Epicardial pacemaker placement is associated with low complication rate and improved quality of life in dogs.

OBJECTIVE: To describe complications and outcomes in dogs undergoing epicardial pacemaker (EP) implantation, identify factors associated with survival, and investigate improvement in clinical signs and health-related quality of life (HRQoL) following surgery. ANIMALS: 52 client-owned dogs that underwent EP placement. METHODS: Medical records of 4 UK-based referral hospitals were searched and data reviewed retrospectively between July 2010 and December 2022. Factors contributing to outcomes after EP placement were assessed. RESULTS: The primary reasons for referral included collapsing/syncopal episodes (n = 36), exercise intolerance (15), and significant bradycardia (46). Third-degree atrioventricular block (39/52 [75%]) was the predominant indication for pacemaker placement, and common reasons for EP placement included previous transvenous pacemaker dislodgment/loss of capture (n = 12) and small body size (10). Intra- and postoperative complications were documented in 11% and 23% of dogs, respectively. Overall, 96% of dogs survived to discharge, and median follow-up time was 462 days (range, 31 to 3,139 days). Presence of coexistent myocardial or valvular disease at the time of EP implantation was associated with a reduced survival. Owners reported decreased clinical signs, increased activity levels, and improved HRQoL. CLINICAL RELEVANCE: Epicardial pacemaker implantation is a valuable option for dogs requiring artificial cardiac pacing. Complications were common but did not impact the overall outcome. Dogs with a coexisting cardiac pathology had a shorter life expectancy after EP placement, but their HRQoL appeared to be good, with an improvement in clinical signs and increased activity levels.

Longitudinal analysis of echocardiographic and cardiac biomarker variables in dogs with atrial fibrillation: The optimal rate control in dogs with atrial fibrillation II study.

BACKGROUND: Rate control (RC; meanHRHolter ≤ 125 bpm) increases survival in dogs with atrial fibrillation (AF). The mechanisms remain unclear. HYPOTHESIS/OBJECTIVES: Investigate echocardiographic and biomarker differences between RC and non-RC (NRC) dogs. Determine if changes post-anti-arrhythmic drugs (AAD) predict successful RC in subsequent Holter monitoring. Evaluate if early vs late RC affects survival. ANIMALS: Fifty-two dogs with AF. METHODS: Holter-derived mean heart rate, echocardiographic and biomarker variables from dogs receiving AAD were analyzed prospectively at each re-evaluation and grouped into RC or NRC. The primary endpoint was successful RC. Between group comparisons of absolute values, magnitude of change from admission to re-evaluations and end of study were performed using Mann-Whitney tests or unpaired t-tests. Logistic regression explored variables associated with inability to achieve RC at subsequent visits. Kaplan-Meier survival analysis was used to compare survival time of early vs late RC. RESULTS: At visit 2, 11/52 dogs were RC; at visit 3, 14/52 were RC; and at visit 4, 4/52 were RC. At the end of study, 25/52 remained NRC. At visit 2, both groups had increased cardiac dimensions, but NRC dogs had larger dimensions; biomarkers did not differ. At the end of study, RC showed decreased cardiac dimensions and end-terminal pro-brain natriuretic peptide (NT-proBNP) compared with NRC. No variables were useful at predicting RC success in subsequent visits. Survival analysis found no differences between early vs late RC. CONCLUSIONS AND CLINICAL IMPORTANCE: The RC dogs had decreased cardiac dimensions and NT-proBNP, suggesting HR-mediated reverse-remodeling might benefit survival, even with delayed RC achievement. Pursuit of RC is crucial despite initial failures.

The effect of obesity and subsequent weight reduction on cardiac morphology and function in cats.

