Brachycephalic Airway Syndrome: How to Help Your Patients Breathe Easier Matthew Keats, DVM, DACVS Chesapeake Veterinary Surgical Services Annapolis, MD

Brachycephaly is definition a having a “short wide head”. The ratio of skull length: width is calculated and if <1.44, brachycephaly is defined. Selective breeding has caused breed-specific airway problems. The Brachycephalic Obstructive Airway Syndrome (BOAS) is defined by multiple lesions. The primary lesions are stenotic nares, elongated and thickened soft palate (traditionally only palate length was considered), tracheal hypoplasia, and caudally displaced turbinates. The commonly considered secondary or acquired lesions are eversion of the laryngeal saccules and laryngeal collapse. There are several other lesions that will be discussed. The breeds commonly affected are English Bulldog, French Bulldog, Pug, Boston terrier, Pekingese, Shih Tzu, Pomeranian, Boxer, and the Persian cat. The English Bulldog is the only one commonly affected by tracheal hypoplasia. Airflow concepts are important to understand in regards to respiratory physiology. Poiselle’s law is a fluid dynamics physics equation describing fluid flow through a tube. Basically, air (a fluid) can be viewed as flowing through various parts of the respiratory using this equation. The equations is: Q= π P r4 / 8 n l Q is flow rate P is the pressure in the tube r is the radius of the tube n is the fluid’s viscosity l is the length of the tube Important concepts to take away from this equation is that changes in a tube’s radius size has an dramatic effect on airflow. Changes in the radius affect flow to the 4th power. For example, a decrease in the radius by a factor of 2 (half the radius) decreases the airflow by a factor of 8! This is more apparent in the smaller patients as the small airways can experience more dramatic changes in lumen size. This increases pressure and these pressure changes stress respiratory system’s physical structure and can damage or collapse them. The areas of the most flow are in the small passages such as the nares or larynx.

Primary components The nares are the entrance of airflow into the body. These areas are often very affected in brachycephalics. This is a commonly overlooked and undertreated part of BOAS. The alar folds are medially displaced and either partial or complete close the nasal meatus. This can be a static or dynamic lesion. In some animals, the nasal wing can be seen to actively medially move during inspiration in response to negative pressure and pinch the nares. The soft palate length affects respiration by obstructing the nasopharynx and rima glottidis and interfering with closure of the epiglottis. The former two cause airway obstruction and the latter can cause aspiration and explains some of the coughing and gagging clinical manifestations. More recently, the thickness of the palate has been studied in CT studies by Grand and Bureau. The palates in clinically affected animals were significantly thicker than unaffected patients. Cross et al examined histologic specimens of resected palates and found salivary hyperplasia, palatine muscular atrophy, and lamina propria atrophy. Caudally displaced nasal conchae (also referred to as “nasopharyngeal turbinates”) have been noted in affected animals. They occur in about 20% of brachycephalics and 82% of those were pugs (Ginn et al.). This displacement causes a caudal obstruction of the nasopharynx. This may be a previously underdiagnosed reason for poor recovery in some animals treated with conventional means. Tracheal hypoplasia is primarily a disease occurring in English Bulldogs. The common method of diagnosis is from lateral thoracic radiographic projections. In this view, the dorsoventral thoracic inlet height is compared to the tracheal diameter. The ratio is calculated and normal ratio is 0.20. A ratio of 0.16 is typical in the brachycephalic breeds and most Bulldogs are at 0.11-0.10. There is currently no treatment but should be recognized and can cause marked respiratory compromise.

Secondary components The sequelae to breathing through undersized airways, is physical damage to structures of the larynx. These changes are permanent and may occur early in disease (reported as early as 6 months of age). This is the laryngeal collapse component. This is diagnosed on sedated or anesthetized per os laryngeal examination. Laryngeal collapse is described in stages. Stage I is comprised of eversion of the laryngeal saccules. The saccules evert out of their crypts and then obstruct the ventral rima glottidis. Initially, they are translucent and soft. With chronic eversion, the saccules become firm and fibrotic. Often, saccule eversion is described as an entity unto itself, but is the first stage of collapse. Medial tipping of the corniculate processes of the arytenoid is stage II. Stage III is defined by contact of the opposing corniculate processes and loss of the dorsal arch of the rima glottidis. This can be diagnosed in young animals and is not a reversible condition. In pugs, the cartilage seems to be softer and may actually be a primary condition. Caccamo et al compared rima

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glottidis indices between English Bulldogs, French Bulldogs, and Pugs. Their study found pugs to have the smallest laryngeal openings overall. Several other conditions and markers of disease have been studied. Increased circulating inflammatory markers such as Tumor Necrosis Factor, Interleukins, and Cardiac Troponins have been identified in affected . Also, gastrointestinal lesions such gastroesophageal reflux, esophagitis, pyloric mucosal hypertrophy, and hiatal may occur secondary to chronic upper airway obstruction. Chronic hypoxia will induce pulmonary hypertension. Additionally, bronchial collapse is reported in some dogs that have laryngeal collapse.

