Contagious Abscesses in Camelids

David E Anderson, D.V.M., MS, Diplomate ACVS
College of Veterinary Medicine
The Ohio State University, Columbus, Ohio

Contagious Abcesses are a growing concern for owners of camelids in North America. The veterinary surgeon must be aware of the possibility for spreading abscesses to other members of the herd if these lesions are treated in a "routine fashion".

History (Anamnesis)

Most often abscesses are detected by owners of camelids if they occur at peripheral locations (e.g., face), when the abscess ruptures, the animal is being prepared for show, or when annual shearing is performed. Affected camelids typically are normal in other respects. Occasionally poor appetite, weight loss, or lethargy are observed.

Physical examination and differential diagnoses

Most abscesses occur subcutaneously, affect peripheral lymph nodes, or affect the tooth roots and cause mandibular swelling. As such, they are easily identified during a thorough physical examination. Physical examination should be performed carefully because the dense fiber coat of camelids may hide abscesses from view or casual palpation. Rarely, these abscesses spread to the thoracic or abdominal cavities. Most abscesses in camelids are not contagious and are caused by Actinomyces pyogenes, Streptococcus spp, Staphylococcus spp, Bacteroides spp, E coli, Fusobacterium spp, and Actinobacillus spp. Coccidioides imitis should be suspected when multiple white, granulomatous lesions are found in multiple abdominal and thoracic organs. Differential diagnosis for contagious abscesses includes Corynebacterium pseudotuberculosis, Mycobacterium bovis, M tuberculosis, M avium.

Diagnosis

Fine needle aspiration of superficial abscesses is diagnostic. Microbial culture of the abscess is indicated to rule out contagious pathogens and guide antimicrobial selection. Ultrasonography may be used for evaluation of involved lymph nodes, any masses, or for evaluation of the abdomen. If the camelid demonstrates any of the clinical signs mentioned above, a complete blood cell evaluation and determination of blood fibrinogen concentration should be performed. When thoracic or abdominal abscesses are suspected, radiography, ultrasonography, paracentesis, laparoscopy, and exploratory laparotomy may be used to facilitated diagnosis. These are rarely indicated. Intradermal tuberculin testing has problems with false positive reactions and testing should be done after consulting your state or federal veterinarian. Caseous lymphadenitis (C pseudotuberculosis) usually is diagnosed by culture, but serologic testing is available. Toxin inhibition tests are performed on sera. I have tested 5 camelids with CL and over 130 exposed but without clinical signs of CL. I have seen 1 false-negative (culture positive of a dermoid cyst) and 1 persistent positive (for more than 1 year after surgical removal of the lesions and no recurrence).

Treatment

Surgical removal of the abscess without contamination of the environment is the treatment of choice. When lymph nodes are involved, I prefer to perform extirpation while the camelid is under general anesthesia. This allows me to perform delicate dissection with minimal risk to vital structures and to achieve optimal cosmetic appearance. If excision without ruptures is achieved, I perform primary closure of the wound. If contamination has occurred during excision, I place a 1/4 inch Penrose drain into the defect and close the remainder of the wound. Daily wound care is performed, when indicated, and antibiotics are administered for 10 to 14 days (procaine penicillin G, 22,000 U/kg body weight, daily; Ampicillin Na, 6 mg/kg, q12h; Ceftiofur Na, 2.2 mg/kg, q12h). If the abscess is lanced or ruptures, the animal should be isolated from the herd until all lesions have resolved. Caseous lymphadenitis may be transmitted by aerosolization; therefore, direct or indirect contact should not be allowed during the isolation period. Surgical extirpation of CL lesions was curative in 5 camelids (3 of which had had abscesses previously treated by lancing, lavage, and antibiotics). I have treated one llama with a tooth root abscess that was culture positive for Actinomyces bovis ("lumpy jaw"). Tooth extraction, daily wound care, and 21 days of antibiotic therapy was curative (no recurrence after 2 years).

Summary

Contagious abscesses are a concern to owners and the camelid industry because of the routine co-mingling of camelids that occurs on a national scale. In my experience, camelids affected with caseous lymphadenitis respond more favorably to treatment and do not develop internal manifestations of the disease compared with other small ruminants. To date, no vaccine has be proven to be efficacious for prevention of infection with C pseudotuberculosis in camelids. The best protection is vigilant hygiene, immediate treatment and isolation, and routine culturing of all abscesses diagnosed in camelids.