Long-term restoration of cardiac dystrophin expression in golden retriever muscular dystrophy following rAAV6-mediated exon skipping.

Although restoration of dystrophin expression via exon skipping in both cardiac and skeletal muscle has been successfully demonstrated in the mdx mouse, restoration of cardiac dystrophin expression in large animal models of Duchenne muscular dystrophy (DMD) has proven to be a challenge. In large animals, investigators have focused on using intravenous injection of antisense oligonucleotides (AO) to mediate exon skipping. In this study, we sought to optimize restoration of cardiac dystrophin expression in the golden retriever muscular dystrophy (GRMD) model using percutaneous transendocardial delivery of recombinant AAV6 (rAAV6) to deliver a modified U7 small nuclear RNA (snRNA) carrying antisense sequence to target the exon splicing enhancers of exons 6 and 8 and correct the disrupted reading frame. We demonstrate restoration of cardiac dystrophin expression at 13 months confirmed by reverse transcription-PCR (RT-PCR) and immunoblot as well as membrane localization by immunohistochemistry. This was accompanied by improved cardiac function as assessed by cardiac magnetic resonance imaging (MRI). Percutaneous transendocardial delivery of rAAV6 expressing a modified U7 exon skipping construct is a safe, effective method for restoration of dystrophin expression and improvement of cardiac function in the GRMD canine and may be easily translatable to human DMD patients.

Percutaneous transendocardial delivery of self-complementary adeno-associated virus 6 achieves global cardiac gene transfer in canines.

Achieving efficient cardiac gene transfer in a large animal model has proven to be technically challenging. Previous strategies have used cardiopulmonary bypass or dual catheterization with the aid of vasodilators to deliver vectors, such as adenovirus, adeno-associated virus (AAV), or plasmid DNA. Although single-stranded AAV (ssAAV) vectors have shown the greatest promise, they suffer from delayed expression, which might be circumvented using self-complementary vectors. We sought to optimize cardiac gene transfer using a percutaneous transendocardial injection catheter to deliver adeno-associated viral vectors to the canine myocardium. Four vectors were evaluated--ssAAV9, self-complementary AAV9 (scAAV9), scAAV8, scAAV6--so that comparison could be made between single-stranded and self-complementary vectors as well as among serotypes 9, 8, and 6. We demonstrate that scAAV is superior to ssAAV and that AAV 6 is superior to the other serotypes evaluated. Biodistribution studies revealed that vector genome copies were 15-4,000 times more abundant in the heart than in any other organ for scAAV6. Percutaneous transendocardial injection of scAAV6 is a safe, effective method to achieve efficient cardiac gene transfer.

Percutaneous Transendocardial Delivery of Self-complementary Adeno-associated Virus 6 Achieves Global Cardiac Gene Transfer in Canines.

Achieving efficient cardiac gene transfer in a large animal model has proven to be technically challenging. Previous strategies have used cardiopulmonary bypass or dual catheterization with the aid of vasodilators to deliver vectors, such as adenovirus, adeno-associated virus (AAV), or plasmid DNA. Although single-stranded AAV (ssAAV) vectors have shown the greatest promise, they suffer from delayed expression, which might be circumvented using self-complementary vectors. We sought to optimize cardiac gene transfer using a percutaneous transendocardial injection catheter to deliver adeno-associated viral vectors to the canine myocardium. Four vectors were evaluated-ssAAV9, self-complementary AAV9 (scAAV9), scAAV8, scAAV6-so that comparison could be made between single-stranded and self-complementary vectors as well as among serotypes 9, 8, and 6. We demonstrate that scAAV is superior to ssAAV and that AAV 6 is superior to the other serotypes evaluated. Biodistribution studies revealed that vector genome copies were 15-4,000 times more abundant in the heart than in any other organ for scAAV6. Percutaneous transendocardial injection of scAAV6 is a safe, effective method to achieve efficient cardiac gene transfer.

Assessment of serum N-terminal pro-B-type natriuretic peptide concentration for differentiation of congestive heart failure from primary respiratory tract disease as the cause of respiratory signs in dogs.