Presentation and diagnostics Historical information can be useful in identifying at-risk patients. Important questions to ask are regarding previous anesthesia problems, loud or labored breathing (at rest or with exertion), exercise tolerance, cyanosis, collapse, gastrointestinal symptoms (vomiting, regurgitation, hacking or gagging when eating or drinking, spitting up foam, difficulty eating due to poor nasal breathing). When taking a history, look for signs of respiratory compromise and interference with glottis, esophageal, and laryngeal function. Initial exam should always be based on patient stability. Abbreviate the exam and provide airway support or intubation if in clinically warranted. Start by watching the patient breathe at rest and without direct interaction. Make observation about respiratory effort and noise. Is the typical nasal stertor heard? Stertor is defined as “ a low-pitched heavy snoring inspiratory sound” and is contrasted by stridor as being “a high-pitched noisy sound”. I will then perform my routine exam and then return to focus of the face and head. Some animal will resent this and more handling thereafter may not be tolerated. Examine for airflow from the nares (independently). Also, look at the nares and evaluate for medial displacement of nasal wing during inspiration. If the patient does not nose breath on its own, close the mouth and observe for changes in effort and noise. If these increase, nasal or nasopharyngeal obstruction is suspected. Increased inspiratory effort is typically seen with the obstructive airway diseases. Some animals will also have cardiac or lower airway disease concurrently. In patients with little clinical signs, medical management may be recommended. This typically consists of weight reduction and environmental modifications to avoid heavy exertion and exposure to hot and humid clients. Antacids, anti-emetics, and gastroprotectants therapy may be initiated and evaluated for response. These patients can have airway examinations electively- this is very reasonable to plan coinciding with elective neutering. Animals with clinical signs should be evaluated further. Stable patient may be electively worked up after appropriate pre-anesthetic testing. Age-appropriate ASA guidelines should be followed with the addition of thoracic and possibly cervical radiographs. Set up with a wide variety of endotracheal tubes and have several undersized tubes available. Use of a pair of laryngoscopes is often helpful to move tissues of the oropharynx and larynx as well as provide more light. Malleable retractors can also be helpful in retracting the tongue or soft palate. Pre-oxygenate patients to avoid hypoxia. I routinely use of anti-emetic and gastroprotectants to minimize the incidence of nausea, vomiting, or regurgitation. I recommend setting up for potential tracheostomy prior to sedating or anesthetizing. Routinely, per os visual exam can be performed to evaluate the components of the upper airway. I typically do this under a very light plane of anesthesia to allow a functional laryngeal exam and then use a deeper plane if the exam is hampered by patient motion or resentment. In cases where lower airway disease is also suspected, bronchoscopy may be indicated. To evaluate the nasal conchae, CT scan and possibly rhinoscopy is recommended. The soft palate should not extend past the caudal borders of the tonsils and should not interfere with the epiglottis. Look for inflammation and thickening of the palate. Avoid applying over-vigorous traction on the tongue, as it will displace the larynx and epiglottis rostrally, which could affect palate length assessment. The larynx and saccules are evaluated for collapse and inflammation.

Surgical treatments Nares resection is typically the first procedure I perform. It is the least demanding technically. For some reason, this procedure is overlooked and underutilized. These small airways can create a lot of resistance and are the entry point of the respiratory tract. I typically use a vertical wedge resection technique in the majority (maybe 90%) of routine cases. In very small patients (and cats), I prefer Trader’s technique (wing amputation) for improved cosmesis and less complicated healing. Horizontal wedge resection, punch technique, and alapexy have all produced successful results. Soft palate reduction (staphylectomy) procedures are typically aimed at reducing length of the palate to an imaginary line at the caudal border of the tonsils or to provide minimal or no contact with the epiglottis. It is important to pay attention to patient positioning for adequate visibility. Use of a head mounted lamp is advantageous. Long-handled instruments are very helpful. Make sure the patient is at an adequate plane of anesthesia to avoid inducing vomiting during manipulation. Do not underestimate the amount sensory stimulation produced by manipulating the soft palate! I prefer to place the patient in sternal recumbency with the head elevated by suspending by the maxilla and using a mouth speculum. Alternatively, the lower jaw may be taped or tied down to keep the mouth open. The tongue needs to be tractioned gently rostrally. Some surgeons perform this procedure with the patient in dorsal recumbency.

