Is Tramadol An Effective Postoperative Analgesic in Dogs?

Postoperative pain control is a critical aspect of the care of surgical patients in veterinary medicine. Many drug types are available for postoperative analgesia such as opioids and non-steroidal antiinflammatories. Tramadol, a synthetic opioid, is a widely used analgesic in humans and has become popular for clinical use in dogs. It is an oral medication usually given at a dose of 2-4 mg/kg every 8-12 hours. It is frequently combined with a non-steroidal anti-inflammatory, such as carprofen, for postoperative analgesia. Side effects of tramadol include sedation, nausea, constipation, and seizures. Tramadol therefore is not recommended for dogs with seizure disorders.

Metabolism

Tramadol is metabolized by the liver to form O-desmethyltramadol, or the M1 metabolite.(1) This metabolite is also an active form of the drug. Pharmacokinetic studies have found that oral administration of tramadol results in adequate blood levels of the drug and its metabolite.(1)

Efficacy

Although rapidly gaining widespread use after introduction to the veterinary market, efficacy studies of the analgesic properties of tramadol have been slow to materialize. One study from several years ago separately evaluated morphine and tramadol for postoperative analgesia after ovariohysterectomy in dogs.(2) Using multiple parameters to evaluate pain, both drugs were found to be effective.  In another study, tramadol was compared to codeine and ketoprofen for analgesia after maxillectomy or mandibulectomy in dogs.(3) All drugs, including tramadol, were found to provide effective postoperative analgesia.

Conversely, more recent studies have found tramadol to compare poorly to other standard analgesics for postoperative pain. Carprofen was more effective than tramadol for postoperative pain in a series of dogs having enucleation.(4) Pain scores were monitored and dogs receiving tramadol were more likely to require rescue analgesics than those receiving carprofen. In another study, after TPLO for ruptured cruciate in 30 dogs, those that received firocoxib orally, alone or in combination with tramadol, had lower pain scores, lower rescue opiate administration, and greater limb function than dogs that received only tramadol.(5) Tramadol was also not effective in providing analgesia in an experimental study using an acute pain model in Beagles.(6)

These studies create a mixed and confusing message to veterinary clinicians about the efficacy of tramadol. Inherent to all pain studies is the difficulty in making objective assessments of postoperative pain in dogs, but well controlled studies using accepted methods of pain scoring should provide useful information. The conflicting results of clinical and experimental studies make it clear that tramadol alone as a postoperative analgesic may not provide the expected level of analgesia. This appears to be particularly true after procedures associated with high pain levels, such as in dogs having major orthopedic surgery.

Conclusions

Even in view of the studies showing lack of efficacy, tramadol’s advantages make it an attractive choice for postoperative analgesia. It is administered orally, is well tolerated by most dogs, and is felt by many clinicians to be a reasonable alternative for dogs in which NSAIDS are contraindicated. We routinely use tramadol in combination with carprofen for postoperative analgesia in dogs. In our clinical experience that combination provides effective analgesia even after orthopedic procedures such as TPLO. Tramadol alone is prescribed in those dogs that cannot take NSAIDS since there are few alternatives and tramadol is certainly better than no analgesic treatment.

What is your clinical expertience with Tramadol? Go to the 1 question survey on the web version of the Veterinary Key Points blog and register your vote! 

References

1. KuKanich, B. and Papich, M. G. (2004), Pharmacokinetics of tramadol and the metabolite O- desmethyltramadol in dogs. Journal of Veterinary Pharmacology and Therapeutics, 27: 239–246.

2. Mastrocinque, S. and Fantoni, D. T. (2003), A comparison of preoperative tramadol and morphine for the control of early postoperative pain in canine ovariohysterectomy. Veterinary Anaesthesia and Analgesia, 30: 220–228.

3. Martins TL1, Kahvegian MA, Noel-Morgan J, Leon-Román MA, Otsuki DA, Fantoni DT.

Comparison of the effects of tramadol, codeine, and ketoprofen alone or in combination on postoperative pain and on concentrations of blood glucose, serum cortisol, and serum interleukin-6 in dogs undergoing maxillectomy or mandibulectomy. Am J Vet Res. 2010 Sep;71(9):1019-26.

