Polypoid Cystitis in Dogs: Not all bladder masses are cancer!

Stephen J. Birchard, DVM, DACVS

Scott Owens, DVM, DACVIM

Polypoid cystitis is a disorder of the urinary bladder in dogs characterized by inflammation and development of one or more polypoid masses within the bladder lumen. (Fig. 1) 

Fig. 1: Pedunculated urinary bladder polyps in a dog

Most affected dogs are female and present with a history of hematuria or recurrent urinary tract infection (UTI).(1) Several different species of bacteria have been cultured from the urine of affected dogs with Proteus spp. being the most common.(1) Polyps tend to be located cranioventrally in the bladder as opposed to transitional cell carcinoma which tends to occur in the bladder neck or trigone area. (Fig. 2)

Fig. 2: Large polyp located in the cranial aspect of the urinary bladder

It is unknown whether persistent or recurrent UTI predisposes to polyp formation or if polyps predispose to UTI. In one study, 7 of 17 dogs with polypoid cystitis also has cystic calculi.(1) Effective treatment combines surgical resection of the polyps combined with medical management of the cystitis. Surgical removal of the polyps is straightforward if just one or a few polyps are found, especially if the polyps are pedunculated and not located near the trigone. Widespread polyps are more difficult to surgically resect, and may require subtotal submucosal resection of the bladder mucosa.(2) (Fig. 3)

Fig. 3: Diffuse small mucosal polyps in a dog.

Alternatively, use of a Holmium:YAG laser via cystoscopy may be an effective minimally invasive method of treatment for patients with low numbers of polyps.(3)

Diagnosis

The diagnosis of polypoid cystitis is straightforward in most cases.  Clinical suspicion should be raised in patients with signs of lower urinary tract disease, including pollakiuria, hematuria, and stranguria non-responsive to initial therapy.  Urinalysis results are non-specific, with microscopic hematuria seen in most cases along with bacteriuria and pyuria, the former if an active infection is present.  Orthogonal view abdominal radiographs are helpful to rule out urolithiasis, while characteristic polypoid structures are most commonly seen via ultrasound of the urinary bladder.(Fig. 4)

Fig. 4: Ultrasound appearance of a pedunculated bladder polyp (arrow) in a dog with polypoid cystitis

In the absence of ultrasound availability, double-contrast cystography may be used.  Confirmation can be made via cystoscopy (Fig. 5) or cystotomy (see below).   

 

Fig. 5: Cystoscopic appearance of bladder polyps in same dog as in Fig. 4.

Surgical Technique

Perform a ventral midline abdominal approach. After routine exploratory, exteriorize the urinary bladder and isolate it from the peritoneal cavity with moistened abdominal sponges.  Carefully examine the bladder; if the polyp can be palpated and its point of attachment to the bladder wall determined, make an initial cystotomy adjacent to this area. (Fig. 6) 

Fig. 6: Large bladder polyp in a dog; cystotomy incision has been made
adjacent to the mass to facilitate resection and closure.

In this way the entire polyp can be removed by partial cystectomy without making an additional incision in the bladder. If the polyp cannot be palpated, or there are multiple polyps present, simply make a routine ventral cytstotomy incision to expose the polyps. Small pedunculated polyps can be removed by submucosal resection at their attachment to the bladder. Large polyps with wide mucosal attachment should be removed by partial cystectomy. (Fig. 7)

 

Fig. 7: Excised polyp (P) and full thickness section of urinary bladder (B)

Prior to bladder closure, obtain a sample of mucosa for culture. Also be sure to submit all resected tissues for histopathology. Close the bladder routinely (see Veterinary Key Points blog from 10/11/2014 entitled: Cystotomy for Removal of Cystic and Urethral Calculi in Dogs: Are you getting them ALL out?).

Postoperative Care

Routine care after cystotomy includes intravenous fluid therapy, analgesics such as opioids and/or NSAIDS (if renal function is normal), and antibiotics if indicated. Monitor urinations as well as vital signs. Most animals can be discharged from the hospital the day after surgery.  Post-operative hematuria should be expected, and if severe the pet owner should be made aware to monitor for urinary obstruction due to blood clot formation.