OBJECTIVE: To determine whether serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is useful in discriminating between cardiac and noncardiac (ie, primary respiratory tract disease) causes of respiratory signs (ie, coughing, stertor, stridor, excessive panting, increased respiratory effort, tachypnea, or overt respiratory distress) in dogs. DESIGN: Multicenter cross-sectional study. ANIMALS: P 115 dogs with respiratory signs. PROCEDURES: Dogs with respiratory signs were solicited for study. Physical examination, thoracic radiography, and echocardiography were used to determine whether respiratory signs were the result of cardiac (ie, congestive heart failure) or noncardiac (ie, primary respiratory tract disease) causes. Serum samples for NT-proBNP assay were obtained at time of admission for each dog. Receiver-operating characteristic curves were constructed to determine the ability of serum NT-proBNP concentration to discriminate between cardiac and noncardiac causes of respiratory signs. RESULTS: Serum NT-proBNP concentration was significantly higher in dogs with cardiac versus noncardiac causes of respiratory signs. In dogs with primary respiratory tract disease, serum NT-proBNP concentration was significantly higher in those with concurrent pulmonary hypertension than in those without. A serum NT-proBNP cutoff concentration > 1,158 pmol/L discriminated between dogs with congestive heart failure and dogs with primary respiratory tract disease with a sensitivity of 85.5% and a specificity of 81.3%. CONCLUSIONS AND CLINICAL RELEVANCE: Measuring serum NT-proBNP concentration in dogs with respiratory signs helps to differentiate between congestive heart failure and primary respiratory tract disease as an underlying cause.

"Candidatus Mycoplasma haemominutum" infections in 21 client-owned cats.

Medical records were reviewed for 21 clinically ill cats testing positive for deoxyribonucleic acid (DNA) of "Candidatus Mycoplasma haemominutum" in their blood. Fever, anorexia, lethargy, and anemia were among the most common abnormalities recorded. Thirteen cats were anemic; seven had evidence of other diseases that could have been the primary cause of anemia or activated hemoplasmosis. For six cats, "Candidatus Mycoplasma haemominutum" was the only recognizable cause of the anemia. Of these cats, anemia resolved in one cat without treatment and in three cats that were treated with doxycycline, with or without prednisone. Results of the study suggest that this hemoplasma species can be a primary pathogen in cats.

Cardiomyopathy in a Harris hawk (Parabuteo unicinctus).

CASE DESCRIPTION An adult sexually intact female Harris hawk (Parabuteo unicinctus) housed at a wildlife hospital was evaluated because of acute collapse during an educational exhibition. CLINICAL FINDINGS Physical examination and hematologic analysis revealed no abnormalities; radiography revealed findings consistent with a previous tibiotarsal fracture. Coelioscopy with histologic examination and fungal culture of lung and air sac samples revealed anthracosis but no fungal infection. The hawk was discharged and temporarily removed from the education program; 1 month later, upon reintroduction into the program, it collapsed again. Physical examination and hematologic findings were similar to those after the first episode. Transcoelomic and transesophageal echocardiography and CT angiocardiography findings were consistent with cardiomyopathy. TREATMENT AND OUTCOME Initial cardiac treatment included furosemide (0.5 mg/kg [0.23 mg/lb], PO, q 24 h) and pimobendan (10 mg/kg [4.5 mg/lb], PO, q 12 h). After 10 days of treatment, peak and trough plasma concentrations of pimobendan were measured at 25, 196 and 715.97 ng/mL, respectively; the dosage was decreased to 0.25 mg/kg (0.11 mg/lb), PO, every 12 hours. No overt signs of toxicosis were detected. A sample was collected to reevaluate plasma pimobendan concentration after 30 days of treatment; results were not obtained prior to the patient's death but revealed a peak concentration of 16.8 ng/mL, with an undetectable trough concentration. The hawk was found dead 6 months after initial evaluation. Necropsy revealed cardiomegaly, but histologic examination did not reveal an inciting cause of cardiac dysfunction. CLINICAL RELEVANCE Cardiac disease in raptors may be underreported. Transcoelomic and transesophageal echocardiography and CT angiography provided useful information for the diagnosis of cardiac disease in the hawk of this report.

Outcome of a heartworm treatment protocol in dogs presenting to Louisiana State University from 2008 to 2011: 50 cases.

