Actinomycosis - a bacterial infection
Actinomycosis is a bacterial infection often leading to painful abscesses.
What is actinomycosis?
Actinomycosis is a relatively rare infection caused by a bacteria called Actinomyces spp In rabbits, this bacteria generally causes one or more abscesses which are localised collections of pus surrounded by a firm capsule of scar tissue.
Abscesses are generally found on the jawline, but also can form on the head, neck, and limbs. Abscesses from actinomycosis can extend aggressively through the skin, muscle and bone tissues.
What signs might my rabbit show?
Signs of actinomycosis vary depending on where in the body the abscess is located. For abscesses near the surface of the skin, they can appear as a painful swelling, firm or fluid filled, of varying size, and with or without discharge of thick white pus. Abscesses may increase in size gradually over a few days, or appear from nothing in a matter of hours.
An infected rabbit may show signs of pain and fever including a decreased appetite and activity level, increased sleeping, teeth grinding, restlessness, sitting with a hunched appearance, or may be reluctant to move. With abscesses on the jaw line, the rabbit may show reluctance to eat, or difficulty chewing and the face will not look symmetrical, as it should do normally. With abscesses on the legs, the rabbit may show lameness.
Actinomycosis in rabbits can also be a chronic disease with internal infection resulting in diarrhoea and weight loss.
How can my rabbit develop this problem?
Actinomycosis can occur in rabbits of any age, gender, or breed.
Like other bacterial infections, the rabbit may be more prone to developing this if it is of poor health, eg immunocompromised, dental disease, respiratory disease, or other major disease like diabetes (although true diabetes is thought to be extremely rare in rabbits).
The rabbit may also be at increased risk if it is kept in unsuitable housing or in unhygienic conditions - sore and wounded feet from improper surfaces such as wire cages, non-padded surfaces; raw skin from urine scalding, or sitting on soiled bedding material, eg due to immobility from obesity or pain. Abrasions, trauma, bite/puncture wounds, overgrown nails or a previous infection could also lead to an increased chance of contracting an infection.
How will my vet diagnose the problem?
Diagnosis depends on the location of the infection and the clinical signs exhibited by the rabbit.
Your vet will take a thorough medical history and perform a complete physical examination. Any wounds or sites of potential infection may be swabbed for bacterial culture to determine the exact type of bacteria causing the infection.
Other diagnostic tests could include faecal samples, tracheal washes, biopsies, blood samples, or radiographs.
What treatment may my rabbit need?
Treatment depends on the location of the infection.
Rabbits have very thick pus that doesn’t drain easily (it has the appearance of toothpaste) so in almost every case, surgery will be needed to open the abscess and remove the pus preferably contained within the capsule to lessen the chance of reoccurrence. If the source of the infection can be identified, eg infected tooth, it must be removed or the infection may not resolve. The surgical wound from opening the abscess is often left open after surgery and flushed daily with antiseptic solution, especially if there was any contamination from the pus during the surgery or the whole abscess was not removed. Once the infection is controlled, the wound will usually close and heal over. Antibiotics will usually be prescribed as well as pain medications.
In cases where the infection has spread extensively throughout the body, hospitalisation with intensive care and fluid therapy for several days may be indicated.