Tracheostomy in cats: 23 cases (1998-2006)

Tracheostomies can be used to provide a patent airway in animals with upper airway obstruction but have been reported to be more difficult to manage in cats than in other animals. The purpose of this study is to retrospectively describe the indications, complications and outcome of cats undergoing tracheostomy. Twenty-three cats underwent tracheostomy for laryngeal mass (n=13), trauma (n=5) and upper airway swelling (n=5). Major and minor complications were recorded in 10 and 17 cats, respectively. Seventeen cats were discharged to home, four cats were euthanased and two cats died in hospital. Complications with stoma healing were reported in one cat. Of seven cats discharged with a permanent tracheostomy, one cat is alive and six cats survived at home for between 2 and 281 days. Although complications are common, temporary tracheostomies can be beneficial for conditions in which the underlying cause can be treated. Despite risk of occlusion, permanent tracheostomies can be effective palliative procedures for cats with severe upper airway disease.     

COMPUTED TOMOGRAPHY OF NONANESTHETIZED CATS WITH UPPER AIRWAY OBSTRUCTION

Upper airway obstruction is a potentially life‐threatening problem in cats and for which a noninvasive, sensitive method rapid diagnosis is needed. The purposes of this prospective study were to describe a computed tomography (CT) technique for nonanesthetized cats with upper airway obstruction, CT characteristics of obstructive diseases, and comparisons between CT findings and findings from other diagnostic tests. Ten cats with clinical signs of upper airway obstruction were recruited for the study. Four cats with no clinical signs of upper airway obstruction were recruited as controls. All cats underwent computed tomography imaging without sedation or anesthesia, using a 16‐slice helical CT scanner and a previously described transparent positional device. Three‐dimensional (3D) internal volume rendering was performed on all CT image sets and 3D external volume rendering was also performed on cats with evidence of mass lesions. Confirmation of upper airway obstruction was based on visual laryngeal examination, endoscopy, fine‐needle aspirate, biopsy, or necropsy. Seven cats were diagnosed with intramural upper airway masses, two with laryngotracheitis, and one with laryngeal paralysis. The CT and 3D volume‐rendered images identified lesions consistent with upper airway disease in all cats. In cats with mass lesions, CT accurately identified the mass and location. Findings from this study supported the use of CT imaging as an effective technique for diagnosing upper airway obstruction in nonanesthetized cats.     

Arytenoid Lateralization for Treatment of Laryngeal Paralysis in 10 Cats

Objective— To describe the signalment, history, clinical signs, surgical technique, and outcome for cats with laryngeal paralysis that had arytenoid lateralization.
Study Design— Case series.
Animals— Cats with laryngeal paralysis (n=10).
Methods— Medical records (1996–2002) for cats with laryngeal paralysis that had arytenoid lateralization were reviewed for signalment, history, clinical signs, degree of paralysis, cause, concurrent medical conditions, surgical technique, and outcome. Follow-up information was obtained from owners or referring veterinarians.
Results— Of 10 cats, 9 had bilateral and 1 had unilateral laryngeal paralysis. Arytenoid lateralization were unilateral (n=7), bilateral (1), and staged bilateral procedures (2), 10 days and 3 years apart, respectively. Postoperatively, 1 cat had persistent inspiratory noise because of minimal enlargement of the rima glottidis and 2 cats required a temporary tracheostomy for management of laryngeal swelling. Three cats developed aspiration pneumonia and died 4, 7, and 150 days after surgery; all 3 had bilateral (simultaneous or staged) procedures. Of the 7 remaining cats, 4 were alive at follow-up and 3 had died of causes unrelated to arytenoid lateralization. The calculated mean survival time for all 10 cats was 406 days (median, 150 days; range, 4–1825 days).
Conclusions— Arytenoid lateralization was effective at enlarging the rima glottidis and reducing signs of airway obstruction in most cats.
Clinical Relevance— Unilateral arytenoid lateralization is a feasible option for the surgical management of cats with marked clinical signs; however, bilateral procedures should be avoided or at least performed with considerable caution because of the apparent risk for aspiration pneumonia.     

