Use of nitinol stents for end-stage tracheal collapse in dogs

Degradation and Fatigue Behavior of 3D-Printed Bioresorbable Tracheal Splints

Severe infantile tracheobronchomalacia (TBM) is often treated with invasive surgery and fixed-size implants to support the trachea during respiration. A novel 3D-printed extra-luminal splint has been developed as a flexible and bioresorbable alternative. Therefore, the goal of the present study was to use an in vitro breathing simulator model to comprehensively evaluate the structural stiffness and failure modes of two sizes of a novel bioresorbable 3D-printed splint design under a range of physiological degradation conditions. Two thicknesses, 2 mm and 3 mm, of a novel 3D-printed bioresorbable splint were evaluated under two different degradation conditions, phosphate-buffered saline (PBS) and sodium hydroxide (NaOH). The splints were subjected to simulated breathing loading, involving a cyclic opening and closing of the splint by 2 mm, for a targeted duration of 7.5 to 30 million cycles. A separate new set of splints were statically soaked in their respective degradation condition for a comparative analysis of the effects of cyclic loading by the degradation medium. After successfully simulated breathing or static soaking, non-destructive tensile and compressive strengths were evaluated, and overall stiffness was calculated from destructive tensile testing. The present study indicates that the splints were more significantly degraded under simulated breathing conditions than under soaking. Cyclic simulated breathing specimens failed far earlier than the intended duration of loading. Over time, both 2 mm and 3 mm splints became increasingly more flexible when subjected to the static degradation conditions. Interestingly, there was little difference in the compressive and tensile strengths of the 2 mm and 3 mm thickness splints. The bioresorbable nature of PCL offers a valuable advantage as it eliminates the need for splint removal surgery and increases device flexibility over time with degradation. This increased flexibility is crucial because it allows for uninhibited growth and development of the infant's trachea over the intended use period of 2 years. The results of this study confirm that the splints were able to withstand tensile forces to prevent tracheal collapse. This study further supports the successful use of 3D-printed splints in the treatment of infantile TBM.

A systematic review and meta-analysis of prevalence of complications after tracheal stenting in dogs

BACKGROUND

Stenting has become popular to treat tracheal collapse in dogs, but complications might arise and negatively affect treatment outcome.

OBJECTIVES

Determine the overall prevalence of complications of tracheal stenting in dogs.

METHODS

A bibliographic search was performed of publications from 2000 to 2020. Studies were assessed for quality of evidence and measured prevalence of the 8 most commonly reported complications after tracheal stenting in dogs (stent fracture, stent migration, relapsing collapse, granuloma formation, tracheobronchial infections, and early, late, and clinically relevant late cough). Random effects meta-analyses were used to estimate pooled complications prevalence.

RESULTS

Fifteen studies met inclusion criteria. Cough (early: 99%; 95% confidence interval [95% CI]: 95%-100%, late: 75%; 95% CI: 63%-85%, and clinically relevant: 52%; 95% CI: 42%-61%), tracheobronchial infections (24%; 95% CI: 14%-35%), and granulomas (20%; 95% CI: 11%-30%) were common after tracheal stenting. Stent fractures (12%; 95% CI: 5%-20%), relapsing collapse (10%; 95% CI: 5%-15%), and stent migration (5%; 95% CI: 1%-9%) were less frequent. Significant heterogeneity among studies was identified for the estimated prevalence of stent fracture, granulomas, infections, and late cough.

CONCLUSIONS AND CLINICAL IMPORTANCE

Tracheal stenting in dogs is associated with a high risk of coughing and a moderate risk of tracheobronchial infections and granuloma formation. Because most complications will impact a dog's quality of life, owners must be informed that tracheal stenting is a second-line procedure that does not necessarily alleviate the need for medical treatment and frequent follow-up visits. Additional studies are warranted to identify the risk factors of these complications.

