Author

Stephen J. Birchard DVM, MS, Diplomate ACVS

Sunday, March 17, 2019

Colonic Volvulus in Dogs: How to fix it and prevent it from recurring.

Case Report

Addy is an 8-year-old female spayed Great Dane (Fig. 1) who presented to the MedVet Toledo emergency service for vomiting and diarrhea after eating garbage 3 days previously.  Six months previously Addy had a prophylactic gastropexy for prevention of gastric dilatation/volvulus and splenectomy to remove a benign splenic tumor.
Fig. 1: Addy, an 8 year old female spayed Great Dane with colonic volvulus.
On physical examination Addy was quiet but alert, responsive and ambulatory. Her vital signs were normal. She was approximately 5% dehydrated and was painful on abdominal palpation. Blood samples were submitted for CBC and serum chemistry profile, which were within normal limits. 

Plain film abdominal radiographs were obtained. Severe gaseous dilation of the proximal large bowel was identified, and mal-positioning of the descending colon was suspected. (Fig. 2) Based on the clinical signs and radiographic findings, a tentative diagnosis of colonic torsion was made. 
Fig 2a: Lateral radiograph of Addy showing severe dilation of the large
bowel in the cranial abdomen.


Fig. 2b: Ventrodorsal radiograph of Addy also showing severe dilation
of the large bowel in the cranial abdomen.
Emergency surgical exploration of the abdomen was recommended to the owners. Addy was placed under general anesthesia and prepared for a ventral midline abdominal exploratory. At surgery, severe dilation and malposition of the ascending colon, transverse colon, and proximal descending colon were found. (Fig. 3) The ascending colon and cecum were located on the left side of the abdomen, and the proximal descending colon located on the right side of the abdomen. Therefore a 180-degree volvulus of the proximal colon on its mesenteric axis had occurred. Although severely dilated, the colonic tissues were only mildly congested and appeared viable with no areas of necrosis.
Fig. 3: Intraoperative photo of Addy in dorsal recumbency, head is to the left.
The descending colon (DC) is malpositioned to the right side of the abdomen,
and the ascending colon (AC) is malpositioned to the left, creating a volvulus
of the transverse colon (AC).
The abnormally positioned colonic segments were replaced back to their normal positions, i.e., cecum and ascending colon back to the right side of the abdomen, and descending colon to the left side. To prevent future episodes of volvulus, a gastrocolopexy and left sided abdominal colopexy between the descending colon and interior abdominal wall were performed. The gastrocolopexy was performed by apposing the transverse colon to the greater curvature of the stomach. The serosal surfaces of the stomach and colon were scarified, and a simple continuous suture of 2-0 PDS was used to approximate the 2 structures. (Fig. 4) 
Fig. 4: Intraoperative photo of Addy after creating the gastrocolopexy (arrows)
between the transverse colon (TC) and the greater curvature of the stomach (S).
The abdominal colopexy was performed by first making a 10 cm cranial to caudal incision in the interior abdominal wall musculature. The descending colon was then scarified and placed adjacent to the abdominal incision. The dorsal edge of the abdominal incision was sutured to the seromuscular layer of the descending colon with 2-0 PDS in a simple continuous pattern, then the ventral edge of the abdominal incision was also sutured to the descending colon in a similar fashion. (Fig. 5) 
Fig. 5: Intraoperative photo of Addy after creating the colopexy (arrows)
between the descending colon (DC) and the abdominal wall (A).
The remainder of the abdomen was explored and no other abnormalities were discovered. The previously performed gastropexy between the pyloric antrum and the right interior abdominal wall appeared to be competent. 

The abdominal incision was closed routinely and Addy was recovered from anesthesia.  Addy did well postoperatively and was discharged from the hospital with analgesic medications and instructions to feed a bland diet for the next several days.  Two weeks postoperatively Addy was doing well with a good appetite and normal stools. 

Discussion
Colonic volvulus is a rarely reported disorder in dogs that is characterized by acute displacement of one or more segments of the large intestine. The disorder is also referred to as colonic torsion. However, on based previous clinical studies and the author’s clinical experience volvulus is a more accurate term to describe the condition since the transverse colon becomes twisted on its mesenteric axis. (1,2)

Although not confirmed statistically, large breed dogs appear to be more susceptible to colonic volvulus. Combining cases found in 3 retrospective studies, 30/31 of the reported dogs were large breeds. (1-3) One study also found a high incidence of previously performed gastropexy in dogs with colonic volvulus. However, this also has not been statistically proven and large breed dogs will be more likely to have had a gastropexy so the association could be coincidental. 