Laryngeal paralysis in cats: 16 cases (1990-1999)

OBJECTIVE: To determine clinical signs, physical examination findings, radiographic features, and concurrent diseases in cats with laryngeal paralysis, as well as evaluate the outcome of medical or surgical management. DESIGN: Retrospective study. ANIMALS: 16 cats. PROCEDURE: Medical records from January 1990 to April 1999 were examined for cats with laryngeal paralysis. Signalment, clinical signs, physical examination findings, cervical and thoracic radiographic findings, laryngeal examination results, and clinical outcome were reviewed. RESULTS: No breed or sex predilection was identified in 16 cats with laryngeal paralysis. The most common clinical signs included tachypnea or dyspnea, dysphagia, weight loss, change in vocalization, coughing, and lethargy. Clinical signs were evident for a median of 245 days. Airway obstruction was apparent on cervical and thoracic radiographic views in 9 cats. Examination of the larynx revealed bilateral laryngeal paralysis in 12 cats and unilateral laryngeal paralysis in 4 cats. The 4 cats with unilateral disease were managed with medical treatment, and 3 of these had acceptable long-term outcomes. Seven of 12 cats with bilateral paralysis underwent surgery; procedures performed included left arytenoid tie back, bilateral arytenoid tie back and ventriculo-cordectomy, and partial left arytenoidectomy. One cat was euthanatized as a result of complications from surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Laryngeal paralysis is an uncommon cause of airway obstruction in cats. Cats with less severe clinical signs (often with unilateral paralysis) may be successfully managed with medical treatment, whereas cats with severe airway obstruction (often with bilateral paralysis) may benefit from surgical intervention.     

The influence of crystalloid type on acid–base and electrolyte status of cats with urethral obstruction

Objective: To compare the effect of a balanced isotonic crystalloid solution with that of 0.9% sodium chloride on the acid–base and electrolyte status of cats with urethral obstruction.
Design: Randomized prospective clinical trial.
Setting: Academic veterinary emergency room.
Animals: Sixty-eight cats with naturally occurring urethral obstruction.
Interventions: Cats were randomized to receive either a balanced isotonic crystalloid solution (Normosol-R, n =39) or 0.9% sodium chloride ( n =29) for fluid therapy. Baseline venous blood gas and blood electrolyte values were obtained at the time of admission and at intervals during the course of therapy.
Measurements and main results: Baseline values were similar between groups. Cats receiving Normosol-R had a significantly higher blood pH at 12 hours, a significantly greater increase in blood pH from baseline at 6 and 12 hours, as well as a significantly higher blood bicarbonate concentration at 12 hours and a significantly greater increase in blood bicarbonate from baseline at 6 and 12 hours. Conversely, the increase in blood chloride from baseline was significantly higher at 2, 6, and 12 hours in cats receiving 0.9% sodium chloride. There were no significant differences in the rate of decline of blood potassium from baseline between groups. Subgroup analysis of hyperkalemic cats (K⁺>6.0 mmol/L) and acidemic cats (pH<7.3) yielded similar findings.
Conclusions: While both crystalloid solutions appear safe and effective for fluid therapy in cats with urethral obstruction, the use of a balanced electrolyte solution may allow more rapid correction of blood acid–base status within the first 12 hours of fluid therapy. The use of a potassium-containing balanced electrolyte solution does not appear to affect the rate of normalization of blood potassium in treated cats with urethral obstruction.     

Surgical relief of severe laryngeal malformation in an English Bulldog

A 22 month old English Bulldog was presented with progressive upper airway obstruction associated with an elongated soft palate, tonsillitis, everted laryngeal saccules and laryngeal malformation. Surgical management of the case consisted of resection of the elongated soft palate and everted laryngeal saccules, unilateral tonsillectomy and correction of the laryngeal stenosis. The latter was achieved by using a castellated incision through the laryngeal cartilages and first tracheal ring. From this case, it is postulated that, at least in some cases, the common upper airway obstruction syndrome in Bulldogs may not be due to laryngeal collapse as previously thought but rather to congenital malformation of the laryngeal cartilages.     