Fatigue analysis of canine tracheal stents using the finite element method

This study aimed to evaluate fatigue of three stent designs when various forces are applied and perform a comparative analyses. A computer simulation using the finite element method was performed. In particular, we constructed a three-dimensional finite element model of nitinol stents with three designs (S6: single-woven wire, wire diameter: 0.006 inch; D6: double-woven wire, wire diameter: 0.006 inch, and D7: double-woven wire, wire diameter: 0.007 inch) that are used to treat canine tracheal collapse (TC). The stents were subjected to a 200 mmHg compression force, a pure torsion force in a perpendicular direction, and a bending-torsion force combining perpendicular and axial forces. The von Mises stress was calculated to evaluate the extent of stent displacement, and Goodman diagrams were plotted to compare fatigue life cycles. D7 exhibited a longer fatigue life compared to S6 and D6. Under compression, pure torsion, and bending-torsion forces, displacement was the smallest for D7, followed by D6 and S6. Similarly, the fatigue life was the longest for D7, followed by D6 and S6. S6 showed the greatest displacement when subjected to external forces; among stents designed using the same wire, D6 displayed less displacement than S6, and D7 exhibited superior fatigue life when subjected to varying degrees of force. This study showed that the structural stability and fatigue life of stents could be effectively compared using finite element method D7 has the greatest stability and structural rigidity under cyclic load.

Double-wire woven nitinol stent for treating dogs with refractory tracheal collapse: A case series

This retrospective case series describes the signalments, clinical signs, diagnostic test results, and postoperative complications obtained from the medical records of 10 client-owned dogs that underwent treatment for grade IV tracheal collapse using double-wire woven nitinol stents between October 2017 and September 2021. Respiratory signs resolved in all dogs immediately after tracheal stent placement. Mild to moderate stent fractures were identified in five dogs, of which two showed concurrent respiratory distress necessitating re-stenting after several months. Minor complications, such as stent migration, were absent. The double-wire woven nitinol stent optimised for the canine trachea showed favourable outcomes and minimal complications.

Bronchial collapse and bronchial stenting in 9 dogs

BACKGROUND

Principal and lobar bronchial collapse is increasingly recognized as an isolated entity.

OBJECTIVE

Retrospectively describe the procedure and outcomes of dogs undergoing bronchial stenting at a single referral hospital.

ANIMALS

Nine client-owned dogs with variable degrees of collapse of the left principal bronchus (LPB), lobar bronchus 1 (LB1), and lobar bronchus 2 (LB2), and with clinically relevant signs of respiratory dysfunction.

METHODS

Data were collected from patient records. All dogs underwent stenting of the LPB and LB2. Anatomic and functional impairment grades were assigned to each case before and 4 weeks after stenting. Data regarding response to stenting and complications were evaluated.

RESULTS

Bronchial stenting was considered successful in all cases, with all dogs experiencing improved quality of life (QOL), and decreased functional impairment grade at 4 weeks post-stenting. Follow-up of >6 months was available for 6 dogs and of these, 5 were alive at 12 months, 3 were alive at 18 months, and 1 was alive at 24 months. Stent-related complications occurred in 4 dogs, and were resolvable in 3. Two dogs developed pneumothorax, 1 developed recurrent pneumonia, and 1 developed new-onset coughing. All dogs had mild and manageable coughing post-stenting.

CONCLUSIONS AND CLINICAL IMPORTANCE

Stenting of the LBP and LB2 might be an effective option for dogs with advanced collapse of these bronchi and associated signs. Although all included dogs had resolution or improvement of clinical signs considered life-threatening or as affecting QOL, ongoing coughing is expected. Patient selection appears important with regard to achieving successful outcomes.