Since 2008, the American Heartworm Society has recommended using a three-dose melarsomine protocol (a single intramuscular injection of melarsomine dihydrochloride at 2.5mg/kg, followed approximately 1 month later with two doses administered 24h apart) for all heartworm-positive dogs, with doxycycline given at 10mg/kg twice daily for 4 weeks prior to administration of melarsomine. To report the efficacy and side effects of this standard heartworm treatment protocol in 50 dogs presenting to our hospital from 2008 to 2011, information on the history, clinical, laboratory, and diagnostic imaging findings and treatment was obtained from medical records. When possible, additional follow-up information was obtained through telephone interviews with referring veterinarians and owners. Twenty-six dogs (52%) experienced minor complications, such as injection site reactions, gastrointestinal signs (vomiting, diarrhea, inappetance), and behavioral changes (lethargy, depression) during or after heartworm treatment. Twenty-seven dogs (54%) experienced respiratory signs (coughing, dyspnea) and heart failure attributed to progressive heartworm disease and worm death. Seven dogs (14%) died within the treatment period. Owners frequently reported behavioral changes, such as depression and lethargy, suspected to be secondary to pain. Fifty percent of owners surveyed indicated that, prior to the diagnosis, they either were not currently administering heartworm preventative, or they had recently adopted the dog from a shelter that did not administer preventatives. After treatment, 100% were administering heartworm preventatives to their pet. Eighteen dogs (36%) received a heartworm antigen test 6 months after adulticide therapy, 12 of which tested negative and six tested positive. Four of the dogs with a positive test at 6 months had negative tests 1 month later with no additional treatment. Adverse effects were common with the recommended protocol, but the majority of these were mild. Dogs in Class 1 (i.e., heartworm positive but otherwise largely lacking clinical evidence of disease) did not experience any major adverse effects or death.

Computed tomography features of bronchial and non-bronchial collateral arterial circulation development in a dog diagnosed with multiple chronic pulmonary thrombi.

A 5 year-old female Lhasa Apso was diagnosed with a large right pulmonary artery thrombus, multiple smaller pulmonary thrombi, and pulmonary hypertension. In addition, thoracic computed tomography angiography revealed numerous periesophageal arterial vessels, tortuous and dilated bronchial arteries, and an enlarged tortuous left phrenic artery, consistent with systemic bronchial and non-bronchial collateral arterial circulation development. These features of chronic pulmonary arterial thrombi have not been described in dogs but are recognized in people. One year after the diagnosis, the dog was still alive and there were no clinical signs reported.

Effect of torsemide and furosemide on clinical, laboratory, radiographic and quality of life variables in dogs with heart failure secondary to mitral valve disease.

OBJECTIVES: Diuretic therapy reduces preload and relieves congestion secondary to cardiac dysfunction. Torsemide (torasemide) is a loop diuretic with longer duration of action, decreased susceptibility to diuretic resistance, and adjunctive aldosterone antagonist properties compared with furosemide. We hypothesized that torsemide would be well tolerated and no less effective than furosemide at diuresis, control of clinical signs, and maintenance of quality of life (QOL) in dogs with congestive heart failure (CHF). ANIMALS, MATERIALS AND METHODS: Seven client-owned dogs with stable CHF receiving twice daily oral furosemide and adjunctive medications. Utilizing a double-blinded, randomized, crossover design, dogs were administered either oral furosemide at their current dose or an equivalent oral dose of torsemide (1/10 of the daily furosemide dose divided into twice daily dosing) on day 0. Crossover occurred at day 7 and the study ended on day 14. Clinical, laboratory, radiographic, and QOL variables were evaluated on days 0, 7 and 14. RESULTS: No dogs developed recurrent CHF during the study. Mean furosemide dose on day 0 was 5.13 mg/kg/day (range 2.8-9.6). Following torsemide treatment, creatinine (P = 0.020), urea nitrogen (P = 0.013), phosphorus (P = 0.032), albumin (P = 0.019), carbon dioxide (P = 0.015) and anion gap (P = 0.005) were significantly increased, and urine specific gravity (P = 0.004) and chloride (P = 0.021) were significantly decreased compared with furosemide dosing. No differences in QOL were found. CONCLUSIONS: Results indicate that torsemide is equivalent to furosemide at controlling clinical signs of CHF in dogs and is likely to achieve greater diuresis vs. furosemide. Larger clinical trials evaluating torsemide as a first or second-line loop diuretic for congestive heart failure in dogs are warranted.

