Cricopharyngeal-laryngeal dysplasia in a horse with sudden clinical onset idiopathic laryngeal hemiparesis

A 7-year-old Thoroughbred racehorse developed loud exercise-related respiratory noises and exercise intolerance over a short period. Examination showed congenital cricopharyngeal-laryngeal dysplasia (rostral displacement of the palatopharyngeal arch) and also left sided idiopathic laryngeal hemiparesis, the latter appearing to be of recent clinical onset. The animal developed colic some months after laryngeal surgery and a nephrosplenic entrapment was surgically corrected. Aerophagia and regurgitation worsened after surgery and, after developing inhalation pneumonia, the animal was destroyed. Post-mortem examination confirmed the presence of idiopathic laryngeal hemiparesis and of cricopharyngeal-laryngeal dysplasia which had some previously undescribed laryngeal muscle abnormalities.     

Preferential denervation of the adductor muscles of the equine larynx. II: Nerve pathology

The terminal branches of the recurrent laryngeal nerve (RLN) of three normal ponies and six horses with sub-clinical laryngeal disease were examined qualitatively and quantitatively in an attempt to explain the preferential denervation of the laryngeal adductor muscles in the neuropathy of idiopathic laryngeal hemiplegia (ILH). The myelinated fibre spectra of all the motor nerve fibres in the left and right abductor and adductor branches of the RLN in three normal ponies were measured. The density of myelinated fibres was also calculated. There was no significant difference between the larger group of myelinated fibres in the adductor or abductor branches. In the six horses with laryngeal hemiparesis, however, there was a marked preferential loss of the medium/large size myelinated fibres in the left adductor branch, although nerve fibre densities were not significantly different. While no simple morphometrical feature was found to explain the selective muscle denervation, the greater loss of large diameter myelinated fibres in the adductor branches confirms the earlier observation of adductor muscle susceptibility in the neuropathy of ILH.     

Bilateral recurrent laryngeal neurectomy as a model for the study of idiopathic canine laryngeal paralysis.

The purposes of this study were to develop an experimental model of canine laryngeal paralysis that mimicked the naturally occurring disease and to document the upper airway changes produced, both clinically and with pulmonary function testing. Ten dogs had bilateral recurrent laryngeal neurectomy performed and were recovered from anesthesia. Tidal breathing flow-volume loop analysis and upper airway resistance measurements were taken before and after the development of clinical laryngeal paralysis while dogs breathed room air and after the individual administration of 2 respiratory stimulants. Clinical signs of laryngeal paralysis developed 38 days (median) following denervation. Although some variations were present, tidal breathing flow-volume loop analyses on room air, following denervation, were similar to those reported in naturally occurring cases. Upper airway resistance increased following denervation and was significantly increased with both respiratory stimulants. We concluded that bilateral recurrent laryngeal neurectomy resulted in clinical signs and respiratory changes similar to those of idiopathic canine laryngeal paralysis.     

Bilateral ventriculocordectomy via ventral laryngotomy for idiopathic laryngeal paralysis in 88 dogs

Bilateral ventriculocordectomy through a ventral median laryngotomy was performed for the treatment of idiopathic laryngeal paralysis in 88 dogs. The purpose of this retrospective analysis was to provide long-term follow-up for a large number of dogs surgically managed with this technique. A combination of medical record and completed client questionnaire information provided short-term (14 days) follow-up for 88 dogs and long-term (>6 mo) follow-up for 42 dogs. Major short-term postoperative complications were identified in 3 of 88 (3.4%) patients. Major long-term complications were identified in 3 of 42 (7.1%) patients. The results of surgery were considered to be very satisfactory in 93% and unsatisfactory in 7%. Three dogs in this series developed aspiration pneumonia. Bilateral ventriculocordectomy through a ventral median laryngotomy is associated with a low incidence of both short- and long-term complications. Due to the ease of this procedure, the minimal surgical trauma to the patient, and the satisfactory results, this surgery should be considered an option for the treatment of idiopathic laryngeal paralysis in the dog.     