Evaluation of unilateral arytenoid lateralization for the treatment of laryngeal paralysis in 14 cats

Laryngeal paralysis is a relatively common cause of upper airway obstruction in middle-aged to older, large-breed dogs; however, it is rare in the cat. The purpose of this study is to describe a series of cats diagnosed with laryngeal paralysis treated by unilateral arytenoid lateralization. Fourteen cats met the criteria of the study. Intraoperative and postoperative complications were seen in 21% (three of 14) and 50% (seven of 14) of cases, respectively. Median duration of follow-up was 11 months (range 3 weeks to 8 years). None of these cats had recurrence of clinical signs. Based on this brief case series, unilateral arytenoid lateralization appeared to be a suitable method for treating laryngeal paralysis in cats. Additional studies are warranted to determine the type and frequency of long-term complications.     

Surgical relief of severe laryngeal malformation in an English Bulldog

A 22 month old English Bulldog was presented with progressive upper airway obstruction associated with an elongated soft palate, tonsillitis, everted laryngeal saccules and laryngeal malformation. Surgical management of the case consisted of resection of the elongated soft palate and everted laryngeal saccules, unilateral tonsillectomy and correction of the laryngeal stenosis. The latter was achieved by using a castellated incision through the laryngeal cartilages and first tracheal ring. From this case, it is postulated that, at least in some cases, the common upper airway obstruction syndrome in Bulldogs may not be due to laryngeal collapse as previously thought but rather to congenital malformation of the laryngeal cartilages.     

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.     

Inflammation and wound healing in cats with chronic gingivitis/stomatitis after extraction of all premolars and molars were not affected by feeding of two diets with different omega‐6/omega‐3 polyunsaturated fatty acid ratios

Feline chronic gingivitis/stomatitis (FCGS) is a painful inflammatory disease in cats. Extraction of teeth, including all premolars and molars, has been shown to be the therapy of choice in cats not responding sufficiently to home care (e.g. tooth brushing) and/or medical treatment (corticosteroids and/or antibiotics). In this study, we hypothesize that a cat food with an omega‐6 polyunsaturated fatty acid (ω6 PUFA) to ω3 PUFA ratio of 10:1 reduces inflammation of the FCGS and accelerates soft tissue wound healing of the gingiva after dental extractions, compared to a cat food with a ω6:ω3 PUFA ratio of 40:1. The cats were fed diets with chicken fat and fish oil as sources of fatty acids. In one diet, part of the fish oil was replaced by safflower oil, resulting in two diets with ω6:ω3 PUFA ratios of 10:1 and 40:1. This double‐blinded study in two groups of seven cats revealed that dietary fatty acids influence the composition of plasma cholesteryl esters and plasma levels of inflammatory cytokines. The diet with the 10:1 ratio lowered PGD₂, PGE₂ and LTB₄ plasma levels significantly, compared to the diet with the 40:1 ratio (p = 0.05, p = 0.04, and p = 0.02 respectively). However, feeding diets with dietary ω6:ω3 PUFA ratios of 10:1 and 40:1, given to cats with FCGS for 4 weeks after extraction of all premolars and molars, did not alter the degree of inflammation or wound healing.     

Nasopharyngeal turbinates in brachycephalic dogs and cats

This retrospective study reports the presence and incidence of nasal turbinates in the nasopharynx (nasopharyngeal turbinates) in a population of brachycephalic dogs and cats exhibiting signs of upper respiratory disease. Medical records were reviewed for 53 brachycephalic dogs and 10 brachycephalic cats undergoing upper airway endoscopy. Nasopharyngeal turbinates were identified in 21% of brachycephalic animals, including 21% of dogs and 20% of cats. Pugs accounted for 32% of all dogs in the study population and 82% of dogs with nasopharyngeal turbinates. The presence of nasopharyngeal turbinates may play a role in upper airway obstruction in the brachycephalic airway syndrome.     

