Kristin A. Coleman1 and Trent T. Gall2 1 Gulf Coast Veterinary Specialists, Houston, TX, USA 2 Gall Mobile Veterinary Surgery, Longmont, CO, USA A caudectomy (partial or full) is a procedure that has many different variations and is performed for several reasons, most of which are in an effort to increase the comfort of the patient. A caudectomy, also known as “high tail amputation” or “complete tail amputation,” is removal of the tail at the sacrococcygeus junction, at a level even with or proximal to the perineum, or at a level with or proximal to the second to third coccygeus intervertebral disc space. Any tail amputation caudal to these parameters is deemed a partial caudectomy. The tail is a continuation of the vertebral column that contains coccygeal or caudal vertebrae of differing numbers depending on the species, breed, and individual with a normal range of 6–23 vertebrae.1 These vertebral bodies are separated by intervertebral discs, are surrounded by several muscles, and are supplied by five different arteries. For the length of the tail, there are two main dorsal (sacrocaudalis dorsalis lateralis and medialis), two main ventral (sacrocaudalis ventralis lateralis and medialis), and two main lateral (intertransversarius dorsalis caudalis and ventralis caudalis) muscles, and the muscles of the pelvic diaphragm attach to the first few coccygeal vertebrae. These muscles, the levator ani and coccygeus, as well as the rectococcygeus muscle, only insert onto the proximal aspect of the tail and should rarely, if ever, be encountered during a caudectomy. The blood supply courses along the lateral aspects (lateral caudal artery), dorsal aspect (small dorsolateral caudal artery), and ventral aspect (median caudal and ventrolateral caudal arteries). The lateral caudal arteries are branches of the caudal gluteal artery, which is a branch of the medial sacral artery. The tail’s venous supply feeds into the caudal vein, which goes into the right internal iliac vein, which then merges with the right external iliac vein to start the caudal vena cava.1,2 As with many anatomic variations among dog breeds, brachycephalic breeds can have an abnormal configuration of their tail as it deviates inward on itself, known by many names but most commonly as an “ingrown tail,” “screwtail,” “twisted tail,” or “corkscrew tail,” that may appear similar to the shape of a cinnamon bun in the dorsal plane. This abnormal tail conformation causes issues due to the deep skin folds created by the characteristic twisting of the tail, which can lead to skin fold dermatitis, pyoderma, and intertrigo caused by the decreased ventilation within the tail fold pocket and proliferation of surface bacteria.3 This condition can lead to a vicious cycle of treating with systemic antibiotics and surface cleansing wipes, infections within the tail pocket penetrating the deeper layers of tissue, and discomfort to the patient, all of which result in continued inflammation and resistant infections. The treatment for this end‐stage condition is often tail amputation to remove the screwtail. Caudectomy, both complete and partial, has many clinical indications and can be grouped in multiple ways: traumatic versus non‐traumatic or therapeutic versus non‐therapeutic. In dogs and cats, the most common indication for partial caudectomy is a wound sustained to the mid‐distal tail,4,5 and in 80% of the cat tail wounds in one study, these were degloving injuries caused by the appendage being stuck in a door.4 If using the therapeutic versus non‐therapeutic classification, the latter basically entails just cosmetic docking. All other reasons for caudectomy would be grouped as “therapeutic” and would include amputating for trauma, “happy tail,” chronic non‐union fractures, infection (bone or soft tissue), severe dermatitis/painful tail skin fold pyoderma that is refractory to medical management (e.g., screwtail), paralysis (e.g., “tail pull” injury) or neuropathy,6 severe tail deformities that result in pain, and neoplasia.4, 7–9 Some small masses may be marginally excised from a tail, but if too much tissue is removed circumferentially, there is a risk of excessive tension leading to a tourniquet effect of the tail. Therefore, if wide margins for particular neoplasms are desired (e.g., 2 cm lateral margins and a fascial plane deep for a mast cell tumor excision, 3 cm lateral margins and two fascial planes deep for a sarcoma excision), a tail amputation is often the recommended procedure to achieve adequate margins and a tension‐free closure. The level at which the surgeon decides to amputate depends on the reason for amputation. A “caudectomy” is also known as a “total” or “high tail amputation,” and this generally means amputation at or anywhere proximal to the third coccygeal vertebra (or simply, cranial to the perineum). A “partial caudectomy” is an amputation anywhere more distal to this point. While this chapter is going to focus on dogs and cats, complete or partial caudectomies may be performed in a variety of animals, including ferrets (Figure 36.1). Instruments needed for a tail amputation include an IV stand to hang the tail for sterile preparation in the operating