4. Cherlene Delgado, DVM, Ellison Bentley, DVM, DAVCO, Scott Hetzel, MS, and Lesley J Smith, DVM, DACVAA. Carprofen provides better post-operative analgesia than tramadol in dogs after enucleation: A randomized, masked clinical trial. J Am Vet Med Assoc. 2014 December 15; 245(12): 1375–1381.

5. Davila D1, Keeshen TP, Evans RB, Conzemius MG.

Comparison of the analgesic efficacy of perioperative firocoxib and tramadol

administration in dogs undergoing tibial plateau leveling osteotomy. J Am Vet Med Assoc. 2013 Jul 15;243(2):225-31.

6. Kogel B, Terlinden R, Schneider J. Characterisation of tramadol, morphine and tapentadol in an acute pain model in Beagle dogs. Vet Anaesth Analg. 2014 May;41(3):297-304

Nasopharyngeal Polyps in Cats: Key words - stertor, traction, and bulla osteotomy

Nasopharyngeal (NP) polyps in cats are characterized by well-circumscribed solid masses that are found in the nasopharynx, tympanic bulla, and Eustachian tube.  They are benign and thought to be secondary to inflammation from bacterial or viral infections.  Similar polyps can also be present in the external ear canal.  Affected cats are usually young (less than 1 year) but all ages can be affected.

Clinical Signs

Presenting signs of nasopharyngeal polyps may vary depending on location. Inspiratory stertor is commonly found due to the fleshy mass just dorsal to the soft palate causing obstruction of the nasal passages. Stertorous breathing in cats should alert the clinician to a mass lesion in the nasopharynx since other causes, such as elongated soft palate, are uncommon in cats.

Signs of otitis media, such as Horner’s syndrome, head tilt, and pain may also be seen. (Fig. 1) 

Fig. 1: Right sided Horner's syndrome seen in a kitten with a
NP polyp. 

Polyps in the external ear canal can result in or be secondary to otitis externa causing head shaking, ear scratching, and malodorous otic discharge.

Diagnosis

A thorough oral examination should be performed. Sedation will probably be necessary since the polyp will likely be obscured by the soft palate. If the mass is large enough simple palpation of the soft palate with a finger may indicate a mass effect. Retraction of the soft palate with stay sutures or a spay hook, with the cat in dorsal recumbency, should expose the mass. (Fig. 2)

Fig. 2: NP polyp in a cat (arrow) adjacent to the soft palate (SP) The cat is in
dorsal recumbency.

Otoscopic examination should also be performed to look for extensions of polyps into the external ear canal. Cleaning of otic discharge and debris may be necessary to adequately expose the mass.

Differential diagnoses for nasopharyngeal polyps are lymphosarcoma, other types of  neoplasia, foreign body, or congenital anomaly of the pharynx or upper airway. In one study of nasopharyngeal disorders in 53 cats 49% of them were diagnosed with lymphosarcoma and  28% were diagnosed as polyps.(1)

Imaging

Skull radiographs with emphasis on the tympanic bulla may provide useful information. Affected cats may show radiographic signs of chronic otitis media such as bony proliferation of the bulla and increased soft tissue density within the bulla.(Fig. 3)

Fig. 3: Bony proliferation of the bulla (arrow) secondary to
a nasopharyngeal polyp in a cat.

However, radiographs of the bullae are not a very sensitive imaging test and significant changes may be present with normal appearing bullae on films.

CT scans are a more sensitive and diagnostic imaging modality for bulla disorders and are useful in cats with nasopharyngeal polyps or other bulla diseases. Increased soft tissue density is commonly seen in one or both bullae. (Fig. 4)

Fig. 4: CT scan of a cat with a NP polyp showing increased soft tissue density
within the bulla. (arrow)

In cases of severe infection or invasive neoplasia, lysis of the bulla may be seen. These findings are useful for preoperative evaluation of cats undergoing ventral bulla osteotomy, a recommended surgery for cats with nasopharyngeal polyps or other chronic middle or external ear disease.

