants – and sometimes they just massage the blockage down and break it up under GA rather than go for full-on surgery. And of course pain relief. In the initial stages they admit and give opiate pain relief, saying that abdominal pain is very severe and in humans you would be given opiates not paracetamol and therefore they give opiates rather than metacam initially, and move onto metacam once things are starting to move/settle. Also assisted feeding (e.g. critical care at 10ml/kg approx 4 times daily) and exercise also helps.
Liquid paraffin is contra-indicated (not to be used) as you’re trying to rehydrate not lubricate, and paraffin does not support this. They don’t use simethicone (infacol) as rabbits cannot burp so they don’t find it adds any value, although it’s unlikely to do any harm. They don’t advocate the use of pineapple/papaya to help break down hair as there is no evidence to support that this works, and believe that anecdotal evidence is due to the provision of rehydration/energy source. As it is sugary and therefore reduces gut motility and increases the risk of bacterial overgrowth especially clostridia which can kill, they don’t advise its use. They also don't advocate the giving of antibiotics 'just in case' unless there is a clear clinical need to do so.
The vast majority of cases presented as stasis or obstruction are treated medically with surgery only in cases of true blockage (and in this case quickly as it's an emergency), which is very rare and usually even the hardest of hairball-looking-"blockages" will resolve themselves through aggressive medical therapy.