room, sterile self‐adhesive bandaging (e.g., VetWrap), a standard “soft tissue surgery pack,” a sterile marker, gauze (radiopaque or non‐radiopaque), and bone‐cutting forceps (e.g., Liston). Optional tools include monopolar electrosurgery and equipment for a tourniquet depending on both availability and surgeon preference. Figure 36.1 Ferret that presented two weeks postoperatively following a high tail amputation for completely excised sarcoma. Source: © Kristin Coleman. After general anesthesia is induced, the tail, perineum, and dorsal pelvic area are clipped. The most distal portion of the tail may be covered with an exam glove and then covered proximally with self‐adhering bandaging to secure it to the tail, since the portion to be amputated does not need to be fully clipped but should be covered in surgery. It is then important to place a purse‐string suture around the anal orifice to reduce the risk of fecal contamination during the procedure. For partial caudectomies close to the distal portion of the tail, purse‐string sutures in the anus are not necessary. Patients are frequently positioned in sternal recumbency and at the edge of the table with the pelvic limbs hanging freely over the edge (Figure 36.2). It is essential to provide plenty of padding over the edge of the table intraoperatively for the patient’s comfort during postoperative recovery, especially since the edge of the table can cause trauma to the hindlimb vasculature, sciatic nerve, or femoral nerve if not properly padded. For the padding, there are several options: multiple beach towels, a pool noodle over the sharp edge, or several blue pads to name a few. An alternative position would be to pull the patient forward with the pelvic limbs abducted and supported by the table. Figure 36.2 Proper patient positioning for partial caudectomy for neoplasia in a Mastiff. The patient is in sternal recumbency with padding in his caudal abdominal region and cushioning the edge of the table, and his tail is suspended with the use of an IV pole. Source: © Kristin Coleman. A tourniquet may or may not be placed around the proximal aspect of the tail to decrease bleeding during the procedure. The duration of tourniquet application depends on its tightness. Loosening and replacing the tourniquet every 20–30 minutes may be necessary to avoid soft tissue and vascular injury.9 The authors do not use tourniquets for tail amputations and prefer to ligate or cauterize blood vessels as they are encountered at the time of dissection. After draping is completed and prior to making an incision, the sterile marker should be used to draw on the patient’s tail at the level of the intended amputation. This is important for surgical planning to avoid tension of the final closure, maintain symmetry, and create a cosmetic incision with the dorsal aspect being slightly longer than the ventral aspect. The first step is to choose the area of amputation and mark the corresponding joint space. If desired, a hypodermic needle may be used as an alternative to identify the location of the intervertebral space.9 The next step is to make an incision in the shape of a “fishmouth with an overbite,” and it consists of two arches drawn on the dorsal and ventral aspects of the tail. The “corners of the fishmouth” are on the lateral aspects, and the proposed incision should be at least one coccygeal vertebra distal to the desired intervertebral amputation site to allow for a tension‐free closure (Figure 36.3). Figure 36.3 Dorsal aspect of tail with lines denoting the palpable dorsal spinous processes of the coccygeal vertebrae to allow for identification of the intervertebral amputation site. The distal transverse line is the arch of the “fishmouth” drawn approximately one vertebral body length distally from the desired amputation site and is where the skin incision will be made (left image). Ventral aspect of tail is marked with the arch of the “fishmouth” (right image). Source: © Kristin Coleman. After making an incision through the skin and subcutaneous layers (Figure 36.4), the tissues are dissected to the level of the desired intervertebral space for disarticulation. While the muscles may be sharply transected, there are several vessels that require ligation, especially in large patients. The lateral caudal arteries are located dorsal to the coccygeal transverse processes in the proximal aspect of the tail and are located ventral to the processes in the distal aspect of the tail, and depending on patient size, they may either be ligated with suture (short‐acting monofilament absorbable), hemoclip, or monopolar electrosurgery (if the vessel is <2–3 mm in diameter). If a nerve block was not performed pre‐operatively, nerves may be locally blocked with a local anesthetic as they are encountered and sharply transected (Figure 36.5). The intervertebral disc space to be transected is confirmed, and the joint space is disarticulated with a #10 blade, Mayo scissors, or bone‐cutting forceps (Figure 36.6). After the tail is removed, the remaining cartilage from the caudal aspect of the proximal vertebral end‐plate is removed with rongeurs. If a tourniquet was used, it should be released prior to