BACKGROUND: In people, obesity is a risk factor for cardiovascular disease, associated with systemic hypertension, cardiac remodelling and systolic and diastolic dysfunction. Weight reduction can reverse myocardial remodelling and reduce risk of subsequent cardiovascular disease. In cats, far less is known regarding the effects of obesity and subsequent weight reduction on cardiovascular morphology and function. This prospective study aimed to assess cardiac morphology and function, heart rate variability, cardiac biomarkers and body composition before and after controlled weight reduction in cats with obesity. Body composition analysis (by dual energy x-ray absorptiometry, DEXA) and cardiovascular assessment (echocardiography, systemic arterial systolic blood pressure, electrocardiography, plasma cardiac biomarkers) were performed prior to weight management in twenty cats with obesity. These investigations were repeated in eleven cats that reached target weight. RESULTS: At baseline, systemic hypertension was not documented, but the majority of cats with obesity (15 out of 19) showed echocardiographic evidence of diastolic dysfunction. Eleven of 20 cats had increased maximal end-diastolic septal or left ventricular free wall thickness (≥ 6.0 mm) at baseline. Median (interquartile range) percentage of weight lost in the cats reaching target weight was 26% (17-29%), with a median reduction in body fat mass of 45% (26-64%). Both the end-diastolic left ventricular free wall (median magnitude of change -0.85 mm, IQR -0.05 mm to -1.55 mm, P = 0.019; median percentage reduction 14.0%) and end-diastolic interventricular septum (median magnitude of change -0.5 mm, IQR -0.2 mm to -1.225 mm, P = 0.047; median percentage reduction 7.9%) thickness decreased after weight reduction. Following weight reduction, pulsed wave tissue Doppler imaging of the left ventricular free wall was consistent with improved diastolic function in 4 out of 8 cats, however there was no significant difference in overall diastolic function class. Further, there was no change in heart rate variability or cardiac biomarkers with weight reduction. CONCLUSION: An increase in left ventricular wall thickness and diastolic dysfunction were common echocardiographic features in cats with obesity within our study and may be reversible with successful weight and fat mass loss. Further studies are required to clarify the clinical consequences of these findings.

Automated echocardiographic left ventricular dimension assessment in dogs using artificial intelligence: Development and validation.

BACKGROUND: Artificial intelligence (AI) could improve accuracy and reproducibility of echocardiographic measurements in dogs. HYPOTHESIS: A neural network can be trained to measure echocardiographic left ventricular (LV) linear dimensions in dogs. ANIMALS: Training dataset: 1398 frames from 461 canine echocardiograms from a single specialist center. VALIDATION: 50 additional echocardiograms from the same center. METHODS: Training dataset: a right parasternal 4-chamber long axis frame from each study, labeled by 1 of 18 echocardiographers, marking anterior and posterior points of the septum and free wall. VALIDATION DATASET: End-diastolic and end-systolic frames from 50 studies, annotated twice (blindly) by 13 experts, producing 26 measurements of each site from each frame. The neural network also made these measurements. We quantified its accuracy as the deviation from the expert consensus, using the individual-expert deviation from consensus as context for acceptable variation. The deviation of the AI measurement away from the expert consensus was assessed on each individual frame and compared with the root-mean-square-variation of the individual expert opinions away from that consensus. RESULTS: For the septum in end-diastole, individual expert opinions deviated by 0.12 cm from the consensus, while the AI deviated by 0.11 cm (P = .61). For LVD, the corresponding values were 0.20 cm for experts and 0.13 cm for AI (P = .65); for the free wall, experts 0.20 cm, AI 0.13 cm (P < .01). In end-systole, there were no differences between individual expert and AI performances. CONCLUSIONS AND CLINICAL IMPORTANCE: An artificial intelligence network can be trained to adequately measure linear LV dimensions, with performance indistinguishable from that of experts.

Optimal rate control in dogs with atrial fibrillation-ORCA study-Multicenter prospective observational study: Prognostic impact and predictors of rate control.

BACKGROUND: The optimal heart rate (HR) in dogs with atrial fibrillation (AF) is unknown. Impact of HR on survival needs elucidation. HYPOTHESIS/OBJECTIVES: Dogs with a 24 hours Holter-derived meanHR ≤125 beats per minute (bpm; rate controlled) survive longer than dogs with higher meanHR. We further aimed to determine which variables predict ability to achieving rate control. ANIMALS: Sixty dogs with AF. METHODS: Holter-derived meanHR, clinical, echocardiographic, and biomarker variables were analyzed prospectively. Survival was recorded from time of rate control, with all-cause mortality as primary endpoint. Cox proportional hazards analysis identified variables independently associated with survival; Kaplan-Meier survival analysis estimated the median survival time of dogs with meanHR ≤125 bpm vs >125 bpm. Logistic regression explored baseline variables associated with inability to achieve rate control. RESULTS: Structural heart disease was present in 56/60 dogs, 50/60 had congestive heart failure, and 45/60 died. Median time to all-cause death was 160 days (range, 88-303 days), dogs with meanHR >125 bpm (n = 27) lived 33 days (95% confidence interval [CI], 15-141 days), dogs with meanHR ≤125 bpm (n = 33) lived 608 days (95% CI, 155-880 days; P < .0001). Congenital heart disease and N-terminal pro-B-type natriuretic peptide were independently associated with higher risk of death (P < .01 and <.0001, respectively) whereas meanHR ≤125 bpm decreased the risk of death (P < .001). Increased left atrial size, increased C-reactive protein concentration and lower blood pressure at admission were associated with failure to achieve rate control. CONCLUSIONS AND CLINICAL IMPORTANCE: Rate control affects survival; an optimal target meanHR <125 bpm should be sought in dogs with AF. Baseline patient variables can help predict if rate control is achievable.

