The anorectic, lethargic rabbit is a common presentation in exotic animal practice. This can be a frustrating condition to diagnose and treat. Part of this stems from the biology, anatomy, and physiology of the rabbit, which leads to unique considerations in the clinician’s approach to this species.
Although domesticated, the modern-day pet rabbit has retained much of the behavioral characteristics of their wild counterpart. Wild rabbits are prey species, and are typically crepuscular and nocturnal feeders, only emerging from their burrows during low-light conditions to feed. The rabbit digestive system is adapted for processing large volumes of plant material that are relatively low in quality and high in long/indigestible fiber. Rabbits are hind-gut fermenters, relying on the ‘wash-back’ colonic separation mechanism to enable retention of smaller, more digestible fiber particles within the cecum for further microbial fermentation. This unique hindgut physiology enables the rabbit to maximize nutrient extraction from their diet. The cecal fermentative process is dependent on an appropriate diet and a healthy population of cecal microflora.
Alterations in hindgut peristaltic activity and dysbiosis are commonly seen in rabbit gastrointestinal disease. The majority of pet rabbits with gastrointestinal disease display non-specific clinical signs of anorexia, lethargy and reduced fecal production. The terminology, Rabbit Gastrointestinal Syndrome (RGIS) has been proposed to describe the various conditions that share these common signs. However, it is important to note that extra-gastrointestinal disease in the rabbit can also present similarly. It is therefore important for the clinician to identify the underlying etiology, particularly as some conditions may require more extensive medical or surgical interventions.
On top of a full clinical history and physical examination, complete bloodwork, urinalysis and abdominal radiography are considered baseline diagnostic investigations in RGIS. Clinical findings including hypothermia, hypotension, anemia, hyperglycemia, hepatic enzyme elevation, BUN elevation, acidosis, and a dilated stomach with a gas cap should alert the clinician to potentially life-threatening diseases, such as intestinal obstruction and liver lobe torsion. These conditions can be further defined using abdominal imaging studies, including serial radiographic studies, ultrasonography and/or contrast-enhanced computed tomography.
Treatment is dependent on the underlying etiology. Fluid therapy and analgesia are considered cornerstones in the management of gastrointestinal disease in rabbits, but other specific treatments such as active warming, intestinal promotility agents, anti-microbials, and nutritional support may also be warranted. Surgery may indicated for some conditions, such as intestinal obstruction, liver lobe torsion, and appendicitis.
- Management strategies
About the presenter
Jo Sheen is an associate veterinarian at Sydney Exotics and Rabbit Vets. Dr. Sheen consults as a primary accession and referral exotic animal medicine veterinarian at Veterinary Specialist & Emergency Centre North Shore in New South Wales, Australia. She graduated from the University of Edinburgh in 2004, and gained her postgraduate qualification in zoological and exotic medicine in 2008. In 2017, she became a Diplomate of the American Board of Veterinary Practitioners in Exotic Companion Mammal Practice. She is only the second Australian veterinarian to achieve these credentials. [MORE]
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Dr. Sheen generously created a pre-recording, so answers to many attendee questions were typed live and are posted below.
What about rabbits who are passing lots of mucous and have a large cecum?
This would tend to suggest a cecal dysfunction. If this is an adult rabbit, I would start with looking at husbandry closely.
Is measurement of urine specific gravity (USG) in rabbits useful for assessing renal concentrating ability? Do you recommend urine culture and a urine protein/creatinine (UPC) ratio?
USG is invaluable together with other biochemical parameters (blood urea nitrogen, creatinine, K+, phosphorus, etc.) for assessment of renal concentrating ability. Culture and sensitivity and UPC will depend on the case and whether I am concerned about disease(s) associated with the urinary system.
Given the huge range of urine specific gravity (USG) in the rabbit at what USG do you consider loss of concentration?
Good question! Published ranges are super wide! I would interpret that together with bloodwork and clinical status of animal. For example, if the rabbit is azotemic and showed USG = 1.005, I would probably consider this significant. However, if the rabbit is azotemic and you have diagnosed intestinal obstruction and the rabbit has been receiving intravenous fluids for the past 12 hours, then a USG of 1.010 is likely to be less concerning.
When taking a series of x-rays to access the progression of the obstruction how much time should be allowed between each of those?
The exact interval will depend on the clinical status of the rabbit. If stable, I usually aim for every 2 hours or so.
Is maropitant dosing/administration the same as in dogs or cats?
I use the same dose as for dogs/cats: 1 mg/kg SC
Ozawa SM, Hawkins MG, Drazenovich TL, Kass PH, Knych HK. Pharmacokinetics of maropitant citrate in New Zealand White rabbits (Oryctolagus cuniculus). Am J Vet Res. 2019 Oct;80(10):963-968. doi: 10.2460/ajvr.80.10.963. PMID: 31556710.
Can you share a dose for opioids…?
What opioid(s) are you thinking specifically? There are doses published for a number of them (buprenorphine, fentanyl, etc.
Visit the Exotic Animal Formulary for specific doses and view the RACE-approved webinar recording Sedation and Pain Management in Exotic Companion Mammals for useful clinical information.
Regarding ranitidine discontinuation – we now get cimetidine compounded and use this adjunctively to cisapride. Do you have any thoughts on this?
Go right ahead 🙂 Just bear in mind the pro-motility effects of H2 receptor blocks ranitidine > famotidine > cimetidine
Does famotidine have pro-kinetic effects, or do you use it as a gut protectant?
It is believed to have both.
Given the complexity of rabbit GI motility – the coordination required between motility of different parts of the gut – isn’t it a bit naive of us vets to believe that prokinetics would be of benefit?
Correct. That’s why I would never recommend using it as a sole therapy without adjuncts e.g. fluids, analgesia etc. However, promotility drugs are unlikely to be detrimental (unless in intestinal obstruction for example).
How do you obtain the cecotrophs from the donor rabbit for transfaunation?
A little bit of luck, speediness, and close observation 🙂
Also putting an e-collar for a while can also work
I have a rabbit with GI issues (due to diet) on pro-fibre long term, should this be stopped if using probiotics is anecdotal?
Ultimately, you’re probably not doing any harm.
How long should we maintain pharmacotherapy in case of intestinal obstruction if the clinical status is declining?
If the owner is open to surgery, then these are the cases I will cut. I would definitely not continue medical therapy indefinitely.
With hair impaction cases where you have ‘milked’ the pellet into the cecum for normal fecal passage, have you had any percent who are persistently obstructed and have had to go back in surgically?
Super rare (fortunately). I would estimate <0.5%
What’s your thought on ketamine in regards as an induction agent? I’ve been told it has a fear induced reaction in rabbits?
Medetomidine and buprenorphine are what we typically use.
If you…need to do an enterotomy what suture would you go with?
I always use a monofilament absorbable suture, usually 5/0 or smaller. The exact type of suture can vary depending on locality and accessibility. In my hospital we use BiosynTM.
This program is approved by the American Association of Veterinary State Boards (AAVSB) Registry of Continuing Education (RACE) to offer a total of 1.00 CE credits to any one veterinarian and/or 1.00 veterinary technician CE credit.
Sheene J. To cut or not to cut: Decision making in rabbit gastrointestinal syndrome. February 9, 2022. Lafeber Vet web site. Available at https://lafeber.com/vet/rgis/