EC / Encephalitozoon cuniculi / Head Tilt / Torticollis
Head Tilt - an Introduction
Head tilt is a common occurrence in rabbits - it usually presents suddenly and in severe cases the balance system is affected, and the rabbits starts uncontrollably rolling and may have flickering eyes (nystagmus). There are 2 main causes of head tilt - one is EC infection, and the other inner ear disease. Trying to work out which one is the cause can be problematic, as recent studies in the UK showed that over 30% of bunnies have undiagnosed inner ear issues, and that up to 75% of rabbits will test positive for EC! Although it looks dreadful, most will survive with early intervention, treatment and nursing care, and only a handful will be left with a residual head tilt after 2-6 weeks.
The following group specialises in support for those who are caring for rabbits with head tilt - Help for Head Tilt Hoppers
What is Head Tilt?
Head tilt, also known as wry neck or torticollis, is a condition in which a rabbit's head tilts sideways.
What Causes Head Tilt?
Possible causes of head tilt include:
*Inner or middle ear infection
*Encephalitozoon cuniculi (E. cuniculi)
*Stroke
*Trauma
*Cancer
The two most common causes are a inner or middle ear infection or E. cuniculi infection.
Let's talk more about these in detail...
Inner or Middle Ear Infection
There are three parts to a rabbit's ear canal: the external canal, the middle canal and the inner canal. All three of these parts have the potential to develop infection. Inner ear infections are the most severe and the most likely to cause head tilt, but middle ear infections can lead to head tilt as well. An ear infection could be caused by bacteria, mites, even an upper respiratory infection. As the infection worsens (especially when it travels to the inner ear canal), it causes inflammation in the vestibular tract which affects the rabbit's balance. A very severe ear infection can cause pus to form and prevent the vestibular system from functioning properly (leading to potentially permanent damage).
E. Cuniculi Infection
Encephalitozoon cuniculi is a parasitic fungus that attacks a rabbit's central nervous system (the brain and spinal cord). It is transmitted through exposure to the urine faces and mucosa, of infected rabbits or through the placenta when a rabbit is born to an infected mother. When it enters the body, e. cuniculi travels through the blood stream and body tissues and targets organs such as the heart, lungs and liver. Eventually, it can make its way to the brain, kidneys and eyes. The body's immune response will create antibodies to fight the infection by limiting tissue damage and preventing the parasites from multiplying. Some infected rabbits may never show symptoms and live normal lives. Others, often when faced with some kind of stress that suppresses their immune system (such as an illness, injury or disability), may start to experience more overt symptoms.
What Are The Symptoms of Head Tilt?
Though symptoms will depend on the individual rabbit and the cause of the head tilt, general symptoms include:
Tilted head
Dizziness/vertigo
Difficulty standing or moving
Rolling or circling
Rapid side-to-side eye movement (nystagmus)
Seizures
Hind end weakness or paralysis
Symptoms may appear suddenly or develop gradually. Sometimes, initial symptoms are almost imperceptible. Regardless, this condition is often progressive and recovery depends on early diagnosis and treatment. If you notice any signs of head tilt, get your rabbit to an experienced veterinarian immediately.
How Do You Treat Head Tilt?
Your veterinarian will begin with a physical exam to determine the cause of the head tilt.
If the cause is suspected to be an inner or middle ear infection, your veterinarian should conduct blood tests and take a culture of the pus inside the ear canal if possible to determine which antibiotics the bacteria will respond to, and then, if necessary, they may conduct a radiograph of the skull or an endoscopic otoscopy (where they use a tiny camera to see and photograph the ear canal). Treatment includes systemic antibiotics, topical antibiotics, irrigation of the ear canal, medications for pain and inflammation and anti-vertigo medication. Your rabbit may or may not require fluid administration or supplemental feedings until they recover.
Overseas if the cause is suspected to be E. Cuniculi infection, the veterinarian may conduct a urinalysis and blood tests. Unfortunately in NZ there is no specific blood tests for EC but even if testing is inconclusive, treatment is often pursued if e. cuniculi is suspected. This includes anti-parasitic medication (usually Panacur/Fenbendazole), anti-vertigo medication and anti-inflammatory medication. Your rabbit may or may not need hospitalisation for a few days until they stabilise. E. cuniculi is not curable, but treatment can stop the progression of the disease and reduce or eliminate the clinical signs.
