Abstract
A 2.5-yr-old male jaguar (Panthera onca) presented acutely lame on the right hind leg during the third week of a 4-wk quarantine at Denver Zoological Foundation. Records review from the previous institution revealed this jaguar had presented with a similar lameness when 1-yr-old. Following examination the diagnosis at that time was a partial rupture of the cranial cruciate ligament (CrCL). The jaguar was treated conservatively with carprofen (Rimadyl®, Pfizer Animal Health, Exton, Pennsylvania, USA; 1 mg/kg, p.o., s.i.d. 14 days) and followed after completing that treatment course with Cosequin® (Nutramax® Laboratories Inc., Edgewood, Maryland 21040, USA; 750 mg, p.o., s.i.d., 15 days). The lameness continued on and off for the next 6 mo at which time the jaguar had normal ambulation for the next 12 mo.
Quarantine examination and radiography at the Denver Zoo revealed effusion of the right stifle, atrophy of the hamstrings, and a palpable click on flexion and extension of the stifle but was negative on the cranial drawer and tibial compression tests for a ruptured CrCL. Seven days later partial rupture of the CrCL and a longitudinal tear of the medial meniscus (MM) was confirmed during computed tomography and arthroscopy. The few remaining fibers of the CrCL were severed and partial meniscectomy of the caudal MM was performed.
Ten days later the instability of the right stifle was corrected using the tibial plateau leveling osteotomy procedure (TPLO).1 TPLO surgery was developed by Drs. Barclay Slocum and Theresa D. Slocum (U.S. patent number 4,677,973, Slocum Enterprises, Eugene, Oregon, USA) due to dissatisfaction with the current intra-articular and extracapsular techniques used to repair the CrCL.1 Preoperative radiographs were taken of the right stifle. A lateral view of the stifle was obtained to determine the amount of tibial plateau rotational correction that would be required to approximate a tibial plateau that is perpendicular to the center of motion for the stifle and the hock. In this jaguar the correction angle was determined to be 25°. An anterior-posterior radiograph of the right stifle was also taken to determine if there was any evidence for genu varum or valgum, which would negatively impact this surgical procedure.
A medial incision was made from mid femur to the proximal third of the tibia. A medial meniscal releasing procedure was performed prior to the TPLO. The tibial plateau was then bluntly dissected and a Slocum jig (Slocum Enterprises, Eugene, Oregon, USA) fixed to the tibia with two pins to act as guide for the Slocum osteotomy saw (Slocum Enterprises) in order to make a perfect cylindric cut in the proximal tibia. The tibial plateau was then rotated 10.4 mm which resulted in actual correction to 12º. In the surgeon’s opinion more correction would risk the stability of the fixation. The tibial plateau was secured to the tibia using a Slocum tibial leveling osteotomy plate (Slocum Enterprises).
It is critical during the first 4 wk postoperatively to severely restrict the patient’s activity while the osteotomy site begins to heal. We dosed the jaguar with the tricyclic antidepressant amitriptyline HCl (Generic brand, Mutual Pharmaceutical Co. Inc., Philadelphia, Pennsylvania, USA; 100 mg, 1.7 mg/kg, p.o., b.i.d.). At this level of sedation the jaguar would eat, drink, and defecate but spent most of the day resting peacefully.
Four and 8 wk postoperatively the jaguar was immobilized to reevaluate the right stifle by palpation and radiography. The anterior-posterior view revealed the initial formation of bony callous at the osteotomy site at 4 wk. In order to encourage additional callous formation and minimize the occurrence of “joint freeze” we discontinued the use of amitriptyline HCl and started regularly (three to four times daily) exercising the jaguar using operant conditioning. At 8 wk we noted more callous formation radiographically and the jaguar was virtually limp free. We are hopeful with more time the jaguar may make a complete recovery.
Literature Cited
1. Slocum B, TD Slocum. 1993. Tibial plateau leveling osteotomy for repair of cranial cruciate ligament rupture in the canine. Roush JK, ed. Vet. Clinics N. Amer. Small Anim. Med. 23: 777–795.