Clinical signs of affected dogs are acute vomiting, anorexia, and discomfort. Radiographically there is dilation of the affected colon, abnormal positioning of the large bowel, particularly the descending colon and cecum, and focal narrowing of the colon. (Ref)

The treatment of choice for colonic volvulus is immediate surgical intervention to replace the affected segments of the colon to their normal position and perform colopexy procedures to prevent recurrence of the volvulus. The gastrocolopexy is intended to stabilize the transverse and ascending colon and cecum to prevent them from flipping from right to left, and the standard descending colon colopexy to the abdominal wall prevents the descending colon from moving left to right.(For a detailed description of abdominal colopexy see: https://drstephenbirchard.blogspot.com/2019/03/how-to-perform-colopexy-in-dogs-and-cats.html.) The limited clinical reports of colonic volvulus indicate that this surgical approach is effective which is consistent with the author’s experience. 

References

1. Bentley AM1, O'Toole TE, Kowaleski MP, Casale SA, McCarthy RJ Volvulus of the colon in four dogs. J Am Vet Med Assoc. 2005 Jul 15;227(2):253-6, 236-7. 
2. Plavec T, Rupp S, Kessler M. Colonic or ileocecocolic volvulus in 13 dogs (2005-2016). Vet Surg. 2017 Aug;46(6):851-859. 
3. Gremillion CL, Savage M, Cohen EB Radiographic findings and clinical factors in dogs with surgically confirmed or presumed colonic torsion. Vet Radiol Ultrasound. 2018 May;59(3):272-278.









Sunday, March 3, 2019

How to Perform a Colopexy in Dogs and Cats


How to Perform A Colopexy in Dogs and Cats

Colopexy is a surgical procedure in dogs and cats intended to produce a permanent adhesion between the descending colon and the interior of the left abdominal wall. The procedure is indicated in animals with conditions such as rectal prolapse that is not responsive to other treatment methods, in selected cases of perineal hernia with rectal sacculation, and in dogs with colonic volvulus. In rectal prolapse the colopexy prevents recurrence of the prolapse since the colon is fixed to the body wall, preventing the rectum from prolapsing through the anus. In some dogs with severe rectal sacculation secondary to perineal hernia, primary herniorrhaphy may not sufficiently ameliorate the rectal pathology. Colopexy in these dogs can help straighten the rectum, reduce the size of the sacculation, and improve rectal function. Finally, colopexy can be used to prevent recurrence of colonic volvulus. Since the proximal portion of the descending colon becomes displaced to the right side of the abdominal cavity in colonic volvulus, colopexy of the descending colon to the left abdominal wall prevents that displacement and therefore prevents recurrence of the volvulus.

Surgical Technique

In the following series of step by step figures using a surgical model, colopexy of the descending colon to the interior of the left abdominal wall is demonstrated. After placing the animal under general anesthesia, the ventral abdomen is clipped and prepared for aseptic surgery. A ventral midline abdominal approach is performed. After a complete abdominal exploratory is performed, the descending colon is identified and placed adjacent to the interior of the abdominal wall at the proposed site of the pexy.

Place towel clamps on the left side of the linea alba incision and retract dorsally to better expose the interior of the abdominal wall. Make a 6-10cm (depending on the size of the animal) in the peritoneum and transversus abdominus muscle from cranial to caudal. (Fig. 1) 

Fig. 1: Make the initial incision in the abdominal wall through the peritoneum
and transversus abdominus muscle from cranial to caudal. (Cr-cranial, Ca-caudal)

The anti-mesenteric aspect of the descending colon is scarified with a scalpel to encourage a better adhesion to the abdominal wall. An incision is not made in the seromuscular layer of the colon to avoid accidental perforation of the colonic lumen.

Place the colon near the abdominal wall incision. Using gentle traction of the colon in a cranial direction, determine the optimal location of the colon on the abdominal wall to accomplish the desired goal. Suture the dorsal side of the abdominal wall incision to the seromuscular aspect of the colon in a simple continuous pattern with 2-0 PDS. (Fig. 2, 3)
Fig. 2: Suture the dorsal aspect of the abdominal wall(A) incision to the
descending colon. (DC) Note that needle direction is always from abdomen
to the colon. 
Fig. 3: Completed closure of dorsal abdominal incision to the colon.
Suture the ventral aspect of the abdominal wall incision to the colon is a similar fashion to complete the colopexy. (Fig. 4, 5)
Fig. 4: Beginning the closure of the ventral abdominal incision to the colon.
Fig. 5: Completed closure of the ventral abdominal incision to the colon. 