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Shortening of the palate may be accomplished in the following manners: • by cutting with scissors and suturing (so called “cut and sew” technique)- my preference • vessel sealing devices (Ligasure and Harmonic scalpel) • CO2 laser • Diode laser • Electrosurgery All can produce satisfactory results. There is significant postoperative inflammation with the use of vessel sealing devices, lasers, and electrosurgery. Diode laser seems to produce more complications than the other methods. Despite being the slowest method, cut and sew is my preference. When using the other techniques, minimizing power to decrease delayed thermal injury and necrosis. More recently, a technique call “folding flap palatoplasty” has been described by Findjie and Duprie. This method both decreases palate thickness and length. It also has an advantage of not leaving a cut mucosal edge exposed at the edge of the palate. The procedure incises the oral palatal mucosa and dissects the palatal muscle. A flap is developed with a caudal base extending to the caudal palate. The flap is retracted rostrally and the resection length is determined once the folding creates the desired length. The edge is resected and the flap sutured in place. This technique worked well in their study and is likely to gain wider use and acceptance. Everted saccules are resected when they are deemed obstructive. I am much more likely to remove chronic appearing saccules than acutely everted saccules. Removed saccules can regrow. They are typically removed by gasping them and excising them at their base. Once I have removed saccules, I am much more observant for potential need for tracheostomy placement in the postoperative period. Laryngeal collapse carries a guarded prognosis and there are no universally accepted treatment techniques other than permanent tracheostomy. Arytenoidectomy, vocal cordectomy, and arytenoid lateralization techniques have all been attempted with varying success. Permanent tracheostomy is a palliative measure that provides successful outcomes in selected cases. Laser-Assisted-Turbinatectomy (LATE) has been reported by Schuenemann et al to remove the obstructive turbinates in affected animals. These animals had excessive contact between adjacent turbinates. After removal, regrowth is expected but a more “clubbed” pattern occurs and results in less contact, which is less obstructive.

Postoperative care Attention to analgesia and relaxation is important to minimize stress and respiratory effort. Oxygen support is provided as needed. There is a delicate balance that must be struck between adequate levels and avoiding over-sedation and potential aspiration. Cooling with a fan is helpful in some patients. In some patients, they are calmed by the noise and airflow provided by the fan. I advise aggressive antiemetics, gastroprotectants, and promotility agents to minimize aspiration risks. These patients must be closely observed as they may rapidly deteriorate. Airway re-obstruction is the most concerning complication and must be treated with re-intubation and possibly tracheostomy (see my other lecture) when severe. I typically hospitalize for at least 24-48 hours. In patients that are more severely affected with clinical signs, I expect longer hospitalizations and am on-guard for complications. In patients with poor recoveries, I evaluate for aspiration pneumonia, laryngeal collapse, eversion of resected saccule edges, postoperative swelling of the palate, and nasal obstruction (swelling or blood).

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Perineal : Let’s Cure the Bulge Matthew Keats, DVM, DACVS Chesapeake Veterinary Surgical Services Annapolis, MD

Perineal hernia results from the disruption of the pelvic diaphragm, which is composed of the and coccygeus muscles, perineal fascia, and the anal sphincters. The is bound by the ischial arch (ventral), 3rd caudal vertebra (dorsally), sacrotuberous ligaments (laterally). The hernia results from weakness of the pelvic diaphragm. This allows bending of the terminal and potential protrusion of other structures.

Hernia review It is important to review the terminology of hernias and general principles of hernia repair. 1. Abdominal hernia: disruption or weakness of the external wall that may allow an organ to protrude 2. hernia components: a. ring- the limits of the wall defect b. sac- peritoneal lining that protrudes through the defect and contains the contents in congenital hernias (traumatic or acquired hernias have no sac but one may form over time) c. contents: viscera protruding through the defect Classification of hernias should be evaluated as thoroughly as possible and included in the medical record for future review. Hernias are classified as follows: 1. site: inguinal, umbilical, perineal, femoral, scrotal, diaphragmatic 2. etiology: acquired vs. congenital 3. content status: reducible, incarcerated, strangulated 4. contents: examples: intestinal, bladder, omentum, etc The four principles of hernia repair have been known and remain unchanged for decades. They apply to all hernias and are important facts for any hernia repair. They are as follows: 1. reduction of contents to their anatomic location. (if this is not possible, sometimes resection is indicated) 2. secure closure of the ring 3. use of native tissue whenever possible 4. removal of redundant tissues before closure