Long-term postoperative care depends on results of histopathology and culture. If polypoid cystitis is confirmed and cultures are positive, appropriate antibiotics are prescribed for at least 3 weeks, followed by repeat culture after being off of antibiotics for several days. NSAIDS, including piroxicam, may be beneficial to reduce inflammation and thereby prevent formation of more polyps.  While this condition is scarcely reported in the veterinary literature, surgical removal as described above has a very high long-term success rate.  Medical management alone is unlikely to be successful. Partial resolution of clinical signs may be achievable, but long-term success is unlikely without surgical intervention.

References

1. Martinez I, Mattoon JS, Eaton KA, et.al. Polypoid cystitis in 17 dogs (1978–2001). J Vet Intern Med 2003;17:499–509

2. Wolfe TM, Hostutler RA, Chew DJ, et.al. Surgical management of diffuse polypoid cystitis using submucosal resection in a dog. JAAHA: July/August 2010: 46(4):281-284.

3. Xu C, Zhang Z, Ye H et al.  Imaging diagnosis and endoscopic treatment for ureteral fibroepithelial polyp prolapsing into the bladder.  J XRay Sci Technol.  2013;21(3):393-9.

Laryngeal Paralysis in Dogs: 5 things we've learned in the past decade

Laryngeal paralysis is a functional disorder of the larynx resulting in decreased abduction of the arytenoid cartilages during inspiration in dogs and cats. This causes airway obstruction, dyspnea and in some cases life threatening hypoxia. Clinical studies of various aspects of the disorder have improved our understanding of laryngeal paralysis. Key elements of some of these studies are listed and briefly described below.

Esophageal Dysfunction

Barium swallow in a dog with significant esophageal pathology

Idiopathic laryngeal paralysis is a disorder affecting more than just the larynx. Studies have conclusively shown that esophageal motility is abnormal in dogs with laryngeal paralysis.(1) This is a significant finding for many reasons, not the least of which is the relationship of esophageal dysfunction with aspiration pneumonia that commonly occurs after surgical correction by arytenoid lateralization. Dogs with esophageal or gastric disorders that predispose them to regurgitation can increase their chance of aspirating and developing pneumonia postoperatively.

When evaluating dogs with laryngeal paralysis, be sure to get a complete history with emphasis on the animal’s ability to prehend food and swallow normally.  Inquire about any regurgitation and vomiting. Obtain thoracic radiographs to evaluate for aspiration pneumonia and megaesophagus. If the dog appears to be a significant risk for aspiration, consider permanent tracheostomy as an alternative to arytenoid lateralization to reduce the risk of pneumonia. Metoclopramide can be administered to laryngeal paralysis dogs as a premedication to reduce the risk of regurgitation during general anesthesia. 

Polyneuropathy

More evidence that laryngeal paralysis is a complicated disorder affecting multiple organ systems are the studies showing its association with peripheral neuropathy.(2,3)  Several clinical investigations have documented generalized neuropathy in dogs that have laryngeal paralysis, emphasizing the need to thoroughly evaluate the neurologic status of these animals. Owners should be educated about this association, particularly in dogs that are not obviously affected by neuropathy when first presenting for their upper airway obstruction. Clinical signs of neurologic deficits may become evident sometime after treatment of the laryngeal paralysis.

Doxapram

An essential part of the diagnosis of laryngeal paralysis is the sedated laryngeal exam. Laryngeal function is assessed by watching the arytenoid cartilages abduct during inspiration. Since laryngeal function may be affected by the sedative drugs administered for the examination, a false positive result can occur if the sedation is excessive. Erratic respirations can also occur, complicating the assessment. Doxapram has been shown to assist in the exam by stimulating respiration allowing a more consistent and accurate evaluation of function.(4) The dosage of doxapram is: 1-5 mg/kg IV.