Postoperative Care

The abdominal incision is closed routinely and the animal is recovered from anesthesia. Supportive care consisting of intravenous fluids and analgesics is given. Monitor for postoperative pain and infection. Also monitor for normal colorectal function. Stool softeners such as Miralax or canned pumpkin can be given if constipation due to abnormally hard stool occurs. Most dogs and cats do well after colopexy with improvement of their condition and low risk of recurrence of rectal prolapse or colonic volvulus. Dogs with perineal hernia will also require primary herniorrhaphy in addition to the colopexy.

Sunday, January 20, 2019

4 Common Mistakes Made When Using Surgical Instruments

One of the most fundamental of surgical skills is proper handling of instruments. Using surgical instruments improperly can make the surgical procedure more difficult and time consuming. Here are 4 mistakes commonly made by inexperienced surgeons, and how to fix them:

1. Needle holders: the instrument is held with the thumb and 4th finger, but there is a right and wrong way to do it (it's all in the thumb!) This also applies to any forceps or scissors with ringed handles. (Fig. 1)
Fig 1a: Incorrect method to hold needle holders or any forceps or scissors
with ringed handles. Note how the thumb is too far inside the ring.
Fig 1b: Correct method to hold needle holders. Note that the only the tip
of the thumb is inserted through the ring of the instrument.

2. Thumb forceps: how the forceps are held can make a world of difference. (Figure 2)
Fig 2a: Incorrect method for holding thumb tissue forceps. This is a
clumsy grip that results in greater tissue trauma. 
Fig 2b: Correct and more precise method for holding tissue forceps. 

3. Retractors: holding them properly will avoid having the assistant's hand obscure the surgical field. (Fig. 3)
Fig. 3a: These are Senn retractors, commonly used in veterinary surgery.
Fig. 3b: Incorrect grip on the retractor. The fingers are too close  to
the end of the retractor resulting in the fingers and hand interfering with
the surgical exposure.
Fig. 3c: Correct grip on the retractor which will keep the fingers away from the
surgical field.

4. Cutting suture ends after tying a knot: here's a hint, use the tips! (Fig. 4)
Fig. 4a: Incorrect method of cutting suture ends with  scissors.
The blades close to the hinge are being used to cut the suture which
obscures the knot, making it difficult to see how long the suture ends will be. 
Figure 4b: Correct method; using the scissor's tips allow the assistant
to see the distance between the knot and the length being cut.
I hope you find these suggestions helpful. Post any questions or comments you may have on instrument handling and technique.

Tuesday, September 18, 2018

How To Repair Diaphragmatic Hernias in Dogs and Cats

 
   Introduction  
   Hernias of the diaphragm can be either congenital or acquired. Acquired hernias are most commonly due to blunt trauma to the abdomen.  Increased intra-abdominal pressure causes the diaphragm to stretch and rupture.  Liver, spleen and intestines are the organs most commonly herniated into the thoracic cavity.(1)  The muscular portion of the diaphragm, at its ventral and lateral aspects, is the most frequently torn area. Congenital hernias include the pericardial peritoneal diaphragmatic hernia (PPDH).

   Clinical Signs  
   Signs of respiratory distress, e.g., tachypnea, dyspnea, or abdominal breathing, are most common.  The animal may have a "tucked-up" appearance to the abdomen due to shifting of viscera into the pleural space.  In chronic cases, weight loss and lethargy may be the only signs the owners describe.(2) Exercise intolerance is also usually seen. In rare cases, the owner may describe signs referable to other organ systems.  For example, herniation of the intestine can cause obstruction of bowel, resulting in vomiting.  Herniation of the liver and biliary system can cause extrahepatic biliary obstruction, causing elevated serum bilirubin and icterus. 
   
   Diagnosis 
   Auscultation of the thorax reveals decreased lung sounds ventrally, and muffled heart sounds.  The thorax is dull on percussion.  Reportedly, auscultation of borborygmus in the thorax is a sign of diaphragmatic hernia, but this is not a consistent finding and should not be depended upon to make the diagnosis.
   Radiographic examination of the thorax may reveal fluid densities and/or bowel loops in the thorax. (Fig 1) Loss of continuity of the diaphragm is also seen. 
Fig. 1: Lateral thoracic radiograph of a dog with a diaphragmatic hernia and
several loops of bowel in the thoracic cavity. 
Hydrothorax may be the only radiographic sign if the liver is the only organ herniated into the thorax.  This fluid appears serosanguineous and is a transudate or modified transudate.  Ultrasonographic examination of the cranial abdomen can help confirm the hernia. 
   
