Essential reptile surgeries (Proceedings)


Essential reptile surgeries (Proceedings)

May 01, 2011

Reptile surgery is performed under general anesthesia, observing sterile technique, with appropriate monitoring and supportive care. The true strength layer for reptiles is the skin. To prevent dysecdysis after a skin incision heals, an everting suture pattern is used. Suture removal for reptiles is generally performed 6 weeks postoperatively, after shedding has occurred.

Follicular stasis/egg retention/dystocia

Gravid reptiles are commonly presented for failure to produce eggs or young. The causes may include inappropriate nesting sites, stress, dehydration, malnutrition, obesity, salpingitis, malformed eggs, or abnormal reproductive anatomy.
     • Snakes: Surgery is indicated if medical therapy, egg manipulation, and/or ovocentesis have failed. An incision is made between the first and second row of lateral scales over the retained egg or fetus. The oviduct is isolated and a salpingotomy is performed. The egg/fetus is removed through the incision, and adjacent eggs are gently massaged toward the incision for removal. If adhered to the oviduct, these may need to be removed by multiple oviductal incisions. With absorbable monofilament (i.e. 4-0 to 5-0 PDS), close the oviduct and the coelom, each in simple continuous pattern. Close the skin with 4-0 to 2-0 monofilament nylon in an everting horizontal mattress pattern.
     • Lizards: The clinician must differentiate between follicular stasis (pre-ovulatory stasis) and egg retention (post-ovulatory stasis). Cases of follicular stasis can be offered ovariectomy as an "elective" procedure, or given the option to monitor and see if yolks are reabsorbed later. Cases of egg retention may respond to medical therapy (oxytocin and calcium injections). If eggs are not laid within 48 hours, then surgery is recommended. In order to avoid the ventral abdominal vein a paramedian abdominal incision is often advised. A long incision provides the best access to the ovaries and reproductive tract. Use care to avoid damaging the bladder, which can be very large. The ovaries are located dorsally in the mid-coelomic cavity.

In preovulatory stasis, ovaries resemble a large cluster of egg yolks. Each ovary is carefully elevated out of the abdomen to expose its vascular supply. The left ovary is attached to a branch of the renal vein. The left adrenal gland (light pink in color) is located between the ovary and the renal vain, and care must be taken not to damage or accidentally remove it while ligating the vessels to the ovary. Hemostatic clips make this process simple. The right ovary is attached directly to the vena cava. Removal is similar, but the right adrenal gland is located on the opposite side of the vena cava, away from the ovary, where damage is unlikely. The oviducts should be examined, but with follicular stasis removal is not necessary as long as both ovaries are removed.

With egg retention, the oviducts are filled with shelled eggs and are easily identified. One oviduct at a time is gently exteriorized. If the patient is to be used for future breeding, perform a salpingotomy is performed, as described for snakes above. In order to make manipulation of the eggs easier, warm sterile saline may be infused into the oviduct. Several incisions may be necessary. For non-breeding pets, ovariosalpingectomy is recommended. The vessels of the oviduct are segmentally ligated, freeing the oviduct from cranial to caudal. The caudal end of the oviduct is ligated as close as possible to the junction with the urodeum. Repeat the procedure on the opposite side. With the oviducts/eggs removed, the ovaries can be identified and removed, as above. This procedure is more difficult when the ovaries are small and inactive. Again, vascular clips make the procedure easier to perform. Care must be taken not to leave any ovarian tissue behind, or ectopic ovulation may result in the future. Closure is routine. The abdominal musculature is gently pulled together with continuous monofilament absorbable suture. The skin is closed with an everting horizontal mattress suture pattern.

     • Chelonians: Turtles with dystocia may present for digging, restlessness, producing a small clutch, being past the due date, anorexia, depression, or straining. Eggs may be palpable through the inguinal fossae, but radiology is the most useful tool to confirm the presence and numbers of eggs. If the retained eggs are normal, then medical therapy should be attempted for several days until all eggs are laid. If medical therapy for dystocia is ineffective, or the eggs are malformed or too large to pass, then surgery is indicated.

The pre-femoral coeliotomy is less invasive than the plastronotomy approach. The patient is placed in dorsal recumbency, and the rear limb is pulled caudally and secured. A retractor may be used to widen the shell opening. A linear skin incision is made in a craniocaudal direction within the fossa, midway between the carapace and plastron. The thin musculature and coelomic membrane are carefully incised, and stay sutures are placed. The oviduct is elevated into the pre-femoral incision. An incision is made over the egg, it is aspirated to collapse it, and it is removed. Remove all of the eggs in a likewise fashion. Take care not to allow leakage of egg contents into the coelomic cavity. The oviduct is then closed with monofilament absorbable suture in a continuous pattern. The coelom and muscle layers are closed with interrupted sutures, and the skin is closed in an everting pattern.