 Minimal Dissection Lateralization

The original surgical description of arytenoid lateralization included an extensive amount of dissection that is no longer felt to be necessary. After completely disarticulating the crico-arytenoid joint, i.e., the muscular process of the arytenoid from its articulation to the cricoid cartilage, the sesamoid band connecting the arytenoids' corniculate processes was also severed. This was a difficult step in the procedure because of poor exposure and in some cases resulted in perforation of the pharynx. 

Diagrammatic view of sharp incision of the inter-arytenoid sesamoid band.
This step in the surgical procedure is no longer considered necessary by many surgeons.
(reprinted from: Fingland RB. Obstructive Upper Airway Disorders. Saunders Manual of Small Animal Practice, 3rd ed., Birchard and Sherding editors,  Figure 161-6, Elsevier, 2006, pg. 1657)

Satisfactory lateralization is possible by simply incising the joint capsule of the crico-arytenoid articulation and leaving the sesamoid band in tact. Low suture tension has also been shown to be an effective means of opening the rima glottis compared to high suture tension.(5) I have used this “minimal dissection” technique for several years now. It provides for adequate arytenoid abduction, helps to prevent over-correction, and has lessened the incidence of aspiration pneumonia in my experience.

The “Tie-Back” is Not For All Dogs

Although the arytenoid lateralization procedure continues to provide satisfactory treatment for many dogs with laryngeal paralysis, it is contraindicated in dogs that are high risk for aspiration pneumonia. Owners need to realize that the lateralization procedure does not make the larynx normal. It opens the airway and relieves obstruction but the larynx is fixed in its position and not capable of closing. If the epiglottis cannot completely cover the laryngeal opening during swallowing, aspiration is likely to occur. Also, as  discussed previously, esophageal dysfunction or any other cause of chronic regurgitation or vomiting (megaesophagus, gastric disorder, etc.) increases the likelihood of aspiration. In these dogs a permanent tracheostomy should be considered to relieve the airway obstruction. 

A recently performed permanent tracheostomy in a dog.

For details on permanent tracheostomy in dogs, see 
http://drstephenbirchard.blogspot.com/2014/12/permanent-tracheostomy-in-dogs-life.html.

References

1. BJ. Stanley, JG Hauptman, MC Fritz, et. al.

Esophageal Dysfunction in Dogs with Idiopathic Laryngeal Paralysis: A Controlled Cohort Study. Veterinary Surgery Volume 39, Issue 2, pages 139–149.

2. Orla M. Mahony, Kim E. Knowles, Kyle G. Braund, et.al. Laryngeal Paralysis-Polyneuropathy Complex in Young Rottweilers. Journal of Veterinary Internal Medicine Volume 12, Issue 5, pages 330–337.

3. Braund KG, Shores A, Cochrane S, Forrester D, Kwiecien JM, Steiss JE. Laryngeal paralysis-polyneuropathy complex in young Dalmatians. American Journal of Veterinary Research 1994, 55(4):534-542.

4. Tobias KM1, Jackson AM, Harvey RC. Effects of doxapram HCl on laryngeal function of normal dogs and dogs with naturally occurring laryngeal paralysis. Vet Anaesth Analg. 2004 Oct;31(4):258-63.

5. S Bureau, E Monnet. Effects of Suture Tension and Surgical Approach During Unilateral Arytenoid Lateralization on the Rima Glottidis in the Canine Larynx Veterinary Surgery Volume 31, Issue 6, pages 589–595.

Permanent Tracheostomy in Dogs: A life-saving surgical option for severe upper airway obstruction.

Permanent tracheostomy is a well-recognized surgical technique used in animals and humans as a salvage procedure to treat severe upper airway obstruction. Although the technique has been used for many years with success, there are many misconceptions among animal owners and veterinarians about the long-term care and complications. Many feel that dogs cannot have a good quality of life because of the problems associated with tracheostomy. Owners frequently expect that dogs with permanent tracheostomy will have an appliance, i.e. a metal or plastic tube that resides with in the trachea and needs constant care.

Indications for tracheostomy in dogs include: severe laryngeal obstruction due to laryngeal paralysis, collapse, neoplasia, or trauma, pharyngeal neoplasia that obstructs the larynx, and non-resectable proximal tracheal neoplasia.