Supportive Care
Rabbits with and recovering from head tilt will have some special care needs beyond those of a "normal" rabbit.
Head tilt rabbits will likely require some changes to their enclosure. Add padding to the sides of their cage or pen (rolled towels, pillows or crib liners). If they are rolling, spinning or struggling to keep their balance, confine them to a smaller space. This will keep them safer and actually help them feel more grounded.
Tip: A laundry basket can be a good safety enclosure during rolling periods. Line the bottom of the basket with some puppy pads, then some soft towels and a top layer of fleece to keep them comfy and dry. Then pad the sides with rolled towels for support.
You will need to keep a careful eye on your rabbit's "down eye." You don't want it to get scratched on bedding or cage bars. Ask your vet for some ointment to keep the eye from getting dry.
Your rabbit may need a low-entry litter box as they will likely have some trouble hopping in and out of a regular one. Try one of the ones recommended in the Toilet Training section.
If your rabbit is having trouble eating and/or drinking on their own, you will need to adapt their dishes for easier access or provide them with assisted feeding. This can be Critical Care or other supplements like DualCare fed via syringe. It is important that your rabbit get enough nutrients during their recovery.
Try to handle your rabbit as little as possible. Rabbit's with head tilt struggle with keeping their balance, especially more so when they do not have their feet on the ground. If you must pick them up, hold them tightly to your chest and brace their sides as much as possible.
Regular exercise (once they are stable) is also a very important part of head tilt treatment and recovery. Having a large area to play in is particularly beneficial.
Tip: During their first few times out, or if they are having particular trouble staying right-side-up during play time, try building a "track" for them. Arrange a long row of pillows or towels on either side with a narrow area for them to move between the padding. This can help orient them and give them support should they feel wobbly.
A stuffed bunny friend can be a welcome companion during head tilt recovery.
During recovery, try to keep your rabbit's living area quiet and as calm as possible. This can be a particularly scary and vulnerable time for your rabbit and loud noises, bright lights, etc., can cause unnecessary anxiety.
Acupuncture and other forms of physical therapy can benefit a rabbit with head tilt.
The following two articles from Special Bunny have good practical advice about caring for and setting up an area for your head tilt bun -
How to house your special needs or disabled bunny rabbit - Special Bunny
How to Care for a Rabbit with Head Tilt - Special Bunny
Prognosis
Head tilt is difficult to cure. Treatment often takes weeks and even months of medication and supportive care. It is common for symptoms can sometimes get worse before they get better, making it hard to assess how treatment is going. Even after treatment, there is the possibility that your rabbit will still have a residual tilt. But, while difficult to treat, it is treatable and many rabbits recover and go on to lead happy lives. Even those with a remaining tilt learn to adapt. The key is commitment and perseverance. With supportive care, proper medication and therapy, patience and a lot of love, your bunny can be back on their feet and binkying in no time. It can be scary, but together you'll get through it!
Source: Head Tilt in Rabbits - Disabled Rabbits
Further Reading:
Causes of Head Tilt / Wry Neck / Torticollis - Differential Diagnosis, MediRabbit
Head tilt may also be known as "wry neck," or the scientific terms "torticollis," or "vestibular disease." It is a fairly common condition in rabbits, with multiple causes.
Head Tilt (Wry Neck) in Rabbits: Causes & Treatment - PetCoach
Signs of torticollis may develop gradually or appear quite suddenly, but the result is the same: a bunny is walking around with her head on sideways.
Head Tilt (Torticollis) in Rabbits: Don't Give Up - by Dana M. Krempels, Ph.D.
A bunny with a head tilt is a very sad sight. Are we doing the right thing to keep him alive? Is he still happy? Will he ever be cured?
Head Tilt: Causes and Treatment - House Rabbit Society
E.C. Overview + Treatment
It is estimated that 52% of pet rabbits were currently or had recently been infected with EC....
What is E. Cuniculi?
E.cuniculi, or Encephalitozoon Cuniculi, is a fungus, which lives inside a rabbit’s body and is a significant cause of disease. All rabbit owners should be aware of it as it can, occasionally, infect humans, especially those who are immunocompromised.
How is it Transmitted?
Once a rabbit has E.cuniculi it passes on the infection through spores in its urine, faeces, mucosa and in utero. Other rabbits pick up the disease by eating these spores in contaminated food and water. Unborn kits — baby rabbits — may also be infected during pregnancy.