closure to assess for hemostasis. Following lavage, closure should start with a buried simple interrupted suture using a short‐acting monofilament absorbable synthetic suture on midline to bring the dorsal and ventral aspects of the subcutaneous tissue over the exposed coccygeal vertebra. This may continue a few more times to symmetrically bisect the deep subcutaneous tissues before routine closure of subcutaneous tissue and skin (Figure 36.7). If any of the edges have appreciable tension, an additional coccygeal vertebra should be removed. While a non‐absorbable suture in a cruciate mattress pattern is ideal for skin closure, an intradermal pattern is chosen in aggressive patients (Figures 36.8 and 36.9). Figure 36.4 A #10 blade is used to make the incision through the skin and subcutaneous layers. After completing this step, the skin is retracted proximally to begin dissection through the musculature at the point of desired amputation. Source: © Kristin Coleman. Figure 36.5 As nerves are encountered, they should be injected with a local anesthetic using a 25‐gauge needle (bevel up) (left image). Whichever ligation strategy is chosen, the lateral caudal arteries should be isolated (center image), ligated (right image), and then transected. Source: © Kristin Coleman. Figure 36.6 Once all soft tissues have been dissected from the intervertebral disc space or vertebral body to be transected, Liston bone‐cutting forceps, Mayo scissors, or a #10 or #11 blade may be used to complete the amputation by disarticulation. If the skin is appreciated as having too much tension after removal of the tail, an additional vertebral body should be amputated. Source: © Kristin Coleman. Figure 36.7 After copiously lavaging the surgical site, the deep subcutaneous tissues are apposed with a buried simple interrupted pattern of a monofilament absorbable suture. This is performed in a bisecting manner, which begins with the center of each dorsal and ventral aspect coming together (top right) and is followed by the center of the right and left sides being apposed next (bottom left). The superficial subcutaneous layer is then apposed in a simple continuous pattern with short‐term monofilament absorbable suture. Source: © Kristin Coleman. Figure 36.8 Closure of skin with non‐absorbable monofilament suture (3‐0 nylon) in a cruciate mattress pattern (left image). Note the tension‐free closure with soft tissue apposed approximately 1/2 vertebral body length from the visible end of the bone (right image). Source: © Kristin Coleman. Figure 36.9 Feline patient with a peripheral nerve sheath tumor of the dorsal proximal tail. A high tail amputation (i.e., complete caudectomy) was performed to attain the recommended 3 cm lateral margins and two deep fascial planes. The patient was healed in two weeks and had no intra‐ or postoperative complications. Source: © Kristin Coleman. The patient is placed in sternal recumbency with the hind limbs hanging off the end of the table. Care must be taken to place substantial padding under the patient’s caudal abdomen/inguinal region and over the edge of the table, since the edge of the table can cause trauma to the hind limb vasculature, sciatic nerve, or femoral nerve if not properly padded. For padding, a rolled towel or even pool noodle works well. A purse‐string suture is placed around the anus with either gauze or tampon in the caudal rectum to prevent fecal contamination during the procedure, and some kind of marker should be placed on the patient, on the anesthetist’s clipboard, on the O.R. checklist, etc. to remind everyone that this purse‐string is present and requires removal postoperatively. A caudal or sacrococcygeal epidural can be performed to help with pain during and after the procedure, though not absolutely required. For this procedure, it is advisable to use monopolar electrocautery due to the vascular nature of the tissues surrounding the tail skin folds. These tend to be quite vascular due to chronic inflammation of the skin. It is possible to perform this procedure without the use of electrocautery, but there will be blood contamination in the surgical field with the need to ligate bleeding vessels. Once the patient is in position and the purse‐string suture is placed, a surgical scrub is performed (at least three times), trying to clean the deep skin folds of the tail pocket as best as possible. However, the surgical technique described below will hopefully avoid any contact of the surgeon or incision with the deep portions of the chronically infected skin fold. An elliptical incision is performed around the tail base and around the tail skin fold (caudal aspect of the sacrum) with the points of the ellipse on the lateral aspects. For added precision to attain a symmetrical incision, a sterile marker may be used to plan the incision and draw on the skin prior to cutting (Figure 36.10). The incision is made between the anus and the ventral skin fold, being sure to leave as much skin possible dorsal to the anus, staying out of the skin fold, and incorporating all of the skin folds into the elliptical incision. The goal is to remove the coccygeal vertebrae and skin folds all en bloc. The subcutaneous