Evaluation of serum cardiac troponin-I concentrations for diagnosis of infective endocarditis in dogs.

BACKGROUND: Infective endocarditis (IE) in dogs is associated with severe disease and a high case fatality rate but often presents with nonspecific clinical signs. HYPOTHESIS/OBJECTIVES: Serum concentration of cardiac troponin-I (cTnI) is elevated in dogs with IE and can differentiate dogs with IE from dogs with other diseases with similar clinical features. Concentration of serum cTnI is negatively correlated with survival time in dogs with IE. ANIMALS: Seventy-two client-owned dogs; 29 with IE, 27 with stage-B myxomatous mitral valve disease (MMVD), and 16 with immune-mediated disease (IMD). METHODS: Retrospective clinical cohort study. Concentration of serum cTnI was measured in all dogs at time of diagnosis. Clinical findings and echocardiographic interpretation were also recorded. Statistical analyses included Kruskal-Wallis test, pairwise Mann-Whitney U tests, receiver operator characteristic, and Cox proportional hazards. RESULTS: Serum concentration of cTnI was significantly higher in the IE group (0.69 ng/mL [0.03-80.8]) than in the MMVD (0.05 ng/mL [0.02-0.11], P < .001) and IMD groups (0.05 ng/mL [0.03-0.57], P < .001). Increased cTnI was a moderately accurate predictor of IE (area under the curve 0.857 (95% confidence interval [CI] 0.745-0.968, P < .001). A cTnI cutoff of 0.625 ng/mL had 100% specificity (95% CI 90%-100%) and 52% sensitivity (95% CI 33%-70%) in this study sample. There was no association between cTnI concentration and survival time in dogs with IE (hazard ratio 1.013, 95% CI 0.993-1.034, P = .2). CONCLUSIONS AND CLINICAL IMPORTANCE: Cardiac troponin-I concentrations are higher in dogs with IE compared to dogs with preclinical MMVD or IMD. In dogs with a compatible clinical presentation, serum cTnI concentrations >0.625 ng/mL are supportive of IE.

Clinical features and outcome of dogs and cats with bidirectional and continuous right-to-left shunting patent ductus arteriosus.

BACKGROUND: Studies describing the clinical progression of animals with reverse patent ductus arteriosus (PDA) are lacking. OBJECTIVES: To describe the signalment, presenting signs, echocardiographic features, and survival in a group of dogs and cats with bidirectional and continuous right-to-left PDA. ANIMALS: Forty-six client-owned animals included, comprising 43 dogs and 3 cats with bidirectional or continuous right-to-left PDA. METHODS: Retrospective multicenter study. Medical records and echocardiographic findings reviewed from animals diagnosed with bidirectional or continuous right-to-left PDA. Impact of ductal morphology, spectral Doppler flow profile, PCV, sildenafil treatment at presentation, sildenafil dose, severity of pulmonary hypertension, general anesthesia with or without surgery and the presence of right-sided congestive heart failure (R-CHF) on crude mortality rate were evaluated via Mantel-Cox log rank comparison of Kaplan-Meier survival curves. Univariable and multivariable Cox proportional hazards analysis was performed, and hazard ratio (HR) (95% confidence intervals [CI]) was presented. RESULTS: Hindlimb collapse was the most common presenting sign in dogs (n = 16). Clinical signs in cats were variable. Median survival time was 626 days in dogs (range 1-3628 days). Dogs with R-CHF had a shorter median survival time (58 days vs 1839 days, P = .03). Dogs treated with sildenafil at initial presentation survived longer (1839 days vs 302 days, P = .03), which was the only independent predictor of survival (HR 0.35, CI 0.15-0.86, P = 0.021). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs and cats with reverse PDA have a variable clinical presentation and prognosis. Survival time was longer in animals prescribed sildenafil at diagnosis. Dogs with R-CHF at presentation have a worse overall outcome.