Computed tomographic evidence of bulla effusion in cats with sinonasal disease: 2001-2004

BACKGROUND: Sinonasal disease is common in cats; chronic inflammatory disease and neoplasia are diagnosed most frequently. Radiographic and computed tomographic (CT) findings in nasal disease have been reported, although involvement of other cranial structures has not been fully described to our knowledge. HYPOTHESIS: We hypothesized that neoplastic or inflammatory obstruction of the auditory tube associated with sinonasal disease could result in CT evidence of effusive bulla disease in affected cats. ANIMALS: 46 cats with sinonasal disease, 18 control cats. METHODS: CT images acquired in cats with (n = 46) and without (n = 18) sinonasal disease were reviewed for evidence of concurrent bulla effusion. CT findings of soft tissue or fluid opacity within the tympanic bulla or thickening of the bone of the bullae were considered evidence of effusive bulla disease. RESULTS: The prevalence of bulla effusion in cats with sinonasal disease was 28% (13/46) and was significantly higher than that observed in cats without sinonasal disease (1/18, P = .043). CT findings that were found in association with effusive bulla disease included imaging features of sinusitis and nasopharyngeal disease. The most common neoplasm associated with bulla effusion was nasopharyngeal lymphoma. Bulla effusion was not observed in any cat with nasal carcinoma. CONCLUSIONS AND CLINICAL IMPORTANCE: Findings of this study suggest that auditory canal dysfunction may play a larger role in feline sinonasal disease than was previously recognized. The implications of these findings for management of cats with chronic inflammatory or neoplastic sinonasal disease require further investigation.     

RADIOGRAPHIC APPEARANCE OF BRONCHOALVEOLAR CARCINOMA IN NINE CATS

Thoracic radiographs of nine cats with confirmed bronchoalveolar carcinoma (BAC) were reviewed retrospectively. Radiographic appearance of BAC was divided into three categories: mixed bronchoalveolar pattern, ill-defined alveolar mass, or mass with cavitation. In addition to these radiographic signs, all nine cats had evidence of some form of bronchial disease. Cavitary lesions were the most common finding (n = 5). In addition, three cats in this category had diffuse bronchointerstitial opacity and one cat had focal peribronchial cuffing. Five cats had either a mixed bronchoalveolar pattern with bronchiectasis (n = 3) or an ill-defined alveolar mass with peribronchial cuffing (n = 2). One cat had both a mixed bronchoalveolar pattern and a cavitary mass. Each of these nine cats had some form of bronchial disease (bronchointerstitial pattern, peribronchial cuffing, or bronchiectasis), which aids in the radiographic diagnosis of bronchoalveolar carcinoma and may represent airway metastasis.     

Feline extranodal lymphoma: response to chemotherapy and survival in 110 cats

O bjective : To determine response to treatment, survival and prognostic factors for feline extranodal lymphoma in the UK.
M ethods : Records of cats diagnosed with lymphoma of extranodal sites at seven referral centres were reviewed and information on signalment, tumour location, prior treatment and chemotherapy protocol recorded. Factors influencing response to treatment and survival were assessed.
R esults : One hundred and forty-nine cases met inclusion criteria. Sixty-nine cats had nasal lymphoma, 35 renal, 15 central nervous system, 11 laryngeal and 19 miscellaneous locations. Sixty-six cats received cyclophosphamide, vincristine, prednisolone, 25 Wisconsin-Madison doxorubicin-containing multi-agent protocol, 10 prednisolone alone and nine other combinations. The response rate for the 110 treated cats was 85·5 per cent. Of cyclophosphamide, vincristine, prednisolone treated cats 72·7 per cent achieved complete remission, median survival 239 days. Sixty-four per cent of Wisconsin-Madison treated cats achieved complete remission, median survival 563 days. Cats with nasal lymphoma achieving complete remission had the longest survival (749 days) and cats with central nervous system lymphoma the shortest (70 days). If complete remission was achieved, prior treatment with corticosteroids significantly reduced survival time.
C linical S ignificance : Cats with extranodal lymphoma respond to chemotherapy and achieve survival times comparable to other locations. Corticosteroid pretreatment reduced survival time in cats achieving complete remission.     