Hernia etiology Perineal hernias are commonly reported in geriatric intact male dogs (median age 7-9 yrs). The following breeds are predisposed: Pekingese, Boston Terriers, corgies, boxers, poodles, Bouviers, and Old English sheepdogs, but mixed-breed dogs are commonly affected. It is not clear if short-tailed dogs are truly at increased risk when compared to their long-tailed counterparts. Many causes have been proposed but not are proven. Suggested causes are straining secondary to prostatic, urinary, anal sac, rectal, or intestinal diseases. Congenital predisposition, anal abnormalities, hormonal imbalances, and structural weakness of the pelvic diaphragm have all been suggested. The cause is likely multifactorial. Rare cases in female dogs have suggested a link to dystocia.

Clinical signs Most common perineal swelling and tenesmus are noted. The swelling can be unilateral or bilateral. About half of cases are unilaterally affected. Owners should be warmed that dogs affected unilaterally, may develop contralateral herniation in the months to years after surgical repair. Dysuria should prompt the clinic to evaluate for incarceration or strangulation.

Diagnosis Diagnosis is made by digital rectal examination. In affected animal, once the finger is inserted rectally, the rectum (and finger) can be brought to the skin. Often the skin can be tented by the finger. It is important to compare this maneuver to a normal animal a few times and the difference is quite dramatic. It is important to evaluate the contralateral sign for a hernia or weakness of the levator ani or coccygeus muscle. If there are large amounts of fecal material present in the hernia, it must be evacuated digitally. In some cases, this requires sedation due to discomfort or lack of patient cooperation. Palpation for reported herniated structures includes , urinary bladder, omentum, intestines, fat, or fluid. Depending on clinical status and symptoms other diagnostics are needed. For example, contrast cystography and ultrasound can be helpful to determine the hernia’s contents.

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Recommended treatment Medical treatment may be indicated with weakness of the pelvic diaphragm only or in animals unsuited for anesthesia and surgery. On a practical note, some owners may be resistant to surgical recommendation and medical therapy can be initiated. Typically, fecal material needs to be gently evacuated from the rectum. A diet to reduce fecal bulk works well in some dogs and in others, high fiber diets work better. Keeping the stool soft is accomplished with diet type and stool softeners (Docusate Sodium or Lactulose). This is typically unsuccessful over time. Some owners become comfortable helping their straining defecate by pressing on the perineal bulging area, but this is inconsistent and seems quite impractical. Surgical treatment is the treatment of choice. It is very important to establish the contents of the hernia. If the hernia is simple, a perineal approach only is needed. With complicated hernias, I prefer an abdominal approach first and a perineal approach. Depending on patient status, this is sometimes a staged procedure.

Pre-operative assessment Prior to surgery, careful patient assessment is needed. Standard age-appropriate ASA pre-anesthetic evaluation (bloodwork, thoracic radiographs, etc) is needed. This will identify pre-existing conditions and co-morbidities. The finding of azotemia should prompt evaluation for urinary bladder involvement. Abdominal radiographs, contrast urography, and ultrasound may be indicated. Azotemic patients should ideally be stabilized prior to surgery if possible. Perineal herniorrhaphy is rarely an emergency if strangulated intestines are present in the hernia. Bladder entrapment can usually be treated by passing a urethral catheter. Once the bladder is decompressed, it is rarely in danger of devitalization. Some surgeons worry about this and will attempt to reduce the bladder into the abdomen after decompression. The catheter is typically maintained during presurgical treatment. It large volumes of stool are present in the rectum or colon, it can be evacuated, but this is usually done immediately prior to surgery. Fasting the day prior to surgery is recommended by some to limit stool volume. are not to be given for several days prior to surgery. Liquid and soft stool is much harder to control from spilling during surgery. If stool softeners are being administered, evaluation of the stool consistency before operating is advised. Surgeon preference dictates surgical procedures. Simple hernias are typically treated by perineal repair and castration. “Complicated” hernias are often treated with celiotomy for bladder reduction and “pexy” procedures. Colopexy may also be performed through this approach. Some surgeons will perform the herniorrhaphy as a separate, later surgery.