Once the fungus has entered a rabbit’s body it is carried in the blood to organs such as the liver, kidney and central nervous system (brain and spinal cord). This results in rupture of these cells, inflammation and clinical signs, primarily in the liver, kidney, brain and spinal cord. Only a small percentage — around 6% — of pet rabbits ever show signs of the disease. Some of these rabbits do not survive.
How to Tell if your Rabbit has EC?
If kits are infected during pregnancy, affected spores are able to cross into the eye. Later on in the rabbit’s life these spores multiply and erupt causing cataracts and lens rupture. This results in inflammation within the eye (uveitis), which is a serious and painful condition. Clinical signs in adult rabbits can include:
neurological disease — head tilt, unsteadiness, weakness of the hind legs, neck spasm, seizures and urinary incontinence
kidney disease
eye disease
heart disease
liver disease
Other causes of head tilt and neurological disease in rabbits should be ruled out, such as spinal trauma, inherited congenital abnormalities (splay leg), abscesses, middle ear infections, listeria infection, toxoplasma infection and lead toxicity.
Diagnosis, Treatment and Prognosis
There is no specific test for EC available in New Zealand
In affected rabbits the inflammation and release of spores results in clinical signs, particularly affecting the target organs (brain, spinal cord and kidneys).
Treatment is aimed at reducing inflammation using anti-inflammatory drugs and drugs to suppress the fungus. Treatment generally involves anti-inflammatory medication - usually Metacam together with Panacur at 20mg/kg PO q24h for 28 days.
Response to therapy is dependent on the severity of the infection at the time of diagnosis.
The organism can survive in a house or a hutch for up to one month at 22c. However, the fungus is sensitive to routine disinfectants - a 30 second exposure to 1% & 10% Bleach solutions, and 70% ethanol controlled EC spores in laboratory tests. Although more research is required, current knowledge is that the parasite is killed off by 28 days of once-daily dosing with Panacur, however often longer courses of medication are needed.
Activity of bleach, ethanol and two commercial disinfectants against spores of Encephalitozoon cuniculi
Control and Prevention
If you have more than one rabbit and one of them develops EC then all of the rabbits should be treated with Panacur for a minimum of 28 days. The rabbits’ environment should be cleaned and disinfected each week, until the end of treatment.
Source - with edits for NZ: What is e cuniculi in rabbits? - VetsNow
Further Reading -
’Encephalitozoon cuniculi (E. cuniculi) is a microsporidium organism that is well recognized as a cause of disease in pet rabbits and is internationally prevalent.’
Encephalitozoon cuniculi in Pet Rabbits - by Brendan Noonan, DVM, DABVP
This video is designed to raise awareness of E. Cuniculi in rabbits. Please learn more about this illness - every bunny can catch it
‘The protozoal parasite Encephalitozoon cuniculi lives in the nervous system and major organs of rabbits. A variety of clinical signs characterize the disease, yet they vary from one rabbit to another, rendering diagnosis of the disease difficult.’
Illustrative guide of clinical signs of rabbits with E. cuniculi - MediRabbit
’Encephalitozoonosis is an infection caused by the parasite Encephalitozoon cuniculi. It is well known in the rabbit community’
Encephalitozoonosis in Rabbits - Pet MD
’Potentially, all rabbits are at risk as infection is most likely caught from the mother. The parasite can also be caught later in life eg after being introduced to an infected newcomer, or sharing a grazing area with a rabbit carrying the infection.’
Rabbits and E. cuniculi (Encephalitozoon cuniculi) - RWAF
‘Probably the most common but least recognized cause of rabbit paralysis is protozoal infection. A disease that has taken its toll on many rabbits across the U.S. is Encephalitozoonosis. The organism that causes it is a protozoan parasite called Encephalitozoon cuniculi, or in short E. cuniculi.’
Encephalitozoon Cuniculi - House Rabbit Society
‘Encephalitozoonosis is endemic in the pet rabbit population worldwide, and is an important cause of neurologic disease in this species.’
Encephalitozoonosis in Pet Rabbits - Lafeber Vet
'Prevention and Treatment of EC Infection in Rabbits with Fenbendazole - MediRabbit
‘Various studies suggest that up to 80% of the healthy rabbit population carries the protozoa Encephalitozoon cuniculi in its body, without ever showing clinical symptoms of the disease and without development of the disease.’
Various treatment options for Encephalitozoon cuniculi, a protozoal parasite of the nervous system in rabbits ? - MediRabbit