Treatment

Traction

Surgical removal of the polyps is the most effective means of relieving clinical signs. Under general anesthesia the cat is placed in dorsal recumbency and a mouth speculum placed to allow exposure of the oral cavity and pharynx. The soft palate is retracted rostrally with either stay sutures or a spay hook. Gentle manipulation of this tissue is important since it is sensitive and prone to edema with manipulation.  Even under anesthesia many cats will exhibit discomfort while the soft palate is being manipulated. Once the polyp is exposed, grasp it with either stay sutures or Allis tissue forceps.(Fig. 5) Gentle but firm rostral and ventral traction is placed on the polyp and continued until the mass is removed. 

Fig. 5: NP polyp (arrow) being removed by traction.

The tissue frequently has a large round component that is connected to a tail that is the Eustachian tube portion of the polyp. Control hemorrhage with direct pressure on the affected pharyngeal tissues.

Bulla Osteotomy

To completely remove the polyp tissues, ventral bulla osteotomy is then performed. Which side to operate depends on the preoperative imaging or lateralizing clinical signs. If lateralization was not possible or if changes are seen bilaterally on imaging, both bullae are ostetomized to be sure of removing all remaining polyp tissues. Although most polyps are unilateral, the author recently treated a cat with bilateral polyps requiring osteotomy of both bullae.

Small fragments of polyp tissue are usually found in the tympanic bullae exposed by the ventral bulla osteotomy. (Fig. 6-7)

Fig. 6: Diagram of a ventral bulla osteotomy in a cat. Rongeurs are used to
remove the ventral aspect of the bulla and expose both compartments.
from: Boothe H. Surgery for otitis media and otitis internal.
From: Saunders Manual of Small Animal Practice3rd ed., Birchard and Sherding, editors. Elsevier, 2006, pg. 601.

Fig. 7: Bulla osteotomy in a cat with NP polyps. The ventral floor of the
bulla has been removed. Note the polypoid tissue filling the bulla cavity. (arrow)

It is important to expose both compartments of the bulla when performing the osteotomy (ventral-medial and dorso-lateral chambers). Care is taken not to injure components of the inner ear, located dorsally in the bulla, when doing polyp excision and curretage.  Save all tissues removed for histopathology and obtain samples from the bulla for culture and sensitivity.

Postoperative Care and Complications

Routine supportive care including analgesics and antibiotics are administered postoperatively. Antibiotic choice is guided by results of culture and sensitivity of samples obtained from the bullae.

Common complications after polyp removal are pharyngeal swelling and Horner’s syndrome due to injury to sympathetic nerves in the middle ear. Both of these problems are usually mild, short term in duration, and not requiring treatment. Recurrence of polyps is more likely if only the nasopharyngeal portion is removed. In a clinical study of 31 cats with nasopharyngeal polyps, 5 recurred postoperatively, 4 of which did not have a bulla osteotomy. (2)

References

1. HS Allen, J Broussard, and K Noone (1999) Nasopharyngeal diseases in cats: a retrospective study of 53 cases (1991-1998). Journal of the American Animal Hospital Association: November/December 1999, Vol. 35, No. 6, pp. 457-461. 
2. Kapatkin, AS, Matthiesen, DT, Noone KE. et.al. Results of surgery and long-term follow-up in 31 cats with nasopharyngeal polyps. J Am An Hosp Assoc 1990 Vol 26 No 4 pp. 387-392.

Message to Massive Liver Tumors in Dogs: We are not afraid of you!

Tumors of the liver are frequently seen in dogs, with the most common being the hepatocellular carcinoma. Affected dogs present for non-specific clinical signs and the tumors can become very large before being discovered. Massive liver tumors are defined as large tumors that are confined to one lobe of the liver.(1) (Fig. 1) 

Fig. 1: Large hepatocellular carcinoma of the liver in a dog

Prior to availability of surgical stapling devices such as the Thoracoabdominal Stapler (TA), liver lobectomy was tedious, risky, and associated with significant blood loss. The stapling device has made removal of even very large hepatic tumors safer and much faster resulting is less morbidity and mortality. (Fig. 2)

Fig. 2: Large liver mass in a dog being removed using
an older version of the thoracoabdominal stapling device

Diagnosis

Dogs with liver tumors present with non-specific signs such as lethargy, anorexia, and weight loss. A large cranial abdominal mass is usually palpable on physical examination. Diagnostic imaging is indicated including plain film abdominal radiographs (Fig. 3), abdominal ultrasound, and thoracic radiographs to look for metastatic lesions.