Partial Arytenoidectomy in Horses

Unilateral partial arytenoidectomy was performed in 22 horses. Six horses had arytenoid chondritis, 14 horses had idiopathic laryngeal hemiplegia (11 of which had been treated unsuccessfully by insertion of a laryngeal abductor muscle prosthesis), and two horses had laryngeal hemiplegia resulting from perivascular injection of an irritant drug. After surgery, eight horses (36%) developed a nasal discharge of food and/or water that was of clinical significance in only two of them. The operation resulted in marked improvement in exercise tolerance in all 20 horses tested, although two could not work because of severe exercise-associated coughing. Mild inspiratory stertor was present in eight horses and was excessive in one. It was concluded that the high incidence of problems related to swallowing rendered the method unacceptable. Modification of partial arytenoidectomy by silicon augmentation produced improvement in one horse.     

Postoperative results of unilateral arytenoid lateralization for treatment of idiopathic laryngeal paralysis in dogs: 39 cases (1996-2002)

OBJECTIVE: To evaluate postoperative results for dogs with idiopathic laryngeal paralysis that underwent unilateral arytenoid lateralization (UAL). DESIGN: Retrospective case series. ANIMALS: 39 dogs with idiopathic laryngeal paralysis. PROCEDURE: Medical records were reviewed, and information on surgical technique, hospitalization time, postoperative treatment, and complications was obtained. Owners were contacted by telephone for additional information if necessary. RESULTS: In all dogs, UAL had been performed by a single surgeon who used a standard surgical technique. Long-term follow-up information was available for all 39 dogs; mean follow-up time was 29.6 months (range, 3 to 61 months). Seven (18%) dogs developed postoperative pneumonia, and 6 of the 7 recovered with treatment. Twenty-two of the 39 (56%) dogs had minor complications, including unresolved coughing or gagging, continued exercise intolerance, vomiting, and seroma formation. Owners of 35 of the 39 (90%) dogs reported an improvement in postoperative quality-of-life score. Median survival time was 12 months; only 1 dog was euthanized because of respiratory tract disease following surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that UAL will improve quality of life in most dogs with idiopathic laryngeal paralysis. However, the complication rate is high, with postoperative pneumonia being the most important major complication. Minor complications were common but did not adversely affect owner-assigned quality-of-life scores in most dogs.     

Caudal cervical disc protrusion in a Bengal tiger (Panthera tigris tigris).

A young adult male white Bengal tiger (Panthera tigris tigris) presented with hindlimb ataxia. Cervical and lumbar myelography revealed a compressive lesion of the cord at C(6-7). Corticosteroid therapy and confinement failed to provide lasting remission of signs. A modified, inverted cone ventral slot decompression was used to remove the fibrous material causing cord compression at C(6-7). Temporary Horner's syndrome and laryngeal paresis developed postsurgically because of excessive tissue retraction. The animal recovered normal ambulatory function 6 wk after surgery.     

Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia

OBJECTIVES: To describe clinical features of brachycephalic airway obstructive disease in dogs, the incidence of laryngeal collapse in dogs presenting for surgery and the outcome after surgery in dogs with laryngeal collapse. METHODS: Basic clinical details were reviewed retrospectively in 73 dogs. Presence of laryngeal collapse and short-term outcomes after surgery were determined for 64 dogs with complete medical records. Long-term outcomes were reviewed for 46 dogs by telephone survey between 19 and 77 months following surgery. RESULTS: Stenotic nares were present in 31 dogs (42.5 per cent), elongated soft palate in 63 (86.3 per cent) and everted laryngeal saccules in 43 (58.9 per cent). The most common breeds were the pug (19 dogs, 26 per cent), Cavalier King Charles spaniel (15 dogs, 20.5 per cent), British bulldog (14 dogs, 19.2 per cent) and Staffordshire bull terrier (4 dogs, 5.5 per cent). Laryngeal collapse was present in 34 of 64 (53 per cent) dogs. No dogs died perioperatively and only one dog was euthanased as a result of its respiratory disease three years after surgery. Telephone interviews indicated that 26 dogs (56.5 per cent) were much improved after surgery, 15 (32.6 per cent) had some improvement and 5 (10.9 per cent) showed no improvement. Signs that persisted after surgery were snoring during sleep (34 dogs, 73.9 per cent), stertor/stridor while conscious (23 dogs, 50 per cent), excessive panting (13 dogs, 28.3 per cent) and dyspnoea (10 dogs, 21.7 per cent). Long-term outcome was considered good, even in dogs with laryngeal collapse. CLINICAL SIGNIFICANCE: Laryngeal collapse is relatively common in dogs presented for surgical correction of brachycephalic airway obstructive disease. Dogs with severe laryngeal collapse often respond well to surgery. Clinical signs rarely resolve completely following surgery.     