Antimicrobial and Antiproliferative Coatings for Stents in Veterinary Medicine-State of the Art and Perspectives

Microbial colonization in veterinary stents poses a significant and concerning issue in veterinary medicine. Over time, these pathogens, particularly bacteria, can colonize the stent surfaces, leading to various complications. Two weeks following the stent insertion procedure, the colonization becomes observable, with the aggressiveness of bacterial growth directly correlating with the duration of stent placement. Such microbial colonization can result in infections and inflammations, compromising the stent's efficacy and, subsequently, the animal patient's overall well-being. Managing and mitigating the impact of these pathogens on veterinary stents is a crucial challenge that veterinarians and researchers are actively addressing to ensure the successful treatment and recovery of their animal patients. In addition, irritation of the tissue in the form of an inserted stent can lead to overgrowth of granulation tissue, leading to the closure of the stent lumen, as is most often the case in the trachea. Such serious complications after stent placement require improvements in the procedures used to date. In this review, antibacterial or antibiofilm strategies for several stents used in veterinary medicine have been discussed based on the current literature and the perspectives have been drawn. Various coating strategies such as coating with hydrogel, antibiotic, or other antimicrobial agents have been reviewed.

Stents in Veterinary Medicine

Stenting in veterinary medicine has been a rapidly growing method of interventional surgery for several years. This procedure is usually performed in the respiratory and urinary tracts, but there are cases of stenting of blood vessels or gastrointestinal structures. It is based on maintaining the permeability of a given tubular structure, thus allowing the passage of gas or liquid. This procedure is often performed as a first-line treatment in situations where pharmacological agents do not work and as an alternative method, often cheaper than the classically performed ones. There are also cases where stenting is used as a palliative treatment, e.g., to enable defecation in colonic obstruction due to tumour infiltration of the colon wall. Stenting is often a life-saving or comfort-improving procedure for animals, but one should also be aware of possible postoperative complications and be prepared for any adversity. For this reason, this review provides an insight into the current knowledge in veterinary medicine about stenting and the consequences associated with this procedure.

Comparison of three different self-expanding metal stents using rabbit models for the treatment of tracheal collapse

Purpose:

To identify an optimal self-expandable metallic stent (SEMS) and verify whether a mechanically superior SEMS would result in better clinical outcomes in the treatment of tracheal collapse.

Methods:

We selected three SEMS (n = 8 each), including an S-type stent with a wire diameter of 0.006 inches (S6) and two D-type stents with wire diameters of 0.006 (D6) and 0.007 inches (D7). Twenty-four New Zealand White rabbits were divided into three equal groups. After the stents were deployed, the clinical signs were recorded daily, and radiographic examinations were performed monthly. All rabbits were euthanized after three months.

Results:

Two rabbits with S6 stents and one rabbit with a D7 stent died within three months because of stent migration or pneumonia. All rabbits with D6 stents survived for three months. On histological examination, the D6 group had the lowest inflammation score.

Conclusions:

Both clinically and histopathologically, the results with D-type stents with a wire diameter of 0.006 inches were superior to those of the other groups (p = 0.001). The use of an optimal intraluminal stent may improve the long-term clinical outcomes in the treatment of tracheal collapse in dogs.

Self-expanding tracheal stent placement in a cat with primary tracheal collapse

A 12-year-old mixed-breed spayed female cat presented with dyspnoea, open-mouthed breathing, and cyanosis that was difficult to control with medical pharmacotherapy; the cat was diagnosed with the primary tracheal collapse of the neck and chest regions. The diagnosis was confirmed by dynamic chest radiography, tracheal endoscopy, and computed tomography (CT). Tracheal endoscopy and CT showed dropsy of the dorsal membranous wall over most of the trachea. A self-expanding Nitinol cross-and-hook braided stent was placed along the entire tracheal lumen using surgical X-ray fluoroscopy. Bacterial cultures in the trachea were negative. Dyspnoea disappeared immediately after the endotracheal stent was implanted. Although the long-term prognosis remains under observation, the short- to medium-term prognosis was very good. These results suggest that stenting may be useful in the treatment of primary tracheal collapse in cats.

Surgical outcomes in dogs with tracheal collapse treated with a novel cross-and-hook braided endoluminal stent

Background

Stenting is an effective treatment option for tracheal collapse in dogs. Cross-braided tracheal stents are currently the norm in veterinary medicine, but cross-and-hook braided stents have recently been adopted in human medicine. We examined whether stents manufactured using this novel braiding technique provided additional advantages for the treatment of tracheal collapse in dogs.

