Author

Stephen J. Birchard DVM, MS, Diplomate ACVS

Wednesday, April 12, 2017

Acute Traumatic Abdominal Hernia in Dogs and Cats: Key Point: Always do a complete abdominal exploratory!

Case Report

Cass is a 2 year old spayed female who presented to the emergency service after been bitten by another dog. She had no pertinent history of other health problems. On physical examination Cass had a palpable soft tissue subcutaneous swelling on the left lateral abdomen. A defect in the abdominal wall was palpable deep to the swelling and viscera were thought to be in the subcutaneous space. 

Plain radiographs of the abdomen confirmed a left lateral abdominal hernia. (Fig. 1) No other radiographic abnormalities were found. 
Fig. 1; Ventrodorsal radiograph of Cass showing the hernia of the left lateral abdomen (arrows).
Cass was initially treated with supportive care consisting of intravenous fluids with a balanced electrolyte solution, analgesics, and antibiotics. Preoperative CBC and serum chemistry profile were within normal limits. Cass was placed under general anesthesia and the ventral abdomen was clipped and prepared for aseptic surgery. (Fig. 2) 
Fig. 2: Cass in dorsal recumbency after clipping and prepping for  abdominal surgery.
Note the bulge on the left lateral abdomen at the site of the hernia.
A ventral midline abdominal approach was made. On thorough exploratory of all abdominal structures herniation of a portion of jejunum was found in a left sided abdominal wall defect.(Fig. 3, 4) 
Fig. 3: Intraoperative view of the abdominal cavity on Cass. (Head is to the left.)
Note herniated bowel and omentum (arrow).
Fig. 4: Same intraoperative view as figure 3 after reduction of the hernia showing the muscular defect.
Gentle traction on the herniated bowel reduced the hernia and the bowel mesentery was bruised but all tissues were viable. The abdominal muscle defect was closed from within the abdominal cavity with 2-0 PDS simple continuous pattern.(Fig. 5) 
Fig. 5: Same intraoperative view as figures 3 and 4 showing closure of the hernia.
The ventral abdominal incision was closed routinely. 

Postoperatively supportive care (IV fluids, analgesics, and antibiotics) was continued. Cass made an uneventful recovery and was discharged the day after surgery. At suture removal 10 days postoperatively Cass was doing well.

Discussion

In animals with severe abdominal trauma, hernias can be missed on initial physical examination. Serial, thorough physical examinations and careful analysis of abdominal imaging is recommended to fully assess trauma patients. Intestine and omentum were the 2 most commonly herniated structures in the study previously mentioned. (1)

Bite wounds were the most common cause of traumatic abdominal hernias in one study, with vehicular trauma being the next most common cause. (1) This is in contrast to an older study that found blunt trauma to be the primary cause of traumatic hernias.(2) Additional injuries, such as bowel perforation, are common complications of abdominal hernias. 

Key Point: Dogs and cats with acute traumatic abdominal hernias should have a complete abdominal exploratory via routine ventral approach. The hernias can be repaired from within the peritoneal cavity by closing the affected interior muscle layers. (3)


References
1. Shaw, Scott P; Rozanski, Elizabeth A; Rush, John E. Traumatic body wall herniation in 36 dogs and cats. JAAHA 39:35-45 2003.
2. Waldron DR, Hedlung CS, Pechman R. Abdominal hernias in dogs and cats: a review of 24 cases. JAAHA, 22:817-822,1986 
3. Smeak, DD. Abdominal wall reconstruction and hernias. In: Veterinary Surgery Small Animal, eds. Tobias KM, Johnston, SA. Elsevier, St. Louis, pg. 1368.

Friday, January 27, 2017

When Is Umbilical Hernia in Dogs An Emergency Operation? Here's a Great Example

Case Report

A 7-year-old spayed female mixed breed dog named Lola presented with acute vomiting and rapid enlargement of a mass over her umbilicus.(Fig.1) 
Fig. 1: Lola, a 7 year old female spayed dog
The owners reported that she had a hernia there since birth but it just recently got much larger. The mass was soft, painful on palpation, and not reducible. An umbilical hernia containing abdominal viscera was suspected.