Although cats may also develop disorders causing severe upper airway obstruction, permanent tracheostomy is associated with frequent, severe complications such as excessive mucous production and stoma stricture.(1) As a result, tracheostomy is rarely recommended in cats.

Preoperative Considerations

Dogs being considered for tracheostomy should be thoroughly evaluated with particular emphasis on the respiratory tract.  A complete history and physical examination followed by appropriate imaging such as thoracic radiographs are important before performing general anesthesia and surgery. Cervical radiographs and even tracheoscopy may be necessary to be certain that the respiratory tract downstream from the larynx is normal. Also, carefully examine the dogs’ ventral cervical area to determine suitability for creating a tracheostomy stoma. Some dogs, such as brachycephalic breeds, have very short necks with excessive skin that can cause problems with skin flaping over the stoma causing obstruction.

Surgical Technique

The dog is placed in ventral recumbency with the neck hyperextended over a soft towel and the front legs extended caudally. The ventral cervical area is clipped and prepared for aseptic surgery. A ventral midline skin incision is made from the larynx to just cranial to the manubrium.  The paired sternohyoideus muscles are divided on their midline using sharp dissection. A large horizontal mattress suture of 2-0 or 3-0 PDS is placed across the sternohyoideus muscles, dorsal to the trachea, to allow retraction of the muscles and cause ventral displacement of the trachea.(Fig. 1) 

Fig. 1: Ventral midline cervical approach for permanent tracheostomy.
The sternohyoideus muscles have been divided and a horizontal mattress suture
is being placed in the muscles to tuck the muscle under the trachea.

Care is taken to avoid trauma to the recurrent laryngeal nerves during passage of the suture. A rectangular window is created in the trachea from the 3^rd to the 7^th ring (4 rings included in the tracheal opening).(Fig. 2) 

Fig. 2: The rectangular window is being created in the tracheal wall.
Note the endotracheal tube present in the tracheal lumen.

The tracheal incisions are begun by incising between rings 3 and 4, then between rings 7 and 8. Be careful not to puncture the cuff of the endotracheal tube when making the initial tracheal incisions. These parallel incisions are then connected using scissors to complete the rectangular shaped defect in the trachea.(Fig. 2)

Close the tracheal wall to the skin in a simple interrupted pattern to create the tracheostomy stoma. Excise a rectangular shaped section of skin on each side of the tracheostomy site to allow the skin incsion to match the rectangular window in the trachea. The suture bites of trachea include the cartilage, and the bites of the skin are placed split thickness, entering the dermal layer and exiting the epidermis.  This allows for accurate apposition of the epidermis to the tracheal mucosa. As in urethrostomy closure, take suture bites from inside out, i.e., start in the tracheal lumen and then take the bite of the skin. The corners of the window are closed first (Fig. 3,4); then the remaining areas are closed in a similar fashion.(Fig. 5) Absorbable suture such as 3-0 or 4-0 PDS is used to avoid having to remove them once the stoma has healed. The skin incisions cranial and caudal to the stoma are then closed routinely.

Fig. 3: The 4 corners of the rectangular tracheal window are closed first.
Note the "inside-out" sequence of suture placement.

Fig. 4: The corner sutures have been placed.

Fig. 6: Completed suture closure of the tracheal stoma. 

Postoperative Care

Alleviation of inspiratory dyspnea is immediate after permanent tracheostomy. See below video of an elderly labrador with laryngeal paralysis before and after permanent tracheostomy. Although laryngeal tie-back is the treatment of choice for most dogs with laryngeal paralysis, permanent tracheostomy was chosen in this dog due to high risk for aspiration pneumonia.

Besides routine postoperative care such as analgesics, cleansing of the stoma is important to prevent build up of discharge and debris. (Fig. 6) Gently wiping the skin around the stoma with moistened gauze sponges is sufficient.

Fig. 6: Typical appearance of a recently preformed permanent tracheostomy
in a Yorkshire Terrier with severe laryngeal collapse.