Evaluation of shock waveform configuration on the defibrillation capacity of implantable cardioverter defibrillators in dogs.

BACKGROUND: Implantable cardioverter defibrillators (ICD) are programmed to detect ventricular arrhythmias and terminate them by delivering an electrical shock. A defibrillation threshold (DFT) at least 10 J below the maximum device output is recommended for successful therapy. Shock waveform configuration is a programmable parameter used to achieve a low DFT. It is hypothesized that a fixed-pulse configuration results in lower defibrillation energy requirements than a fixed-tilt configuration. ANIMALS: 10 mongrel dogs. MATERIALS AND METHODS: ICD generator and transvenous lead were surgically implanted. Defibrillation threshold was determined using a protocol guided by the upper limit of vulnerability. Fixed-pulse and fixed-tilt (50%/50%) waveform configurations were tested in a random order. Plasma cardiac troponin I (cTnI) was measured for signs of myocardial injury. RESULTS: The experiment was completed in 9 dogs. Overall mean DFT value was 424 ± 88 V (9.2 ± 3.9 J). Mean differences among voltage, energy and impedance at the DFT for fixed-pulse (422 ± 97 V, 9.1 ± 4.2 J, 62.6 ± 13.8 Ω) and fixed-tilt (426 ± 83 V, 9.3 ± 3.8 J, 62.8 ± 18.5 Ω) configurations were not statistically significant (All P > 0.21). Cardiac TnI concentration changed from 0.03 ng/mL (95% CI: 0.02-0.04) at baseline to 0.11 ng/mL (95 CI: 0.08-0.16) after DFT was obtained with the first waveform configuration and 0.19 ng/mL (95% CI: 0.13-0.28) at the end of the study period. There were no significant changes in heart rate, end-tidal CO2 and blood pressure over time (all P > 0.09). CONCLUSION: The tested ICD device and lead placement reliably produced acceptable DFT values, based on a 10-J safety margin below the maximum device output. A benefit of fixed-pulse configuration could not be demonstrated over the standard fixed-tilt waveform. Signs of acute myocardial damage from repeated high-voltage shocks and episodes of ventricular fibrillation seemed of limited clinical significance.

Prediction of first onset of congestive heart failure in dogs with degenerative mitral valve disease: the PREDICT cohort study.

OBJECTIVE: To identify risk factors for first-onset congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD). ANIMALS: Eighty-two dogs with and without CHF secondary to DMVD were retrospectively assigned to a derivation cohort. Sixty-five dogs with asymptomatic DMVD were recruited into a prospective validation cohort. METHODS: Variables associated with risk of CHF in dogs were identified in a derivation cohort and used to construct a predictive model, which was then prospectively tested through longitudinal examination of a validation cohort. RESULTS: Logistic regression analysis of the derivation cohort yielded a predictive model that included the left atrial to aortic root dimension ratio (LA:Ao) and plasma concentration of N-terminal pro-B-type natriuretic peptide (NT-proBNP). When this model was prospectively applied to the validation cohort, it correctly predicted first-onset of CHF in 69.2% of cases. Analysis of the validation cohort revealed that plasma NT-proBNP concentration and indexed left ventricular end-diastolic diameter (LVIDd:Ao) were independent risk factors for development of first-onset CHF in dogs with DMVD (NT-proBNP ≥ 1500 pmol/L, odds ratio (OR), 5.76, 95% confidence interval (CI), 1.37-24.28, P = 0.017; LVIDd:Ao ≥ 3, OR, 6.11, 95% CI, 1.09-34.05, P = 0.039). CONCLUSIONS: Measures of left heart size and plasma NT-proBNP concentration independently estimate risk of first-onset of CHF in dogs with DMVD. These parameters can contribute to the management of dogs with DMVD.

Use of the loop diuretic torsemide in three dogs with advanced heart failure.

Diuretics are a mainstay of therapy in dogs with heart failure. In dogs with advanced heart failure, moderate to high doses of loop diuretics such as furosemide are used with diminishing effects as profound activation of neuroendocrine systems promote signs of congestive heart failure. The loop diuretic torsemide has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects. This case report details the administration of torsemide in 3 dogs with advanced heart failure and apparent furosemide resistance.