Complications associated with the use of the cuffless endotracheal tube in the horse

Complications following the use of the cuffless large animal endotracheal tube during general anesthesia in 2 horses are reported. One horse developed laryngeal edema during recovery. The edema was treated successfully with dexamethasone, but severe laryngeal trauma was confirmed 24 hours later at necropsy. The second horse had a swollen tongue and had difficulty eating for 3 days after anesthesia. The condition resolved without treatment. this report is a reminder of the potential damage which can occur from endotracheal intubation.     

Laryngeal dysplasia: Computed tomographic findings in an Oldenburg mare

A 5-year-old Oldenburg mare presented for poor performance, head-tossing and bucking when ridden. An abnormal respiratory noise was audible during exercise. Computed tomography (CT) revealed right laryngeal dysplasia; an absent cricothyroid articulation, abnormally shaped thyroid cartilage, underdeveloped cricopharyngeus muscle, rostral displacement of the palatopharyngeal arch and an oesophageal air column. In this case, it was unlikely that the laryngeal pathology was related to the horse's clinical signs. This case report provides a reference CT examination of laryngeal dysplasia, corroborating previous findings using magnetic resonance imaging, radiography, ultrasonography and post-mortem examination.     

Pentastomiasis in Bosc's monitor lizards (Varanus exanthematicus) caused by an undescribed Sambonia species.

Two wild-caught Bosc's monitor lizards (Varanus exanthematicus) developed clinical signs of pentasomiasis approximately 3 yr after arrival in the United Kingdom. One died of chronic parasitic pneumonia associated with adult pentastomids of an undescribed Sambonia species. Eggs and immature pentastomids were also seen in histologic sections of the lungs and liver. The other animal was treated for pneumonia and for nodular inflammation of the larynx that restricted the diameter of the glottis. Fragments of pentastomid larvae were seen in a laryngeal biopsy, and the animal recovered after treatment with ivermectin and supportive therapy.     

Laryngeal paralysis in immature and mature dogs as one sign of a more diffuse polyneuropathy

Six dogs with laryngeal paralysis had clinical, electrophysiologic, and pathologic evidence of a more generalized polyneuropathy. Three of the dogs were young Dalmatians, one was a young Bouvier des Flandres, and two were older, large-breed dogs. The results of this study suggest that laryngeal paralysis in dogs may frequently be one clinical sign of an underlying, more generalized polyneuropathy. Two forms of this generalized polyneuropathy may exist: an early form, as seen in young dogs with congenital or hereditary disease, and a delayed-onset form that is usually found in older dogs with so-called idiopathic laryngeal paralysis, some of which may have hypothyroidism.     

Laryngeal fistula formation after laryngoplasty in two Warmblood mares

Recurrent laryngeal neuropathy usually results in left‐sided laryngeal hemiparesis or hemiplegia and is one of the most common problems of the upper respiratory tract in equids. There are multiple methods of management, and the laryngoplasty procedure is still the most common surgical treatment. Different nonabsorbable suture materials and techniques are used for laryngoplasty. Post surgical complications are not uncommon. Of these complications, coughing is the most common. The following case report describes diagnosis and treatment of 2 horses with chronic coughing after laryngoplasty due to infection at the surgical site and laryngeal fistula formation. In both horses an elastic material (probably Lycra) had been used as part of the prosthesis implant. This material had deteriorated into multiple small pieces making removal difficult, and therefore use of this material for a laryngoplasty procedure should be avoided.     