   Preoperative Care  
   Diaphragmatic herniorraphy is usually considered an emergency operation. Although historically some authors advocated delaying surgical repair for several hours (3), a more recent study found that patients operated within the first 24 hours after presentation had very good outcomes (90% survival) (4). If the animal with diaphragmatic hernia does not stabilize with initial supportive care or if stomach or strangulated bowel is in the thorax the repair must be done immediately.(5) Stomach in the thorax can become dilated with air and cause life threatening hypoventilation. (Fig. 2) 
Fig. 2: Lateral thoracic radiograph of a dog with diaphragmatic hernia and stomach in the thorax cavity.
The stomach is severely dilated with air. 
If this occurs, pass a stomach tube to initially decompress the stomach If a stomach tube cannot be passed perform gastrocentesis percutaneously by placing a needle or over the needle catheter into the stomach through the chest wall.  When respiratory parameters have improved, anesthesia and surgery can then be performed.
   
   Anesthesia  
   Since these patients have markedly reduced ventilatory capacity, anesthetic induction and intubation must be rapid and smooth.  Pre-oxygenation of the patient in an oxygen cage or with an anesthetic mask is helpful to prevent hypoxia during the stress of anesthetic induction.  Rapidly acting intravenous induction agents, such as propofol, allow prompt intubation.  Begin positive pressure ventilation as soon as the endotracheal tube is placed.  Inhalant anesthetics, such as isoflurane, are acceptable for maintenance of anesthesia.
   During the clipping and prepping of the animal for surgery, the prep table can be tilted so that the head is elevated and the hindquarters lowered.  This helps prevent movement of abdominal viscera into the thorax.  
    
   Key Point: It is important to realize that when the abdominal cavity is surgically opened in an animal with diaphragmatic hernia, the animal will no longer be able to ventilate on its own. The rent in the diaphragm allows air to enter the thoracic cavity when the abdomen is open, eliminating the negative intrathoracic pressure that is necessary for normal ventilation. Intermittent positive pressure ventilation (IPPV) is therefore necessary during the surgical repair of the diaphragm. 
   
   Surgery 
   The ventral midline abdominal approach is indicated for most diaphragmatic hernias. (Fig. 3) 
Fig. 3: Intraoperative appearance of a left diaphragmatic hernia
exposed via a ventral midline abdominal approach.
(arrows indicate edges of the ruptured diaphragm).
The liver is present in the thoracic cavity.
Balfour retractors and large malleable retractors facilitate the exposure.  Grasping the edges of the diaphramatic defect with Babcock forceps or stay sutures can help in closure of the defect.  In many cases, the diaphragmatic defect must be enlarged to allow the viscera to be pulled back (reduced) into the abdomen.  When enlarging the defect, be sure to make the diaphragmatic incision in an accessible portion of the diaphragm to simplify closure. Chronic hernias may be associated with adhesions between the herniated organs and the lungs or mediastinum.(2) Break these down carefully to avoid injury to lung or other organs.  After reducing herniated organs back to the abdominal cavity carefully examine the lungs for evidence of atelectasis.  If atelectasis is found it is best not to acutely re-expand those lung lobes since re-expansion pulmonary edema can occur.  This is especially true in chronic hernias.  Place a thoracic drain tube before closure of the diaphragm to allow for re-establishment of negative pressure in the pleural space once the diaphragmic rent is repaired.  
   A variety of techniques for herniorrhaphy have been described.  The author prefers a continuous suture pattern using 2-0 or 3-0 PDS depending on patient size. Suturing is begun at the most inaccessible area of the defect (usually the dorsal aspect) progressing to the most accessible.(Fig 4) 
Fig. 4: Same dog as in figure 3 after suture closure of the diaphragmatic hernia.
Be very careful when working around the central part of the diaphragm because of the caudal vena cava.  Take care to not make the closure too tight around the caval hiatus.  Incorporation of the ribs with the soft tissues during suturing is sometimes necessary for those hernias that occur along the costal arch.
   In rare cases there is not enough diaphragmatic tissue to permit primary closure.  For example, chronic hernias in which the diaphragmatic tissue tears directly off the costal arch or dorsally from the spine.  In these cases reconstruction of the defect with a mesh implant such as Marlex mesh can be used.  The mesh is sutured in place with non-absorbable sutures such as monofilament polypropylene.  Prophylactic antibiotics are indicated in these cases.
   Once closure of the diaphragm is completed, remove residual air from the thorax.  This can be done either directly through the diaphragm using a needle or over the needle catheter or by placing a thoracostomy tube. When postoperative pneumothorax is a potential problem, such as those cases with lung adhesions, an indwelling thoracic drain tube should be placed and left in for as long as necessary to ensure stable negative intrapleural pressure. As previously mentioned in animals with chronic hernias and lung atelectasis, slowly evacuate the air in the pleural space over several hours to prevent re-expansion pulmonary edema. 
   