Cardiac gene transfer of short hairpin RNA directed against phospholamban effectively knocks down gene expression but causes cellular toxicity in canines.

Derangements in calcium cycling have been described in failing hearts, and preclinical studies have suggested that therapies aimed at correcting this defect can lead to improvements in cardiac function and survival. One strategy to improve calcium cycling would be to inhibit phospholamban (PLB), the negative regulator of SERCA2a that is upregulated in failing hearts. The goal of this study was to evaluate the safety and efficacy of using adeno-associated virus (AAV)-mediated cardiac gene transfer of short hairpin RNA (shRNA) to knock down expression of PLB. Six dogs were treated with self-complementary AAV serotype 6 (scAAV6) expressing shRNA against PLB. Three control dogs were treated with empty AAV6 capsid, and two control dogs were treated with scAAV6 expressing dominant negative PLB. Vector was delivered via a percutaneously inserted cardiac injection catheter. PLB mRNA and protein expression were analyzed in three of six shRNA dogs between days 16 and 26. The other three shRNA dogs and five control dogs were monitored long-term to assess cardiac safety. PLB mRNA was reduced 16-fold, and PLB protein was reduced 5-fold, with treatment. Serum troponin elevation and depressed cardiac function were observed in the shRNA group only at 4 weeks. An enzyme-linked immunospot assay failed to detect any T cells reactive to AAV6 capsid in peripheral blood mononuclear cells, heart, or spleen. Microarray analysis revealed alterations in cardiac expression of several microRNAs with shRNA treatment. AAV6-mediated cardiac gene transfer of shRNA effectively knocks down PLB expression but is associated with severe cardiac toxicity. Toxicity may result from dysregulation of endogenous microRNA pathways.

Long-term systemic myostatin inhibition via liver-targeted gene transfer in golden retriever muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal, X-linked recessive disease affecting 1 in 3,500 newborn boys for which there is no effective treatment or cure. One novel strategy that has therapeutic potential for DMD is inhibition of myostatin, a negative regulator of skeletal muscle mass that may also promote fibrosis. Therefore, our goal in this study was to evaluate systemic myostatin inhibition in the golden retriever model of DMD (GRMD). GRMD canines underwent liver-directed gene transfer of a self-complementary adeno-associated virus type 8 vector designed to express a secreted dominant-negative myostatin peptide (n = 4) and were compared with age-matched, untreated GRMD controls (n = 3). Dogs were followed with serial magnetic resonance imaging (MRI) for 13 months to assess cross-sectional area and volume of skeletal muscle, then euthanized so that tissue could be harvested for morphological and histological analysis. We found that systemic myostatin inhibition resulted in increased muscle mass in GRMD dogs as assessed by MRI and confirmed at tissue harvest. We also found that hypertrophy of type IIA fibers was largely responsible for the increased muscle mass and that reductions in serum creatine kinase and muscle fibrosis were associated with long-term myostatin inhibition in GRMD. This is the first report describing the effects of long-term, systemic myostatin inhibition in a large-animal model of DMD, and we believe that the simple and effective nature of our liver-directed gene-transfer strategy makes it an ideal candidate for evaluation as a novel therapeutic approach for DMD patients.

Computed tomographic changes associated with the prepatent and early patent phase of dirofilariasis in an experimentally infected dog.

Evolution of pulmonary arterial and parenchymal changes as assessed with computed tomography (CT) is described in a dog experimentally infected with Dirofilaria immitis. The dog was imaged 125, 168, 216, and 402 days after infection. Initial changes during the prepatent phase of infection included enlargement of the peripheral caudal lobar pulmonary arteries and intermittent periarterial interstitial infiltrates. The changes were progressive, involving additional arteries over time, but remained mild. With the presence of adult filariae a filling defect was observed in the caudal lobar pulmonary artery using CT angiography. Recognizing thoracic CT findings associated with the prepatent phase of canine heartworm infection may be important in endemic areas.

Cardiac troponin-I concentrations in dogs with bradyarrhythmias before and after artificial pacing.

