An Introduction to Reptile Surgery: A Chance to Cut is a Chance to Cure
World Small Animal Veterinary Association World Congress Proceedings, 2015
M. Mitchell, DVM, MS, PhD, DECZM (Herpetology)
University of Illinois, Urbana-Champaign, IL, USA

Introduction

In the past, the majority of the surgeries being performed on reptiles were emergency based. However, as reptile husbandry has improved, and the longevity of these animals has increased, there has been a shift from performing only emergency surgeries to elective procedures.

Coeliotomy

The coeliotomy is one of the most common surgical procedures performed in captive lizards and snakes. In chelonians, the same procedure is generally described as a plastronotomy/plastronectomy and will be discussed later, although a pre-femoral approach to the coelomic cavity of chelonians can be made without incising the shell. The initial incision for a coeliotomy in a lizard is via the ventral body wall, while the initial approach in a snake is through the ventrolateral body wall (first and second rows of dorsal scales). In lizards, a paramedian approach is generally preferred, as this helps avoid accidentally lacerating the large ventral abdominal vein. Some surgeons recommend a ventral midline approach regardless of the location of the vein, and suggest ligating the vein if it is lacerated. They argue that this approach allows for the linea alba to serve as the primary holding layer for closure. However, the author believes that the limited size of the linea alba in these animals precludes it from being of significant value, and instead would suggest that the skin is the primary holding layer in lizards. In addition, the volume of blood that can be lost from a lacerated vessel in a small reptile could be significant, especially if the animal was already anemic or had some other hematologic disturbance. In snakes, the initial approach to the coelom is made between the first and second rows of the dorsal scales. This ensures that the patient does not apply as much tension on the incision nor does it contaminate the incision with material from the substrate. Some authors recommend incising the skin between the scales; however, this is difficult to do for most species. The author generally finds that a #15 scalpel blade works best for making the initial incision. Because it can be difficult to incise the scales with a scalpel blade, the author finds that the scalpel can be best used to "puncture"/incise the skin, and a pair of scissors used to complete the incision. To make the initial incision with a scalpel blade, the skin should be tented, the scalpel blade held upside down, and the tip of the blade gently pushed through the skin to make the incision. The size of the incision should be large enough to provide exposure to the surgical site. Once the skin is incised, the muscles of the ventral body wall should be incised. In most reptiles, these muscles are only 2–4 millimeters thick. To avoid accidentally puncturing an organ, the author, again, uses a combination of a scalpel and scissor to open the coelomic cavity. It is important to always fully investigate the coelomic cavity during a coeliotomy. Closure of the body cavity can be done using a two layer closure. First, the coelomic membrane and abdominal muscles can be closed. A simple continuous pattern is preferred. Suture size will vary based on the size of the animal; however, the author generally finds that 3-0 to 5-0 suture is best. The skin should be closed using an everting suture pattern. If an everting pattern is not used, the scales tend to roll in along the edge of the incision, and delay healing. The author always uses a horizontal mattress pattern to close the skin of reptiles. Either an absorbable or non-absorbable suture can be used to close a skin incision. The sutures should remain in place for a minimum of 4–6 weeks to ensure complete re-epithelialization.

