Vestibular Disease in Rabbits

The vestibular system is a very essential part of the sensory organs that help in ensuring proper body orientation, balance, and coordinated trunk and limb movements. It is composed of the inner ear’s labyrinth, vestibular nerve, and the brain’s medulla.

Any diseases or conditions that affect the vestibular system in rabbits is what we are referring as to vestibular diseases and conditions. 

Symptoms

Owing to the critical role that the vestibular system play, some of the symptoms your rabbit may have to include the following:

• A false sense of movement due to lack of sense of orientation, motion and balance that may result in stumbling, rolling, circling or vertigo
• Nystagmus or wobbling eyes characterized by repetitive and uncontrollable eye movements. The eye-rolling can be horizontal, vertical or rotary (in a circular pattern). 
• Vertigo or loss of balance (circling, rolling and stumbling)
• Torticollis or wry neck
• Head tilt towards the affected side
• Hearing loss
• Eye and nasal discharges
• Tremors
• Head dropping
• Middle and inner ear infection symptoms depending on the cause of the infection
• Nausea
• Loss of appetite

These are common symptoms. However, there might be others that will be tied to the cause as well as how severe the problem is.

Causes

There are many causes of vestibular diseases and conditions with the lop-eared breeds showing higher susceptibility. Also, old rabbits, as well as dwarf ones, tend to suffer from ear infections that might affect the vestibular system. [1]

The causes can involve nerve and brain center (central vestibular disease) or inner ear (peripheral vestibular) and each have their own unique causes.

Peripheral vestibular disease can be due to ear infection through blood or via eustachian tube, otitis externa, foreign bodies, and trauma. Also, cancerous growths and toxins can cause this condition. Infectious cases are caused by bacteria, fungi or yeast.

On the other hand, central vestibular diseases can be due to brain abscesses, tumors, toxins, protozoan diseases (such as E. cuniculi or Toxoplasmosis), liver and kidney disease. Dullness, anorexia, seizures, and paralysis will often accompany central vestibular diseases.

Generalized causes include:

• Brain abscesses
• Inner and middle ear infections that cause inflammation including by Pasteurella multocida or formation of small stones inside the vestibular organ [2]
• Toxicity such as aminoglycoside intoxication and lead poisoning
• Bone neoplasia or tumors
• Degenerative disease
• Trauma including fractures. Also, flushing ears aggressively may predispose this pet for ear infections.
• Immunosuppressed rabbits (common in aging or diseased bunnies).
• Idiopathic vestibular syndrome whose cause is unknown

Risk factors include lop-eared breeds, overcrowding and poor living conditions, malnutrition, lesions on pinna, among others. 

Diagnosis

To begin with, symptoms history will be noted, and differential diagnosis will be used to help pinpoint from among the many causes, what is the most likely cause.

Diagnosis will include blood tests, CT scans, MRI, serology, biopsies, and so on depending on what is suspected as a possible cause.

Also, otoscopic examination (under sedation) may be used to see if the tympanic membrane is ruptured or check for the presence of pus, debris, foreign bodies, and crusting. Crusting will indicate parasitic external ear infestation.

Radiography such as the use of X-ray can help check for lesions, foreign objects, tumors, or middle ear infections which are presented as graying mash in radiographs.

Bloodwork including complete blood count as well as a urinalysis may be conducted. If available, your vet will collect a sample of the ear discharge, to know whether the pathogen bacterial or a yeast infection.

A culture and sensitivity test may be performed to decide on the right medications to use in case of a bacterial infection. 

Treatment

Treatment options will largely depend on what diagnosis shows as the cause and its severity. Hospitalization may be necessary in case of severe symptoms.

Treatments may include fluid replacement therapy, change of drugs that cause adverse effects, reducing trauma pain or repair of fractures surgically. 

Trauma will require NSAIDs (reduce pain if the liver works well), bacterial infections will need antibiotics, while fungal ones will require antifungals. Culture and sensitivity test will determine the best antibiotics which may be used for 4-6weeks.

In the case of medicine toxicity, your vet may recommend safer alternatives. On the other hand, parasitic infections including E. cuniculi may require ivermectin injection among other treatments.

Forced feeding including syringe feeding may also be required if your pet does not eat using the various commercial feeds. Also, anti-nausea medications may help this pet to eat. 

Note that vestibular disease, especially when it is accompanied by anorexia may cause “gastrointestinal syndrome (RGIS) or GI stasis. Provide fluid therapy and nutritional support via a syringe or nasogastric tube as needed.” [3]

Recovery and prognosis

Prognosis will depend on the cause as well as how soon the problem is detected. If the cause is ear mite infestation, the prognosis will be fair while some inner and middle ear damages may be irreparable and may cause irreversible damage, head tilt or deafness. Also, treatment and full recovery may take weeks.

Providing soft warm bedding, a flat flooring will help minimize effects and injuries from ataxia. Ear mites should be treated and a good diet including grassy hay such as timothy hay will be recommended. Also include leafy greens such as collard greens, kales, dandeli0n greens, carrot tops, cilantro, parsley, romaine lettuce, spinach and so on.

Pelleted diets will also be ok. However, avoid those that are high in fats and starch as they may cause bloating, diarrhea, gas and so on.

Also, encourage your bunny to be involved in activities that will help restore and enhance vestibular system recovery as soon as it is safe. Unless too tired, try to encourage 10-15 minutes of exercise after a quarter to a third a day.

Finally, include a bonded pair if you must modify their environment. This will ensure the affected bunny does not feel lonely. Also, keep their hutches clean and groom them to avoid fur matting if they cannot groom themselves.