tissue is then dissected down to the level of the palpable coccygeal vertebrae dorsally, ventrally, and on both lateral aspects to the area of the “twist” in the vertebrae (Figure 36.11). This can be challenging because the surgeon should ideally stay just outside of the subcutis of the offending tail folds/tail pocket without entering the infected area. If the pocket or folds cannot be appreciated during dissection, an instrument, such as a Kelly hemostat, should be placed into the pocket area as a landmark. Remember that whatever instrument is passed into the tail fold depth is considered contaminated and should not be handled by the surgeon on the portion contacting the skin. Figure 36.10 The patient is positioned with hindlimbs hanging over the end of the surgical table. Dorsal is at the top of the image, and ventral is at the bottom of the picture. A sterile surgical marker was used to make the outline of the elliptical incision. Dorsal margin is the caudal aspect of the sacrum, and the ventral margin is proximal to the anus. Source: © Kristin Coleman. When dissecting ventrally to the vertebrae, be very careful not to stray away from the vertebrae, since the rectum is directly below the dissection area. Blunt dissection (i.e., with a finger), opposed to sharp dissection (i.e., Metzenbaum scissors), ventrally may be beneficial in this region to avoid inadvertent penetration into the rectum. Once the “twist” in the vertebrae has been reached, the coccygeal and levator ani muscles are severed at their tendinous insertion onto the vertebrae, and any bleeding vessels are cauterized or ligated. After the bone of the coccygeal vertebrae is exposed, a bone‐cutting forcep or Gigli wire is used to transect the bone at the level of the vertebral body or cut in the intervertebral disc space at the level of the “twist.” Any soft tissue connections that are remaining can be dissected away (Figure 36.12). The twisted coccygeal vertebrae and skin fold are then removed en bloc. It is possible to remove the entire piece in one conglomeration without touching or going into the soft tissue envelope of the skin fold, which helps decrease the risk of contamination. The surgical field is lavaged with copious amounts of sterile saline, and a culture is obtained by either a swab or a small piece of tissue to assess for deep‐seated infection within the surgical site from the chronically infected tail pocket. If the muscles surrounding the vertebrae are robust enough, these get apposed with a fascial closure over the cut end of the vertebrae. In the authors’ experiences, these muscles are often too small for a fascial closure over the vertebral end. If there is redundant skin, it can be excised at this time. The deep subcutaneous tissue is closed with a long‐term absorbable monofilament suture in a bisecting fashion to close the ellipse in a buried simple interrupted pattern, which allows the closure to remain symmetrical. The author likes to start in the center of the incision with a deep subcutaneous ligature and then place a ligature in the center of each of the sides (Figure 36.13). The superficial subcutaneous tissue is closed with a short‐term absorbable monofilament suture in a simple continuous pattern. The skin is closed routinely. At this time, REMOVE THE PURSE‐STRING SUTURE AND GAUZE‐PACKING/TAMPON! Digitally palpate the rectum to make sure it has not been breached during the procedure (Figure 36.14). Figure 36.11 Dorsal dissection is performed in the left image. The use of retractors (Senn and Gelpi) is very helpful to visualize the chosen plane of dissection. Allis tissue forceps are also essential for handling of the infected tail fold tissue to retract and manipulate the tail segment. In the right image, ventral dissection is performed to stay close to the ventral aspect, and care must be taken NOT to breach the rectum. Dissection is continued completely around the skin fold and coccygeal vertebrae. Source: © Kristin Coleman. Figure 36.12 In the left image, dorsal dissection is performed to the level of the coccygeal vertebrae at the level of the “twist” or just dorsal to the “twist” in the vertebrae. In the right image, Liston bone‐cutting forceps are used to transect the intervertebral disc space just cranial to the abnormality and palpable cranial end to the tail pocket once all soft tissues have been dissected from the area. Note the two Gelpi perineal retractors and assistant retracting the dorsal tissues with a Senn retractor for aiding in visualization. Source: © Kristin Coleman. Figure 36.13 In the left image, the caudectomy has been performed, and the site is now inspected for signs of rectal perforation, remaining hair or skin, and success of hemostasis. The muscles often cannot be closed over the cut end of the vertebra in this area. If this is the situation, close deep subcutaneous tissues as in the right image. Source: © Kristin Coleman. Figure 36.14 Immediate postoperative picture of skin closure with cruciate mattress sutures of 3‐0 nylon. Be sure to REMOVE THE PURSE‐STRING SUTURE AND ANY PACKED GAUZE FROM THE RECTUM!!! Source: © Kristin Coleman. In cases of both complete and partial caudectomy, the same