Plastronectomy/Plastronotomy

Chelonians pose a special problem for the veterinary surgeon. The shell of these animals serves as an excellent method for protecting the internal viscera from not only predators but veterinary surgeons too! When a pre-femoral approach in a chelonian is inadequate to achieve a desired surgical exposure, a plastronectomy is required. The approach to preparing the plastron for surgery is similar to that described for other reptiles. The animal should be placed in dorsal recumbency and secured for the procedure. A cutting tool is required to make the incision into the plastron, and there are a number of different commercial saws that can be used for the procedure. Diamond-tipped saw blades are preferred. When making the cuts in the scutes, the saw should be placed at a 45 degree angle to create an edge that holds the plastron in place once it is replaced. Prior to making the initial incision it is important to decide how much exposure to the coelom is needed and exactly where in the coelom the procedure will occur. For example, a cystotomy to remove cystic calculi will require a more caudal approach then one required for a gastrotomy to remove foreign material from the stomach. In general, the abdominal and femoral scutes provide the best exposure. When incising the femoral scutes it is important to identify the location of the pubic bones, as a caudal incision into the femoral scutes could result in cutting these bones. When making the initial incisions it is important to decide whether to perform a four-sided or three-sided incision. For the four-sided plastronectomy, the incised section should be removed and stored in warmed physiologic saline during the procedure. For a three-sided incision, the scutes can be "bent" along the unincised scute. Directly below the scutes will be the coelomic membrane and two ventral abdominal vessels. The vessels can either be displaced laterally or ligated. Once the exploratory surgery is completed, the incised plastron can be replaced and sealed with an epoxy.

Ovariohysterectomy

The ovariohysterectomy is commonly performed in captive lizards. This procedure can be done as an elective procedure or as an emergency surgery (e.g., dystocia). In the author's practice, the majority of these surgeries are performed on green iguanas and bearded dragons (Pogona vitticeps). It is preferred to perform the surgery during the lizard's reproductive cycle. During the reproductive cycle, the follicles are large and the mesovarium stretched. In this condition, it is often possible to extract the ovary from the body wall to visualize the ovarian artery and veins. When the lizards are not reproductively active, this is not possible, and the surgeon must work from within the crowded coelomic cavity. The coeliotomy described earlier is the approach to use to perform this procedure. Once within the coelomic cavity, the ovaries should be identified. They are generally located in the distal third of the dorsal coelomic cavity (in a similar position to the ovaries of mammals). The gonads should be gently manipulated, as the follicles can rupture and cause an egg-yolk coelomitis. Once the ovaries are identified, it is important to ligate the ovarian artery and veins. Either hemoclips or suture can be used to ligate the vessels. In lizards, an ovariectomy can be done and the remaining reproductive tract (uterine horns) left intact; however, if the uterine horns are removed (hysterectomy), then the ovaries should be removed too. Closure is routine (see coeliotomy).

Orchidectomy

Orchidectomies are generally being pursued in green iguanas as a method to control behavior. Research shows that this procedure may be of benefit if it is done early in these animals. This surgery is similar to the ovariectomy. The testicles are white to tan in color and found in the distal third of the body cavity in the dorsal coelomic cavity. The testicles, like the ovaries, are held in place by a membrane (the mesorchium in males). There is generally one artery and 3–4 veins associated with the testicle. To gain access to the vessels, the author places a stay suture through the testicle. It is important to use care when "tugging" on the suture, as it can easily be pulled through the testicle. Again hemoclips (preferred) or suture can be used to ligate the vessels. Closure is routine.

Cystotomy

Cystotomies are most often performed in chelonians and lizards. The approach to the urinary bladder in lizards can be done using the basic coeliotomy approach. In chelonians, either a plastronotomy or pre-femoral approach can be made. The urinary bladder of reptiles is thin in comparison to mammals. The bladder can generally be located easily in the caudal coelomic cavity. Once it has been identified, it is important to place lap pads around the bladder to limit urine contamination in the coelomic cavity. Urine should be removed from the bladder via a syringe to limit spillage. Because of the urate crystals in the urine, it may be difficult to remove all of the bladder contents. The bladder is relatively avascular compared to mammals. Two stay sutures may be placed into the bladder to facilitate tissue manipulation. The incision should be made into an avascular area and the calculi removed. Closure of the bladder is generally done using a single-layer closure. A double-layer closure may be possible in some larger species, but the tissue fragility typically limits this from being possible. Closure of the body wall is routine.

References

References are available upon request.

  

Speaker Information
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M. Mitchell, DVM, MS, PhD, DECZM (Herpetology)
University of Illinois
Urbana-Champaign, IL, USA


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