Evaluation of a modified castellated laryngofissure for alleviation of upper airway obstruction in dogs with laryngeal paralysis

A modified castellated laryngofissure procedure (castellated laryngofissure, vocal fold resection, and bilateral arytenoid lateralization) was performed on 12 dogs with bilateral laryngeal paralysis. Clinical signs of airway obstruction were assessed and a pulmonary function test (tidal breathing flow volume loop) was used to evaluate the severity of obstruction. The dogs were evaluated before surgery and at various periods from 4 days to 15 months after surgery. One dog died immediately after surgery and 3 dogs died due to nonrelated or unknown causes 1, 9, and 11 months after surgery. Clinical signs of upper airway obstruction disappeared or decreased in severity in the 11 dogs that recovered from surgery. Tidal breathing flow volume loop values were normal in 7 of 10 dogs evaluated within 5 to 189 days after surgery. The modified castellated laryngofissure procedure provided successful long-term relief of upper airway obstruction associated with bilateral laryngeal paralysis.     

Effects of genetic and environmental factors on chronic lower airway disease in horses

Background : Environment and genetics influence the manifestation of recurrent airway obstruction (RAO), but the associations of specific factors with mild, moderate, and severe clinical signs are unknown.
Hypothesis : We hypothesized that sire, feed, bedding, time outdoors, sex, and age are associated with clinical manifestations of mild, moderate, and severe lower airway disease.
Animals : Direct offspring of 2 RAO-affected Warmblood stallions (F1S1, n = 172; F1S2, n = 135); maternal half-siblings of F1S1 (mHSS1, n = 66); and an age-matched, randomly chosen control group (CG, n = 33).
Methods : A standardized questionnaire was used to assess potential risk factors and to establish a horse owner assessed respiratory signs index (HOARSI 1–4, from healthy to severe) according to clinical signs of lower airway disease.
Results : More F1S1 and F1S2 horses showed moderate to severe clinical signs (HOARSI 3 and HOARSI 4 combined, 29.6 and 27.3%, respectively) compared with CG and mHSS1 horses (9.1 and 6.2%, respectively; contingency table overall test, P < .001). Sire, hay feeding, and age (in decreasing order of strength) were associated with more severe clinical signs (higher HOARSI), more frequent coughing, and nasal discharge.
Conclusions and Clinical Relevance : There is a genetic predisposition and lesser but also marked effects of hay feeding and age on the manifestation of moderate to severe clinical signs, most markedly on coughing frequency. In contrast, mild clinical signs were not associated with sire or hay feeding in our populations.     

Upper airway obstruction (partial asphyxia) as the possible cause of exercise-induced pulmonary hemorrhage in the horse: An hypothesis

New evidence confirmed that over 90% of Thoroughbreds have some degree of recurrent laryngeal neuropathy (RLN). This and the recognition that anything less than full extension of the atlanto-occipital joint in a racehorse implied a reduction in patency of the nasopharynx provided the basis of the hypothesis that exercise-induced pulmonary hemorrhage (EIPH) may be caused by an upper airway obstruction and that partial asphyxia could be the primary mechanism. EIPH was associated most frequently with the congenital (hereditary), left-sided, hemiparetic form of RLN. Other obstructive diseases, such as laryngeal chondritis and subepiglottic cysts, may be rare causes. Atlanto-occipital flexion on its own might also cause EIPH but more commonly was thought to be a factor which added to the upper airway obstruction resulting from RLN. Supporting evidence for this hypothesis was derived from retrospective and prospective studies of medical records; from necropsy findings on naturally occurring and experimentally produced cases of EIPH; from surveys on the prevalence of RLN; and from a literature review on asphyxia in man and animals.Clinical evidence which supported the hypothesis indicated that EIPH was a clinical sign of RLN. The epidemiology and prevalence of EIPH and congenital RLN appeared to be the same and both problems had a similar historical antiquity. It was already known that bilateral RLN caused asphyxia and EIPH and it appeared from this study that so also does untilateral RLN also does. Clinical signs of both EIPH and RLN were induced by exercise; both were capable of causing exercise intolerance; both were exacerbated by high ambient temperatures and humidity; both problems were permanent and incurable. EIPH was associated with neither the clinical signs nor the pathology of any other pulmonary disease, but was consistently associated with RLN. For it to be argued that EIPH was predominantly a clinical sign of RLN it was necessary that both problems should belong to the same etiological family. Once again, this condition seemed to be met, as EIPH and RLN both appeared more likely to be hereditary rather than environmental diseases.The pulmonary pathology of EIPH was compatible with asphyxia and similar to asphyxia in man. The bilateral symmetry of pulmonary hemorrhage in EIPH suggested an upper airway location for its causal mechanism. Secondary mechanisms might include such factors as increased upper airway resistance, increased pulmonary negative pressure, pulmonary congestion, hypoxemia, hypercapnia, pulmonary hypertension, increased capillary-alveolar pressure gradient, pulmonary edema, increased capillary permeability and microrupture of alveolar walls.Attempts to disprove the hypothesis failed. A prospective study of 201 Thoroughbreds showing EIPH revealed that all had an upper airway obstruction and 98% had RLN. The authors concluded that the hypothesis appeared to be viable. EIPH would seem to be not only a clinical sign of congenital RLN but possibly the most common sign of this common disease. In relation to RLN, the hypothesis could be restated as follows:

