Facial abscesses

 

 

Michel Gruaz, with Esther van Praag, Ph.D.

Warning: this page may contain pictures that may be distressing for some persons.

In past times, when a rabbit developed a large sized abscess on the cheek, the cause was believed to be bovine hypodermosis or warbles caused by the larva of the ox warble-fly Hypoderma bovis. Lumps (sterile abscesses) on the back of cattle or deer contain young warbles/larva. The presence of a facial abscess should, however, be taken seriously. Main causes are dental problems and bacterial infections like staphylococcosis and pasteurellosis. 

An abscess is a pocket of fluids and pus that results from an attack by pyogenic organisms (bacteria that produce pus), followed by cell destruction. The content consists of pus, dead phagocytic white blood cells, necrotic cells and dead or living bacteria. The pocket grows in size when the amount of pus increases. During the encapsulation phase, the abscess gets isolated from the surrounding tissues and blood circulation. If the abscess is not treated, it can burst to the inside or at the surface of the skin. Bacteria and their toxins will be released in the blood, which is life-threatening (septicemia, which is difficult to treat in rabbits) and painful.

Many rabbits suffering from abscesses have a history of pasteurellosis or infections caused by other bacteria, e.g., Streptococcus sp., Pseudomonas sp. and/or fusiform – spindle shaped bacteria. The development of jaw abscesses may have a genetic origin (malocclusion, abnormal elongation of a molar), but can also relate to apical (tooth root) problems due to dental trauma (fracture) or to the presence of a foreign body such as a piece of hay stuck between molars. Bacteria can enter the space between the gum tissue and the tooth and reach the dental root. Often Staphylococcus sp. or Pasteurella sp. bacteria are isolated, but Fusobacterium sp., Actinomyces sp. or Streptococcus sp. (which can infect humans teeth) may be the cause as well.

No specific clinical signs are linked to the presence of an abscess. In a primary stage, it is possible to feel a lump or a bump along the bone of the mandibular jaw. Abscesses can feel hard or as a soft paste like lump that can be moved. Their presence does not appear to cause pain in rabbits, unlike observed in other animals. Growth of abscesses is usually fast, and their size can double within a few days.   

 

MediRabbit

MediRabbit

Flora, a Rex female rabbit aged 7.5 years, suffered from paralysis of the hind limbs caused by the parasite Encephalitozoon cuniculi, developed an apical abscess of the incisor on the lower jaw (arrow). These can double size within 24 hours ! After analysis of a needle aspiration sample by a veterinary analysis laboratory, the diagnosis came back as osteosarcoma. In reality, it was an apical abscess (root abscess) that spread to the surrounding jaw bone (osteomyelitis), causing bone decay.

This stage is often overlooked the rabbit continues to eat normally. Then, gradually, an unusual limp appears, accompanied by a reduced appetite, increased drinking and sometimes fever.

 

Caroline Charland

Rescued rabbit that suffers from a non-treated facial abscess that burst open and dried out (left). Detail (right).

Identification of the problem - diagnosis

If the visual examination and palpation of head conclude to the presence of a maxillary or mandibular abscess, the oral cavity of the rabbit must be carefully examined. This is best done on a sedated or anesthesized rabbit.

 

Akira Yamanouchi

Anesthesia of a rabbit (top left) allow taking precise images

Akira Yamanouchi

Once the rabbit is anesthesized, precise  and high resolution X‑rays can be taken under different angles

Akira Yamanouchi

Examination of the oral cavity by means of an othoscope

Akira Yamanouchi

Visual examination of the molars

Jen Smuck

Examination of the teeth by means of an endoscope. The yellow stains on the teeth are normal.

The anesthesized rabbit is immobilized to avoid any movement that could blur the images. Ideally, radiographs are taken from different angles (ventrodorsal, lateral et oblique). Images must be of irreproachable quality, high resolution when available. In order to provide information of the dental problem such as e.g., bone deformation, root-related problems, presence of abscesses, and spread of the infection to the jaw bone. Computed tomography (CT scan) can help refine diagnosis, e.g., by locating the dental problem precisely and image its extent, evaluate prognosis and predict therapeutic outcomes.

 

Cheryl Morales

Right lateral (left) and ventro-dorsal (right) views of the skull of a dwarf rabbit with several occlusion problems of incisors and molars.

The jaw bone can get infected. A sample can be aspirated in a syringe with a needle of smaller gauge and sent to a specialized laboratory. Unfortunately, it happens that diagnosis comes back with an incorrect diagnosis such as osteosarcoma (tumor of the bone, rare in rabbits) instead of dental abscess with bone infection (osteomyelitis). This mistake can have disastrous consequences, delaying proper treatment and administration of antibiotics.

 

Treatment

Treatment of a facial abscess is difficult and long, and requires cooperation and dedication of the owner for post-surgical care. Recurrence is frequent.

