Ovarian Pedicle Tie for Feline Ovariohysterectomy
Holly Anderson, DVM Class of 2010 Clinical Advisor: Dr. Elizabeth Berliner Basic Science Advisor: Dr. Paul Maza
Senior Seminar Paper Cornell University College of Veterinary Medicine
Date of Seminar: February 24th, 2010
KEYWORDS: Ovariohysterectomy, spay, pedicle tie, ovary, cat

ABSTRACT In order to reduce the overpopulation of cats and dogs, and thereby reduce euthanasia in
shelters, veterinarians in high-quality, high-volume spay/neuter clinics have developed many techniques to safely increase the efficiency of their surgeries. One surgical technique that is commonly used for feline ovariohysterectomies in these clinics is the ovarian pedicle tie. The procedure is analogous to self-ligature of the spermatic cord for feline castration. It is primarily used to reduce surgical and anesthetic time for the patient. This paper will explain and illustrate how the ovarian pedicle tie is performed. The advantages and disadvantages of the technique will be discussed, as well as the reasons why it can be used in all cats, but cannot be used in dogs.
INTRODUCTION Approximately four million cats and dogs are euthanized every year in animal shelters in
the United States.1 Recently, the focus on high-quality, high-volume spay/neuter (HQHVSN) programs has increased in an effort to reduce the reproduction of cats and dogs and their subsequent overpopulation.2 Spay/neuter veterinarians generally strive to maximize the number of cats and dogs they sterilize while minimizing the risk of complications. Many surgical techniques have been developed for increasing the efficiency of spays and neuters, while not causing any greater risk of complications for the patient.3 In fact, the patients may have a lower risk of complications due to decreased surgical and anesthetic time.
One surgical technique that is commonly used in HQHVSN clinics for feline ovariohysterectomies is the ovarian pedicle tie (the ovarian "pedicle" refers to the ovarian artery and vein, and the surrounding connective tissue). This technique is analogous to self-ligature of the spermatic cord for feline castration.4,5 Although only recently described in the veterinary
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literature,3 the ovarian pedicle tie has been widely used by spay/neuter veterinarians for many years to increase the efficiency of cat spays.6-8 This paper will describe and illustrate how the ovarian pedicle tie is performed. It will discuss the use of the technique in kittens, pregnant queens, and cats in estrus, as well as explain why it cannot be used in dogs. The advantages and disadvantages of the ovarian pedicle tie will also be described.
CASE STUDY A one year old intact female domestic shorthair cat presented to the Humane Alliance
Spay/Neuter Clinic on January 18th, 2010, for an elective ovariohysterectomy. The Humane Alliance Spay/Neuter Clinic is located in Asheville, North Carolina, and sterilizes more than 23,000 companion animals each year.9 This female cat presented with a history of no known health issues. She had previously been vaccinated against feline viral rhinotracheitis, feline calicivirus, feline panleukopenia, and rabies. The owner reported that the cat had not shown any signs of disease and was not receiving any medications. She had not eaten since the previous evening.
Upon physical examination, the cat was bright and alert. Her vital parameters were within normal limits. She was in good body condition (body condition score of 4/9). No ocular or nasal discharge was present. The cat's mucous membranes were pink and moist, with a capillary refill time of less than two seconds. Upon cardiopulmonary auscultation, no murmurs or arrhythmias were heard, and her lungs sounded clear bilaterally. Her pulses were strong and synchronous. No abnormalities were detected upon abdominal palpation. The remainder of the physical exam was unremarkable, and the cat was accepted for the elective surgery.
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The patient was anesthetized and prepared for the ovariohysterectomy using Humane Alliance's standard protocol.10 Acepromazine and buprenorphine were administered intramuscularly for pre-medication and telazol was injected intramuscularly for induction. Anesthesia was maintained using isoflurane. The cat was placed in dorsal recumbency, and her abdomen was clipped, prepped, and draped for the ovariohysterectomy using standard aseptic technique.
