E. Cuniculi in Rabbits

You’ve been noticing it for a few months now. Your bunny just hasn’t been acting like itself. You can’t quite put a finger on it, but it just seems ‘off’ somehow. Then you see a bit of a head tilt, which grows worse with time. Sometimes you catch your bunny stargazing. Then you realize it seems just a bit weaker than usual on its hind legs. It’s not jumping as high and isn’t running to the door to greet you as usual. A few months later it’s practically holding its head to the floor. What could possibly be wrong with it? Is it a brain tumour or some rare bacterial infection?

It’s probably something far more common; a protozoal infection by a parasitic organism called Encephalitozoon cuniculi.

E. cuniculi is a severely under-diagnosed, but increasingly widespread problem in rabbits. Transmission is usually oral, through the ingestion of spores from contaminated tissues, foods or by ingestion of infected urine. Rabbits may also get it by licking the coats of infected animals. Often baby rabbits get it at the breeder, but do not show signs until they are particularly stressed or sick, which could be many years later. The immune system of a healthy rabbit can keep the infection at bay; but when the animal becomes ill or grows old and fragile, the “E” can take advantage of their weakened condition. The parasite can then spread to the brain, eyes or kidney, and cause different symptoms based on where it lands. E. cuniculi is on the rise; in fact it is the number one diagnosis made by rabbit vets when they see older bunnies with neurological signs!

Getting a confirmed diagnosis can be tricky (and expensive), so often, a response to drug therapy is used instead. If a bunny is suspected of having E. cuniculi, they usually show a vast improvement with the addition of proper drugs. Thankfully, E. cuniculi can be treated if caught early. Anti-inflammatory and anti-parasitic drugs can be used in combination with your vet carefully monitoring the dose between check-ups. Even in some severe cases, drugs have managed to improve conditions greatly. Some bunnies completely debilitated and slated for euthanasia have been brought back to their old selves once a diagnosis of E. cuniculi was made.

The next time you or a fellow rabbit enthusiast notice any odd behaviour in your bunnies, like difficulty hopping, gazing off into space for long periods, seizures or a head tilt, don’t think bacteria or a tumour. Bring your rabbit in to the vet and talk to them about E. cuniculi!