Surgical preparation After anesthetic induction digital evacuation of the rectal and anal sac contents is performed. A pursestring suture is placed. The perineum is clipped widely (especially if bilateral repair is planned). If an abdominal surgery is planned, the skin preparation is performed at the same time. Preparation for castration is also needed. For the perineal procedures, care is taken to prevent side effects of this positioning. While placed in the perineal position, the edge of the operating table is well padded to protect the patient from femoral nerve injury. The patient is placed in a slightly head-down position. The increased abdominal pressure on the diaphragm can impair ventilation. Therefore, ventilatory support should be provided (PEEP valves, assisted or mechanical ventilation).

Surgical herniorrhaphy Typically, repair starts with incision over the hernia. The incision starts lateral to the tail base and extends beyond the tuber ischii. After skin incision, the hernia sac is incised which often releases various amounts of serous fluid and sometimes necrotic fat. Structures present need to be evaluated. Presence of intestines, urinary bladder, omentum, and prostate are commonly noted. Tissue viability is assessed. Identification of the exact hernia site, followed by reduction of the hernia contents. Repair of the hernia follows. In cases with small hernias, primary repair (“Traditional repair”) of the hernia by apposition of the separated levator ani and coccygeus muscles from the external anal sphincter. Preplacement of sutures from dorsal to ventral is recommended. Ventrally, the closure includes fascia of the external obturator muscle (without elevation). This can distort the anus especially if bilateral procedures are performed (staging by several weeks has been recommended). I have rarely used this procedure. Internal obturator muscle transposition (“Obturator roll-up”) has worked well in a large number of cases. On the dorsal aspect of caudal border of the ischiatic table, the internal obturator muscle is elevated. Careful elevation is needed to avoid damage to the flap. I try to incised the periosteum along this caudal border and use a sharp elevator working medially and laterally to obtain the full width of the muscle, prior to elevating more cranially. The is located at the caudal aspect of obturator foramen. The elevation stops at that level to avoid damage to the nerve. The caudal rectal vessels are associated with the nerve. The nerve can usually be visualized but the presence of the vessels can help identify the neurovascular structures due to the presence of the pulse. In some cases, the tendon of the internal obturator muscle can be severed to allow a larger defect to be closed. When doing this

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procedure, it is very important to visualize the tendon and not cut blindly to avoid damage to the sciatic nerve located adjacent to this. The muscle is the rolled dorsally into the defect. Like in the standard repair, interrupted sutures are placed dorsally to ventrally and then sutured. In many cases, a primary muscular repair is performed dorsally and the roll-up fills the more ventral part of the defect. Grafts and implants have been used successfully especially in large defect closure. Synthetic nonabsorbable mesh appears much like window or door screening material and is made from polypropylene. In most cases, I will use this in revision surgery or with very large defect, or poor obturator or tail muscle quality. It is used with caution since it is a large, permanent implant that can become infected and create abscessation or draining tracts. It is folded into a double ply and cut to match the defect size. Sutures are preplaced dorsal to ventral. Tension is assessed prior to suturing in place. Some tension is desired to create a trampoline-like effect. Other biologic implants that have been used in the same manner are fascia lata fascial autograft and porcine (allograft). Results have been good for with polypropylene mesh, fascia lata grafting, and porcine submucosa. Superficial gluteal muscle transposition and semitendinosus muscle transposition have also been used. I have no personal experience with these techniques. With all herniorrhaphy procedures, several pitfalls must be avoided: 1. Avoiding penetration of the rectal wall is important to avoid abscess formation. 2. If the sacrotuberous ligament is used in the repair, sciatic nerve injury is a risk. Penetration of the ligament is better than passing a suture around the ligament to avoid this. 3. Infection can be very difficult to deal with in perineal incisions. Pay close attention to surgical asepsis, glove or instrument contact with skin and anus, avoid rectal perforation 4. Incontinence can be minimized by identification and protection of the caudal rectal nerve. With large amounts of hernia contents, this can be difficult. Retraction of herniated tissues via celiotomy can make dissection and visualization better (more later) 5. Palpate carefully during surgery to check the security of the repair 6. Repeat rectal examination after surgery to assess the repair and for baseline for subsequent exams