   Postoperative Care 
   Close observation of the patient is mandatory postoperatively.  If available the patient is kept in an oxygen cage until recovered.  In most cases recovery is unremarkable.  Acute, severe pulmonary edema can occur in some animals postoperatively and must be treated aggressively using diuretics, oxygen, and assisted ventilation.  In general the prognosis for postoperative survival is very good for patients with either acute or chronic diaphragmatic hernias. (2,4)
   
   References
1. Wilson GP, Newton CD, Burt JK. A review of 116 diaphragmatic hernias in dogs and cats. J Am Vet Med Assoc 1971; 159:1142-1145
2. Minihan AC, Berg J, Evans KL. Chronic diaphragmatic hernia in 34 dogs and 16 cats.
J Am Anim Hosp Assoc. 2004 Jan-Feb;40(1):51-63. 
3. Boudrieau RJ: Pathophysiology of Traumatic Diaphragmatic Hernia, in Bojrab MJ (ED): Disease Mechanisms in  Small Animal Surgery, ed 2. Philadelphia, Lea & Febiger, 1993, pgs 103–108
4. Gibson TW1, Brisson BA, Sears W. Perioperative survival rates after surgery for diaphragmatic hernia in dogs and cats: 92 cases (1990-2002).J Am Vet Med Assoc. 2005 Jul 1;227(1):105-9.
5.Bjorling DE. Thoracic Trauma, in Birchard SJ, Sherding RG, ed. Saunders Manual of Small Animal Practice. St. Louis, Elsevier, 2006, pgs. 1721-1722.



Thursday, May 31, 2018

Do Lawn Treatment Chemicals Cause Cancer in Pets? A growing body of research says yes!





Cancer is one of the most important health issues affecting household pets. Causes of cancer are many and varied, including genetic predispositions, certain viruses, and exposure to environmental toxins. Many studies in both humans and animals have focused on the increased risk of cancer from chronic use of chemicals such as pesticides and herbicides around the household.  Since dogs and cats have significant exposure to grassy areas of properties, lawn chemicals in particular have been studied for the potential of causing health problems.

Several studies have now shown an association between the frequently used chemicals on household lawns and cancer in dogs.(1-4) Dogs chronically exposed to the herbicides and pesticides in lawn sprays and granules are more likely to get cancers such as lymphoma and transitional cell carcinoma of the urinary bladder. An initial study published in the Journal of the National Cancer Institute in 1991 found that homeowners that frequently used the herbicide 2,4- dichlorophenoxyacetic acid on their lawn had a statistically significant higher rate of lymphosarcoma in their dogs.(1) Lymphosarcoma, also called malignant lymphoma, is a common cancer affecting lymph nodes and other organs and lymphatic tissues. This study was heavily criticized by other investigators who questioned the validity of the results. However, a more recent study published in 2012 analyzed 263 dogs with lymphosarcoma and found a 70% increase in risk of the cancer in households with professionally applied pesticides on the lawns.(2)

Two studies at Purdue University College of Veterinary Medicine have also found disturbing results of dogs exposed to herbicides, particularly the phenoxy herbicides such as the previously mentioned 2,4- dichlorophenoxyacetic acid, also called 2,4-D.(3,4) 

Herbicides were found in the urine of 76% of dogs from households that used them on their lawn.(4) The herbicides were also found in the urine of some dogs from households where the herbicide was not used, indicating they were exposed to them in areas other than their own property. 

The additional study from Purdue found that Scottish Terriers living in households that used herbicides alone or herbicides and pesticides on their lawns were markedly more prone to transitional cell carcinoma of the urinary bladder.(3) This study, along with the former one looking at the chemicals being present in the urine, are convincing evidence that the herbicide exposure is directly related to bladder cancer in this breed. Other breeds could be examined in the future to further define the risks of exposure. 

