E.cuniculi in Rabbits – Separating Facts from Myths

Presenter – Molly Varga – BVetMed CertZooMed DZooMed (Mammalian) MRCVS currently runs first opinion and referral exotics service, Cheshire Pet

Many of us will be diagnosing E.cuniculi in rabbits and treating these cases with varied success in practice. However getting to grips with the pathogenesis and potential pitfalls when diagnosing and managing this condition is quite a feat due to the complexity of this disease.

Within a recent veterinary webinar organised by The Webinar Vet, Molly Varga helped give clarity to this complex infection by dispelling some of the myths that exist about E.cuniculi and giving practical advice on how to diagnose and treat these affected rabbits in a way that makes sense with the disease’s pathogenesis.

Molly cited a very useful timeline for the sequential events taking place within a rabbit infected with E.cuniculi. This timeline starts from the point of ingestion of the spores at day 1 to the point where the organisms can be histologically visible in the organs of predilection at day 98.  Within this timeline, IgM titres become positive at day 14 and IgG titres become positive between day 14 to day 28. At day 38 the IgM titres become negative and urinary shedding of spores takes place at day 42. This timeline demonstrates some of the problems we can encounter when trying to make a diagnosis. Just because a rabbit is seropositive does not necessarily mean it has an active infection. However rising IgG and IgM titres 2-4 weeks apart does indicate an active infection. There is also no direct correlation with the level of the titre and severity of the disease. However if a titre is negative it does rule out E.cuniculi as a disease, and other underlying causes for clinical signs should be sought.

Fenbendazole is good at killing E.cuniculi and, according to the company that makes the licensed product a 28 day course is necessary. However when you look at the 98 day timeline cited by Molly, this 28 day figure does not seem to make much sense. Molly explained the cited figure of 28 days was based on a publication back in the 1990s and wasn’t based on the biology of the disease. The problem with the 28 day regime is that E.cuniculi is constantly cycling and reinfecting the host, with the spore being particularly resistant within the environment lasting up to 4 weeks at 22C. Molly advises when treating a rabbit for E.cuniculi, to follow the licensed schedule but to combine this treatment with good cleaning and disinfection of the environment with products such as Trigene and F10.

Molly also went on to discuss other treatments including the use of lufenuron which disrupts the chitin found within E.cuniculi. This treatment clearly has potential but has yet to be scientifically proven. Molly advises against using catabolic steroids as they lower the rabbit’s immunity but Molly does consider that the fluoroquinolones may be useful as they can be helpful in treating microsporidium disease. The use of motility agents, intravenous fluids and anti-seizure drugs was also discussed. In cases of chronic renal disease as can be seen with E.cuniculi infections, Molly doesn’t rule out using anabolic steroids as they aren’t immunosuppressive and are good at maintaining muscle mass and well-being.

This veterinary webinar was crammed with useful and relevant information and I now have confidence in my knowledge behind this disease and realise there is so much more I could be doing for these cases rather than just reaching for a 28 day course of fenbendazole.

The Stethoscope