Owners should be advised to avoid putting anything inside of the trachea and to not use any irritating materials around the stoma such as peroxide or other antiseptics. Small amounts of a petroleum-based ointment (e.g., triple antibiotic ointment) can be placed on the skin around the stoma to prevent discharge from adhering to the skin and make cleaning easier. Discharge from the tracheal stoma tends to gradually decrease over the first few weeks postoperatively. Systemic antibiotics are not routinely prescribed since incisional infections are very rare.

Life Style Limitations

Dogs with a permanent tracheostomy cannot go swimming and should avoid very dusty environments or running in tall grass or weeds. These dogs will also will have difficulty barking or at least have a softer sound than pre-operatively. In rare cases dogs with long hair will need clipping of the hair around the stoma to prevent irritation of the tracheal mucosa and accumulation of debris.

Prognosis

Most dogs with permanent tracheostomy do well and have minimal chronic problems. The most common long-term postoperative problems are pneumonia and stricture of the stoma requiring surgical revision.(2) In a recent study sudden death occurred after tracheostomy in 5 of 19 dogs at variable times after surgery, presumably due to obstruction of the trachea although necropsy was not performed in any of the cases.(2)

Permanent tracheostomy is considered an appropriate surgical option for dogs with severe upper airway obstruction. Complications can occur but some, like stoma stricture and skin fold occlusion, can be treated by revision surgery. Owner education is important to explain potential risks and life style limitations.

References

1. Stepnik MW1, Mehl ML, Hardie EM et. al. Outcome of permanent tracheostomy for treatment of upper airway obstruction in cats: 21 cases (1990-2007). J Am Vet Med Assoc. 2009 Mar 1;234(5):638-43.

2. Lindsay L. Occhipinti and Joe G. Hauptman. Long-term outcome of permanent tracheostomies in dogs: 21 cases (2000–2012) Can Vet J. Apr 2014; 55(4): 357–360.

Intravenous Fluids in Anesthetized Dogs and Cats: Are we giving too much?

Intravenous fluid therapy is one of the most important perioperative treatments veterinarians provide for their patients. Intravenous fluids are considered a necessary part of the anesthesia protocol because of hypotension and vasodilation that can occur due to the anesthetic drugs. 

All animals being prepared for anesthesia and surgery need to be assessed for hydration status and disorders that create fluid losses, e.g. vomiting and diarrhea. Intravenous fluid dosages will be influenced by the animal’s current hydration and ongoing fluid losses. Intravenous fluid dosages may also be affected by disorders that could predispose the animal to over-hydration such as cardiac or renal disease.

The traditional intravenous fluid rate for healthy animals under anesthesia has been 10ml/kg/hour.(1) In the recent AAHA/AAFP fluid therapy guidelines, this recommendation has been revised.(2) Table 4 from the paper describes current fluid therapy guidelines for anesthetized cats and dogs:

Table: Recommendations for Anesthetic Fluid Rates (from: 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats. Harold Davis, BA, RVT, VTS (ECC), Tracey Jensen, DVM, DABVP, Anthony Johnson, DVM, DACVECC, et.al., J Am Anim Hosp Assoc 2013; 49:149–159)

- Provide the maintenance rate plus any necessary replacement rate at <10 mL/kg/hr

- Adjust amount and type of fluids based on patient assessment and monitoring

- The rate is lower in cats than in dogs, and lower in patients with cardiovascular and renal disease

- Reduce fluid administration rate if anesthetic procedure lasts 1 hr

- A typical guideline would be to reduce the anesthetic fluid rate by 25% q hr

until maintenance rates are reached, provided the patient remains stable

Rule of thumb for cats for initial rate: 3 mL/kg/hr

Rule of thumb for dogs for initial rate: 5 mL/kg/hr

Note that not only are the initial fluid rates lower than the previously recommended 10ml/kg/hr, but a schedule for gradual reduction of fluid rates as the anesthetic period progresses is also recommended. These guidelines are considerably different from what was previously thought to be necessary fluid rates for anesthetized animals, but are based on carefully considered factors, evidence based medicine, and clinical experience of board certified specialists.