An approximately 1 cm skin incision was made on the ventral midline about halfway between the umbilicus and pubis. The linea alba was tented and incised to enter the abdomen. A spay hook was used to locate the right uterine horn, which was followed to the right ovary. The ovary and uterus were in normal condition (the cat was not in estrus or pregnant). The suspensory ligament was isolated from the ovarian vasculature and sharply dissected. A window was created in the broad ligament adjacent to the ovarian vessels via blunt dissection. The ovarian pedicle tie was then used for self-ligature of the ovarian vessels; this technique will be described in detail in the following section. The pedicle was transected, and the left ovary was removed in the same fashion. The broad ligament was broken down using blunt dissection. The uterine body was then ligated using a modified Miller's knot with 2-0 polydioxanone suture (PDS) and transected. The uterine stump was inspected for hemorrhage and replaced into the abdomen. The body wall was closed with 3-0 PDS in a cruciate pattern; the skin was closed with 3-0 PDS in an intradermal pattern. Meloxicam was administered subcutaneously for analgesia, and the patient recovered from anesthesia without complications.
Before discharge to the care of her owner the following morning, the patient appeared bright, alert, and comfortable. Her incision was inspected and appeared to be healing normally with no excessive swelling, redness or discharge.
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OVARIAN PEDICLE TIE Many surgical techniques have been described in the veterinary literature for performing
feline ovariohysterectomies.11-17 It is beyond the scope of this paper to review all the variations on traditional spay techniques that are currently being used by veterinarians. However, in a general sense, commonly-used techniques for cat spays involve clamping one or more hemostatic forceps on the ovarian pedicle and/or proper ligament of the ovary. The surgeon then places one or two ligatures using suture material on the ovarian pedicle prior to transecting it. In all cases, completely removing both ovaries and achieving hemostasis are essential.2 An alternate technique for accomplishing these goals is the ovarian pedicle tie.3 The pedicle tie does not use any suture material. It can be created with the same hand motions commonly used for selfligature of the spermatic cord ("cord tie") for feline castration.4,5 For this reason, the technique is already familiar to many veterinarians.
To perform the ovarian pedicle tie, the surgeon first elevates the ovary through the incision and into the surgical field. The ovarian vessels, broad ligament, and suspensory ligament of the ovary are fanned out in the surgeon's fingers in order to separate them and clearly visually identify the location of each. The suspensory ligament is then severed as close to the ovarian pedicle as possible using sharp dissection or manual traction (Figure 1, A).3 Anecdotally, some surgeons routinely observe increases in patients' heart and respiratory rates when the suspensory ligament is manually ruptured, but not when it is sharply transected.3 Therefore, some surgeons prefer sharp dissection because it may cause less pain for the patient, though both techniques are acceptable and commonly used. The feline suspensory ligament contains few blood vessels, and since they are very small, transecting the suspensory ligament never causes a significant amount of hemorrhage.
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Next, the surgeon uses blunt or sharp dissection to create an aperture in the broad ligament immediately adjacent to the ovarian vessels (Figure 1, B). It is very important that the surgeon completely isolates the ovarian vessels from the surrounding connective tissue before performing the pedicle tie. This is because excessive connective tissue can add tension to the pedicle that will make the knot more difficult to create; furthermore, any surrounding tissue will be incorporated into the ligature and may compromise its security.3 Once the vascular pedicle has been completely isolated, the proper ligament of the ovary is grasped in the surgeon's nondominant hand and gently pulled toward his/her side of the table (Figure 1, C). A closed mosquito hemostat is held in the surgeon's dominant hand with the tip facing away from the surgeon. The tip of the hemostat is directed under the ovarian pedicle, from the surgeon's left to right side (Figure 1, D). Many veterinarians prefer to use a curved mosquito hemostat rather than a straight one because the curved tip (when pointed upwards) helps prevent the pedicle from inadvertently sliding off the end of the hemostat when creating the knot. The tip of the hemostat is then directed over the far side of the pedicle, and the instrument is rotated between 90 and 180 degrees in a counter-clockwise direction (Figure 1, E). The jaws of the hemostat are opened and the near side of the pedicle is directed into the tip of the hemostat (Figure 1, F). The instrument is then clamped to the first ratchet (Figure 1, G). The pedicle is sharply transected between the hemostat and the ovary (about 2-3mm from the hemostat) using a blade or scissors (Figure 1, H).3