Plain film abdominal radiographs were obtained and confirmed an umbilical hernia with loops of intestine in the hernia sac. (Fig.2)  The remainder of the abdomen was radiographically within normal limits. 
Fig. 2: Lateral abdominal radiograph in Lola showing
an umbilical hernia with incarcerated bowel (arrow)
Complete blood count and serum chemistry profile were unremarkable. An intravenous catheter was placed and a balanced electrolyte solution administered to correct dehydration. Under general anesthesia the ventral abdomen was clipped and prepared for aseptic surgery. (Fig.3) 
Fig. 3: Appearance of the hernia in Lola after clipping for surgical repair
A ventral abdominal approach was performed with care taken to not injure structures within the hernia. A strangulated loop of jejunum was found in the hernia. (Fig.4) The remainder of the abdomen was normal. 
Fig. 4: Intraoperative photo of Lola during abdominal exploratory showing the
strangulated portion of jejunum after it was reduced.
The affected segment of intestine was resected and an end to end anastomosis performed (see http://drstephenbirchard.blogspot.com/2013/10/intestinal-anastomosis-made-simple.html for details on technique for intestinal anastomosis).  Debridement of the tissue edges of the hernia was not necessary and it was repaired as part of the routine linea alba closure with 2-0 PDS, simple continuous pattern. The remainder of the abdominal incision was closed routinely. Postoperative abdominal radiographs confirmed satisfactory closure of the hernia. (Fig. 5) 
Fig. 5: Lateral abdominal radiograph of Lola 1 day after repair of the umbilical hernia.
Lola recovered well from surgery and was released from the hospital 2 days postoperatively.

Discussion

Lola is an example of a dog with an incarcerated (non-reducible), and strangulated (loss of blood supply of the hernia contents) umbilical hernia. Umbilical hernias are common in dogs and cats but rarely do they contain intestine or other abdominal organs.(1) More commonly umbilical hernias are small and contain a portion of the falciform ligament or greater omentum. 

Plain film radiographs were diagnostic for the hernia in Lola. Ultrasonography can also be useful to determine if a hernia is present and if organs are located in the hernia sac. 

The clinical signs of acute vomiting and pain on palpation were suggestive of intestinal obstruction, and possibly strangulation. Vomiting was predictive of non-viable intestine in inguinal hernias in dogs in one study.(2) Emergency surgery is indicated when this type of hernia is suspected. 

In Lola the hernia repair was straightforward since adequate local tissues, i.e. rectus muscle fascia, was available for closure without tension across the suture line. Larger defects may require a muscle flap or mesh implant, such as polypropylene mesh, for effective repair. Mesh is well tolerated in dogs and provides a strong and stable closure for abdominal wall defects with minimal complications.(3)

Complications of hernia repair include pain, seroma, infection, reoccurrence and mesh rejection requiring removal.   However, complications are rare and the prognosis for successful repair of congenital and traumatic hernias is generally good. 

This is the first in a series of Veterinary Key Points blogs addressing congenital and acquired hernias in dogs and cats. Watch for future articles on other hernia types and their treatment.

References

1. Ruble RP, Hird DW. Congenital abnormalities in immature dogs from a pet store: 253 cases (1987-1988). J Am Vet Med Assoc. 202(4) 633-636, 1993

2. Water DJ, Roy RG , Stone EA. A retrospective study of inguinal hernia in 35 dogs. Vet Surg 22:44, 1993

3. Bowman K, Birchard SJ, Bright RM. Complications associated with implantation of polypropylene mesh in dogs and cats: A retrospective study of 21 cases (1984-1996). J Am An Hosp Assoc 34:225-233, 1998

Friday, December 16, 2016

Canine Lung Lobectomy Video


Introduction
This is a brief description and video of lung lobectomy in a 14 year old male neutered West Highlight White Terrier named Chester.(Fig. 1) Chester presented for coughing for several weeks, and on plain film thoracic radiographs a mass was seen in the right middle lung lobe. (Fig. 2)
Fig. 1: Chester, a 14 yr old male neutered Westie diagnosed with a primary lung lobe tumor
Fig. 2a: Lateral thoracic radiograph of Chester showing a mass in the right middle lung lobe. (arrows)



Fig. 2b: Ventrodorsal thoracic radiograph of Chester showing the mass in the right middle lung lobe. (arrows)

Surgery
After inducing general anesthesia and placing the dog on a ventilator, a routine right 5th intercostal space thoracotomy was performed. A mass was found on the dorsal aspect of the right middle lung lobe. (Fig. 3)
Fig. 3: Right lateral thoracotomy exposing a neoplasm of the right middle lung lobe (black arrow) in Chester.
Dorsal is to the bottom of the photo.
A lobectomy of the affected lung lobe was performed using the TA 30 (V3) Surgical stapling device. (Fig. 4 and video)
Fig. 4: TA Surgical Stapling device.
(Blue cartridge is shown, white cartridge (V3) was used in the case
described here. (Medtronic.com)



A thoracic drain tube was placed and the thoracotomy closed routinely.