References

1. Ann Weil, DVM, DACVAA. Anesthesia reboot: Erase these myths and misconceptions. Veterinary Medicine, October 2014, pg. 318.

2. Harold Davis, BA, RVT, VTS (ECC), Tracey Jensen, DVM, DABVP, Anthony Johnson, DVM, DACVECC, et.al. 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats. J Am Anim Hosp Assoc 2013; 49:149–159.

Questions:

What are your thoughts or opinions about this change in recommended fluid dosage?

In private practice, in which anesthetized patients do you typically run intravenous fluids; in all animals or do you have some kind of selection criteria? In other words, what do you think the standard of care should be for fluid administration under anesthesia?

Please post comments either here on the blog site or on my facebook page:

Dr. Stephen Birchard, Veterinary Continuing Education

.

Large Tumor On The Skull of a Dog: The story of "Rocky" the Norwegian Elkhound

Rocky was a 7 year old male castrated Norwegian Elkhound. Several months previous to presentation he developed a slowly growing firm mass on the dorsal cranium.  The owners reported no other significant health problems. 

Fig. 1: This is Rocky under anesthesia being prepared for surgery.
Note large mass on the dorsum of the skull.

On physical examination the mass was well circumscribed but not movable.(Fig. 1) Neurologic exam revealed mild posterior paresis. In all other respects Rocky was behaving like a normal dog.

Diagnostic Evaluation

Radiographic evaluation found no evidence of metastasis of the mass in the lungs or abdomen.  A complete blood count and serum chemistry profile was within normal limits. MRI of the skull showed a very large ossified mass of the dorsal cranium extending ventrally into the cranial vault.(Fig. 2)

Fig. 2: MRI of Rocky's head. Note large skull mass (arrows) that extends ventrally.

Surgery

Although Rocky’s owners were warned about risks of surgery such as brain injury, hemorrhage, infection, and possible incomplete resection of the mass, they wanted to pursue surgical removal. They also knew that the most likely neoplasms causing the tumor were osteosarcoma or multilobular osteochrondrosarcoma.

Rocky was anesthetized and placed in sternal recumbency. His entire head was prepared for aseptic surgery. (Fig. 3)

Fig. 3: Preoperative view of Rocky just prior to beginning of surgery

A midline approach over the mass was performed. Sharply dissecting soft tissues including the temporalis muscles, and retracting them laterally, easily exposed the mass. (Fig. 4) 

Fig. 4: Surgical exposure of the skull mass after dissection of the soft tissues.
Dorsal is to the top of the photograph.

Careful blunt and sharp dissection at the base of the mass allowed for gradual moblilization, and the mass and the involved cranium then easily lifted off the remainder of the skull and were excised. (Figs. 5,6)

Fig. 5: Most of the skull mass has been reflected off the remainder of the skull and is
being held upside down in my hand.

Fig. 6: The resulting skull defect after complete removal of the mass.

Moderate hemorrhage occurred from remnants of tumor attached to the dura and at the edges of the skull. Hemostasis was achieved with judicious electrocautery and hemostatic sponges. Careful debridement of the remaining gross tumor was attempted but was difficult because of poor exposure due to recurrent hemorrhage, and attachment of the mass to the dura.

The skull defect was filled with an autogenous fat graft that was aseptically harvested from Rocky’s lumbar area. The temporalis muscles were then mobilized by undermining them from the skull and used as the first layer of closure by suturing them together on the midline. The remaining tissue layers were closed routinely.(Fig. 7)

Fig. 7: Closure of the temporalis muscles over the skull defect

Postoperative Care and Follow Up

Rocky made an uneventful recovery from anesthesia. Repeat neurologic examination revealed no change from his preoperative status. Routine supportive care and analgesic therapy was administered.

Rocky was discharged from the hospital several days postoperatively. Histopathology of the mass revealed a multilobular osteochondrosarcoma. Two weeks later he was examined for suture removal and was doing very well, including improvement of his posterior paresis. He was rechecked again several weeks later and was continuing to do well.(Fig. 8)

Fig. 8: Rocky at his recheck examination several weeks postoperatively

The owners declined any adjunctive therapy such as radiation or chemotherapy, for the tumor.  Approximately 9 months postoperatively Rocky’s mass began to re-grow. Several months later the owners elected to have Rocky euthanized. 