More research is needed to elaborate the dangers of lawn chemicals to our pets, but these well designed and executed studies make it clear that the commonly used pesticides and herbicides being indiscriminately sprayed and broadcast on our lawns are causing cancer in dogs. Many provinces in Canada have completely banned what they call “cosmetic” use of herbicides and pesticides because of the potential health problems. Cosmetic is a good term because the cancer causing chemicals are being used merely to improve the appearance of our lawns. Maybe we should be more tolerant of less than perfect grass if it decreases the adverse health effects on our pets. 

Although additional studies will help to better define the problem, we now have sufficient evidence to raise serious concerns about the dangers of herbicides and pesticides used on lawns. Homeowners should be educated about these issues so that they can take appropriate action to protect their pets from harm. Professional lawn care companies also need to carefully consider their protocols and make necessary changes to stop contaminating the environment with chemicals that are now proven to be carcinogenic to pets. 

References

1. Hayes HM1, Tarone RE, Cantor KP, Jessen CR, McCurnin DM, Richardson RC. Case-control study of canine malignant lymphoma: positive association with dog owner's use of 2,4- dichlorophenoxyacetic acid herbicides. J Natl Cancer Inst. 1991 Sep 4;83(17):1226-31. 

2. Biki B. Takashima-Uebelhoer, Lisa G. Barber, Sofija E. Zagarins, Elizabeth Procter- 
Gray, Audra L. Gollenberg, Antony S. Moore, and Elizabeth R. Bertone-Johnson. Household Chemical Exposures and the Risk of Canine Malignant Lymphoma, a Model for Human Non-Hodgkin’s Lymphoma. Environ Res. 2012 January ; 112: 171–176. 

3. Glickman LT1, Raghavan M, Knapp DW, Bonney PL, Dawson MHJ. Herbicide exposure and the risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers. J Am Vet Med Assoc. 2004 Apr 15;224(8):1290-7. 

4. Knapp DW1, Peer WA, Conteh A, Diggs AR, Cooper BR, Glickman NW, Bonney PL, Stewart JC, Glickman LT, Murphy AS. Detection of herbicides in the urine of pet dogs following home lawn chemical application. Sci Total Environ. 2013 Jul 1;456-457:34-41. 




Saturday, April 21, 2018

Axial Pattern Flap Reconstruction of a Chronic Non-Healing Elbow Wound in a Golden Retriever

Ginger is a 7-year-old female spayed golden retriever who presented to MedVet Toledo with a chronic non-healing open skin wound over the right elbow. (Fig. 1) 

Fig. 1: Ginger
The owner adopted Ginger 1.5 years prior to presentation and the wound was present at that time. Ginger was otherwise healthy with no major medical issues. Serous fluid drained from the wound occasionally. Antibiotic therapy previously prescribed did not result in significant improvement of the wound.

Physical examination of Ginger was normal except for a large (8cm diameter) open wound over the right elbow that appeared to be a decubital ulcer. (Fig. 2) 
Fig. 2: The non-healing chronic open wound over the right elbow on Ginger
Extensive fibrotic scar tissue was present around the periphery of the circular wound, and unhealthy granulation tissue was seen in the wound center. Little to no discharge was present on the wound surface.

A fine needle aspirate of the peripheral scar tissue was performed to rule out neoplasia and the cytology results indicated chronic inflammation. Routine preoperative CBC and serum chemistry profile were normal. The plan was to anesthetize Ginger, perform an extensive surgical debridement of the fibrotic peripheral tissues, and reconstruct the skin using an axial pattern skin flap. 

Ginger was anesthetized and the right elbow and surrounding skin clipped and prepared for aseptic surgery. The donut shaped abnormal scar tissue was removed using blunt and sharp dissection. (Fig. 3) 
Fig. 3: The right elbow of Ginger immediately after surgical debridement of the chronic wound. 
During this dissection it became clear that the tissue was highly vascularized. Hemostasis was difficult and bleeding became brisk throughout the dissected area. The hemorrhage was controlled with electrocautery and direct pressure. We elected to delay the skin flap reconstruction so that open wound management with tie-over bandages could be used on the elbow to allow the debrided area to be in more optimal condition for the definitive reconstruction procedure. (for more information see: tie-over bandages)

One week after the surgical debridement Ginger was re-admitted to the hospital for the skin flap procedure. Ginger was placed under general anesthesia and a thoracodorsal axial pattern skin flap was performed to reconstruct the elbow decubitalulcer. (Fig. 4)
(for more information see: axial pattern skin flaps
Fig. 4: Completed thoracodorsal axial pattern flap reconstruction of the elbow on Ginger.
White arrow indicates direction of transfer of the rectangular skin flap harvested from skin over the scapula.
Complete coverage of the wound was achieved with the skin flap. A spica bandage was placed over the leg and thorax to protect the incisions and Ginger was recovered from anesthesia. 