Postoperative Care
The dog recovered well postoperatively and was given supportive care including intravenous fluids, analgesics, and monitoring of vital signs. Minimal amounts of air and fluid were recovered from the drain tube overnight. The drain tube was removed the following day and the dog discharged from the hospital. One week postoperatively the owner reports that Chester continues to do well at home. 

Histopathology of the mass revealed an adenosquamous carcinoma of the lung. Resection was felt to be complete with clean margins. Chester is currently receiving chemotherapy under the direction of our internist, Dr. Joanna Fry and Jessica Herzig, RVT. More updates to come!




Sunday, December 4, 2016

Episioplasty for Perivulvular Dermatitis in Dogs

Intertriginous dermatoses, or skin fold pyoderma, is a well recognized disorder caused by excessive skin folds in various regions in dogs, such as nasal, lip, and perivulvular skin folds.(Fig. 1a,b)
Fig. 1a: Excessive skin fold in perivulvular area of a  spayed mixed breed dog.

Fig. 1b: Same dog as Fig. 1a; the chronically inflamed vulva is exposed by
pushing the skin fold dorsally.
Redundant skin in these areas leads to skin friction, excessive moisture, and poor air circulation.(1a-b) Trapped skin secretions are fertile ground for surface bacteria and yeast to establish infection. Chronic skin infection in the perivulvular region can also lead to ascending urinary tract infection(UTI). 

Medical treatment consisting of hair clipping, medicated soaps and shampoos, and topical and systemic antibiotics may improve the condition, but surgical resection of the excessive skin is necessary to achieve successful long-term resolution.(1) Episioplasty is a skin reconstructive surgical procedure to correct excessive perivulvular skin folds and is well described in standard surgical textbooks.(Fig.2)
Fig. 2: Schematic representation of episioplasty in dogs. A: initial incision of skin to be resected;
B: beginning skin closure; C: completed closure.
From: Bellah JR. Surgery of intertriginous dermatoses. In: Saunders Manual of Small Animal Practice. 3rd edition, 
Birchard and Sherding, eds., Elsevier, St. Louis, 2006. Pg. 537
Episioplasty has been used for many years to treat perivululvar dermatitis in dogs that did not respond to more conservative treatment but has also been shown to be an effective treatment for the chronic urinary tract infection associated with perivulvular dermatitis.(2) In this blog we will describe the surgical technique and postoperative care for episioplasty in dogs. 

Surgery 
After placing the dog under general anesthesia, it is positioned in ventral recumbency and the perivulvular region clipped and prepared for aseptic surgery. Administer prophylactic intravenous antibiotics, such as cefazolin, to establish blood levels prior to the surgical procedure. Empty the anal sacs and place a purse string suture in the anus to prevent fecal contamination during the perioperative period. Pull the tail dorsally and cranially and secure with tape. 

The redundant perivulvular skin is carefully examined to determine how much will require resection. The proposed area of skin to be removed is marked to aid in excision.(Fig.3) 
Fig. 3: The proposed area of perivulvular skin to be resected is marked with a sterile marking pen.
The skin incisions are made with a scalpel and the skin removed with blunt and sharp dissection using Metzenbaum scissors.(Fig.4) 
Fig 4: Appearance of the surgical site after resection of the perivulvular skin fold..
Electrocautery is used for hemostasis. Only the skin is removed; subcutaneous fat is left in tact in order not to create excessive dead space under the reconstructed skin. The deep fascia and subcutaneous tissues are closed first with absorbable suture in a simple interrupted pattern. The first sutures are placed at the 10, 12 and 2 o’clock positions, then the remainder placed as needed to provide accurate apposition of the skin.(Fig.1) Skin closure can be with skin sutures, intradermal sutures, or continuous absorbable skin suture (e.g. 4-0 Monocryl).(Fig.5)
Fig. 5: Appearance of the surgical site after completion of  the skin closeure.
Remove the pursestring suture in the anus after completion of the procedure. 

Postoperative Care 
Postoperative care consists of analgesic therapy such as tramadol and a NSAID (if not contraindicated), ice packs on the incision for the first 24 hours followed by warm compresses, and exercise restriction until the incision is healed and skin sutures removed.(Fig.6) 
Fig 6: Appearance of the surgical site 3 weeks postoperatively.
Keep the incision clean and free of urine and fecal soiling. If episioplasty was performed for chronic UTI, maintain antibiotic therapy for 2-3 weeks followed by repeat urine culture and sensitivity. Continue antibiotics until the urine culture is negative. 

