This case report describes a four-year-old, eighty-five pound, male neutered Labrador retriever that was admitted with unilateral lameness and clinical findings consistent with a unilateral gostrocnemius tendon rupture. A prior history of trauma was not identified. Ultrasonagraphic evaluation revealed bilateral gastrocnemius tendon defects in which approximately 80% of the tendon was ruptured on the clinically normal side, yet mechanical function and anatomical length were not apparently altered. Bilateral surgical repair was performed utilizing primary tendon reconstruction, supported by fascia lata, autograft and polypropylene mesh. The repairs were protected with rigid costs for two weeks following surgery, and replaced with orthotics through the complete recovery period. Orthotics provided semi-rigid support and allowed removal for controlled intermittent physical therapy. This surgical repair technique, combined with orthotic support, allowed for early mobilization and good ultimate outcome for a complicated bilateral condition.