The following day Ginger’s bandage was changed and she was discharged from the hospital. Bandage changes occurred every 2-3 days until the incisions were healed and staples removed. (Fig. 5) 
Fig. 5: Appearance of the surgical incisions on Ginger 10 days postoperatively.
Ginger finally was discharged with no rechecks necessary unless problems arose. However 5 months later she represented to MedVet Toledo for problems unrelated to her elbow. The owner reported that since the skin flap reconstruction Ginger had been much more comfortable and mobile. Ginger’s skin flap had grown a thick, bushy amount of hair. There was redundant skin at the elbow but the overall cosmetic appearance was quite satisfactory. (Fig. 6) In general the owner was very pleased with the end result of the reconstruction.
Fig. 6: Appearance of Ginger's right elbow area 5 months after reconstruction.
Chronic wounds of the elbow in dogs are one of the most difficult to manage. Skin tension, excessive motion, and trauma to the area combine to interfere with healing in this part of the body. Debridement and local advancement of skin over the defect is generally unrewarding for reconstruction, particularly if it results in a suture line directly over the olecranon. Skin flap techniques that bring healthy, robust tissue into the site without creating a suture line over the olecranon, such as an axial pattern flap, is more likely to be successful.

Several aspects of the postoperative care are key to the success of this procedure. A well-padded bandage to protect and cushion the skin flap is mandatory for at least 10-14 days postoperatively. Exercise restriction is also important along with frequent postoperative rechecks to monitor for flap survival and healing. 

One clinical study of 10 dogs having thoracodorsal axial pattern flaps found complications to be common but good functional and cosmetic outcome resulted in 6 of 7 dogs long term follow up. (1)

References

1. Aper R, Smeak, D:  Complications and Outcome After Thoracodorsal Axial Pattern Flap Reconstruction of Forelimb Skin Defects in 10 Dogs, 1989–2001 32:4, 2003, Pages 378-384.

Sunday, December 31, 2017

How To Safely Place a Chest Tube in Dogs and Cats

Indications

Thoracic drain tubes are indicated for animals with disorders of the thoracic cavity  that cause accumulation of air or fluid in the pleural space. Some examples are: pneumothorax due to trauma or spontaneous causes such as emphysematous bullae, or pleural effusion due to infection (pyothorax) or neoplasia. If repeated drainage of the thorax is anticipated for palliative care of the patient, a thoracic drain is more effective and less painful for the patient than repeated thoracocentesis with a needle or catheter. A properly performed thoracic drain tube placement is a safe and effective means of managing patients with acute or chronic pleural disorders.

Technique

Equipment
Basic surgical pack
Red rubber catheters (8 – 20 Fr),
or Argyle catheters with trocar (same sizes)
3-way stopcocks
Christmas tree adapters
Syringes (12 – 60mls)
Bandage materials
Antibiotic ointment
Suture material  (2-0 or 3-0 monofilament non-absorbable)