Objectives

To evaluate the outcomes of cross-and-hook braided stent implantation in the treatment of tracheal collapse in dogs.

Methods

The medical records of 22 client-owned dogs that underwent luminal placement of cross-and-hook braided Fauna Stents for the treatment of tracheal collapse between January 2018 and July 2021 were examined and data on canine signalment, clinical signs, diagnostic test results, surgical outcomes, and postoperative complications were retrieved and analyzed statistically.

Results

Twenty-six stents were surgically implanted, with 20 dogs (90.9%) receiving one stent and the remaining two (9.1%) receiving two or more stents. All dogs survived the procedure. The median survival time at a median follow-up of 990 days was 879 days. At the final follow-up examination, loss or mild improvement of cough was observed in all dogs.

Conclusions

Compared with conventional lumen stents, the cross-and-hook braided Fauna Stent offered a higher survival rate and improved clinical symptoms in all patients. The results of this study suggest that the Fauna Stent may be a promising treatment option for dogs with tracheal collapse.

ACVIM consensus statement guidelines for the diagnosis, classification, treatment, and monitoring of pulmonary hypertension in dogs

Pulmonary hypertension (PH), defined by increased pressure within the pulmonary vasculature, is a hemodynamic and pathophysiologic state present in a wide variety of cardiovascular, respiratory, and systemic diseases. The purpose of this consensus statement is to provide a multidisciplinary approach to guidelines for the diagnosis, classification, treatment, and monitoring of PH in dogs. Comprehensive evaluation including consideration of signalment, clinical signs, echocardiographic parameters, and results of other diagnostic tests supports the diagnosis of PH and allows identification of associated underlying conditions. Dogs with PH can be classified into the following 6 groups: group 1, pulmonary arterial hypertension; group 2, left heart disease; group 3, respiratory disease/hypoxia; group 4, pulmonary emboli/pulmonary thrombi/pulmonary thromboemboli; group 5, parasitic disease (Dirofilaria and Angiostrongylus); and group 6, disorders that are multifactorial or with unclear mechanisms. The approach to treatment of PH focuses on strategies to decrease the risk of progression, complications, or both, recommendations to target underlying diseases or factors contributing to PH, and PH‐specific treatments. Dogs with PH should be monitored for improvement, static condition, or progression, and any identified underlying disorder should be addressed and monitored simultaneously.

Bacterial infection before and after stent placement in dogs with tracheal collapse syndrome

Background

Dogs with tracheal stents often have positive airway bacterial cultures. The pathogenicity of these organisms and risk factors for infection have not been investigated.

Objective

Describe bacterial infection in dogs with tracheal collapse before and after tracheal stent placement.

Animals

Fifty‐three client‐owned dogs.

Methods

Retrospective review of medical records of dogs receiving tracheal stents with thoracic radiographs, tracheoscopy, and endotracheal lavage.

Results

There was no difference between the overall prevalence of dogs with positive bacterial cultures before (31/38; 82%) or after stent placement (24/31; 77%) (P = .67). An increased number of geriatric (17/28; 61%) and traditional‐type collapse (TTC) (16/26; 62%) dogs had positive pathogenic airway infections before stent placement, compared to young (8/25; 32%; P = .04) and malformation‐type collapse (MTC) dogs (9/27; 33%; P = .04). After tracheal stent placement, geriatric dogs had a 52% reduction in pathogenic bacteria infection frequency (P = .02) and dogs with TTC had a 56% reduction in pathogenic bacteria infection frequency (P = .01). Significant risk factors for pathogenic infection included a history of pneumonia (OR = 3.6; 95% CI, 0.28‐43.36) and cardiac disease (OR = 1.25; 95% CI, 0.16‐9.92) in geriatric dogs, and hepatomegaly in young dogs (OR = 1.5; 95% CI, 0.12‐19.44).

