Submandibular Abscessation – Rabbit

Description

Submandibular abscessations (with involvement of the teeth) and mandibular osteomyelitis are frequently encountered in pet rabbits. This condition is an extremely difficult one to treat satisfactorily due to the deep-seated nature of the infection involved. See Harcourt-Brown (2009).

Aetiology

The commonest organism found in this situation is said to be Pasteurella multocida and the infection penetrates deeply into the mandibular bone. Other micro-organisms involved include Actinomycetes sp., Aspergillus sp., Brucella sp., Corynebacterium pyogenes, Fusobacterioum necrophorum, Fusobacterium nucleatum, Pasteurella multocida, Staphylococcus aureus and/or Pseudomonas aeruginosa (Garibaldi et al 1990). Poor vascularity, sclerosis and fibrosis may prevent the access of antibiotics to the organisms.

Odontogenic tumours are fairly common in humans but are frequently missed by ordinary histopathologists. One wonders if the same condition could be occurring in rabbits and rodents.

Treatment

Treatment of submandibular abscessation involves curettage and aggressive antibiotics. Rabbit pus is usually inspissated and does not flow easily. Initial therapy may be followed by the parenteral administration of antibiotics (as indicated by antibiotic sensitivity testing for years), maybe even for the rest of the animal's life if necessary. This condition illustrates the importance of veterinary nurse attendance or of the training of owners to administer injections to pet rabbits.

There have been reports from practitioners of the empirical use of clindamycin (Antirobe® Capsules 25mg; Upjohn) in the treatment of this condition (Chappell 1994). The abscess is curetted thoroughly and as much diseased tissue as possible is removed. A 25 mg Antirobe® capsule is pierced several times through with a hypodermic needle and placed in the wound. The skin is sutured over the capsule. No other antibiotic treatment is given. Some practitioners of this treatment claim that there is a very successful rate of improvement and can claim to have monitored some animals for up to twelve months after treatment with perfectly satisfactory results and no recurrence (Cartwright 1992 Personal Communication).

In this situation, the fact that so many practitioners are claiming success for the regime of treatment may be due to the fact the lesion is "walled off" from the systemic circulation and levels of clindamycin do not reach "dangerous proportions" in the lumen of the gastrointestinal tract. IT IS VERY IMPORTANT TO NOTE THAT THERE IS AN ABSOLUTE CONTRAINDICATION TO THE USE OF LINCOSAMIDES ORALLY AND PARENTERALLY IN THIS SPECIES. The thickening of the mandible after the infection has resolved is perfectly acceptable as it does not interfere with eating or drinking. Gentamicin is also be effective if administered intralesionally, methacrylate impregnated beads now being very popular. Packing the abscess cavity with calcium hydroxide after thorough curretage is also worth trying. I think the reason for success is the obliteration of dead space but you must clean all the pus and other traces of infection from the cavity before applying the calcium hydroxide. See Remeeus and Verbeek (1995).

In all cases systemic antibiosis oxytetracycline SC q 72hrs (Engemycin 5%®; Intervet) or procaine penicillin SC q3-7days for life if necessary is always indicated. Levamisole might boost the immune system.