OBJECTIVES: To quantify cardiac troponin-I (cTnI) concentration in dogs with symptomatic bradyarrhythmias before and after artificial pacing and to correlate cTnI concentration with diagnosis, echocardiographic parameters, serology, and outcome. ANIMALS, MATERIALS AND METHODS: Medical records from the University of Pennsylvania from 2006 to 2009 were reviewed, and 14 dogs with cTnI assay results before and after pacemaker were identified. The ECG diagnosis included complete atrioventricular block (AVB), sick sinus syndrome, 2nd degree AVB, and atrial standstill. Serology, presence of premature beats, echocardiographic measurements, and pacing modality were recorded. RESULTS: Mean cTnI concentration was elevated both pre- and post-pacing, and was significantly higher pre-pacing vs. post-pacing. Post-pacing cTnI concentration in 9 of 14 dogs (64%) remained above the reference range. Four dogs yielded high serum titers for Bartonella spp. Four dogs with markedly increased cTnI concentration had progressive left ventricular enlargement and myocardial failure as compared to pre-pacing examination. CONCLUSIONS: Elevated cTnI concentration suggests that cardiac injury persists after artificial pacing in dogs with bradyarrhythmias. Myocarditis secondary to Bartonella spp. or other causes may be an important cause of AVB in dogs. Prospective studies investigating the correlation of cTnI to potential etiology and development of post-pacing LV dysfunction and outcome are needed.

Weekly variability of plasma and serum NT-proBNP measurements in normal dogs.

OBJECTIVES: To determine the weekly variability of serum and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in healthy dogs. ANIMALS, MATERIALS AND METHODS: Fifty-three normal dogs were examined prospectively. Serum (n=25) or plasma (n=28) samples were obtained for NT-proBNP assay at one week interval for 3 consecutive weeks. RESULTS: Median serum or plasma NT-proBNP concentration did not change over 3 consecutive weeks. Twenty-two of 53 dogs (42%) had at least one NT-proBNP value >500 pmol/L, including 14 dogs with at least one serum NT-proBNP concentration >500 pmol/L and 8 dogs with at least one plasma NT-proBNP concentration >500 pmol/L during the 3-week sampling period. The difference between the maximum and minimum NT-proBNP value obtained over the 3-week sampling period was <100 pmol/L in 40% of dogs, between 100 and 200 pmol/L in 40% of dogs, and >200 pmol/L in 20% of dogs. Of the 19 dogs with a value >500 pmol/L on either week 1 or 2, 11 dogs (58%) had a subsequent NT-proBNP value <500 pmol/L on either week 2 or 3. CONCLUSIONS: There is a high degree of variability in weekly serum and plasma NT-proBNP values in healthy dogs. Individual variability should be considered when interpreting NT-proBNP results in dogs.

Utility of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) to distinguish between congestive heart failure and non-cardiac causes of acute dyspnea in cats.

BACKGROUND: Circulating plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration facilitates emergency diagnosis of congestive heart failure (CHF) in people. Its utility to discriminate between dyspneic cats with CHF vs. primary respiratory disease requires further assessment. Our objectives were to determine if NT-proBNP (1) differentiates dyspneic cats with CHF vs. primary respiratory disease; (2) increases with renal insufficiency; (3) correlates with left atrial dimension, radiographic cardiomegaly, and estimated left ventricular filling pressure (E/E(a)). METHODS: NT-proBNP was measured in 167 dyspneic cats (66 primary respiratory disease, 101 CHF) to evaluate (1) relationship with clinical parameters; (2) ability to distinguish CHF from primary respiratory disease; (3) optimal cut-off values using receiver operating characteristic (ROC) curve analysis. RESULTS: NT-proBNP (1) was higher (median and inter-quartile [25th-75th] percentile) in CHF (754 pmol/L; 437, 1035 pmol/L) vs. primary respiratory disease (76.5 pmol/L; 24, 180 pmol/L) cohorts (P<0.001); (2) positively correlated in CHF cats with increased inter-ventricular septal end-diastolic thickness (rho=0.266; P=0.007) and LV free wall thickness (rho=0.218; P=0.027), but not with radiographic heart size, left atrial size, left ventricular dimensions, E/E(a) ratio, BUN, creatinine, or thyroxine; (3) distinguished dyspneic CHF cats from primary respiratory disease at 265 pmol/L cut-off value with 90.2% sensitivity, 87.9% specificity, 92% positive predictive value, and 85.3% negative predictive value (area under ROC curve, 0.94). CONCLUSIONS: NT-proBNP accurately discriminated CHF from respiratory disease causes of dyspnea.