Association of diet with left ventricular wall thickness, troponin I and IGF-1 in cats with subclinical hypertrophic cardiomyopathy.

BACKGROUND: Cats with subclinical hypertrophic cardiomyopathy (sHCM) have elevated serum insulin and serum amyloid A concentrations correlating with the degree of cardiac hypertrophy. Diet might affect these and other cardiac variables. OBJECTIVE: Evaluate the effect of a complete, balanced diet with restricted starch and supplemented with eicosapentaenoic acid + docosahexaenoic acid (EPA + DHA) on echocardiographic variables and cardiac biomarkers in cats with sHCM. ANIMALS: Forty-four client-owned cats with sHCM. METHODS: A prospective, randomized, double-blind, multicenter study enrolled cats with end-diastole interventricular septum thickness (IVSd) or left ventricular wall thickness (LVWd) ≥6 mm, or both. Nonsedated, fasted cats were examined at baseline and after 6 and 12 months of Test (restricted starch and EPA + DHA supplements) (n = 23) or Control (unrestricted starch without EPA + DHA supplementation) (n = 21) diet. Assessments included auscultation, body weight, body condition score, echocardiography and blood analysis. Linear and generalized mixed models analyzed diet, time and diet * time interactions (5% significance level). RESULTS: No differences between diet groups were significant for any variable at any timepoint. There were significant decreases in the Test but not Control group in maximum IVSd (P = .03), maximum LVWd (P = .02) and insulin-like growth factor-1 levels (P = .04) after 12 months, and in ultrasensitive cardiac troponin I (cTnI) (P = .001) after 6 months; effect sizes (95% confidence interval) were 0.53 (0.09; 0.99), 0.63 (0.18; 1.09), 0.61 (0.16; 1.07), and 0.37 (-0.06; 0.8), respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Cats with sHCM fed Test diet had significant decreases in echocardiographic variables of sHCM and in cTnI and IGF-1.

Effect of pimobendan on left atrial function in dogs with preclinical myxomatous mitral valve disease.

Background: Left atrial (LA) function is an important determinant of the left ventricular (LV) filling, playing a key role in maintaining optimal cardiac performance. Pimobendan is a phosphodiesterase III inhibitor with positive inotropic and vasodilator effects. The present study aims to investigate the effects of pimobendan on LA function in dogs with stage B2 myxomatous mitral valve disease (MMVD). Aim: The aim of this investigation was to study the effects of pimobendan on LA function in dogs with preclinical MMVD. Methods: Twenty-seven dogs with stage B2 MMVD were retrospectively included. LA function was assessed before and 1-6 months following pimobendan initiation. For each dog, two-dimensional (2D) echocardiography was performed to assess LA diameter and volume for each phase of the LA cycle and to assess complete, passive, and active LA function. Pulsed-wave tissue Doppler imaging (TDI) of the left ventricular longitudinal myocardial velocity associated with atrial contraction (A'), both at the level of the interventricular septum and the LV free wall, was also used as an indicator of LA function. Results: There were no significant differences in any of the left atrial variables pre- and posttreatment. Conclusion: Echocardiographic estimates of LA function by 2D diameters and volumes and TDI A' in dogs with MMVD do not change after treatment with pimobendan.

PRELIMINARY CHARACTERIZATION OF DILATED CARDIOMYOPATHY IN A CAPTIVE POPULATION OF BANDED MONGOOSES (MUNGOS MUNGO).

Between 2006 and 2015, a high incidence of dilated cardiomyopathy (DCM) was diagnosed in a captive population of banded mongooses (Mungos mungo) at Chester Zoo, United Kingdom. The aim of this study was to characterize DCM in these mongooses in order to raise awareness of this condition and help inform management and clinical decisions. Prospective clinical assessments, including echocardiography, radiography, and cardiac biomarkers, were carried out in four mongooses remaining in the collection. Radiographs from 15 mature mongooses were reviewed and cardiac size and metrics assessed. Ten postmortem reports and the histologic sections from nine of these cases were reviewed for cardiac lesions. Echocardiographic findings were consistent with a diagnosis of preclinical DCM in one out of the four cases assessed, and it was considered equivocal in a second case. Taurine levels were within normal limits for domestic carnivores. Radiographs in seven mongooses showed right-sided or generalized cardiomegaly. The width of the heart in intercostal spaces and vertebral-tracheal angle on the lateral view were the most-discriminatory radiographic variables for diagnosis of cardiac disease. At necropsy, there was gross pathological evidence consistent with DCM in seven out of 10 mongooses examined. Histopathologically, mild multifocal fibrosis and rare intermyofiber edema were observed. This study provides preliminary evidence that DCM occurs in captive banded mongoose, but etiology and wider prevalence need to be determined.