Next, a second hemostat is placed on the proper ligament of the ovary to prevent any hemorrhage from the remaining blood supply to the area. Alternatively, the second hemostat may be clamped on the ovarian pedicle immediately proximal to the ovary, and it may be placed before transection of the pedicle.3 The ovary and uterine horn are then laid to one side of the
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surgical field (Figure 1, I). The knot is slid over the tip of the hemostat, while being careful not to place excessive traction on the pedicle (Figure 1, J).3 To facilitate sliding the knot off the tip of the hemostat, some surgeons prefer to clamp the hemostat completely shut and direct its tip downwards toward the incision. The knot is tightened by applying gentle pressure proximally to ensure its security (Figure 1, K). Finally, the pedicle is inspected for hemorrhage and replaced into the abdomen. The procedure is repeated on the contralateral pedicle.3
The ligature for the ovarian pedicle tie can be performed in other variations based on the surgeon's preference. Some veterinarians prefer to initially direct the ovary toward the far side of the table. In this case, the hemostat is initially held with the tip facing the surgeon, and then the instrument is rotated clockwise so that the tip faces away from the surgeon.3
DISCUSSION An important advantage of the ovarian pedicle tie compared to traditional surgical spay
techniques is that it reduces the surgical and anesthetic time for the patient.3 An experienced spay/neuter surgeon using small incisions, a spay hook, and ovarian pedicle ties can often complete a routine ovariohysterectomy in five minutes or less. The time saved by using the pedicle tie is especially important in HQHVSN clinics. Spay/neuter surgeons routinely perform a large number of feline spays in a given day, and are generally striving to maximize the number of surgeries they can perform in a given time period in order to reduce pet overpopulation.
Another advantage of the ovarian pedicle tie compared to standard techniques is that no suture material is implanted into the patient during removal of the ovaries. The body of the uterus still requires ligation using suture material as in conventional techniques, but the amount implanted during the surgery is reduced overall. Subjectively, the pedicle tie may also be less
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painful for the patient when the suspensory ligament of the ovary is transected using sharp dissection rather than ruptured manually.3
Unfortunately, there is no published data on the incidence of intraoperative or postoperative complications when using the ovarian pedicle tie for feline ovariohysterectomies. Studies on this topic are necessary. Anecdotally, complications when using the pedicle tie are very uncommon. When they do occur, it is often due to failure of the hemostat to function correctly. Occasionally, when hemostats become old or bent, the jaws at the tip of the hemostat no longer meet perfectly. The hemostat is necessary for holding the pedicle while the knot is created and tightened securely. If the jaws at the tip of the hemostat do not meet properly, the pedicle can slide through them. If this occurs, the surgeon must locate the dropped pedicle in order to ligate it, which often involves extending the incision. Therefore, it is important to only use hemostats that are working properly for this technique.
In order to avoid complications when using the pedicle tie, it is also important that surgeons utilize gentle tissue handling. The vascular pedicle can be very small and thin, especially in young kittens, and manipulation of it is necessary to create the pedicle tie. Surgeons must always be careful to not place excessive traction on the pedicle to avoid rupturing it,3 although it is actually quite elastic and resilient.
The pedicle tie can be used to remove the ovaries of cats of all ages and in any stage of the reproductive cycle. However, it is recommended that veterinarians initially learning the technique practice on models until they are comfortable before using it in patients. The pedicle tie can be safely used in cats with large ovarian vessels, including queens that are pregnant (any stage) or in estrus.3 Anecdotally, some surgeons believe that it is actually easier to perform the pedicle tie on cats with large ovarian vessels because there is more room in which to create the
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knot. The technique can also be used in young kittens, as long as the surgeon uses gentle tissue handling because the ovarian vessels may be very small.
In contrast to cats, the pedicle tie can never be used for dog spays. In dogs, unlike cats, a large amount of fat surrounds the ovarian vessels. This fat prevents the surgeon from completely isolating the ovarian vessels prior to ligation.3 Furthermore, the dog pedicle has less laxity than the cat pedicle, which would make tying the knot difficult if not impossible. If a surgeon did manage to perform the pedicle tie for a dog spay using the entire fatty pedicle, the ligature would probably not be secure enough to prevent hemorrhage. Therefore, the pedicle tie should never be used for dog spays, or for rabbit spays for similar reasons.
