Turtle and Tortoise Shell Repair
Melissa Kaplan, 1995
This is an overview of the process used to repair chelonian shells that have been fractured or damaged by infection; there is another document that covers the treatment of shell rot. This is not intended to be a "do-it-yourself" manual but more what you should expect when you take such a turtle or tortoise to an experienced veterinarian for treatment. Remember that the shell serves the same purpose as skin: it protects the interior of body. If skin, or shell, is penetrated, that gives access to bacteria, fungal spores and parasites. The broken shell must be treated as if it were lacerated skin: the tissue and body cavity must be treated first before the shell is closed up.
This first section is a summary of the procedures outlined by Fredric L. Frye in his Reptile Care (TFH Publications):
Repair fractured or surgically invaded plastron and carapace (first cleaned with several applications of ether or acetone and air dried) with single or multiple layers of sterilized fiberglass cloth impregnated with freshly prepared, rapid-polymerizing epoxy resin, and topped with several coats, allowing each to dry before the next coat is applied. (Cut and autoclave round pieces which will overlap the defect by 1.5-3 cm; square ones tend to unravel at the edges.) To insure good chemical bonding is achieved, the dried rapid dry epoxy should be lightly sanded and wiped down with diethyl ether or acetone before the next coat is applied In aquatic or semi-aquatic turtles, a top coat of slower polymerizing boat-repair resin should be applied a day or two after the patch.
Epoxy is applied to the periphery of the defect - not the edges and never inside the defect or cavity...if it gets on the edge of the bony plate it may impede bone healing.
The first patch is worked in to the ring of epoxy. A light coat of resin is applied to the center of the patch enough to just coat and get worked into it -- not saturate through into the coelomic cavity. You will know you have enough worked in when the cloth becomes transparent and the weave sort of disappears. The patches must be completely water- and airtight to prevent invasion by any microorganisms. Generally two layers, plus the top coat, is enough to complete such repairs.
The two-part epoxy components are used in a 1:1 ratio, the time for polymerization is about 3-5 minutes. The resin loses its tackiness and hardens in another 4-5 minutes.
Before placing that chelonian back in its enclosure, spraying the patch with a vegetable oil spray will help prevent substrata from sticking to the fresh patch, especially on ventral patches.
Several sources (not specified) have described the use of cold-curing dental acrylic plastic. Per Frye, regardless of the type of resin used, a laminating layer of the impregnated fiberglass cloth should be used to reduce wear and tear, abrasion, etc.
In most case, Frye continues, the patch should be left in place for a year or two, during which time new bone will regenerate across the gap. If the chelonian is a rapidly growing juvenile, some of the patch will have to be removed to allow the shell to expand unimpeded. Patches may be left in place permanently on adult (fully grown) chelonians) For information on how to do this, see Frye's Reptile Care, chap 13.
If shell has been fractured traumatically, the edges should be debrided and any depressed fragments elevated and returned to proper location. If the fracture is less than 3 cm in diameter, the devascularized bone fragments may be removed. If the gap is very large or pieces are missing, the defect can still be closed with the resin-impregnated fiberglass; while new bone may never fully bridge the gap, it should regenerate to some extent and generally does not interfere with the chelonian's physiologic function.
When grafting bone fragments together, epoxy them first to the patch, and allow the patched pieces to dry before the patch is attached to the edges of the defect.
Occasionally, wiring and plating of severely crushed shells may be done to repair massive trauma, but if there is evidence of paralysis or posterior limb paresis, or both, the prognosis is dim, and euthanasia should be considered.
Zeman, W. Z., et al. 1967 describes this process for a box turtle in Repair of the carapace of box turtle using polyester resin. Lab Anim Care 17:424-425
Harwell G. 1989. Repair of Injuries to the chelonian plastron and carapace. In Current Veterinary Therapy, Vol X, pp 789-791.
Heinrich G, and Heinrich D. 1986. A technique for the repair of chelonian shell fractures with a historical review of shell fracture repair. Proc Nat Wildlife Rehab Assoc, pp 1-18.
Doug Mader also wrote on this subject in a early issue of the Journal of Small Exotic Animal Medicine (1990-1991).
This paper is from Katherine T. Belisle, DVM, Wildlife Rehabilitation Clinic, University of Minnesota, St. Paul, MN 55108:
The shell of a turtle or tortoise is composed of an upper dome-shaped piece called the carapace and a lower plate called the plastron. These two are joined together by bony bridges. In most species, except for the soft-shelled turtles, the carapace is composed of bony plates overlaid by hard dermal plates. The most obvious function of the turtle shell is to provide the animal with a protective fortress. Some species, box turtles in particular, have a hinged shell which allows even greater protection. Shells of turtles and tortoises grow larger as the anima matures. This fact will become very important when we consider how to repair a damaged shell.
Shells are injured most often when these animals are run over by cars while crossing the road. They may also be damaged by attacks from dogs or wildlife, lawn mowers, or even surgery. The location of the shell damage and the type of wound will determine best how to repair the defect.
At this point, the wound should be carefully inspected for damage to internal structures. You may need the assistance of a veterinarian to determine the possibility of repair or if euthanasia is the best alternative. No repair of a turtle shell should be done on an animal that is paralyzed. Physical exam should include an assessment of the neurological function to both the front and rear legs. This is best accomplished by pinching the toes strongly and watching for a response. A proper response would include a move away from the source of pain or a turn of the head to look at the source of pain. A simple withdrawal of the leg is not sufficient to consider neural function to be intact. Another means of assessing function swim and note the movement of all four limbs. Be careful not to allow water to seep into an open would. If limb function appears intact you can now begin to repair the wound.
The final condition of the repaired shell should not hamper the animals survival in the wild.
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