By Brigitte Lord (nee Reusch)
BVetMed CertZooMed MRCVS. Lecturer in Rabbit Medicine
and Surgery at the University of Edinburgh. BRC Veterinary
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.
Urine test: 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.
Tissue biopsy: 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.