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Figure 1 – The ovarian pedicle tie. For all images, the cranial side is to the left. A, The ovary is elevated into the surgical field and the suspensory ligament, ovarian vessels, and broad ligament are identified. The suspensory ligament is sharply transected as close to the ovarian pedicle as possible. B, An aperture is created in the broad ligament immediately adjacent to the ovarian vessels. C, The ovarian vessels are completely isolated and the ovary is gently pulled toward the surgeon. D, A closed mosquito hemostat with the tip facing away from the surgeon is directed under the ovarian pedicle, from the surgeon's left to right side. E, The tip of the hemostat is directed over the far side of the pedicle, and the hemostat is rotated at least 90 degrees counter-clockwise. F, The hemostat is opened and the near side of the pedicle is directed into the tip. (Continued)
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Figure 1, continued – G, The hemostat is clamped to the first ratchet. H, The pedicle is sharply transected between the hemostat and the ovary, a few millimeters from the hemostat. I, A second hemostat is placed on the proper ligament of the ovary to prevent any hemorrhage from the remaining blood supply to the area. The ovary and uterine horn are laid to one side of the surgical field. J, The knot is slid over the tip of the hemostat. K, The knot is tightened. The pedicle is inspected for hemorrhage before it is replaced into the abdomen.
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REFERENCES 1. Humane Society of the United States Web site. Pet Overpopulation. Available at: http://www.humanesociety.org/issues/pet_overpopulation/. Accessed Feb 8, 2010. 2. Looney AL, Bohling MW, Bushby PA, et al. The Association of Shelter Veterinarians veterinary medical care guidelines for spay-neuter programs. J Am Vet Med Assoc 2008;233:7486. 3. Griffin B, DiGangi BA, Bohling MW. A review of neutering cats. In: August JR, ed. Consultations in feline internal medicine, volume 6. St. Louis: WB Saunders Co, 2010;776-792. 4. Hedlund CS. Surgery of the reproductive and genital systems. In: Fossum TW, ed. Small animal surgery. 3rd ed. St Louis: Mosby, 2007;702-774. 5. Boothe HW. Testes and epididymes. In: Slatter DH, ed. Textbook of small animal surgery. 3rd ed. Philadelphia: WB Saunders Co, 2003;1521-1530. 6. Humane Alliance Web site. Feline ovariohysterectomy. In: Training and Operations Manual. Available at: http://www.humanealliance.org/downloads/vet_manual_0507.pdf. Accessed Feb 11, 2010. 7. Humane Alliance Web site. Pedicle Tie Video. Available at: http://www.humanealliance.org/index.php?option=com_content&view=article&id=49&Itemid=9 8. Accessed Feb 11, 2010. 8. Maddie's® Shelter Medicine Program at Cornell Web site. Ovarian Pedicle Tie. Available at: http://www.sheltermedicine.vet.cornell.edu//spayNeuter/pedicle/. Accessed Feb 11, 2010. 9. Humane Alliance Web site. Our History. Available at: http://www.humanealliance.org/index.php/about-us/our-history. Accessed Feb 8, 2010.
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10. Humane Alliance Web site. Feline Drug Protocol. Available at: http://www.humanealliance.org/downloads/FelineDrugProtocol.Nov2009.pdf. Accessed Feb 9, 2010. 11. Appel LD, Hart RC. Spay and neuter surgical techniques for the animal shelter. In: Miller L, Zawitowski S, eds. Shelter medicine for veterinarians and staff. 1st ed. Ames, IA: Blackwell Publishing, 2004;355-376. 12. Aronsohn MG, Faggella AM. Surgical techniques for neutering 6- to 14-week-old kittens. J Am Vet Med Assoc 1993;202:53-33. 13. Fingland RB, Probst CW, Mullen HS. Uterus. In: Bojrab MJ, ed. Current techniques in small animal surgery. 4th ed. Baltimore: The Williams & Wilkins Co, 1998;489-502. 14. Knecht CD, Allen AR, Williams DJ, et al. Chapter 10: selected small animal procedures. In: Fundamental techniques in veterinary surgery. 3rd ed. Philadelphia: WB Saunders Co, 1987;278332. 15. Stone EA. Chapter 98: ovary and uterus. In: Slatter DH, ed. Textbook of small animal surgery. 3rd ed. Philadelphia: WB Saunders Co, 2003;1487-1502. 16. Stubbs WP, Crane SW, Mann FA, et al. Testicles. In: Bojrab MJ, ed. Current techniques in small animal surgery. 4th ed. Baltimore: The Williams & Wilkins Co, 1998;511-525. 17. Tracy DL. Chapter 4: small animal surgery. In: Tracy DL, ed. Small animal surgical nursing. 3rd ed. St. Louis: Mosby, 2000;259-322.
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