Prognosis 
Complete resolution of the skin fold pyoderma should occur after resection of the excessive skin. Episioplasty is effective in treating perivulvar dermatitis.and in treating chronic urinary tract infection that is secondary to ascending infection from excessive skin folds around the vulva.(2) 

References 
1. Bellah JR. Surgery of intertriginous dermatoses. In: Saunders Manual of Small Animal Practice. 3rd edition, Birchard and Sherding, eds., Elsevier, St. Louis, 2006. Pg. 537. 
2. Lightner BA, McLoughlin MA, Chew DJ, Beardsley SM, Matthews HK. Episioplasty for the treatment of perivulvar dermatitis or recurrent urinary tract infections in dogs with excessive perivulvular skin folds: 31 cases (1983-2000). J Am Vet Med Assoc 219: 1577-1581, 2001

Sunday, September 11, 2016

Caserean Section in Dogs and Cats: Surgical Technique

Indications

Cesarian section (C-section) in dogs and cats is indicated for a variety of reasons such as uterine inertia, oversized neonates, narrowed maternal pelvic canal, and others. Fetal dystocia is common in brachycephalic breeds such as Bulldogs, prompting some breeders or owners to schedule the C-section as an elective procedure in these kinds of dogs. Evidence fetal death or uterine infection would also warrant immediate C-section. The readers are referred to other publications for more information on dystocia in dogs and cats.(1)

Cesarian section is a safe surgical procedure and one study found fetal survival actually slightly higher with C-section than natural birth.(2) For information on pre-operative assessment and anesthesia for C-section see Veterinary Key Points blog by Dr. Lisa Ebner posted June 14, 2016.

Surgical Procedure

The abdomen is clipped and an initial scrub performed prior to beginning anesthesia. This minimizes the time spent under anesthesia helping to prevent depression of the puppies or kittens. Perform other pre-operative and anesthestic protocol as described in the Veterinary Key Points blog by Dr. Lisa Ebner posted June 14, 2016 on anesthesia for C-section.

Place the animal in dorsal recumbancy and perform a routine ventral abdominal midline approach. Be careful to avoid trauma to the enlarged uterus when entering the peritoneal cavity. Exteriorize the entire uterus including both uterine horns. (Fig. 1) This simple step is important to relieve pressure on the caudal vena cava by the very enlarged uterus and therefore improve venous return to the heart. Isolate the uterus from the peritoneal cavity with moistened abdominal sponges.
Fig. 1: Gravid uterus exteriorized from the abdominal cavity
Make an incision in the ventral aspect of the uterine body just proximal to the bifurcation of the horns.(3)  Take care to avoid trauma to the puppies inside the uterus. Once inside the uterine lumen, carefully begin removing puppies one by one.(Fig. 2)
Fig. 2: Begin removing puppies from the incision in the uterine body midline.
fromSicard GK, Fingland RB. Surgery of the ovaries and uterus. In: Saunders Manual of Small Animal Practice, 3rd edition, Birchard SJ, Sherding RG, eds. Elsevier, St. Louis, 2006
Begin with puppies in the uterine body, then milk them down each horn to the incision and then remove. The uterine incision may have to be extended into the horns to reach and remove all puppies.

When each puppy is removed from the uterus, gently tear the placental membrane and remove it from the fetus.(Fig. 3) 
Fig. 3: After removing puppy from the uterus gently open and peel away placental membranes
from: Sicard GK, Fingland RB. Surgery of the ovaries and uterus. In: Saunders Manual of Small Animal Practice, 3rd edition, Birchard SJ, Sherding RG, eds. Elsevier, St. Louis, 2006
Take care to avoid spillage of fluids into the peritoneal cavity. A convenient area to perforate the thin membrane is at the ventral neck of the puppy. Once the membrane has been removed, place 2 small hemostatic forceps on the umbilical cord, transect the cord between the clamps, and hand the puppy off to an assistant.(Fig.4a, b ) 
Fig. 4a: After removing placental membranes from the puppy, double clamp
the umbilical cord with small hemostats, cut between them, and pass the
puppy off to an assistant.


Fig. 4b: Double clamp umbilical cord and cut between the clamps.
from: Sicard GK, Fingland RB. Surgery of the ovaries and uterus. In: Saunders Manual of Small Animal Practice, 3rd edition, Birchard SJ, Sherding RG, eds. Elsevier, St. Louis, 2006
The assistant will then ligate the cord with absorbable suture and begin routine care to stimulate respirations and assessment 
(see http://drstephenbirchard.blogspot.com/2016/06/anesthesia-for-cesarian-section-in-dogs.html).

