Pet Factsheets

Ear base abscesses

An ear base abscess
©David Perpiñán

Abscesses can be found literally anywhere on the body, but abscesses that are associated with the ears in rabbits (ear base abscesses) can be difficult to diagnose and treat. It is therefore important to examine your rabbit regularly and seek veterinary advice at the soonest opportunity.

What is an abscess?

Abscesses are pockets of infection (bacteria) as well as inflammatory cells which invade an infected area to help fight an infection. Abscesses are the bodies’ way of trying to clear itself of an infection. However, in rabbits, abscesses can cause more problems than they solve and are commonly found in several locations. They are often associated to dental or ear disease and can be incredibly difficult to treat and cure.

Why are abscesses difficult to treat in rabbits?

In other species, such as cats, abscesses are usually much easier to treat, as the pus they form is of liquid consistency, so it is normally possible to drain and flush the abscess out, affecting a cure.  However, the type of pus formed in rabbit abscesses is much more solid (like toothpaste) and a thick, fibrous capsule forms around the abscess. The capsule ensures that the infection remains within the abscess, so it doesn’t spread into the rabbit’s bloodstream, which could prove fatal. Whilst this is a good infection control method, it means that with abscesses associated with the ears, it is nearly impossible to get antibiotics into the abscesses to treat it. On top of this rabbits rely upon ‘friendly’ bacteria within their digestive system for digestion. Some antibiotics are not suitable to use on rabbits due to the negative effect it has on the digestive bacteria. Some are so dangerous they can be fatal if used, so the selection of antibiotics used on rabbits is limited compared to dogs and cats.

What are ear base abscesses?

Ear base abscesses are those which form at the base of a rabbit’s ear. Often it may only be evident on one side. As a prey species and as a survival method, rabbits try and hide signs of illness for as long as possible, so often don’t scratch excessively at the ear or shake their head. Sometimes the ear may feel hot or look red, but often the infection is deeply seated within the ear, so external signs may not be obvious.

It may be possible to feel a small, hard lump at the base of the ear. Sometimes this is only the size of a pea and is often non-painful. If you do feel a lump on one side, that isn’t evident on the other then you should get your vet to examine your rabbit as soon as possible. Other signs may include a head tilt, nystagmus (flicking of the eyes up and down or left and right), ataxia (difficulty moving around or falling over) and constriction of the opposite side of the face (the muscles are tightened so it pulls up one side of the face). The rabbit may also appear unwell, go off their food and stop producing droppings. This is normally because the rabbit is painful, and emergency veterinary advice must be sought.

How will my vet diagnose an ear base abscess?

Your vet will perform a thorough clinical examination. They will use an otoscope to look down the ears to see if there is any obvious sign of infection, however this can only examine the outer ear and not the middle or inner ear, which is where ear base abscesses are often located.

If your vet suspects your rabbit to have an ear base abscesses, they will probably recommend further investigations. The lump that can often be felt at the base of the ear is usually the tip of the iceberg, as the abscess will usually extend much deeper into the ear structures. X-rays may be advised but are often of limited use. The best way to diagnose ear base abscesses and assess them for the most suitable treatment is with a CT scan. This allows your vet to plan the treatment more effectively, which will improve the chances of successful treatment. If your rabbit is insured this may be covered on their insurance.

Supportive treatment is also required whilst investigations and treatment are undertaken. This will involve pain relief and supportive feeding and fluids, with prokinetic medications if the rabbit isn’t eating and drinking properly.

How will my vet treat my rabbit?

There are many factors when deciding upon what treatment is best and each case will be assessed on an individual basis.

Treatment is often invasive and expensive with no guarantee of a successful outcome. Ear drops are ineffective as they cannot reach the route of the infection since this is almost always deep set within the ear; surgery is often the best treatment option.

The type of surgery undertaken depends on the severity of the abscess and where it extends to, which is why having a CT scan is advised. Sometimes surgery to open up the ear canal (marsupialisation) is needed. This allows for the abscess to be cleaned regularly over the coming weeks. Other times removing part of the ear canal is necessary as well as closing over the bulla of the ear. This is required when the infection extends into the lower canal, past the ear drum and into the middle ear. Many owners worry that their rabbit will be deaf after this surgery and how they will manage, but these rabbits are already completely deaf due to the destruction caused by the abscess, so removal of the ear canal makes no difference to them. The aim of the surgery is to completely remove all pus and infected tissue to cure the abscess.

Can my rabbit be cured?

Success is in no way guaranteed for all cases of ear base abscesses and depends on whether all the infected tissue can be removed. If this is not possible then curing the infection is unlikely. Marsupialisation surgery is only possible in the early stages of infection and can lead to further reoccurrence.

How can I prevent my rabbit getting an ear base abscess?

Ear base abscesses are generally only ever seen in lop eared rabbits and not those with ears that point upwards.

All owners and especially people who own lop eared rabbits should get into the habit of feeling their rabbit’s ear bases regularly to check for any lumps. Early intervention is usually associated with a higher success rate.

Routine cleaning of the ears is of limited use and is likely to simply lead to trapping of the ear cleaner within the ear, leading to an increase in the likelihood of infection.

One could argue that we should be breeding rabbits with confirmation as nature intended and moving away from breeding lop eared rabbits.

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