Bilateral arytenoid cartilage paralysis after inhalation anesthesia in a horse

An 8-year-old Quarter Horse gelding was anesthetized for surgical exploration and debridement of a chronic draining wound in the intermandibular space. Anesthesia was without complication other than persistently low PaO2. Severe airway obstruction was evident immediately after extubation, requiring tracheostomy. Endoscopic diagnosis was bilateral arytenoid paralysis, which gradually resolved over the next 7 days. Compression, trauma, or tension of the recurrent laryngeal nerves are the postulated causes of idiopathic laryngeal hemiplegia in horses. The extremely extended position of the head and neck during anesthesia, perhaps compounded by low arterial oxygen content, may have resulted in a hypoxemic insult to the recurrent laryngeal nerves and caused bilateral arytenoid paralysis in this horse.     

Complications and Long-term Results after Partial Laryngectomy for the Treatment of Idiopathic Laryngeal Paralysis in 45 Dogs

Forty-five dogs with severe respiratory signs caused by idiopathic, acquired laryngeal paralysis were treated by partial laryngectomy. The predominant postoperative complications were coughing in 28 dogs and pneumonia in 15 dogs. Eight dogs required a second operation to alleviate persistent or recurrent upper airway obstruction. Results of surgery were considered excellent in 11 dogs (25%), good in 18 dogs (40%), fair in 6 dogs (13%), and poor in 10 dogs (22%). Poorer results were obtained by surgical residents than by more experienced surgeons. Death in the immediate postoperative period was related to pneumonia (8 dogs) and laryngeal collapse (1 dog). Nine dogs died later of respiratory disease. Although partial laryngectomy is effective for the treatment of laryngeal paralysis, it is not recommended because of the high incidence of postoperative complications.     

Ventriculocordectomy as the sole treatment for recurrent laryngeal neuropathy: long-term results from ninety-two horses

OBJECTIVE: To evaluate the effect ventriculocordectomy (VC) for treatment of recurrent laryngeal neuropathy (RLN) on exercise performance and owner satisfaction in a mixed-breed population of horses. STUDY DESIGN: Retrospective study. ANIMALS: Adult horses (n=92) with a history of abnormal respiratory noise and RLN. METHODS: Retrospective analysis of horse that had unilateral VC (and contralateral ventriculectomy in 63 horses) for treatment of idiopathic RLN. Owners/trainers completed a questionnaire about complications and outcome at least 1 year after surgery. Performance index was determined using race records for previously raced Thoroughbreds to evaluate outcome. RESULTS: Clinical signs included abnormal exercise-induced respiratory noises (noises; 52%), poor performance (11%), and noises and poor performance (37%). The median preoperative resting endoscopic grade of laryngeal function was Havemeyer grade III.1 (mild asymmetry). No discharge from the laryngotomy 1 week postoperatively occurred in 62% horses, 22% coughed after surgery, 66% made no noises, 9% continued to make noises at the canter, 21% made noise at the gallop, and 4% of owners were unsure whether noises were present. Ninety-three percent of horses returned to full work after surgery. Overall, 86% of owners considered the surgery worthwhile, 3% did not consider it worthwhile, and 11% were unsure. Surgery had a significantly beneficial effect on the racing performance index in Thoroughbreds (P=.004). CONCLUSIONS: VC is a useful alternative to laryngoplasty for selected cases of RLN and is associated with a positive effect on exercise performance, a low postoperative complication rate, and a high rate of owner satisfaction. CLINICAL RELEVANCE: Unilateral VC should be considered as a sole treatment in horses with low grades of RLN.     

The effect of recurrent laryngeal neurectomy in conjunction with laryngoplasty and unilateral ventriculocordectomy in thoroughbred racehorses