If the lump can be felt, but is small in size, an antibiotic treatment can be attempted. In one case, the rabbit had lost a tooth, and the cavity was filled with pus. The combined administration of daily marbofloxacin and weekly injection of long-acting penicillin cured the problem. If the rabbit presents sensitivity to penicillin, this antibiotic can be replaced by e.g., metronidazole. The use of systemic antibiotics is, however, not always efficacious and a more aggressive approach is necessary.

The safest approach is full excision of the abscess capsule and of surrounding infected and/or necrotic tissues. During the surgery, it is important to verify that all fibrous channels leading to abscess cavities located deeper in the tissue are removed. If those pockets cannot be removed, they should be flushed with an antiseptic solution (chlohexiderme or povidone iodine) by means of a catheter. The debrided cavity can be filled with products impregnated with antibiotics. Another option is to place a drain to facilitate post-surgical care and help healing.

Dr. Gil Stanzione

Left lateral (left) and right-lateral view of the skull of a rabbit suffering from advanced dental disease. The presence of an abscess is noted around the right last molar (arrow)

Dr. Gil Stanzione

Dorso-ventral view of the skull of a rabbit suffering showing the presence of an abscess is noted around the right last molar (arrow)

 

Dr. Gil Stanzione

Surgery to remove the abscess: presence of pus (left), excision of the infected pocket and molar (right), after which the cavity was debrided and filled with a PMMA bead impregnated with amikacin. Post-surgical care included the administration of the analgesics buprenorphine hydrochloride (Buprenex), and later meloxicam (Metacam), as well as a daily injection of penicillin during a month.

If surgical excision is not possible, the abscess pocket should be carefully debrided. Every trace of pus, of tooth or bone fragments, or of necrotic tissue should be removed to promote a good healing. The pocket can be filled with PMMA beads impregnated with antibiotics, with cellulose-based sponges or calcium hydroxide, before the incision is sutured. Details about fillings can be found here: Skin abscess in rabbits. Another option is to keep the wound open by suturing the edges of the incision to the skin (marsupialisation). This enables an “easy” daily care, such as flushing with chlohexiderme or povidone iodine or filling with products that dry out the cavity (e.g., dextrose, medical honey, manuka honey). During the healing process, the cavity will progressively fill with scar tissue and heal.

If osteomyelitis, its extension in the jaw bone must be assessed. If the infection spreads over a few molars, prognosis is guarded and the option of humanely putting the rabbit to sleep should be considered. Treatment includes the administration of systemic antibiotics that penetrate the bone, chosen according to the results obtained from the bacterial culture and antibiotic sensitivity tests. The choice of antibiotics safe to use in rabbits is limited. The treatment must be aggressive and long, between 4 to 6 weeks. If the antibiotics fails to reduce the infection, or bone has been destroyed, surgical debridement should be considered.

After the surgery and during recovery, analgesics should be given to the rabbit. Several products such as e.g., creams/gel with d’Echinacea or HEALx Soother Plus have properties that promote healing.

It must be taken into consideration that abscesses are often difficult to treat and healing cannot be 100% guaranteed. Post-surgical follow-up are, therefore, recommended.

Acknowledgement

A big thank you to (alphabetic order) Caroline Charland (www.BunnyBunch.org), to Michel Gruaz (Suisse), to Debbie Hanson (USA) and her rabbit Stella, to Dr. Cheryl Morales (Prestonwood Animal Clinic, Houston, TX, US), to Bonnie Salt (USA), to Tal Saarony (USA) and her rabbit Motek, to Dr. Gil Stanzione (Dakota Veterinary Clinic, White Plains, NY, US), to Jen Smuck (USA), and to Akira Yamanouchi (Veterinary Exotic Information Network, Japan) for the permission to use their pictures.

Further information

Capello V. Case Report: Use of HEALx Soother Plus in Postoperative Treatment of a Dental-related Abscess in a Pet Rabbit. http://www.exoticdvm.com/mammal

Capello V, Gracis M, Lennox A. Rabbit and Rodent Dentistry Handbook. Lake Worth - FL, USA: Zoological Education Network; 2005.

Harcourt-Brown F. Textbook of Rabbit Medicine. Oxford, UK: Butterworth-Heinemann; 2001.

Meredith A, Flecknell P. BSAVA Manual of Rabbit Medicine and Surgery. Cheltenham, UK: British Small Animal Veterinary Association; 2006.

Quesenberry KE, Carpenter J. Ferrets, Rabbits, and Rodents. St-Louis-MO, USA: Saunders; 2004.

Van Praag E, Maurer A, Saarony T. Skin Diseases of Rabbits. Geneva, CH: MediRabbit.com; 2010.

 


 

e-mail: info@medirabbit.com