Cytological diagnosis of cardiac masses with ultrasound guided fine needle aspirates.

BACKGROUND: Cardiac masses are uncommon in the canine population. When present, an attempt should be made to obtain a definitive diagnosis. Our goal with this case series was to report that as long as anatomic location permits, obtaining fine needle aspirates (FNAs) for cytological evaluation is practical, safe, and may provide a definitive diagnosis. METHODS: Our database has been retrospectively searched for cases where FNA of cardiac masses have been performed. RESULTS: A total of six cases were retrieved. Four dogs were under general anaesthesia and two were sedated. Ultrasound guided transthoracic FNAs were obtained in all cases with only minor complications: mild self-limiting pericardial effusion (n = 1) and one ventricular ectopic complex (n = 1). All dogs were closely monitored during the procedure (pulse oximetry, electrocardiography and blood pressure). A diagnosis was obtained in all cases: inflammation (n = 1), haemangiosarcoma (n = 2), sarcoma (n = 2) and chemodectoma (n = 1). CONCLUSION: A cytological diagnosis allows clinicians to make appropriate clinical decisions, has dramatic impact on treatment recommendations and gives information about prognosis.

Pulmonary artery dissection in eight dogs with patent ductus arteriosus.

OBJECTIVES: To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA). ANIMALS: Eight dogs. METHODS: Retrospective case series. RESULTS: Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure. CONCLUSIONS: Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome.

Septic pericarditis and myocardial abscess in an English Springer spaniel.

Septic pericarditis and myocardial abscess are rare conditions in dogs. They are usually caused by foreign bodies, penetrating wounds, systemic infections or extension of local infections such as endocarditis, pleuritis or pulmonary infections to the myocardial tissue. Here we report a septic pericardial effusion and myocardial abscess in a young English Springer spaniel presenting with a long history of pyrexia and lethargy. No cause could clearly be identified although a penetrating injury or dissolving foreign body was highly suspected. The patient was successfully treated with a surgical approach in combination with broad spectrum antibacterials resulting in resolution of clinical signs without recurrence of the infection.

Expression of matrix metalloproteinases, their inhibitors, and lysyl oxidase in myocardial samples from dogs with end-stage systemic and cardiac diseases.

OBJECTIVE: To compare the degree of mRNA expression for matrix metalloproteinases (MMPs), tissue inhibitors (TIMPs), and lysyl oxidase in myocardial samples from dogs with cardiac and systemic diseases and from healthy control dogs. SAMPLE: Myocardial samples from the atria, ventricles, and septum of 8 control dogs, 6 dogs with systemic diseases, 4 dogs with dilated cardiomyopathy (DCM), and 5 dogs with other cardiac diseases. PROCEDURES: Degrees of mRNA expression for MMP-1, -2, -3, -9, and -13; TIMP-1, -2, -3, and -4; and lysyl oxidase were measured via quantitative real-time PCR assay. Histologic examination of the hearts was performed to identify pathological changes. RESULTS: In myocardial samples from control dogs, only TIMP-3 and TIMP-4 mRNA expression was detected, with a significantly higher degree in male versus female dogs. In dogs with systemic and cardiac diseases, all investigated markers were expressed, with a significantly higher degree of mRNA expression than in control dogs. Furthermore, the degree of expression for MMP-2, TIMP-1, and TIMP-2 was significantly higher in dogs with DCM than in dogs with systemic diseases and cardiac diseases other than DCM. Expression was generally greater in atrial than in ventricular tissue for MMP-2, MMP-13, and lysyl oxidase in samples from dogs with atrial fibrillation. CONCLUSIONS AND CLINICAL RELEVANCE: Degrees of myocardial MMP, TIMP, and lysyl oxidase mRNA expression were higher in dogs with cardiac and systemic diseases than in healthy dogs, suggesting that expression of these markers is a nonspecific consequence of end-stage diseases. Selective differences in the expression of some markers may reflect specific pathogenic mechanisms and may play a role in disease progression, morbidity and mortality rates, and treatment response.