Before uterine closure, be sure to check the entire uterus including the body and vagina for any remaining fetuses. Routine ovariohysterectomy can be performed now if requested by the owner. If the uterus is to be preserved, close the uterine incision with absorbable suture (Monocryl or PDS) in a Cushing pattern.  Lavage the abdomen with warm sterile saline if spillage of uterine contents has occurred into the peritoneal cavity. Close the abdominal incision routinely. Intradermal closure of the skin layer is preferred to avoid the irritation associated with skin sutures and nursing puppies.

Postoperative Care

When the bitch is fully recovered from anesthesia the puppies can be placed with her and encouraged to nurse. Carefully monitor the puppies and bitch to be sure she does not accidentally injure the pups. Soon after anesthetic recovery is it usually best to discharge the dog and her puppies back to the home and educate the owner on care of the bitch and puppies. See blog on C-section anesthesia for postoperative analgesia of the mother.

References

1. Graves T. Diseases of the ovaries and uterus. In: Saunders Manual of Small Animal Practice, 3rd edition, Birchard SJ, Sherding RG, eds. Elsevier, St. Louis, 2006, pgs. 987-991.
2. Moon PF, Erb HN, Ludders JW, Gleed RD, Pascoe PJ Perioperative management and mortality rates of dogs undergoing cesarean section in the United States and Canada
JAVMA [1998, 213(3):365-369
3. Sicard GK, Fingland RB. Surgery of the ovaries and uterus. In: Saunders Manual of Small Animal Practice, 3rd edition, Birchard SJ, Sherding RG, eds. Elsevier, St. Louis, 2006, pgs. 996-999.

Tuesday, June 14, 2016

Anesthesia for Cesarian Section in Dogs and Cats: Dr. Lisa Ebner, DACVAA

Cesarean section (c-section) is a commonly performed surgical procedure in small animal practice. In the first segment of this 2-part blog on c-section, anesthetic management of the pregnant bitch or queen is presented by board certified anesthesiologist Dr. Lisa Ebner. In the 2nd segment we will focus on surgical management. The readers are referred to other publications for material on diagnosis and medical treatment of dystocia in small animals.            

As with any anesthesia and surgery the primary goal is to induce and maintain a surgical plane of anesthesia to eliminate pain and allow a safe recovery of the animal upon completion of the procedure. In Cesarean section the neonates complicate the anesthetic management. Anesthetic protocols must consider the health and well being of the unborn puppies and kittens as well as the mother.

With a planned c-section, the gestation length is known, the patient has been properly fasted, and the procedure takes place during normal business hours when plenty of staff members are available to assist.  This contrasts with the emergency c-section where often the patient has been straining for hours, may be in a compromised metabolic state and the viability of the puppies may be compromised. In clinical studies both maternal and puppy mortality was significantly increased with emergency compared to planned c-sections (1,2).

Pre-anesthetic Considerations
Anesthesia planning begins with assessment of patient risk. Obtain a thorough history that includes any concurrent medical conditions and medications.  Determine how long the bitch has been in labor and if any puppies, dead or alive, have been delivered.  A thorough physical exam is important and diagnostic imaging, such as abdominal ultrasound or radiographs, is very helpful. (Fig. 1) 
Fig. 1: Lateral radiograph of late term pregnancy in a dog.

Abdominal ultrasound is more sensitive in detecting fetal viability; while abdominal radiographs help determine the number, size, and position of the fetuses.  If possible, assessment of fetal heart rate can be a good indicator of a healthy (150-220 bpm) vs. a stressed fetus (100-150 bpm).  Laboratory evaluation of the bitch or queen is also indicated.  Selection of lab tests will depend on patient assessment, but a minimum database of PCV, total solids, BUN, glucose, ionized calcium, and other electrolytes prior to anesthesia is recommended. 

Physiologic Changes With Pregnancy
Pregnancy causes significant alterations in the mother’s physiology that need to be considered. Due to higher plasma volume in relation to the number of RBCs present, the pregnant bitch or queen has a “relative” anemia. Therefore if the PCV is within the normal range then she may actually be dehydrated. Pain or catecholamine release can cause tachycardia and increased cardiac output.  Compression of the great vessels in the abdomen during pregnancy does not appear to have the same potential in animals as it does in humans.  Based on clinical studies, small dogs under 25 kg do not appear to exhibit postural influences on systemic blood pressure but large breed, full term bitches could have the potential for a decrease in blood flow to the uterus (3,4). This effect may be exaggerated in animals that are dehydrated or have other illness affecting their cardiopulmonary system. The gravid uterus also displaces the diaphragm cranially, leading to a decreased tidal volume in the patient.  Hyperventilation may also be present due to pain and distress in a patient presenting for a c-section.  Overall there is an increased need for oxygen coupled with lower functional residual capacity that ultimately can result in hypoxemia. 

