Spaying reptiles and birds (Proceedings)

Spaying reptiles (lizards)

Indications

• Intact females have a high rate of Pre-Ovulatory Follicular Stasis (POFS) and Post Ovulatory Egg Stasis (POES)

     o Complications can include egg yolk coelomitis

• Rare cases include teratomas of the ovaries.

Anatomy

• Great variation in the anatomy of the Class Reptilia

     o Contains ca. 7000 species

• The ventral abdominal vein is located directly on the ventral midline and can be accidentally incised when a midline incision is used.

     o The author prefers a paramedian incision to avoid this risk

     o Evidence exists in the human literature supporting the paramedian over the midline approach due to a lower risk of post-surgical complications, such as herniation, pain and infection1-4.

       The ovaries are located dorsally in the mid-coelomic region

• The ovary are not very mobile in lizards due to a short mesovarium (in constrast to being very mobile in chelonians)

• The ovarian vessels are not well developed

• The right ovary is very closely adhered to the adrenal gland and the abdominal vein (vena cava).

Preparations

• Ideally a minimal screen (hematocrit, total solids, and blood glucose) should be run on all animals prior to anesthesia

• Evaluate older animals (over 8 years old) thoroughly for sub-clinical forms of renal disease

     o Run a full chemistry panel, and check Ca : P ratio/product and uric acid levels

• Make sure animal is optimally hydrated

     o Maintenance is approximately 30 ml/kg/day

• Animal should be placed on a ventilator for IPPV during anesthesia (esp. chelonians when in dorsal recumbency)

Procedure

Ventral approach

• Paramedian skin incision (1-2 cm off midline)

• Make incision in coelomic wall with sharp scissors and extend 3-4 inches

• Locate ovaries under GI tract in mid-coelomic area

     o Start with left ovary

     o Right ovary is closely adhered to adrenal gland

• Gently lift ovary up and place hemoclips on mesovarium. Incise between clips

• Ovary can be extremely small and whitish in color or large and full of preovulatory follicles

     o Follicles are easy to handle and do not break easily

     o Avoid breaking of follicles as this will lead to egg yolk coelomitis.

          √ Flush copiously in case of rupture

          √ Start antibiotic treatment

• Right ovary

     o Apply careful traction and place hemoclip above adrenal gland and below ovary. Incise between clips.

• Leave oviducts behind if empty

     o Will regress and atrophy after removal of ovaries

     o No complications reported

• Close in a 3 layer fashion with body wall, subcutaneous, and skin sutures

     o Use an everting horizontal mattress suture pattern to close skin

          √ Take 2-3 rows of scales laterally to evert skin margins

          √ An everting pattern opposes vital tissues for healing

Follow-up:

• Make sure animal is eating, and producing urates and feces

• Recheck suture site frequently

• Animal should not soak in water for at least 2 weeks

• Sutures need to be removed in 6-8 weeks

Common complications:

• Rupture of egg yolk, leading to coelomitis

Spaying birds (salpingohysterectomy)

Indications:

• Chronic egg laying, reproductive behavior

• Chronic inflammatory diseases of the oviduct

• Cloacal prolapse of the oviduct

• Torsion, rupture of the oviduct

Anatomy:

In female birds only the left side of the reproductive tract is functional.

     o Left ovary and left oviduct

       The ovary is not removed during the procedure.

     o The risk of fatal hemorrhage is too high

• The avian oviduct is suspended via its dorsal and ventral ligaments within the coelomic cavity.

• The blood supply is well established for the oviduct and so the vessels which are primarily in the dorsal ligament need to be carefully identified and ligated.

Preparations

• A CBE and chemistry panel should be run prior to anesthesia

• Radiographs should be obtained prior to the procedure to detect any potential complications with the reproductive tract

• Place an intravenous (intraosseous) catheter

     o In case of blood loss, have hetastarch, oxyglobin, or a blood donor available

Procedure

• The ventral approach will be described here

     o Both a ventral and the left lateral approach are possible

• Place patient in dorsal recumbancy.

• Approach by ventral midline incision

     o Alternatively a midabdominal transverse incision may be used

• Lift skin and make stab incision in skin just caudal to the sternum

• Extend skin incision from sternum to pelvis

• Separate the skin from the coelomic wall

     o Left transverse incisions can be placed at the cranial and/or caudal end of the midline incision to produce an L shape or an U shape incision to help with visualization and easy access of the oviduct.

• Incise through coelomic wall and abdominal airsac.

     o Duodenum crosses across mid-coelomic area and is attached to the body wall. Take care not incise this structure.

     o Anesthesia may become more demanding due to open respiratory tract.

• Start with caudal structures and work proximally

• Locate oviduct close to the cloaca, ligate and incise

     o Make sure ureter is not included in ligature

• Bluntly dissect cranially along the dorsal oviductal ligament, locating and ligating individual blood vessels

• The ovary is frequently well hidden under the ribs and not easily visible if no major pathology is present.

     o Left ovary is the only ovary in bird

     o In order to visualize ovary, often ribs need to be cut

• Once the cranial oviductal vessel is identified and ligated, the oviduct can be incised and removed

     o Hemoclips will speed procedure up otherwise use 5-0 Maxon or PDS

     o Radiocauthery can be used on smaller uterine vessels

• Close coelomic wall and skin in a 2 layer fashion

Follow-up

• make sure animal is eating, and producing urates and feces

• recheck suture site frequently

Common complications

• suture removal by animal

• potential for ligation of ureter when ligating oviduct at cloaca

References:

Burger, J.W., M. van 't Riet, and J. Jeekel, Abdominal incisions: techniques and postoperative complications. Scand J Surg, 2002. 91(4): p. 315-21.

Grantcharov, T.P. and J. Rosenberg, Vertical compared with transverse incisions in abdominal surgery. Eur J Surg, 2001. 167(4): p. 260-7.

Guillou, P.J., et al., Vertical abdominal incisions—a choice? Br J Surg, 1980. 67(6): p. 395-9.

Proske, J.M., J. Zieren, and J.M. Muller, Transverse versus midline incision for upper abdominal surgery. Surg Today, 2005. 35(2): p. 117-21.

Coke, R. Surgical Management of Dystocia in Chameleons. Exotic DVM 1.2. page 11

Stahl, S. Surgical Resolution of Reproductive Disorders in Female Green Iguanas. Exotic DVM 1.0 page 5

Stahl, S. Squamata Celiotomy: Celiotomy in Lizards. Exotic DVM 1.3 page 10

Stahl, S. Squamata Celiotomy: Celiotomy in Snakes. Exotic DVM 1.3 page 13

Lewis, W. Dystocia in a Tortoise. Exotic DVM 5.1 page 14

Kramer, M; Harris, D. 2002 Ventral Midline Approach to Avian Salpingohysterectomy Exotic DVM 4.4 page 23-27