Myocardial cytokine expression in dogs with systemic and naturally occurring cardiac diseases.

OBJECTIVE: To compare myocardial cytokine expression in dogs with naturally occurring cardiac or systemic diseases and dogs without cardiac or systemic diseases (control dogs) SAMPLE: Myocardial tissue samples from 7 systemic disease-affected dogs (SDDs), 7 cardiac disease-affected dogs (CDDs), and 8 control dogs. PROCEDURES: mRNA expression of interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-ß1, TGF-ß2, TGF-ß3, and growth differentiation factor-15 in myocardial tissue samples obtained from CDDs, SDDs, and control dogs were analyzed via quantitative PCR assays. RESULTS: In control dogs, only mRNA for TNF-α, TGF-ß1, and TGF-ß3 was detected; concentrations were significantly higher in male than in female dogs. In SDDs and CDDs, all cytokines, growth factors, and growth differentiation factor-15 were expressed. Compared with findings in SDDs, IL-1, IL-6, IL-8, IL-10, TNF-α, and IFN-γ expression was significantly increased in CDDs; specifically, IL-1, IL-8, TNF-α, TGF-ß1, and TGF-ß3 expression was increased in the atria and IL-8, IL-10, TNF-α, and IFN-γ expression was increased in the ventricles of CDDs. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggested that the alterations in cytokine expression in SDDs and CDDs, compared with control dog findings, were a result of inflammatory system activation. The differences in cytokine expression in atria and ventricles between SDDs and CDDs were suggestive of different remodeling processes. A better knowledge of myocardial involvement in SDDs and of immune regulation in CDDs might beneficially affect morbidity and mortality rates and provide new treatment approaches.

Underlying diseases in dogs referred to a veterinary teaching hospital because of dyspnea: 229 cases (2003-2007).

OBJECTIVE: To identify the most frequent underlying diseases in dogs examined because of dyspnea and determine whether signalment, clinical signs, and duration of clinical signs might help guide assessment of the underlying condition and prognosis. DESIGN: Retrospective case series. ANIMALS: 229 dogs with dyspnea. PROCEDURES: Case records of dogs referred for dyspnea were reviewed and grouped according to location or etiology (upper airway, lower respiratory tract, pleural space, cardiac diseases, or obesity and stress). Signalment, clinical signs at initial examination, treatment, and survival time were analyzed. RESULTS: Upper airway (n = 74 [32%]) and lower respiratory tract (76 [33%]) disease were the most common diagnoses, followed by pleural space (44 [19%]) and cardiac (27 [12%]) diseases. Dogs with upper airway and pleural space disease were significantly younger than dogs with lower respiratory tract and cardiac diseases. Dogs with lower respiratory tract and associated systemic diseases were significantly less likely to be discharged from the hospital. Dogs with diseases that were treated surgically had a significantly better outcome than did medically treated patients, which were significantly more likely to be examined on an emergency basis with short duration of clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs examined because of dyspnea, young dogs may be examined more frequently with breed-associated upper respiratory tract obstruction or pleural space disease after trauma, whereas older dogs may be seen more commonly with progressive lower respiratory tract or acquired cardiac diseases. Nontraumatic acute onset dyspnea is often associated with a poor prognosis, but stabilization, especially in patients with cardiac disease, is possible. Obesity can be an important contributing or exacerbating factor in dyspneic dogs.

Biliothorax in a Siamese cat.

A 2-year-old male neutered cat presented for further investigation of biliothorax. The cat was initially treated for pyothorax, including bilateral chest drains for lavage of the pleural space. Five days later, the pleural effusion turned clear-yellow and had a bilirubin concentration of 427 µmol/l compared to the serum bilirubin concentration of 15 µmol/l. Exploratory surgery revealed a 2mm tear in the diaphragm, with a corresponding 2mm defect in the diaphragmatic surface of the gall bladder, creating a fistula between the gall bladder and the pleural cavity. The defects were repaired routinely and the cat made a full recovery. It was suspected that the tears had been created at the time of the thoracostomy tube placement. Biliothorax has not been described before in a cat, and appears to be a rare complication following thoracostomy tube placement.