Conclusions and Clinical Importance

Tracheal stent placement does not increase the overall rate of pathogenic bacterial infection in dogs with tracheal collapse and can decrease the rate of subsequent pathogenic infections in geriatric dogs and dogs with TTC that require tracheal stenting. Airway culture and cytology should be performed in all dogs undergoing tracheal stent placement.

Permanent Implantable Medical Devices in Exotic Pet Medicine

Medical devices are defined as implantable if they are intended to remain in the body after the procedure. In veterinary medicine, use of such devices is marginal but may find some indications. Use in exotic pet medicine is even more challenging due to size restriction and the limited data available. This review focuses on the esophageal and tracheal stent in the case of stricture, ureteral stent and subcutaneous ureteral bypass in the case of ureteral obstruction, permanent urinary diversion in the case of bladder atony, and pacemaker in the case of severe arrythmias. Comparative aspects are developed.

Correlations among tracheal dimensions, tracheal stent dimensions, and major complications after endoluminal stenting of tracheal collapse syndrome in dogs

Background

Endoluminal tracheal stenting can relieve signs associated with tracheal collapse syndrome (TCS) in dogs, but major complications can result.

Objective

To identify associations among tracheal dimensions, stent dimensions, and subsequent complications requiring additional stent placement after endoluminal stenting for TCS.

Animals

Fifty‐two dogs from the hospital population.

Methods

Medical records of dogs that received an endoluminal self‐expanding tracheal stent for TCS by the interventional radiology service between 2009 and 2014 were reviewed for relevant data. Signalment and clinical details, including tracheal collapse type, tracheal measurements, nominal stent dimensions, follow‐up evaluation times, and stent complications, were recorded.

Results

Fifty‐two dogs that received an endoluminal stent for TCS met the inclusion criteria. Major complications included stent fracture (13/52; 25%), obstructive tissue ingrowth (10/52; 19%), and progressive tracheal collapse (6/52; 12%). Natural tracheal taper (P = .04) and more stent diameter oversizing (P = .04) in the intrathoracic (IT) trachea were associated with caudodorsal stent fracture. Only stents with a 14‐mm nominal diameter fractured. Progressive tracheal collapse was associated with smaller maximum tracheal diameters (P = .02). The majority of dogs with obstructive tissue ingrowth (7/10; 70%; P = .30) and all dogs with thoracic inlet fractures (3/3; 100%) had tracheal malformations.

Conclusions and Clinical Importance

A higher taper in tracheal diameter may lead to increased risk of fracture in the IT location. Dogs with tracheal malformations may have higher risk for thoracic inlet fracture and development of obstructive tissue ingrowth. Clinicians should be aware of the possible risk factors for tracheal stent complications.

Long-term outcomes of 54 dogs with tracheal collapse treated with a continuous extraluminal tracheal prosthesis

OBJECTIVE

To describe the surgical placement of a continuous extraluminal tracheal prosthesis (CETP) and report the subsequent postoperative clinical outcomes in dogs with tracheal collapse.

STUDY DESIGN

Retrospective case series.

ANIMALS

Fifty-four dogs.

METHODS

Medical records of dogs in which cervical and/or thoracic inlet tracheal collapse was diagnosed and treated by placement of a CETP between 2010 and 2017 were reviewed to evaluate postoperative complications, changes in respiratory function, and survival. Histological examinations of tracheal tissues performed in 2 dogs at 51 and 57 months after surgery were also reviewed.

RESULTS

Fifty-three (98%) dogs survived to discharge. Postoperative complications included laryngeal paralysis (1 dog), disseminated intravascular coagulation (1 dog), and recurrent tracheal collapse (2 dogs). None of the dogs exhibited clinical evidence of tracheal necrosis. Preoperative dry, harsh cough resolved in 87% of the dogs after surgery. Goose honking cough was resolved in 25 of 26 (96%) dogs. Median follow-up time was 30 months (range, 16 days to 76 months). The survival rate at 36 months was 86% (CI: 75%-96%). On histological examination in 2 dogs, the tracheal tissue surrounding the prosthesis was well preserved and without evidence of chronic inflammation.