Abdominal procedures for the treatment of “complicated” cases Celiotomy approach is an easier manner to reduce some “complicated” hernia contents. It can be difficult to push large amounts of omentum (for example) through the perineal approach and is much easier to use gentle traction and ensure complete reduction of the tissues. At the same time, several “pexy” procedures can be used to maintain the reduction of the urinary bladder and maintain “tube-like” rectal alignment. Some clinicians will stage procedures and perform these procedures prior to herniorrhaphy. I have had owners fail to follow up with definitive hernia with that plan. Interestingly, some patients can be improved greatly by these procedures. Ideally, pexies are performed with seromuscular incisions in the two tissues to be apposed (think like gastropexy technique). This takes careful dissection to avoid luminal penetration (especially with colopexy). Vasopexy and cystopexy have been used with good results. The cystopexy is less challenging and entails a 1-2 cm incision through the seromuscular layer of the craniolateral (right) area of the urinary bladder and a similar incision in the right paramedian (about 2 cm lateral) in the body wall (peritoneum and transverse abdominal muscles) and suturing the two together with simple interrupted sutures. Some surgeon abrade both tissues and suture without making an incision. Vasopexy requires open castration and separation of the ductus deferens from the testicular vasculature during castration. The ductus (and vas) deferens are retrieved into the abdomen by traction through the inguinal canal (bilaterally). Bilateral paired “belt-loop” incisions are made in the ventral paramedian abdominal wall (same depth as above). The ductus are pulled through the loops and sutured back to itself (each ductus on its respective side). Make sure the bladder is pulled cranially enough to approximate in a normal position prior to pexy. Colopexy is performed similarly. It is important to retract the descending colon cranially enough (this technique is the same for ). The incision is routinely performed on the left side due to the descending colon’s location. A similar 1-2 cm incision is used. Extreme caution is used to avoid incision into the lumen or suture placement into the lumen. This should be performed before vasopexy (if that technique is chosen). Dogs with these complicated hernia have more complications. Urine dribbling and tenesmus are reported in about 10-20% of cases long-term. These are more common in the immediate postoperative period but many resolve over a few weeks.

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Soft Tissue Sarcoma: Radiation Therapy or Aggressive Surgery Matthew Keats, DVM, DACVS Chesapeake Veterinary Surgical Services Annapolis, MD

Soft tissue sarcomas are a group a tumors that are locally invasive and, in general, have low metastatic potential. They are common skin and subcutaneous tumors that occur in older dogs and cats. They tend to be locally expansive and can become quite large, making removal difficult. As a whole, they tend to be problematic if they are not removed with a wide margin early in their course as they recur so readily.

Tumor types Soft tissue sarcomas include fibrosarcoma, myxosarcoma, hemangiopericytoma, peripheral nerve sheath tumor, liposarcoma, undifferentiated sarcoma. They are generally grouped together due to the difficulty in differentiating them and the similar biological behavior (following a scheme used in man).

Tumor characteristics These tumors are characterized by proliferation of connective tissue elements. The tumors have a “pseudocapsule” that is typically a thin rim of compressed tumor and reactive connective tissue. As a group, the metastatic rate in dogs is about 20%.

Clinical characteristics These tumors typically occur in older dogs and cats. (median age of 10 years old in dogs and 8-11 years in cats). They present as patients with non-painful, large swellings anywhere on the body. They are often slow growing. Owners will sometimes report recent rapid growth or slow steady growth over many months or years. They are more common in medium and large breed dogs. Soft tissue sarcomas are common in the skin and subcutaneous tissues but can arise anywhere in the body. Some additional clinical signs may be reported depending on tumor location. For example, limb, axillary, or inguinal tumors will cause lameness or gait abnormalities due to disruption of normal movement. Large or rapidly growing tumors will sometimes ulcerate or rupture due to stretching or damage of the overlying skin or necrosis. Secondary infections can occur in this scenario.

Diagnostics and staging Aspirates of soft tissue sarcoma are not always readily diagnostic in most cases. Many times they appear as “mesenchymal proliferation” or are merely read as a sarcoma. Aspirates are typically indicated as an initial diagnostic test as they can help rule out many of the other differential diagnosis (mast cell tumor, lymphoma, etc, as well as inflammatory or benign lesion). Additionally, a standard minimum database including CBC, full chemistries, UA, and three-view thoracic radiograph study are indicated.

