Abstract

Regional digital intravenous perfusion (RDIP) was used to control phalangeal osteomyelitis in a 45 yr old female African elephant (Loxodonta africana) for 7 mo. This approach was developed as an alternative to surgery, and was intended to be palliative. The elephant developed osteomyelitis of the second phalange (P-2) after a sole abscess abruptly worsened. She was in poor general health at the time, and was being treated for immune-mediated interstitial nephritis (ascites, polyuria, hyponatremia, hypoalbuminemia). Although surgical removal of infected phalanges has been successful in elephants, post-operative complications (secondary infections, contralateral limb problems) are common.^3,4,6 In this case, the risks of surgery outweighed the potential benefits, particularly in view of this elephant's compromised immune system and age.

The perfusion technique was extrapolated from methods used in domestic horses and cattle,^1,2,5,7,8 using a pneumatic tourniquet designed for elephant foot surgery (Pneumatic Tourniquet, CDA Products, Potter Valley, CA; Tel: 707 743-1300) The procedure was performed in a free contact setting using food rewards. The affected limb was elevated on a stand and fitted with the tourniquet placed below the elbow; the pressure was inflated to 10-12 psi for the duration of the procedure (35-45 min). Venous access was achieved using a 21-ga butterfly catheter or a 22-ga 1.5" needle fitted with an adapter and 21-ga butterfly. Initially, superficial veins along the posterior or lateral aspect of the carpus or metacarpus were chosen. At these sites, significant pressure was required to administer the antibiotics and flush. As the elephant became accustomed to the procedure, larger veins located anteriorly over the carpus, metacarpus, and digits were used repeatedly with excellent flow.

The perfusate consisted of the following: 10-20 ml of local anesthetic, 2 g of antibiotic diluted to 20 ml with 1:1 local anesthetic and heparinized saline, (20 ml of heparinized flush between antibiotics if two different agents were used), and 60-120 ml of heparinized saline flush. The tourniquet was left in place with the foot elevated for at least 20 min after administration of the antibiotics. The saline flush volume was initially much larger (500 ml) in order to ensure adequate perfusion, but the larger volume appeared to contribute to venospasm and thrombosis. Local anesthetics used were Carbocaine (2% mepivicaine hydrochloride, Abbott Laboratories, Chicago, IL) or Lidocaine (2% lidocaine hydrochloride, Elkins-Sinn, Cherry Hill, NJ)

The antibiotics used for RDIP were selected based upon culture and sensitivity, and response to therapy. A number of organisms were recovered from the draining tract, including beta Streptococcus, Staphylococcus, Fusobacterium, Bacteroides, Klebsiella, and Pseudomonas. Initially, cefotetan (Cefotan, cefotetan disodium, Zeneca Inc., Wilmington, DE) was administered via RDIP every other day for 4 wk. During this 4-wk period (20 treatments), the P-2 osteomyelitis continued to progress. A cephalosporin-resistant Klebsiella was cultured, and the antibiotics were switched to amikacin (Amiglyde-V, amikacin sulfate, 250 mg/ml, Fort Dodge Animal Health, Fort Dodge, IA) once daily for 1 wk. However, radiographs at this time revealed complete loss of P-2 and early signs of osteomyelitis involving distal P-1. Biopsy of infected bone recovered from the draining tract revealed few colonies of gram-positive cocci. The perfusate was changed again to a combination of cefoxitin (Mefoxin, cefoxitin, Merck & Co., Inc. West Point, PA) and amikacin every other day.

Over the next 3 wk of RDIP using cefoxitin and amikacin, the distal 1/3 of P-1 was destroyed by the osteomyelitis. However, over the next weeks and months, there was no subsequent bone loss of P-1. This combination was continued and the treatment frequency was reduced to three times per week for 2 mo (27 treatments total). Gentamicin (Gentocin, gentamicin sulfate, 100 mg/ml, Schering-Plough Animal Health Corp., Kenilworth, NJ) was then substituted for amikacin in order to conserve costs. Gentamicin and cefoxitin RDIP was continued two times per week for the next 2 mo (20 treatments) and then once weekly for another 3 mo (12 treatments). Aside from bony production, the radiographic appearance of P-1 changed minimally over 7 mo of therapy.

RDIP was well tolerated by the elephant, although venous scarring did occur. This technique could be modified for other elephant management situations (e.g., protected contact, standing sedation) and could prove useful in the treatment of post-operative infections. If initiated early, RDIP may even help prevent the progression of a nail or sole abscess to osteomyelitis.

Acknowledgments

The following individuals were instrumental in the development of this technique: the NZP Elephant House Staff, Drs. Murray Fowler, Laurie Gage, John Pascoe, Mark Papich, and Liz Santche. Special thanks to Charlie Anderson of CDA Products for the loan of the elephant pneumatic tourniquet.

References

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