CONCLUSION

Continuous extraluminal tracheal prosthesis placement in dogs with tracheal collapse resulted in low postoperative complication rates and good long-term outcomes.

CLINICAL SIGNIFICANCE

Continuous extraluminal tracheal prosthesis placement provides a viable alternative surgical option for managing dogs with tracheal collapse.

Atypical lateral tracheal collapse in a Yorkshire terrier

A 10-month-old, neutered female Yorkshire terrier was presented with a 6-month history of inspiratory dyspnoea, coughing and exercise intolerance. Tracheoscopy revealed marked lateral-to-lateral fixed collapse of the cervical trachea and mild collapse of the thoracic trachea. Surgical exploration revealed a marked reduction in lateral tracheal width and multiple malformed tracheal rings. Placement of extraluminal ring prostheses around the cervical trachea resulted in widening of the tracheal diameter and an immediate improvement in clinical signs. 6 years postoperatively the patient was reported to have an excellent quality of life with complete resolution of clinical signs.

Immediate, short-, and long-term changes in tracheal stent diameter, length, and positioning after placement in dogs with tracheal collapse syndrome

BACKGROUND

Intraluminal tracheal stenting is a minimally invasive procedure shown to have variable degrees of success in managing clinical signs associated with tracheal collapse syndrome (CTCS) in dogs.

OBJECTIVES

Identify immediate post-stent changes in tracheal diameter, determine the extent of stent migration, and stent shortening after stent placement in the immediate-, short-, and long-term periods, and evaluate inter-observer reliability of radiographic measurements.

ANIMALS

Fifty client-owned dogs.

METHODS

Retrospective study in which medical records were reviewed in dogs with CTCS treated with an intraluminal tracheal stent. Data collected included signalment, location, and type of collapse, stent diameter and length, and post-stent placement radiographic follow-up times. Radiographs were used to obtain pre-stent tracheal measurements and post-stent placement measurements.

RESULTS

Immediate mean percentage change was 5.14%, 5.49%, and 21.64% for cervical, thoracic inlet, and intra-thoracic tracheal diameters, respectively. Ultimate mean follow-up time was 446 days, with mean percentage change of 2.55%, 15.09%, and 8.65% for cervical, thoracic inlet, and intra-thoracic tracheal diameters, respectively. Initial mean stent length was 26.72% higher than nominal length and ultimate long-term tracheal mean stent shortening was only 9.90%. No significant stent migration was identified in the immediate, short-, or long-term periods. Good inter-observer agreement of radiographic measurements was found among observers of variable experience level.

CONCLUSIONS AND CLINICAL IMPORTANCE

Use of an intraluminal tracheal stent for CTCS is associated with minimal stent shortening with no clinically relevant stent migration after fluoroscopic placement. Precise stent sizing and placement techniques likely play important roles in avoiding these reported complications.

Effect of Variations in Stent Placement on Outcome of Endoluminal Stenting for Canine Tracheal Collapse

The study's objective was to determine effects of relative size and placement location of endoluminal stents on incidence of complications and survival for canine tracheal collapse. Measurements were obtained on lateral radiographs before and after stenting to determine percent of the trachea occupied by the stent. These values were monitored over time and compared to complication rates and survival. Overall median survival time was 502 days. Six month survival rate was 78%, 1 yr survival was 60%, and 2 yr survival was 26%. Median percent of trachea occupied by the stent at initial placement was 79% (range, 41-93%). Percent of the trachea occupied by the stent at the time of placement did not significantly correlate to complication rate (0.397) or survival time (0.853). Incidence of serious complications was 37%, including granuloma formation, pneumonia, material failure, and stent migration. For patients experiencing serious complications, median survival was shorter, at 208 days, but was not significantly different from survival without serious complications. Within the margins of the data from this study, the proportion of the trachea occupied by the stent at the time of placement does not appear to impact incidence of complications or survival time in dogs with tracheal collapse.

