Abstract

Trauma to the ungulate foot may result in microbial invasion of its soft tissues and compromise of pedal circulation, conditions that can lead to osteomyelitis of the distal phalangeal bone, and/or infectious arthritis of the distal interphalangeal joint. Early diagnosis of foot injuries with complete delineation of soft tissue wound margins is essential to successful treatment.

Some of these injuries involve infection with multiple pathogens that differ in their patterns of antimicrobial sensitivity. Lack of pharmacokinetic data for African hoofstock species, inconsistent consumption of oral antibiotics by these animals, and the difficulties inherent in delivering drugs to them repetitively via parenteral routes may prevent ideal case outcomes. Use of regional intravenous antibiotic perfusion, antibiotic impregnated polymethylmethacrylate beads, and portable, battery-powered drug infusion pumps are among the various strategies that can be used to combat foot infections in these species.^2-4,6,8 Cases progressing to osteomyelitis and infectious arthritis are addressed with surgical debridement and lavage therapy.

Some animals with infectious arthritis and/or osteomyelitis do recover with our assistance. When infection is cleared, formation of “false joints” and osseous proliferation may still occur as part of the animal’s natural attempt to support its weight with compromised joint and skeletal structures.

Treatment failure occurs in some of these cases despite aggressive management and numerous immobilizations of the animal. Euthanasia is certainly a humane option when therapy fails. In our experience, salvage procedures such as joint fusion and amputation of the distal phalanx give temporary reprieve to the animal and to zoo staff reluctant to terminate the animal’s life. However, lameness frequently recurs due to abnormal weight-bearing that produces conditions such as proliferative osteopathy and tendinous calcification in the originally affected or contralateral foot. Quality of life issues become legitimate concerns. Continued work on early diagnosis and monitoring of osteomyelitis plus pharmacokinetics in African hoofstock will increase our chances for success in these cases.^1,5,7

Literature Cited

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2.  Burston, R.J., M.C. Schramme, M.H. Garlick, and J.V. Davies. Treatment of intrasynovial infection with gentamicin-impregnated polymethylmethacrylate beads. Vet Rec. 138;19:460–464.

3.  Hartley, M.P., and S. Sanderson. 2003. Use of antibiotic impregnated polymethylmethacrylate beads for the treatment of mandibular osteomyelitis in a Bennet’s wallaby (Macropus rufogriseus rufogriseus).

4.  Hirsbrunner, G., and A. Steiner. 1998. Treatment of delayed union and septic osteomyelitis of Metacarpus III/IV in a calf using gentamicin impregnated collagen sponges and minimal external coagulation. Vet Comp Ortho Traum. 11;1:19–22.

5.  McClellan, P. Visualizing a fracture with ultrasonography. J Equine Vet Sci. 15;1:20–21.

6.  Murphy, E.D., E.M. Santschi, and M.G. Papich. 1994. Local antibiotic perfusion of the distal limb of horses. In: Proc Annu Conv Am Assoc Equine Pract. 39:141.

7.  Southwood, L.L., D.D. Frisbie, C.E. Kawcak, and C.W. Mcllwraith. 2003. Evaluation of serum biochemical markers of bone metabolism for early diagnosis of nonunion and infected nonunion fractures in rabbits. Am J Vet Res. 64;6:727–735.

8.  Spelman, L.H., M.R. Loomis, and G.S. Davidson. 1994. Intravenous antibiotic therapy in hoofstock using a portable, battery powered infusion pump. In: Proc Am Assoc Zoo Vet Annu Meet. 321–323.