Rabbits Part 2: GI Diseases
Previously: Husbandry Basics
Rabbits are hind-gut fermenters, relying on a cecum loaded with bacteria to digest the incredible amount of plant material they ingest. They are also incapable of vomiting! Rabbits require that their guts are always moving for them to remain healthy. What could possibly go wrong?
Rabbits are coprophagic, meaning that they ingest their own feces. This is done with special ‘night feces’ or cecotrophs, a softer version than their normal stool that resembles a grape cluster. Their composition is very different from that of the hard, round stools that rabbits pass. You should not find cecotrophs. Rabbits eat them directly from the source to recycle important gut bacteria and B vitamins.
The health of a rabbit’s gut is reliant on the Gram positive organisms that live and ferment feed there. It is imperative to choose antibiotics that do not primarily kill Gram positive bacteria to avoid enterotoxemia. Use of oral β-lactams, lincomycin, clindamycin, and erythromycin is contraindicated.
Rabbits are prey animals and to avoid the attention of predators, they do their very best to hide pain and discomfort. Rabbits who are in pain may exhibit small or decreased fecal output, grinding of the teeth, grimacing, hunched posture, reluctance to move, decreased feed intake, or belly-pressing. Some rabbits will not display these signs until their disease has become more advanced. This is why it is incredibly important to note any changes in feeding habits, whether this be amount or substrate preference! Close monitoring of stools can also be a good indicator of health.
Never, ever, ever fast a rabbit. It is critical that a rabbit’s gut remain moving and without food, why would it? They are not at risk for aspiration pneumonia due to vomiting because they CAN’T vomit. Anesthesia without fasting. No fasting. Don’t do it.
GI Stasis The ‘silent killer’ of rabbits. I have to put this in quotes because GI stasis does not kill a rabbit immediately like an aneurysm. Rabbits do display symptoms of GI stasis and if we are astute, then the signs are quite evident. Causes: this is attributable to stress, pain, improper diet (especially those that are high in carbohydrate, low in fiber), insufficient exercise, dental disease. **Bezoars (hairballs) are present in the stomach of healthy rabbits because rabbits are fastidious groomers. The general consensus these days is that they are not the primary cause of GI stasis, but are a sequelae of GI hypomotility** Clinical Signs: anorexia, decreased fecal size/ output, no fecal output, distended abdomen, absent borborygmi, colic (belly-pressing), restlessness. Ain’t doin’ right
Diagnosis: clinical signs + Rads
The rabbit on the left represents a normal radiograph, while the rabbit on the right may have just eaten a large amount of ingesta. However, the history was anorexic on presentation and without any fecal output. You can see that there is quite a bit of gas accumulation in the intestinal tract because the gut is not moving.
Treatment: Getting the gut moving is critical using a combination of exercise, medication to alleviate pain like meloxicam, cisapride and/or metoclopramide. Rehydration with fluids. If the stomach is markedly distended with gas, a nasogastric tube should be passed to decompress the stomach. If not, the rabbit is at risk of rupturing their stomach. Force-feeding with Oxbow Critical Care until the rabbit eats on their own. (**Now is NOT the time to change an improper diet. We can worry about that after we get the bunny better**) (This is not a plug for Oxbow, but is a commercially available, nutrient rich diet that can be syringe-fed to a sick rabbit). Hospitalization = stress, which can be a contributing factor to GI stasis. It’s not recommended unless the rabbit is critical. Owners need to know that their rabbit is going to require intensive nursing care in order to recover from GI stasis. These will be their sleepless nights.
Enterotoxemia Causes: Overgrowth of GI bacteria or loss of GI bacteria (which then leads to overgrowth of inappropriate bacteria). Secondary to stress, poor diet, or antibiotics administration. In young rabbits 4 - 8 weeks, this is usually caused by Clostridium spriforme organism. In adult rabbits, this is usually associated with the improper use of antibiotics and the subsequent dying off of essential bacteria. Clinical Signs: diarrhea, lethargy, inappetance, colic, dehydration. Treatment: Depends on the overgrowing bacteria, but should include supportive care like fluid therapy, feeding if the rabbit is off feed.
Malocclusion Occlusion is where the surfaces of the upper and lower teeth come into contact with each other on their occlusal surfaces, we hope. Malocclusion is any deviation from the way the teeth should come together naturally. This is especially important for normal wear of the continuously growing teeth. If these teeth wear abnormally, tooth spurs may poke into the tongue or cheek, incisors may grow until they become completely unusable by the rabbit. Overgrowth of the molar teeth lingually may even entrap the tongue. There are two categories of malocclusion Primary: the alignment of the teeth within the mandible and/or maxilla is improper, leading to life-long improper wear, regardless of diet. This form is usually more common in brachycephalic breeds like Lionheads, Netherland Dwarves, lop breeds. Secondary: results from improper husbandry. Diet or environment is inappropriate, resulting in abnormal wear of the incisors and/or molars.
Overgrowth of the lower incisors.
Diagnosis: a good physical exam, which may require anesthesia for more subtle cases. Rabbits are very sensitive to having you put anything in their mouth and if you stress a rabbit too much, you may put them off their feed. Sedation and anesthesia are your friends! Treatment: There have been a lot of veterinary professionals who have clipped rabbit teeth (with cuticle trimmers or even canine nail trimmer), but I hope to convince you that this is NOT a good plan. Whenever the tooth is clipped, there is a risk of fracturing the tooth, which you likely will not see, but you will see the complications. These fractures may lead to root exposure and subsequent infection. These infections can result a myriad of complications which may threaten the rabbit’s life. To name a few, anorexia, fractured mandibles, loosening or death of the tooth which requires extraction. Does it happen every time? No, but the consequences can be something a rabbit has to deal with for life. Get comfortable with a dremel or bone rongeurs to grind down teeth safely. Yes, it requires anesthesia. Yes, you need to know what the teeth and occlusal surfaces should appear like. Yes, it will take more time. The benefits are that you may already require anesthesia to do a complete oral exam. The risk of fracturing a tooth is substantially lower. Dremels will not leave sharp edges. You are providing better patient care (# 1 priority). A lot of clients may be used to having their rabbit’s teeth clipped by other practices. It is our job to educate them about the potential dangers of doing this why we do something that is more complicated. Clients care about their bunnies and we have to show them why this is the better way to provide care. Some will not like the higher price tag, but doing things the right way and explaining why will bring around the people who are open-minded.
Respiratory Diseases are up next!