COMPARISON OF FLUOROSCOPY AND COMPUTED TOMOGRAPHY FOR TRACHEAL LUMEN DIAMETER MEASUREMENT AND DETERMINATION OF INTRALUMINAL STENT SIZE IN HEALTHY DOGS

Tracheal collapse is a progressive airway disease that can ultimately result in complete airway obstruction. Intraluminal tracheal stents are a minimally invasive and viable treatment for tracheal collapse once the disease becomes refractory to medical management. Intraluminal stent size is chosen based on the maximum measured tracheal diameter during maximum inflation. The purpose of this prospective, cross-sectional study was to compare tracheal lumen diameter measurements and subsequent selected stent size using both fluoroscopy and CT and to evaluate inter- and intraobserver variability of the measurements. Seventeen healthy Beagles were anesthetized and imaged with fluoroscopy and CT with positive pressure ventilation to 20 cm H2 O. Fluoroscopic and CT maximum tracheal diameters were measured by three readers. Three individual measurements were made at eight predetermined tracheal sites for dorsoventral (height) and laterolateral (width) dimensions. Tracheal diameters and stent sizes (based on the maximum tracheal diameter + 10%) were analyzed using a linear mixed model. CT tracheal lumen diameters were larger compared to fluoroscopy at all locations (P-value < 0.0001). When comparing modalities, fluoroscopic and CT stent sizes were statistically different. Greater overall variation in tracheal diameter measurement (height or width) existed for fluoroscopy compared to CT, both within and among observers. The greater tracheal diameter measured with CT and lower measurement variability has clinical significance, as this may be the imaging modality of choice for appropriate stent selection to minimize complications in veterinary patients.

Tracheal stent placement for the emergency management of tracheal collapse in dogs

Dogs with tracheal collapse may present with life-threatening upper airway obstruction. In most instances, a conservative approach to treatment including oxygen support coupled with sedation and cooling measures will relieve respiratory effort and thus relieve airway obstruction. Dogs that fail this conservative approach require endotracheal intubation to ensure a patent airway. This population of patients would benefit from a more definitive, yet palliative treatment option to acutely relieve upper airway obstruction. Placement of a self-expanding metallic stent that spans the affected portion of the trachea will acutely provide the patient with a sustained patent airway and optimize the likelihood of a positive outcome.

Long-term outcome, complications and disease progression in 23 dogs after placement of tracheal ring prostheses for treatment of extrathoracic tracheal collapse

OBJECTIVE

To report complications, long-term outcome, and disease progression in dogs with extrathoracic tracheal collapse treated by surgical placement of commercially available extraluminal rings.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n = 23).

METHODS

Medical records (2002-2011) of dogs treated with extraluminal rings for extrathoracic tracheal collapse were reviewed. Owner interviews, conducted at >10 months postoperatively, determined response to surgery, progression of clinical signs after surgery, and frequency of medication administration. Long-term re-evaluation (>10 months after surgery) was offered for surviving dogs, including radiographs and tracheoscopy if indicated.

RESULTS

Of 23 dogs, 22 survived to discharge after surgery. Clinical signs improved in all dogs at 2 weeks after surgery and at long-term re-evaluation. Fourteen dogs (65%) required no medical management for respiratory signs after surgery. Four dogs (17%) were diagnosed with laryngeal paralysis at some point after surgery, but only 9% were diagnosed within 48 hours of the surgery. Additional rings were placed between previously placed rings in 2 dogs, and 1 dog was treated with an endoluminal stent for intrathoracic tracheal collapse. Three dogs had clinical signs consistent with progression of tracheal collapse. Based on owner questionnaire, all owners were satisfied with surgical outcome.

CONCLUSIONS

Treatment of severe cervical tracheal collapse with commercially-available extraluminal ring placement leads to an overall improvement in quality of life and good long-term results, with about one-third of dogs requiring continued medical management. Most dogs do not have clinical signs consistent with disease progression after surgery.