NADENE STAPLETON BVSc MRCVS
RCVS recognised advanced practitioner in zoological medicine. Burgess Excel Rabbit Vet of the year 2021. Nadene graduated from the University of Melbourne veterinary school in 2000. After a varied and globe trotting career, including a spell as a volunteer in China working with bears she joined the RVC Beaumont Sainsbury Animal Hospital in 2009, where she has remained. During her time here she has worked as apart of a team that has built the biggest first opinion and referral exotic practice in London.
Nadene begins her veterinary webinar with a brief summary of the common signs of gut stasis, before contrasting this with those of megacolon. She describes recurrent bouts of gut stasis, rabbits that are ravenously hungry, but with progressive weight loss and/or loss of body condition. There may be a bloated abdomen, intermittent pain, increased gut noises (sometimes can be heard across the room), abnormal faeces, which may be liquid and collect around the perineum and a potent risk for fly strike. Affected rabbits have a huge caecum and are unstable under general anaesthesia. This is a potential problem to remember when performing neutering.
On physical examination there is a lot of ingesta in the gastrointestinal tract and radiographs characteristic or a routine stasis case. Pellets produced by rabbits with megacolon are very large and are illustrated in comparison with normals.
Obstipation/caecal impaction represents a crisis with stressed rabbits, dehydration, palpable hard faces and extreme pain. These patients don’t move, are anorexic, with teeth grinding, belly pressing and grunting.
For those unfamiliar with the condition, myself included, the next part of the webinar is particularly interesting and educational. Megacolon is considered a genetic condition affecting English breed rabbits. Affected rabbits can be identified from their coat colour markings. The basic genetic defect is based on an understanding that the En gene is responsible for white marking and is dominant over the en gene, which is responsible for solid or ‘self’ marking.
Megacolon rabbits are homozygous En/En. Excellent rabbit photos will enable you to recognise potentially affected rabbits, including those with the ‘Chaplin’ moustache! There is more detail on the genetics elsewhere in the webinar but this is very well presented. It allows you to identify not only those rabbits at risk, what percentage involvement exists, but also additional information on the basic genetic defects.
The pathology is relatively complex, but again well presented, and shares features with Hirschsprung’s disease in humans, a genetic condition of babies. Notably there is a lack of innervation to part of the colon. The treatment in affected babies is surgical removal of the affected section of bowel, which is not an option in rabbits as they are hindgut fermenters.
Disease progression depends on genetics and other factors and varies in the time of onset. There are periodic episodes of stasis, but ultimately the condition is progressive and is considered incurable.
There are excellent sections on management of an acute episode, a stasis episode and follow up maintenance. Nutritional support is essential, involving high fibre feeding formulae, soaked pellets, favourite foods or grass and ad-lib hay.
A striking radiograph of a terminal end -stage caecal impaction is shown, and although there are some recommendations of how to attempt to rescue these cases, the prognosis is poor and therefore euthanasia needs to be a consideration.
The webinar ends with a detailed description of a clinical case. We see difficulties with anaesthesia for neutering, parasitic skin problems, megacolon markings, abnormal faeces, and recurrent dental disease, which required repeated episodes of ‘firefighting’. There are some magnificent 3 D images of retrobulbar abscess and mandibular abscess. The rabbit in question only lived to 20 months, but many other affected rabbits will have much longer life expectance. Cases are quite variable in severity, and many have no problems with dental disease, while others show only very mild intermittent signs throughout life.
Prevention of megacolon is dependent on client education. Getting the diet right, comprehensively explained in the webinar, is essential. Clients also need to be prepared for potential sequelae, such as dental disease. Megacolon can be avoided by breeding practices-English x self rabbits, not English x English.
This webinar is excellent throughout and in just 40 minutes will educate you on all aspects of this serious rabbit disease. It is quite obvious, that in addition to be well on top of her subject, Nadene also likes teaching. She speaks very clearly throughout at just the right pace with no jargon. It is teaching at its very best and the webinar is thoroughly recommended to all colleagues that want to progress in rabbit medicine.