Anesthesia Protocol
Before beginning anesthesia consider administering 3 to 5 minutes of pre-oxygenation with 100% O2 provided by a tight-fitting oxygen mask (as long as this does not cause undo stress to the animal).  Hypocalcemia may be present in small breed dogs, dogs with large litters, or with uterine inertia. This abnormality should be corrected along with any fluid deficits prior to anesthesia and surgery.

To reduce complications and depression of the neonates, anesthesia and surgery time should be as short as possible.  Clip and perform the initial scrub of the patient prior to induction of anesthesia.  The surgeon should already being scrubbed, gowned, gloved and ready to begin draping as soon as the final surgical prep has been done.  The actual time from induction of anesthesia to removal of the neonate(s) should ideally be less than 5 minutes. 

Anesthetic Drug Selection
Avoid premedication in the pregnant animal because opioids are associated with respiratory depression in the neonates and other tranquilizing or sedating drugs, such as acepromazine or alpha2 agonists, are associated with decreased vigor in the newborns.  Even though some of the premedication drugs are reversible by administration of an antagonist, it is still best to avoid then because there is an increased risk of morbidity and mortality for the neonates.

Intravenous Induction
An intravenous catheter should always be placed for administration of IV fluids and emergency drugs if needed during anesthesia.   After adequate time for pre-oxygenation, the bitch or queen can be induced with propofol IV to effect (typically 4 mg/kg) and intubated with an appropriately sized endotracheal tube that is inflated to prevent a leak at 20 cm H2O.

Inhalation Anesthetics
For anesthesia maintenance isoflurane or sevoflurane, in oxygen, is acceptable.  Ideally, the concentration of the inhalant should be kept as low as possible to prevent the animal from responding to surgical stimulation but also prevent the dose-dependent vasodilation and accompanying hypotension associated with use of inhalants. 

Local or Regional Anesthetics
In order to keep the inhalant concentration to a minimum, local-regional anesthesia is often incorporated.  A line block can be performed preoperatively and will continue to provide analgesia post-operatively.  Bupivacaine (0.5%) is often selected for the line block due to its prolonged duration of action compared to lidocaine (4 to 6 hours vs. 60-90 minutes).  However, the time to onset is slightly longer than lidocaine. 

Another technique that can be included in the anesthetic protocol is a lumbosacral epidural with lidocaine (2%).  Lidocaine is selected because the shorter duration of action is actually preferred since most patients will go home with the owner soon after recovery from anesthesia.  The volume of drug used in the epidural should be decreased about 20-25% compared to a non-pregnant patient because the epidural space is actually decreased in a pregnant patient due to increased size of epidural veins.  It is an option to add morphine to the lumbosacral epidural.  Be careful performing epidurals in animals that are hemodynamically unstable because the local anesthetic drug can have a vasodilatory effect in the epidural space, leading to hypotension.  Other contraindications for epidural include infection of the skin at the site of needle puncture, coagulopathy, and an obese patient that makes palpation of the landmarks unreliable.  Although acceptable to perform c-section with only an epidural technique, such as is done in humans and many large animals, it would depend on the comfort and experience level of the anesthetist since an incomplete block may occur and the patient could respond to surgical stimulation.  Also, the patient would not have a protected airway and is at risk for aspiration pneumonia if regurgitation occurs. 

Neonatal Care
Once the neonates are delivered have several experienced staff on hand to help resuscitate them.  Organize the personnel as well as necessary drugs and supplies prior to induction.  After delivery gently clear fluid from the oral cavity of neonates of fluid with a bulb syringe.  Do not “swing” the neonate to clear its airway, as this has been associated with intracranial trauma (5).  If not already done by the surgeon, clamp the umbilical cord with a small hemostat and place a ligature with absorbable suture around the cord. Typically the cord is dipped in povidone-iodine solution after it is transected. 

Rub the neonates with a soft, absorbent towel immediately to stimulate spontaneous ventilation. (Fig. 2) 
Fig. 2: Newborn puppy being gently rubbed with a dry towel to stimulate respirations.
If there is no sign of spontaneous breathing, administer supplemental oxygen and preferably manual breaths after endotracheal intubation (should be attempted if it can be carefully done).  Most endotracheal tubes will be too large for neonates, but removing the stylet from a 16 gauge IV catheter and using only the polyurethane flexible catheter portion is an option.  If no heart-beat can be palpated, begin gentle cardiac compressions (ideally > 180 bpm).  If the puppy or kitten is bradycardic, this is most likely due to hypoxemia and not due to increased vagal tone.  Drugs that can be used for neonate resuscitation include epinephrine, doxapram, and naloxone (only if opioids were given to the mother).  The dose for each drug is typically 1-2 drops administered under the tongue.  The neonate may also benefit from an oral dose of 2.5% dextrose if it is able to swallow a few drops.  Finally, an important aspect of neonatal care is to keep them warm by placing them in an incubator or under a heat lamp until they can be with their mother when she is fully recovered. 

