Abscesses

An abscess is a localized collection of pus contained within a fibrous capsule. Abscesses are common in rabbits and can either be slow-growing or become large very quickly. Unlike cats and dogs, abscesses in rabbits do not often rupture and drain. The pus in a rabbit abscess is very thick and cheesy. Abscesses can extend aggressively into surrounding soft tissue and bone, and abscesses with bony involvement can be very difficult to treat, and require surgical intervention and prolonged medical care with a fair to poor prognosis depending on the severity and location.

Symptoms
Affected rabbits often appear to not be painful unless bone infections or dental disease is present. Generally, abscesses are associated with a combination of inflammation (pain, swelling, loss of function), tissue destruction, and/or organ system dysfunction caused by the accumulation of pus.

Causes
Abscesses in rabbits are often associated with an underlying cause, and the identification and correction of the underlying cause is important for successful treatment.

Abscesses occur most commonly on the face and are almost always caused by dental disease. Occasionally, they may be secondary to upper respiratory infections, ear infections, or trauma. Abscesses on the rest of the body are often caused by trauma, puncture, or bite wounds, abrasions, foreign bodies, skin boils (furunculosis), or bone infections (osteomyelitis).

Dwarf and lop-eared rabbits are predisposed to abscesses caused by dental disease. Rabbits that are housed together but not properly bonded will usually lead to abscesses caused by fight wounds. Wire cages can also lead to abscesses on feet from pododermatitis. :331

Pus-causing bacteria include the following:
 * anaerobic bacteria such as Fusobacterium nucleatum, Prevotella spp., Peptostreptococcus micros, Actinomyces israelii, and Arcanobacterium haemolyticum
 * Bacteroides spp.
 * Escherichia coli
 * Pasteurella multocida
 * Proteus spp.
 * Pseudomonas spp.
 * Staphylococcus aureus
 * Streptococcus spp. and b-hemolytic Streptococcus spp.

Diagnosis
Abscesses in rabbits are often diagnosed with the following methods:
 * Radiography of underlying structures: often teeth, skull, limbs, or chest.
 * Blood biochemistry and hematology.
 * Urinalysis.
 * Ultrasonography for internal abscesses.
 * Fine-needle aspiration of mass.
 * Gram stain of aspirate.
 * Bacterial culture and sensitivity of abscess capsule. Culture of pus is often unrewarding due to the low presence of bacteria. :331
 * Complete oral and dental examination under sedation or anesthesia.
 * CT scan to examine and determine the extent of internal abscesses and facial abscesses.

Treatment
Possible treatment options include the following:
 * Medication: alone, antibiotic therapy is often unrewarding. :331
 * Surgical excision: cut out the entire abscess.
 * Lancing, flushing and draining: generally unsuccessful. :331
 * Marsupialization: surgically create an open pocket that allows the abscess to be cleaned out through flushing or curetting (a spoon-like surgical device) until all infected tissue has been removed.

Why are abscesses hard to treat?
A rabbit's immune system is different than the typical mammal. Rabbits are good at walling off bacteria but bad at killing them outright. The pus in an abscess is also very thick and cheesy and does not allow for easy draining and flushing. Rabbits cannot tolerate all the antibiotics that can be used in other species. If not all the infected tissue is removed, recurrence is common. :332

Rabbits are also very sensitive to stress, and the stress of illness, surgery, and medication suppresses the immune system and makes healing harder.

There is a new, effective treatment for abscesses in rabbits called the Bicillin Protocol, developed by Marcy E. Rosenfield, DVM. It involves injections (not oral dosing) of Bicillin every other day for at least 8 weeks, until the abscess is cured. Bicillin is an injectable combination of benzathine penicillin and procaine penicillin, 300,000 units/ml. Penicillin must not be given orally to rabbits.

Extra resources
The following are various articles on possible treatments for rabbit abscesses in various locations.
 * Dana Krempels, Ph.D. (2013). Non-Surgical Treatment of Head Abscesses in Rabbits
 * Marcy E. Rosenfield. (2002). Successful Eradication of Severe Abscesses in Rabbits with Long-Term Administration of Penicillin Benzathine + Penicillin Procaine
 * R. Avery Bennett, DVM. Management of Abscesses in the Head in Rabbits
 * Christine Macey & Esther van Praag. (2009). Abscess Management in Rabbits: an Illustrated Guide
 * Vittorio Capello, DVM. (2006). Surgical Treatment of Periapical Mandibular Abscess in Rabbits [PDF]
 * Katrina D. Ramsell Ph.D, DVM. (2013). The Rabbit Advocate, Spring 2013, Treating abscesses in rabbits requires multi-pronged approach

Experiences
The following are some anecdotal experiences with abscesses.


 * Nicola Di Girolamo - Nic the Animal Doctor. (2018). Facebook post about a tooth abscess surgery (Graphic)
 * Highcroft Rabbit, Small Mammal & Exotic Vets. (2017). Facebook post about Dennis with a jaw abscess
 * Pete the Vet. (2015). Inqui, a five-year-old rabbit who had a jaw abscess
 * House Rabbit Society. (1998). Pandora's Battle with a Jaw Abscess