Planning Wide surgical excision is typically regarded as the initial treatment of choice. Planning for this type of surgery is a 2-3 cm peripheral margin around the mass. If this is not possible deep to the tumor, excision using one fascial plan as a deep barrier is needed. Ideally, this barrier should not be fat or loose connective tissue. If anatomic location readily permits this plan, this should be pursued. This can be relatively easy to plan in the case of a small, non-adherent tumor on the side of the abdomen or trunk, but if the mass is fixed or large, it is advisable to obtain advanced imaging. Magnetic Resonance Imaging (MRI) or Computed Tomography (CT scan) are helpful in planning excision to evaluate the deep tissue involvement and plan for reconstruction needed in closure of these defects. In some cases, amputation should be considered. Creating surgical wounds with these large margins creates large wound defects that need closure. The surgeon must be well versed in closure techniques and plan the incisions appropriately as well as plan for multiple different closure techniques. It is important to consider the size of mass/wound, the location, local tension, motion, and dead space potential when planning resection. Commonly used techniques are rotational flaps, transpositional flaps, pedicle flaps, releasing incisions, axial pattern flaps, or skin grafting. It is very important at to consider that the first surgical procedure offers the best chance for cure. Incomplete resections ultimately decrease patient survival and quality of life. This is also the time to make sure the owners are well educated and have a clear understanding of the disease and go forward in a manner that suits them. If this type of surgery is not possible due to anatomic location (such as being located on an extremity or near the mouth, anus, eye, etc), consideration to an alternate plan must be given. Local excision with planned postoperative full-course radiation therapy (RT) is an excellent alternative. This plan is better than performing an ill-planned, large-scale resection that gives an inadequate margin that

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still needs RT for long-term disease control. This is also a suitable plan when wider resection and its risks are not acceptable to the owner and/or patient. Additional imaging may still be indicated if the deep extent of the mass is not readily apparent. Local resection is relatively uncomplicated in the majority of cases. This involves removal of the tumor while staying outside of the pseudocapsule and little skin removal. In cases will large tumors, this can still be very involved and required advanced techniques for closure. It is very important to realize that skin grafting is not appropriate in the case that RT is anticipated. The grafted skin will not tolerate RT. Necrosis of the graft is expected.

Pre-surgical biopsy What is the merit of a pre-surgical biopsy? A biopsy can be helpful in obtaining a biopsy grade if that is going to greatly impact planned procedures (such as RT). The biopsy will give a prognosis, but in some cases, this can be misleading as the sample collected may not represent the grade ultimately assigned-this is an important point to emphasize to owners! In some cases, amputation becomes a more viable option with a high-grade limb tumor. If a biopsy is obtained, the incision must be in a site that can be easily removed at the time of definitive removal.

Radiation therapy Unfortunately, there are only about 75 board-certified diplomates in Radiation Oncology . This means that there is often a need for distant referral for RT. Pre-surgical planning (especially including incision location and orientation) is very important to success. Sparing a strip of tissue that is at least several millimeter wide from inclusion in the RT field is an important feature of this plan. This strip is along the long axis of a limb is needed to avoid permanent problems secondary to lymphatic obstruction. Working with a radiation oncologist usually means speaking to them before surgery to avoid creating an unacceptable radiation field. Once you have gained some familiarity with your radiation oncologist, it will become easier to operate subsequent cases. A poorly planned surgery can sometimes lead to the inability to have the planned RT performed. RT is indicated in cases of incomplete tumor excision (re-excision of the scar can be considered also). About 15% of cases will have re-growth with either RT or re-excision (range is higher with RT up to about 30%). Radiation is given in a 42-57 Gray (Gy) total dose fractioned over 4 weeks in most cases. This is typically started once normal wound healing has taken place and skin sutures or staples are removed. An additional week is waited with oral tumors. Most radiation oncologist perform the treatment 5 days per week over 4 weeks (19 total treatments). Preoperative radiation therapy produces significantly more morbidity.