Postoperative Analgesia
The postoperative pain management of the bitch is always a cause for concern due to the possibility of transfer of drugs in to the milk and therefore the neonate. Based on current research many analgesic drug classes may be safely given during the lactation period without adverse effects on the neonates (6).  Drugs that have high lipid solubility, low molecular weight, and are non-ionized are secreted more easily in to the milk.  However, it appears that only 1-2% of the maternal dose goes in to the neonate.  So opioids such as morphine or hydromorphone post-operatively would be a suitable choice for the mother. Animal studies indicate that buprenorphine has the potential to inhibit milk production. Tramadol use in lactating dogs and cats has not been specifically studied, but in humans it appears that short-term use during establishment of lactation is compatible with breastfeeding (7).  Studies have not established the safety of NSAIDs, such as carprofen, in pregnant or lactating dogs.  So it is generally recommended to avoid NSAIDs in pregnant patients and only use a single dose with caution in nursing dogs.  Clinical judgement of the attending veterinarian should prevail when it comes to selecting an analgesic drug for a patient and it should be based on assessing the patient for pain, considering the species, health status of the patient, and potential for effects on the nursing neonates.  Signs of pain in the mother could include vocalizing, not allowing to neonates to nurse, trouble moving around, and a lack of interest in food. (8)


Summary
In summary, anesthesia and cesarean section can be safely performed on dogs and cats when the anesthetist carefully selects a drug protocol, properly prepares the animal for the anesthetic episode, minimizes the anesthetic time, and provides supportive care to the neonates and mother postoperatively.

Table: Summary of Anesthesia Protocol for C-section in Dogs and Cats

Pre-medication: no drugs; (3-5 minutes of pre-oxygenation, clip and initial scrub of surgical site)
Induction: Intravenous propofol
Maintenance: isoflurane or sevoflurane
Local or regional anesthesia: lidocaine line block on proposed incision site or lidocaine epidural
Postoperative analgesia for mother: Tramadol for bitch, buprenorphene for queen

Reference List:
1. Moon PF, Erb HN, Ludders JW, et al 2000. Perioperative risk factors for puppies delivered by cesarean section in the United States and Canada. J Am Anim Hosp Assoc 36: 359-368.
2. Moon PF, Erb HN, Ludders JW, et al 1998. Perioperative management and mortality rates of dogs undergoing cesarean section in the United States and Canada. J Am Vet Med Assoc 213: 365-369.
3. Probst CW, Webb AI. 1983. Postural influence on systemic blood pressure, gas exchange, and acid/base status in the term pregnant bitch during general anesthesia. Am J Vet Res 44: 1963-1965.
4. Probst CW, Broadstone RV, Evans AT. 1987. Postural influence on systemic blood pressure in large full-term pregnant bitches during general anesthesia. Vet Surg 16: 471-473.
5. Grundy S, Liu S, Davidson A. 2009. Intracranial trauma in a dog due to being “swung” at birth. Top Companion Anim Med 23: 100-103.
6. Raffe, Marc. Veterinary Anesthesia and Analgesia: the 5th edition of Lumb & Jones. Wiley Blackwell: 2015. 34.
7. Ilett KF, Paech MJ, Page-Sharp M, et al. Use of a sparse sampling study design to assess transfer of tramadol and its O-desmethyl metabolite into transitional breast milk. Br J Clin Pharmacol. 2008 May;65(5):661-6. doi: 10.1111/j.1365-2125.2008.03117.x. Epub 2008 Feb 20.
8. Aarnes, Turi and Bednarski, Richard. Canine and Feline Anesthesia and Co-Existing Disease. Wiley Blackwell: 2015. 16.
             



Sunday, May 8, 2016

Surgical Removal of Giant Lipomas in Dogs


Lipomas are benign tumors of adipose tissue that are common in dogs. Most lipomas are small, well circumscribed, movable, and not painful. They most commonly occur in the subcutaneous space but in rare cases can form in a body cavity such as the abdomen (Fig. 1a-c), or between large muscles such as the semimembranosis and semitendonosis (1).
Fig. 1a: Lateral abdominal radiograph in a dog with an abdominal lipoma.
Note large fat density mass in the mid to caudal abdomen.
Fig. 1b: Ventrodorsal radiograph of same dog as Fig. 1a.
Fig. 1c: Operative photograph of an abdominal lipoma in same dog as the above radiographs.