a) A horse with laryngeal paraplegia, a rare form of RLN, may develop pulmonary hemorrhage with minimal exercise.

b) A horse with laryngeal hemiplegia, a more common form of RLN, may develop pulmonary hemorrhage with severe exercise.

c) A horse with laryngeal hemiparesis, the most common form of RLN, may develop pulmonary hemorrhage with maximal exercise.

From this a maxim could be distilled regarding the conditions which may be needed for inducing pulmonary hemorrhage: The greater the airway obstruction, the smaller the exercise stress; the smaller the airway obstruction, the greater the exercise stress. The study drew attention to the importance of including in the routine necropsy protocol an examination of the intrinsic muscles of the larynx. Asphyxia has not in the past been considered as a possible explanation for sudden death in the horse but it became apparent that this represented an omission.     

Upper airway obstruction in canine laryngeal paralysis

The type and the severity of airway obstruction in 30 dogs with bilateral laryngeal paralysis was assessed, using tidal breathing flow-volume loop (TBFVL) analysis. The dogs had clinical evidence of mild-to-severe upper airway obstruction (ie, respiratory distress, exercise intolerance, stridor). Seventeen dogs had TBFVL consistent with a nonfixed (inspiratory) obstruction, 10 had TBFVL indicative of a fixed (inspiratory/expiratory) obstruction, and 3 had normal TBFVL. Analysis of TBFVL confirmed that dogs with laryngeal paralysis have upper airway obstruction that differs in type and severity. Use of TBFVL provided a quantitative evaluation of airway obstruction and demonstrated the effects of bilateral laryngeal paralysis on the breathing patterns of dogs.     

Branchial remnant cysts of mature and juvenile horses

This clinical report describes 8 cases of branchial remnant cysts (BRC) in the horse. The horses presented with bimodal age distribution, with 5 cases in mature horses (age 8–21 years) and 3 in foals (age 1, 6 and 10 months). Mature cases presented for dysphagia or intermittent oesophageal obstruction (2/5), and retropharyngeal swelling (3/5), whereas respiratory stridor and visible mass were presenting complaints in the foals. Presence of a right‐sided (5/8) or dorsally located (2/8) palpable retropharyngeal mass of 3–35 cm diameter was noted clinically; one left‐sided mass was identified as an incidental finding at necropsy. Ultrasonography typically revealed a thick‐walled cyst containing hypoechoic fluid with dependent hyperechoic masses consistent with blood clots. Radiographs and upper airway endoscopy were also consistent with a retropharyngeal mass. Fluid cytology revealed chronic haemorrhage in 6/8 cases, and squamous epithelial cells in one case. Histopathology in all cases demonstrated an epithelium‐lined cyst with no smooth muscle or thyroid tissue. Two cases was subjected to euthanasia; one due to concurrent laryngeal anomalies and one due to financial constraints. The remaining 5 cases were treated via surgical excision. Post operatively, right laryngeal hemiplegia was observed in 4/5 cases. All previous reports of BRC in the horse have described juvenile individuals. Brachial remnant cyst should be considered a differential diagnosis for mature horses with masses of the throatlatch area and can be definitively diagnosed by the presence of squamous epithelium in aspirated fluid or by histopathology of the excised mass. Right recurrent laryngeal nerve damage is a common complication of surgery.