OBJECTIVE: To investigate the effects of recurrent laryngeal neurectomy (RLN) in combination with laryngoplasty and ventriculocordectomy on the postoperative performance of Thoroughbred racehorses treated for grade III left laryngeal hemiparesis (LLH). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Fifty-five Thoroughbred racehorses. METHODS: Medical records for Thoroughbred racehorses treated surgically by laryngoplasty and laser ventriculocordectomy with or without RLN between June 1993 and December 1996 were reviewed. Outcome was evaluated subjectively by assessment of performance obtained from telephone interviews with owners and trainers, and objectively by assessment of racing performance for 3 races before and after surgery using a performance index (PI). RESULTS: Fifty-five Thoroughbred racehorses with resting endoscopic grade III LLH were treated by laryngoplasty and ventriculocordectomy either with (39 horses) or without (16 horses) RLN. For RLN horses, respondents for 38 horses believed performance was improved in 19 horses, unchanged in 16 horses, and decreased in 3 horses. For horses without RLN, respondents for 9 horses reported that performance was improved in 5 horses, unchanged in 2 horses, and decreased in 2 horses. PI scores were improved in 18 RLN horses and in 6 horses without RLN; there was no statistical difference in outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Use of RLN in combination with laryngoplasty and ventriculocordectomy for treatment of grade III LLH may not improve postoperative racing performance.     

A study of an electrodiagnostic technique for the evaluation of equine recurrent laryngeal neuropathy

The electrodiagnostic measurement of the thoracolaryngeal reflex (TLR) ('slap test') latency was compared to 5 other diagnostic techniques used for evaluation of laryngeal function, namely laryngeal muscle palpation, resting and immediately postexercise endoscopic examinations, and palpable and endoscopic responses to the TLR. Compared to resting endoscopy, the electrodiagnostic measurement of TLR latency was not found to be an accurate test for the evaluation of recurrent laryngeal neuropathy (RLN), nor was laryngeal muscle palpation or the endoscopic response to the TLR. Twenty-five (71%) of 35 Clydesdale horses examined were affected by RLN; 16 (46%) had mild, 5 (14%) moderate, 3 (9%) severe hemiparesis and 1 (3%) had total laryngeal paralysis. Within these 35 horses, physical traits such as height or neck length did not correlate with the incidence or severity of RLN. Ten control ponies showed no evidence of abnormal laryngeal function.     

Surgical management of intrathoracic tracheal avulsion in cats: long-term results in 9 consecutive cases

OBJECTIVE: To evaluate the outcomes and complications in a consecutive series of cats undergoing surgical repair of intrathoracic tracheal avulsion injuries. STUDY DESIGN: Retrospective clinical study. ANIMALS: Nine client-owned cats. METHODS: The medical records of all cats undergoing surgical repair of intrathoracic tracheal avulsion injuries from 1994 to 1997 were reviewed. The results of physical examination, laboratory evaluations, radiography, tracheoscopy, surgery, and patient follow-up were reviewed. Complications that arose and long-term outcome were noted. RESULTS: Long-term resolution of clinical signs was achieved in all cats after resection of the damaged trachea and its repair by end-to-end anastomosis. Follow-up periods ranged from 12 months to 2.9 years. One cat developed unilateral left-sided laryngeal paralysis 2 to 3 months after surgery; however, this was transient and resolved without intervention within 6 months of surgery. CONCLUSIONS: Surgical management of intrathoracic tracheal avulsion injuries in cats can be accomplished via a right lateral thoracotomy. Careful anesthetic technique is an integral part of the surgical procedure if a successful outcome is to be achieved. The incidence of both short-term and long-term complications was low. Care should be exercised to visualize and protect the left recurrent laryngeal nerve if postoperative iatrogenic unilateral left-sided laryngeal paralysis is to be prevented. CLINICAL RELEVANCE: This retrospective study documents the successful surgical correction of a series of clinical cases of intrathoracic tracheal avulsion in cats.     

Evaluation of a stented laryngoplasty for correction of cranial glottic stenosis in four dogs

After laryngeal surgery, cranial glottic stenosis secondary to laryngeal web formation was diagnosed as the cause of upper airway obstruction in 4 dogs. Initial treatment of 3 dogs by peroral laryngeal web excision resulted in rapid recurrence of clinical signs. Subsequently, these 3 and the fourth dog were treated by scar excision, mucosal flap coverage, and placement of a silicone intraluminal laryngeal stent for 14 days. By 5 months (average) after surgery, on the basis of clinical evaluation of exercise intolerance, respiratory distress, and stridor, all dogs had alleviation of upper airway obstruction.