Encephalitozoon cuniculi (E. cuniculi) in Rabbits
What is E. cuniculi?
E.cuniculi is caused by a parasite that primarily affects the nervous system (brain and spinal cord) and kidneys of the rabbit. The name of the disease is Encephalitozoonosis.
E. cuniculi spores are carried in an infected rabbit’s urine and are then eaten (or less commonly, inhaled) to infect another rabbit. Wild rabbits and rodents can be carriers of the parasite but often do not show symptoms. However, they can spread the disease in the outside environment. This should not stop you from letting your rabbit enjoy the outside – the advantages of having space to move and fresh grass to eat certainly outweighs the risks.
The parasite can also be transmitted from a pregnant doe to her off-spring. In some cases the parasite affects the kit’s eyes, leading to destruction of the lens and the development of cataracts later in life.
In a recent study, over 50% of healthy rabbits were found to have E. cuniculi antibodies, which means it is carried by a relatively large proportion of rabbits.
As the parasite is zoonotic, in theory, it can be spread to humans but this is rare and generally only affects people whose immune system is impaired. However, it makes sense to follow strict hygiene measures when handling rabbits.
What are the Signs?
- Head tilt
- Loss of balance
- Bladder weakness
- Kidney failure (leading to increased thirst & weight loss)
- The most common sign, in mature rabbits, is hind leg weakness and, in advanced cases, paralysis.
Unfortunately, in advanced cases, some rabbits have to be put to sleep.
Is there a test for E. cuniculi?
A blood test can tell us that the rabbit has been exposed to E. cuniculi at some stage in its life. So if the rabbit is showing signs of disease that are suggestive of encephalitozoonosis, a positive test does not necessarily mean that the parasite is causing these signs.
More information can be obtained by taking two blood samples one month apart. If the antibody levels rise during that period, it indicates that the rabbit has an active infection. Unfortunately, if the antibody levels stay the same between the first and second blood sample, then no true conclusion can be reached.
If the antibody levels fall between the 2 samples, then this is suggests that the rabbit is recovering from a recent infection and that treatment is having a positive effect.
A urine test can confirm if the rabbit is actively shedding the parasite. Usually the parasite is shed in the first 3 months after the rabbit is infected, although it can still be shed from time to time after that. Urine samples should be collected over a 3 day period and sent to a veterinary laboratory.
Unfortunately, a negative result is not conclusive, as the rabbit may not have been shedding the parasite during the urine collection time.
Taking a tissue biopsy is the most accurate test but this requires a general anaesthetic. A small bit of kidney tissue is obtained and analysed in a laboratory.
What treatment is available for E. cuniculi?
Symptomatic treatment can be provided to support some of the effects of disease but there is currently no treatment that will reverse the damage already caused by the parasite.
Fenbendazole (brand names, Panacur or Lapizole®) can slow or halt the rate of multiplication of the E. cuniculi parasite within the body. Daily dosing is required for a minimum period of 28 days – 1 ml/kg/day by mouth.
Preventing a rabbit getting E. cuniculi
As soon as you get a pet rabbit, a single course of Lapizole or Panacur should be given as routine for 4 weeks by mouth. This treatment regime means that if the rabbit is carrying E. cuniculi, the drug will kill the parasite before it causes further damage and may prevent clinical signs from developing.
Treating a rabbit that does not have E. cuniculi should not cause any problems.
This treatment is not long-lasting. Therefore, if a rabbit comes into contact with the parasite after receiving the treatment course, it is still at risk of developing the disease.
Any new rabbits entering a home with other rabbits should undergo isolation and be treated for the full treatment period.
If putting a rabbit in a hutch or run, then hygiene is of the upmost importance. Spores are relatively resistant to environmental change. At average temperatures, and in dry conditions, the average spore survival time is four weeks. The parasite is, however, easily killed with hypochlorite based disinfectants. Make sure you choose one that is suitable and safe for animal accommodation. Always follow the manufacturer’s instructions and adhere to the recommended contact time.
For another article covering lots of other common rabbit diseases click here
And, if you enjoyed reading about rabbit health you may be interested to read my other blog
Encephalitozoon cuniculi (E. cuniculi) By Jenna Richardson BVM&S MRCVS, Rabbit, Exotic Animal and Wildlife Clinician at Royal (Dick) School of Veterinary Studies