Abstract
Scoliosis is known to occur in both stranded and wild, free-swimming cetaceans. Etiologies undoubtedly vary but, in general, are poorly understood. “Trigger points” are a focus of hyperirritability in a tissue resulting in localized tenderness and pain. In humans, trauma and immobility can result in the formation of trigger-points2 that may result in a functional scoliosis due to uneven muscle contraction. Among stranded cetaceans a suspected rhabdomyolysis has been described by Bossart et al.1 Muscle atrophy due to emaciation/catabolism and lack of normal swimming activity is often associated with a developing scoliosis in stranded dolphins. This type of functional scoliosis can have a rapid onset and may become permanent if vertebral fusion (exostosis) occurs.
A stranded 85-kg, adult female common dolphin, Delphinus delphis, was transported to the dolphin and whale hospital (DWH) following 8 days of treatment for gastric ulcers and infections in a small pool at the Virginia Marine Science Museum. Inclement weather prevented earlier transport of the dolphin. Upon arrival at the DWH, the dolphin presented emaciated, with a C-shaped lateral curvature to her peduncle that was slightly dorsiflexed, with muscle trembling. The position and trembling of the peduncle was thought to perhaps be a “protective” response to gastric pain from the ulcers. The dolphin had an excellent appetite and would swim briefly for food but was weak and required physical support most of the time. Blood work revealed moderate elevations of LDH, AST, and CK. We commonly observe such elevations following the stranding event in many cetaceans. Antibiotics, ulcer medications, and supportive care were continued, and physical therapy (myofascial massage, range of motion) was begun twice a day. Over the next 4 days the tail curvature and muscle tremors gradually decreased coinciding with a general improvement in her condition. However, on day 13 the dolphin developed a counter spinal curvature, cranial to the first, forming a backwards S-shape to her peduncle. Several concurrent therapies were then initiated in an effort to reverse this further developing scoliosis including: a single injection of vitamin E/selenium, neuromuscular electric stimulation (Electro-stimulator, Model AVS-4, Cefco, Inc., Inola, OK, USA) performed twice daily, trigger-point release techniques performed on alternate days utilizing acupuncture, daily positional release therapy (PRT) by a licensed physical therapist, and the use of a muscle relaxant, methocarbamol (25 mg/kg PO TID). No improvement was noted following the vitamin E/selenium injection; however, it was difficult to evaluate its efficacy in this case due to the concurrent therapies. Positive results were seen immediately following neuromuscular electrostimulation, acupuncture, and the PRT. The scoliosis had all but resolved after 5 days of treatment when the dolphin unfortunately died of an unrelated cause, pulmonary thromboembolism.
Necropsy confirmed ulcers in the second gastric compartment. Transverse cut sections through the epaxial muscles revealed normal firmness and texture but a gradation of red coloration to the tissues. Along one area of the concave curvature of the epaxial muscle a small, pale, muddy-pink, elliptical lesion was seen measuring ∼1 cm maximum diameter by ∼4 cm in length, tapered at both ends. Microscopic evaluation of this lesion revealed it to be abnormal muscle tissue. Left and right epaxial and left and right hypaxial muscles had nearly the same mass. The skeleton appeared unaffected. We recommend combining neuromuscular electrostimulation, acupuncture, and PRT by a trained physical therapist in future cases but advise against the use of methocarbamol in cetaceans because of the high risk of aspiration pneumonia due to slowed respiratory reflexes.
Acknowledgments
We wish to thank Patrick Martone, Karen Sayles, Matt Kelcourse, and the courageous volunteers and staff of the North Carolina Stranding Network and of the Virginia Marine Science Museum for their heroic rescue and initial care of “Ginny” under severely adverse conditions. The United States Navy transported the dolphin to the DWH for which we are most grateful. We also thank Cheryl Shames, at Integrated Physical Therapies, Inc. for donating her time and physical therapy expertise in the treatment of this case. A special thanks goes to the many skilled, dedicated volunteers at the dolphin and whale hospital, without whom we could not mount the intensive effort needed in cetacean rehabilitation.
Literature Cited
1. Bossart, G.D., B.E. Guthrie, M.A. Triss, J.D. Caron, S.M. Roth, S. Hayes, and P. Lehean. 1991. Neuromuscular electrical stimulation therapy for scoliosis in stranded short-finned pilot whales (Globicephala macrorhynchus) with suspected regional rhabdomyolysis and skeletal muscle atrophy. In: Proceedings from Ninth Biennial Conference on the Biology of Marine Mammals, Chicago, IL. 9.
2. Travell, J.G. and D.G. Simons. 1983. Thoracolumbar paraspinal muscles. In: Myofascial Pain and Dysfunction, The Trigger Point Manual. Williams and Wilkins, Baltimore, MD. Chapter 48;644.