Lipomas that are large and grow between fascial planes are called infiltrative lipomas. (2,3)

Simple (not infiltrative) lipomas that are small, quiescent, and not causing pain or dysfunction are usually not treated. However, in some cases because of the sheer size and location of the lipoma, surgical resection is recommended. For example, a very large lipoma of the axilla like in the dog illustrated in this article may cause serious functional problems with the front limb.(Fig.2) 
Fig. 2: Preoperative appearance of a very large lipoma of the right axilla in this Labrador retriever
Surgical resection can be performed to allow better use of the leg and relief of discomfort. Even giant lipomas, if not infiltrative, can frequently be surgically removed. However, attention to anatomic detail and meticulous surgical technique are critical to avoid complications.

Diagnosis
Lipomas are suspected in any subcutaneous mass that is soft on palpation, movable, and well circumscribed. Fine needle aspirate samples appear grossly as oil droplets on a slide and reveal few cells microscopically. Radiographs (Fig. 1a,b) or CT scan of the mass may be indicated for very large or infiltrative lipomas that could be near or surrounding vital structures or in a body cavity.(4) 

Preoperative Considerations
Since many patients with lipomas are geriatric, appropriate preoperative evaluation would include a thorough history and physical examination, laboratory tests (CBC and serum chemistry profile) and thoracic radiographs if cardiopulmonary issues are suspected. 

Surgical Technique
After induction of general anesthesia, clip and aseptically prepare a wide field over the lipoma. Make an incision that spans the length of the lipoma. 
Fig. 3: Initial incision in the lipoma on same dog as in Fig. 2.
Using blunt and sharp dissection, define the borders of the mass and separate it from surrounding tissues. Finger dissection is usually effective in defining tissue planes and extracting the mass. When dissecting into deep tissue planes, use retractors to improve exposure and identify important structures such as large vessels and nerves. 
Fig. 4: Dissection of the lipoma in same dog as Fig. 2. The axilla artery and vein
and elements of the brachial plexus are seen at the base of the mass. 
Encapsulated lipomas will usually “peel out” well, but after removal inspect all surrounding tissues for residual lobules of lipoma. 
Fig. 5: Completed resection of the massive lipoma from the axillary space in dog from Fig. 2.
Prior to wound closure, inspect the surgical field for hemorrhage. Since removal of lipomas results in large areas of empty space in the tissues, place a closed suction drain to prevent fluid accumulation and seroma. (See Veterinary Key Points blog on the Jackson-Pratt drain.) 
Fig. 6: A closed suction drain has been placed in the Labrador in Fig. 2
and the incision closed routinely.
Close the wound routinely and place a light bandage on the animal to protect the drain tubing and reservoir. Leave the drain in place until drainage has reduced to trivial amounts. 

In the following video see dissection of a massive lipoma from the lateral cervical region of a dog. Removal of the mass exposed the trachea, carotid artery, and vagosympathetic trunk. 



Prognosis
Simple lipomas, even large ones, have a good prognosis since they are benign and slow growing. Postoperative recurrence is rare, but careful monitoring for development of new lipomas in other parts of the body is advised. Liposuction removal of lipomas was reportedly successful in 1 study but complications were common and recurrence of lipoma was high (28%) (5)

Infiltrative lipomas have a more guarded prognosis because they can be difficult to completely excise and recurrence is more common than with simple lipomas. Depending on the clinical study, one-third to one-half of dogs with infiltrative lipoma will develop recurrence after surgical removal. (2,3) Carefully monitor the surgical area for evidence of regrowth that can occur months or years postoperatively.

References
1. Thomson MJ, Withrow SJ, Dernell WS, Powers BE Intermuscular lipomas of the thigh region in dogs: 11 cases. J Am Anim Hosp Assoc. 1999 Mar-Apr;35(2):165-7.
2. McChesney AE, Stephens LC, Lebel J, Snyder S, Ferguson HR. Infiltrative lipoma in dogs.Vet Pathol. 1980 May;17(3):316-22
3.Bergman PJ1, Withrow SJ, Straw RC, Powers BE. Infiltrative lipoma in dogs: 16 cases (1981-1992) J Am Vet Med Assoc. 1994 Jul 15;205(2):322-4.
4. McEntee MC1, Thrall DE. Computed tomographic imaging of infiltrative lipoma in 22 dogs.Vet Radiol Ultrasound. 2001 May-Jun;42(3):221-5
5. Hunt GB1, Wong J, Kuan S. Liposuction for removal of lipomas in 20 dogs. J Small Anim Pract. 2011 Aug;52(8):419-25.