potential complications exist intra‐ and postoperatively as with any surgery with an incision, including but not limited to death under anesthesia, bleeding, nerve damage, infection, dehiscence, or seroma formation. In addition, complications associated with caudectomy also include fecal incontinence, self‐trauma, tension leading to dehiscence or incisional irritation, and neuroma formation, particularly those secondary to tail‐pull injuries or high tail amputations.3,9 With higher tail amputations comes an increased number of potential complications, which may include decreased rectal sensation with adequate anal tone, failure to posture to defecate, and post‐op draining tracts immediately after surgery (12% in one study) and delayed wound healing, persistent tail chasing behavior, and temporary changes in defecation habits at the time of suture removal (13% in one study).3 There are several tips for reducing the risks of complications. Peri‐operative antibiotics are recommended with a 22 mg/kg IV dose of cefazolin being given 30–60 minutes prior to skin incision and repeated every 90 minutes throughout the procedure. In cases of screwtail caudectomy or in cases of infection or trauma as the reason for caudectomy, antibiotics are continued postoperatively. In cases where the infected or traumatized tissue has been removed with caudectomy with no culture obtained, empirical antibiotics are continued for approximately seven days. In cases of screwtail where the risk of deep‐seated infection exists and a culture was obtained, broad‐spectrum antibiotics should be dispensed until the culture and sensitivity results are finalized, at which point the authors dispense appropriate antibiotics for an additional one to two weeks.3 Neuroma formation may have decreased risk if individual nerves encountered during surgery are sharply transected with scissors or a blade (NOT with electrosurgery) and if local anesthetics are used to infuse the area around the nerves. In cases of partial caudectomy, the patient often remains hospitalized only until recovered from anesthesia and then may be discharged from the hospital, which is often the same day as surgery. Due to the more invasive nature of a screwtail caudectomy in a brachycephalic breed of dog, these patients are kept overnight for monitoring of both surgical site comfort and respiratory watch. Once these patients are discharged, they are advised to wear a hard cone collar for two weeks until their recheck appointment with suture removal/incision check. With partial caudectomies, a longer than normal cone collar may need to be sent home to reduce ability for self‐mutilation of the site. Pain medications dispensed typically include gabapentin and, if not contraindicated, a non‐steroidal anti‐inflammatory drug (NSAID). Some surgeons recommend that the client applies triple antibiotic ointment or a petroleum‐based product (e.g., Vaseline) to the incision two to three times daily for the first two weeks postoperatively. The purpose is to prevent contaminants, particularly fecal material, from directly contacting the incision as it is healing, and if the owner notices contaminants stuck to the ointment, they may simply wipe it away. The patients should be kept in a small room without carpet (to reduce the risk of scooting behavior) with no running, jumping, or playing and should only be taken out on a leash for short walks. After two weeks, the incision should be healed, and the patient may resume normal activity (Figure 36.15). Due to the surgical site’s proximity to the anal orifice and possible reason for performing surgery being infection in cases of screwtail caudectomy, antibiotics are often initiated or simply continued from their preoperative course in the authors’ cases. One study had 76% of their postoperative screwtail amputation patients continue antibiotic therapy after surgery for an average of 13.5 days.3 In this study of caudectomy in brachycephalic dogs with screwtails, surgery resolved clinical signs with no long‐term complications. Figure 36.15 Two‐week postoperative status prior to suture removal. Source: © Kristin Coleman.
36
Caudectomy
Introduction
Anatomy
Indications/Pre‐operative Considerations
Surgical Procedure
Partial Caudectomy
Positioning
The tail is suspended with tape or a towel clamp to an IV stand or pole (or similar object) to allow a hanging‐type preparation and draping technique a few centimeters proximal to the proposed incision. Quarter‐draping is either performed on the proximal aspect of the tail or around the dorsal pelvic and perineal region. An impermeable drape or sterilized aluminum foil should be used to grab the distal aspect of the tail (the portion that has not been aseptically prepared), followed by application of a sterile self‐adhering bandage (e.g., VetWrap) to cover the distal portion of the tail. The surgeon should be careful to not contaminate themselves during this portion of draping (Video 36.1).
Incision
Dissection
Ligation/Transection
Closure
Caudectomy for Screwtail
Positioning
Incision
Dissection/Ligation/Transection
Closure
Potential Complications
Postoperative Care/Prognosis
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