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Rabbits and Encephalitozoon cuniculi
By Brigitte Lord (nee Reusch) BVetMed CertZooMed MRCVS. Lecturer in Rabbit Medicine and Surgery at the University of Edinburgh. BRC Veterinary Adviser
What is Encephalitozoon cuniculi?
E.cuniculi is a common parasite that is spread in urine and affects primarily the nervous system (brain and spinal cord) and kidneys. Other animals can carry the parasite including wild rabbits but in a recent study very few of them are infected with the disease.
What signs will my rabbit show with E.cuniculi?
Back leg weakness and paralysis is a result of the swelling surrounding the parasite causing destruction of the nervous tissue. Other signs commonly seen with this disease include a head tilt, fitting; loss of balance, tremors, kidney failure and bladder weakness. Unfortunately once the rabbit develops severe clinical signs this can lead to death. Signs of kidney failure may include increased thirst, increased urination, weight loss and decreased appetite.
The E.cuniculi parasite can infect the eyes of un-born rabbits that are infected whilst in the womb. This may cause destruction of the lens and eye later in life (6 months to 2 year old are commonly seen). Medical treatment can be effective in saving the eye if this is carried out early enough. Otherwise surgery may be required. The rabbit may develop a cloudy lens and cataract. Then the eye may become red a swollen.
How can my rabbit be tested for it? Blood test:
A blood test can be carried out to measure antibodies that are produced by the rabbit if it has been exposed to the disease at some stage in its life. Over 50% of healthy rabbits were found to have antibodies to this parasite in a study carried out, which makes it difficult to interpret the blood results fully.
More information indicating the stage of infection and immune response can be obtained by taking two blood samples one month apart. If the antibody levels to E.cuniculi are falling, this suggests that a recent history of infection or flare up of an existing E.cuniculi infection has occurred. Rising antibody levels between the 2 blood samples is more suggestive of a current active infection or flare up. However if the antibody levels are the same at the first and second blood sample, it is difficult to conclude too much.
There is now a simple urine test that can test if your rabbit is shedding the parasite in it's urine. Most of the parasite is shed in the first 3 months after the rabbit has been infected, but it may be shed intermittently after that. We recommend urine samples are collected for 3 days and sent to the laboratory.
This is the most accurate way of confirming if your rabbit has the disease. The rabbit has to have a general anaesthetic to allow a small biopsy of kidney tissue to be obtained. We can now carry this out with key-hole surgery. This is something we may recommend in certain cases.
What treatment is available for this condition?
Unfortunately at this stage we can only support rabbits with the condition, because at present there is no specific treatment that will reverse the damage caused by the presence of the parasite.
Medication (Fenbendazole, Lapizole, Panacur) can slow or halt the rate of multiplication of the E.cuniculi parasite with in the body.
We can also offer a variety of supportive care and medication to support the signs of bladder problems or nerve disorders.
How can I prevent my rabbit getting E.cuniculi?
We recommend all rabbits recently acquired (purchased or rescued) receive a single course of fenbendazole for 4 weeks by mouth or on the pellet part of the diet daily. If you rabbit has the parasite it will kill the parasite before it causes further damage and may prevent clinical signs developing. If your rabbit does not have E.cuniculi it will not cause any side effects. There is no lasting effect so if your rabbit comes into contact with the parasite it can be at risk of disease. Hygiene is also important as the parasite is easily killed with contact for only 30 seconds with 1-10% bleach.