Prognosis The prognosis is dependent on tumor size, grade, stage, and completeness of removal. The grading scheme (one through three) is based on degree of cellular differentiation, pleomorphism, mitotic index, matrix formation, and necrosis. The metastatic rate with grade I and II tumors is about 13% and 40-50% for grade III tumors. Overall, the metastatic rate in cats is 15-20%. Metastasis typically occurs to the lungs. Large tumor size negatively affects prognosis. There is data suggesting that about 10% of grade I soft-tissue sarcomas excised on the limbs recurred. In these dogs, median disease-free interval (DFI) and survival time (MST) were not reached by 1,000 days (Stefanello et al.) Recurrence is uncommon with wide resection that have clean margins. A study by Bacon et al, found that scar resections with margins from 0.5-3.5 cm resulted in only a 15% recurrence rate by 816 days. Radiation therapy was not used in this study. They found that recurrence of grade I and II tumors does not always influence survival most likely due to a generally slow tumor recurrence and the fact that patient population is generally older. McKnight el al. had very good results in dogs with soft-tissue sarcomas resected to <3 cubic centimeters that subsequently received full-course RT. Two main negative prognostic factors identified were metastasis and local recurrence. Only 16% developed recurrence and this occurred at a median DFI of 700 days (71-1533 days); when all dogs were included, this DFI was 1082 days. Of the dogs with local recurrence, 50% of these died soon after due to metastasis. The other 50% with recurrence, experience long survival and disease-free times at about 4 to 6 years with a second surgical resection. MST exceeded the length of the study. The 1 and 2 year survival rate was 87%, the 2 and 3-year rates were 81%, and the 5-year survival rate was 76%. In a study by Forrest et al., dogs were treated with complete excision to microscopic disease (different than the McKnight et al. study) and full-course RT. In this study, a 31% local recurrence rate occurred. They found a 14.3% pulmonary metastasis rate. MST was 1851 days (5.1 years). Median DFI was not reached but was over 798 days. Although not found to be statistically significant, Fibrosarcoma MST was >914 days compared to that for hemangiopericytomas was found to be 5.1 years. In those that had died, 38% were dead from causes unrelated to the tumor. Oral location MST was 1.5 years compared to all other sites at 6.2 years and this is certainly a clinical feature to keep in mind for client education.

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Grade III tumors are different in the fact the they have significant metastatic potential. There is a significant reduction in survival time with this grade (236-856 days- Bacon et al., Kuntz et al.). Chemotherapy is sometimes recommended with this grade of tumor but its role is still unclear. In feline patients, overall reported survival time ranges from 11-20 months after surgery alone. (Davidson et al., Dillon et al.) Complete excision resulted in a significantly longer survival time (>16 months) than incomplete excisions (9 months) (Davidson et al.)

Surgical details Before surgery, it is important that owners have a clear idea of the surgical procedure intended as well as the goals of the proposed surgery. During the consultation, I like to illustrate on the patient to show the owners where the incisions may be as well as give them an idea of the size of the incisions and scars. I typically inform the owners that a very large part of the patient will be clipped. This is because sometimes more generous incisions or more robust flaps are needed for closure and to avoid contaminating the field during closure. In the operating room, use a surgical marking pens to draw proposed incisions with the planned margin from the tumor or scar. Drawing planned flaps at the same time can be helpful in the planning of the incisions. This is a good time to assess the mobility of the skin as well as attachment to underlying tissues. Proper positioning of the patient can avoid creating “false” tension. After the patient is placed on the table, gently manipulating the surgical site and “gathering” skin can prevent skin from becoming trapped under the patient and pinned between the body and the table. This is particularly applicable to tumors on the trunk, abdomen, and neck. The incision is started at the proposed margin previously marked. The skin incision should be completed. At the “patient” side of the incision (not the “tumor” side) the incision should be continued to the proposed deep margin. It is important to avoid the temptation and tendency to start dissecting towards the tumor. Only once the deep tissue layer has been incised, can dissection be carried out towards the center. Use of hemostats, hemostatic clips, or electrosurgery as the dissection proceeds is advisable-as opposed to removing everything and then returning to find the vessels. At the completion of surgery, no gross or visible tumor should be present. Also, with wide excisions, the masses should never be seen directly. Gloves and instruments should be changed at this time. If too many instruments have been handled or used, sometimes it is best to open a new pack for closure. This is a very important general surgical oncology principle to avoid contamination with residual tumor cells. At this time, reassessment of tissue tension and mobility can take place. Sometimes, the draping or clamping process can produce some tension that can be relieved by simply manipulating the patient’s skin and the drapes or drape clamps. If primary closure or minimal undermining of the skin can be employed, this is usually readily apparent at this time. Pre-placement of several interrupted or mattress sutures can sometimes close wounds that do no seem “closable” at first. Otherwise, the selected closure technique is used. I typically use a closed-suction drain with large flaps and occasionally with some other techniques. Drains pose some risks and they should be used appropriately. Once the surgery is completed, it is very important to mark the mass’ surgical margin. Inking works very well with deep margins. Lateral margins can be marked with different colored sutures, different numbers of sutures/staples. There are also commercially available multi-colored inking kits. Include detailed notes in the pathology submission to make it as clear as possible. Pain control is important in the postoperative period. The protocol needs to be tailored to the procedure and patient needs. The use of protective collars is essential to prevent damage to the surgical site. Bandages can be used judiciously to protect the incisions and prevent seroma formation. Activity restriction is essential to minimize motion, tension, and seroma formation.

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