Place the animal under general anesthesia and prepare the lateral thorax for aseptic surgery. Make a small (2-3 cm) skin incision at the 10th intercostal space.
Incise through the subcutaneous tissue and the lattisimus dorsi muscle. Use a Carmalt or Pean forcep to create a tunnel underneath the lattisimus dorsi muscle from the skin incision to the 8th intercostal space. Grasp the tip of a red rubber catheter with a Carmalt forcep or use an Argyle trocar catheter. (Fig. 1)
Fig 1: The end of a red rubber catheter is grasped within a Carmalt clamp
from: Bateman SW, et.al. Emergency and Critical Care Techniques and Nutrition. 
In: Saunders Manual of Small Animal Practice. 3rd edition, 
Birchard and Sherding, eds., Elsevier, St. Louis, 2006. Pg. 29
Insert the tip of the tube into the skin incision and advance it through the tissue tunnel to the level of the 8th intercostal space.(Fig 2)
Fig. 2: The red rubber tube and Carmalt clamp are advanced from the 10th to the 8th intercostal space
Firmly grasp the tube and insert through the chest wall with a forceful but controlled effort. (Fig. 3)
Fig. 3: Cross sectional view of Carmalt clamp and chest tube entering the pleural cavity through the  intercostal space.
from: Bateman SW, et.al. Emergency and Critical Care Techniques and Nutrition. In: Saunders Manual of Small Animal Practice. 3rd edition, Birchard and Sherding, eds., Elsevier, St. Louis, 2006. Pg. 29
Once the tube has penetrated the chest wall, advance it into the pleural space. If using the Argyle tube, slide the trocar out of the tube and then slide the tube inside the pleural cavity.(Fig. 4)
Fig. 4: Sequence of steps(A-D) for inserting an Argyle thoracic drain tube with inner trocar into the chest cavity.
from: Crisp MS, Buffington CA. Critical Care Techniques. In: Saunders Manual of Small Animal Practice. 2nd edition, Birchard and Sherding, eds., Elsevier, St. Louis, 2000, pg. 21.
If using a red rubber catheter and forceps, after entering the chest open the forceps, slide the catheter into the pleural cavity, then remove the forceps from the incision. Promptly place a clamp on the tube after entering the chest to prevent pneumonthorax.

Place a 3-way stopcock on the end of the tube(Fig. 5); a Christmas tree adapter may be necessary to fit the stopcock to the flared end of the tube. 
Fig. 5: Stopcock secured to the end of the chest tube with wire; heavy
suture can also be used.
Use large suture or wire to secure the stopcock and adapter to the tube and place a purse string and finger trap pattern suture to secure the tube to the skin (Fig. 6).   
Fig. 6: Secure the thoracic drain tube to the skin with a purse string /finger trap suture combination.
A “C” clamp can also be placed on the tube for added safety in case the stopcock should become dislodged.  Apply antibiotic ointment to the tube entry site in the skin and protect the tube on the patient with a bandage.

Postoperative Care

Obtain radiographs of the thorax to ensure correct placement of the tube.(Fig. 7)
Fig. 7: Lateral thoracic radiograph of a cat with a thoracic drain tube in place.
Patients with thoracic drain tubes require 24 hour monitoring. If the tube becomes damaged or the stopcock is dislodged, immediate pneumothorax will occur and could be life threatening. Change the chest bandage as needed and check the tube location to be sure it is not pulling out and that the stopcock and Christmas tree adapter are tight and not leaking. Place an Elizabethan collar on the animal if necessary.

Evacuation of air and/or fluid can be performed either manually or with a continuous suction device which, when connected to a source of negative pressure, allows for drainage of the thoracic cavity. In most animals intermittent manual drainage of the chest cavity is sufficient to keep the animal’s respiratory status stable. 

In some cases a sudden increase in the amount of air being pulled from the drain tube can be due to a leak in the tube or its apparatus. Test the integrity of the tube by clamping the tube close to the patient and try applying negative pressure to the stopcock with a syringe. If air is easily withdrawn, a leak is present. Check all connections for tightness and check the tube for cracks or holes allowing air to leak into the system.

In addition to other routine supportive care measures, analgesic therapy with a NSAID or opioid such as Tramadol is indicated due to the painful nature of the indwelling tube in the pleural space. The pleura is one of the most sensitive tissues in the body and the tube acts as a foreign body rubbing on the pleural membranes. 

Thoracic drain tubes can be left in the patient for several days or even a few weeks at a time depending on the need for continued drainage. Since dogs do not have a complete mediastinum, a unilateral tube is usually adequate for drainage of both sides of the pleural cavity. However in some cases, such as chronic pyothorax or chylothorax, fibrinous adhesions in the cavity can make the fluid loculated, decreasing the function of the tube. Bilateral tubes may then be necessary.

Remove the chest tube when the amount of fluid or air is minimal. The chest tube acts as a foreign body in the pleural space and can create 1-2 mls/kg/24 hours of fluid. After removal of the tube apply antiobiotic ointment to the skin incision and keep the incision covered with a bandage for another 1-2 days.

The following is a video produced by my colleague Dr. Ron Bright demonstrating chest tube placement on a cadaver dog using an Argyle thoracic drain tube with trocar.

References

Bateman SW, et.al. Emergency and Critical Care Techniques and Nutrition. In: Saunders Manual of Small Animal Practice. 3rd edition, Birchard and Sherding, eds., Elsevier, St. Louis, 2006. Pg. 29