Discussion

Multilobular osteochondrosarcoma (MLO) is a well-described tumor of bone and frequently found on the skull in dogs.(1) The tumor is typically slow growing but locally invasive and can be metastatic. Complete resection of a small MLO can have a good prognosis. However, recurrence of tumor commonly occurs after incomplete resection (approximately 50% of cases) as was the case in Rocky. After surgical treatment, disease free interval of 288-1332 days has been found depending on tumor grade. (2)

Options for reconstruction of large defects of the cranium include rigid materials like polymethylmethacrylate, mesh implants, or autogenous soft tissues using the temporalis muscles. (3) An autogenous fat graft to protect the dura combined with temporalis muscle reconstruction was an effective option for Rocky.

An extraordinary aspect of this case is that Rocky had severe compression of his cerebrum by the tumor, yet had only mild neurologic signs. He also made a surprisingly uneventful recovery from surgery and lived about 1 year postoperatively. Of course we would have preferred to achieve a complete resection of the mass but that was not possible without risking serious complications.

Post questions or comments about Rocky either here or on my Facebook page, Dr. Stephen Birchard, Veterinary Continuing Education. Thanks!

References

1. Straw RC, LeCouteur RA, Powers BE, Withrow SJ.

Multilobular osteochondrosarcoma of the canine skull: 16 cases (1978-1988).

JAAHA 1989, 195(12):1764-1769]

2. Veterinary Society of Surgical Oncology website: http://www.vsso.org/Bone_MLO.html

3. Boston, SE. Craniectomy and orbitectomy in dogs and cats. Can Vet J. May 2010; 51(5): 537–540.

Closure of Elliptical Incisions in Dogs: The "Rule of Halves"

Elliptical incisions commonly result from removal of skin tumors, other lesions, or debridement of traumatic wounds. Since loss of a section of skin occurs, the closure of the defect can result in so called “dog-ears” at each end of the incision (small flaps of skin that protrude from the ends of the incision).  An easy method to prevent dog-ears and create a cosmetic and secure closure is the “rule of halves” technique, also called bisectional closure. (Fig. 1)

Fig. 1: The rule of halves for closing elliptical incisions.
Dotted lines represent placement of sutures

This technique is used for the deep fascia and subcutaneous layers of the wound. The sutures below the skin relieve the tension across the incision and align the skin edges making the final suturing of the skin much easier.

Technique for the Rule of Halves Closure

Take the first suture bite of the deep fascia and/or subcutaneous tissue in the middle of the incision. (Fig. 2)

Fig. 2: Surgical model of elliptical incision.
The subcutaneous tissue is red, the skin is pink.
Dotted line indicates where first subcutaneous suture is placed.

This divides the incision into 2 equal parts. (Fig. 3)

Fig. 3: First subcutaneous suture has been placed.
Dotted lines indicate placement of the next 2 sutures.

Now take suture bites in the middle of each of the 2 defects, then in the middle of the 4 defects, and so on until the subcutaneous layer is completely closed. (Fig. 4) 

Fig. 4: Final subcutaneous suture being placed. Note that the suture knot
is buried by taking the first bite, from inside out, on the side closest to the surgeon.

Then suture the skin routinely. (Fig. 5)

 

Fig 5: Completed closure

This technique for wound suturing, although somewhat more time consuming than doing simple continuous patterns for the subcutaneous layer, results in a very secure and cosmetic closure. (Figs. 6-8)

Fig. 6: Proposed lines for excision of a mast cell tumor in a dog.  (X = tumor,
circle indicates 3 cm margins, elliptical lines are proposed incision)

Fig. 7: Same dog as in Fig. 6 after excision of the tumor and surrounding skin.
Dotted line indicates location of first suture.

Fig. 8: Completed closure of same dog in Fig. 6.

Post questions or comments here or on my Facebook page (Dr. Stephen Birchard, Veterinary Continuing Education)