Fig. 3: Plain film abdominal radiograph of a liver tumor in a 12 year old Labrador retriever (arrow)
(photo courtesy of Dr. Laura Lemmons)

CT scan can also be performed (Fig. 4), however it may not provide more significant information than radiographs and ultrasound.

Fig. 4: CT scan of a 10 year old golden doodle with a large right sided liver
mass.(arrow) The mass was surgically removed and histopathology revealed a hepatic adenoma.

Preoperative Care

Appropriate preoperative diagnostics are necessary to rule out metabolic diseases and metastasis of primary liver tumors.  Preoperative hemograms and coagulation status should be assessed since many liver and biliary diseases can cause deficiency of clotting factors.  Serum proteins should also be evaluated.  The patient's fluid and electrolyte status should be considered and abnormalities corrected before surgery.  Significant blood loss can occur during or after partial hepatectomy which may require blood tranfusion.

Applied Anatomy

The liver is divided into 6 lobes, the caudate, right lateral, right medial, quadrate, left lateral, and left medial. 

Fig. 5: Normal gross anatomy of the canine liver lobes.

The liver has a dual blood supply, receiving circulation from both the portal vein and the hepatic arteries.  Major hepatic portal vein branches are the right lateral trunk, right medial branch, and left lateral trunk supplying the left lobes.  The liver portal vasculature can also be classified as right divisional (caudate and right lateral), central divisional (right medial and quadrate), and left divisional (left medial and left lateral). Six to eight major hepatic veins drain into the caudal vena cava.  The liver is attached to other structures in the abdomen via the triangular ligaments and the hepatogastric and hepatoduodenal ligaments.

Surgical Approaches

The liver is best approached via a ventral midline celiotomy.  Although rarely done, a right or left paracostal incision can be combined with the midline approach for large liver masses or other conditions that require greater exposure.  Caudal ventral midline sternotomy can be combined with the midline abdominal incision if necessary for cranially located masses.

Partial hepatectomy

Liver lobectomy using surgical staples is the procedure of choice for most surgeons. Complete or partial lobectomy can be performed. Omental adhesions to the mass will require hemostasis and sharp dissection to release them from the tumor. The Ligasure or electrocautery device is useful for hemostasis. After exposing the mass, incise triangular ligaments as needed to mobilize the liver lobe. Be cautious working around the hepatoduodenal ligament since the hepatic arteries and common bile duct are in the region. Caudal traction on the liver lobe is necessary to accurately place the stapler proximal to the tumor. (Figs. 6,7)

Fig. 6: Surgical removal of a large hepatocellular carcinoma
in a dog using the Thoracoabdominal stapler. 

Large hemostatic clips may be needed to control occasional arterial bleeders that were not adequately compressed by the staples. The Ligasure device can also be used to control liver bleeding. 

Fig. 7: Liver mass in same dog as in Fig. 3; histopathology of the
mass revealed an hepatic adenoma.

The liver has a remarkable ability to regenerate. Up to 60-70% of the liver tissue mass can be removed without impacting liver function.

Postoperative Care and Complications

Liver surgery patients should be closely monitored and supported after liver surgery.  Postoperative hemorrhage is possible and should be monitored via the patient's color, heart rate, peripheral PCV (measured several hours after surgery), and evidence of bleeding from the incision or blood in the abdominal cavity.  Routine postoperative supportive care with intravenous fluids and analgesics is administered. In the absence of complications, most dogs can be discharged from the hospital the day after surgery.

Prognosis
The prognosis for dogs after removal of massive liver tumors, even hepatocellular carcinoma if completely excised, is very good. In one study of 42 dogs, mortality rate was only 4.8% and median postoperative survival was greater than 1460 days.(1)  In contrast, dogs treated without surgery had a median survival was 270 days.

References

1. Julius M. Liptak, BVSc, MvetClinStud; William S. Dernell, DVM, MS, DACVS; Eric Monnet, DVM, PhD, DACVS; Barbara E. Powers, DVM, PhD, DACVP; Annette M. Bachand, PhD; Juanita G. Kenney; Stephen J. Withrow, DVM, DACVS, DACVIM. Massive hepatocellular carcinoma in dogs:48 cases (1992–2002) JAVMA, Vol 225, No. 8, October 15, 2004

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.