Distinguishing cardiac and noncardiac dyspnea in 48 dogs using plasma atrial natriuretic factor, B-type natriuretic factor, endothelin, and cardiac troponin-I

BACKGROUND: It is challenging to differentiate congestive heart failure (CHF) from noncardiac cause of dyspnea. HYPOTHESIS: Circulating concentrations of atrial natriuretic peptide (NT-proANP), B-type natriuretic peptide (BNP), endothelin-I (ET-1), and cardiac troponin-I (cTnI) can be used to help distinguish between cardiac and noncardiac causes of dyspnea in dogs. ANIMALS: Forty-eight client-owned dogs admitted to a veterinary teaching hospital for respiratory distress. METHODS: Blood samples from patients were prospectively obtained. The etiology of dyspnea was determined by using physical examination, thoracic radiographs, and echocardiography. RESULTS: CHF was diagnosed in 22 dogs, and dyspnea of noncardiac origin (noHD group) was diagnosed in 26 dogs. Analyses revealed significant difference between groups for NT-proANP (geometric mean, 95% confidence [CI]; no HD: 0.26 nmol/mL, 95% CI 0.17-1.09; CHF: 1.38 nmol/mL, 95% CI 1.09-1.74 nmol/mL; P < .0001), BNP (noHD: 12.18 pg/mL, 95% CI 10.91-16.17 pg/mL; CHF: 34.97 pg/mL, 95% CI 23.51-52.02 pg/mL; P < .0001), and ET-1 (noHD: 0.32 fmol/mL, 95% CI 0.23-0.46 fmol/mL; CHF: 1.26 fmol/mL, 95% CI 0.83-1.91 fmol/mL; P < .0001). Plasma cTnI concentrations were not significantly different between groups (noHD: 0.29 ng/mL, 95% CI 0.12-0.72 ng/mL; CHF: 0.42 ng/mL, 95% CI 0.18-0.97, P = .53). Receiver operating curves indicated areas under the curve for NT-proANP, BNP, and ET-1 of 0.946, 0.886, and 0.849, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Plasma NT-proANP, BNP, and ET-1, but not cTnI, appear useful for distinguishing between dogs with cardiac and noncardiac causes of dyspnea, with plasma NT-proANP having the highest sensitivity (95.5%) and specificity (84.6%).     

When, why, and how to perform cardiac radiofrequency catheter ablation

Radiofrequency catheter ablative techniques provide a unique opportunity to cure dogs of certain supraventricular tachyarrhythmias, rather than simply controlling the rhythm with drug therapy. Accessory pathways, which can participate as one limb of a rapid, narrow complex tachyarrhythmia circuit, have a particularly high cure rate with radiofrequency catheter ablation. Focal atrial tachycardias also provide a substrate that can be amenable to ablation. Tachycardia-induced myocardial dysfunction resulting from frequent tachyarrhythmic episodes will resolve after a successful ablation. This report outlines the indications, equipment, and techniques used in dogs for performing catheter ablation with temperature-controlled radiofrequency energy delivery.     

The toxic effects on cardiac myocytes of tyledoside F, a cumulative neurotoxic cardiac glycoside isolated from Tylecodon grandiflorus

To investigate the cardiac cellular effects of tyledoside F, a cumulative neurotoxic bufadienolide and ouabain, a non-cumulative cardenolide, the whole-cell clamp method was used to measure the Na-K pump current after the Na-K pump had been activated by high intracellular Na2+. The toxic effects of tyledoside F and ouabain on cardiac myocytes were also investigated by observing the effect of the Ca2+ overload on the variability of myocytes during a period of 75 min. From the results it is clear that there are similarities in the direct effects of tyledoside F and ouabain on the Na-K pump. It was found that ouabain inhibited the Na-K pump current more than that of tyledoside F. With regard to Ca2+ overload, there are differences in their mode of production of Ca2+ overload because cinnarizine protects the myocytes against ouabain-induced Ca2+ overload but not against tyledoside-induced Ca2+ overload. This study shows that with the whole-cell clamp technique tyledoside F inhibited the Na-K pump in a manner similar to inhibition of the pump by ouabain. Viability studies with myocytes indicated that tyledoside F also has other effects which are different from these of ouabain.     

Hemolysis,myopathy, and cardiac disease associated with hereditary phosphofructokinase deficiency in two Whippets

Abstract: Two male castrated Whippet littermates were presented at 1 year of age for pallor, tachycardia, systolic heart murmur, dark yellow to orange feces, intermittent lethargy, pigmenturia, and muscle shivering or cramping after exercise. Persistent macrocytic hypochromic anemia with marked reticulocytosis and metarubricytosis was found when CBC results were compared with reference values for Whippets. Increased serum creatine kinase activity and hyperkalemia also were sometimes present over the 4‐year period of evaluation. Progressively increasing serum concentrations of N‐terminal prohormone brain natriuretic peptide suggested cardiac disease. Erythrocytes from the whippets were less osmotically fragile but more alkaline fragile than those from control dogs. Erythrocyte phosphofructokinase (PFK) activities and 2,3‐diphosphoglycerate concentrations were decreased. Restriction enzyme‐based DNA test screening and DNA sequencing revealed the same mutation in the muscle‐PFK gene of the Whippets as seen in English Springer Spaniel dogs with PFK deficiency. This is the first report of PFK deficiency in Whippet dogs. In addition to causing hemolysis and exertional myopathy, heart disease may be a prominent clinical component of PFK deficiency in this breed and has not been previously recognized in PFK‐deficient English Springer Spaniels.     

Diprosopus with multiple craniofacial, musculoskeletal, and cardiac defects in a purebred Suffolk lamb

A stillborn Suffolk ewe lamb with 2 heads was found to have tarsal arthrogryposis, kypholordosis, craniorachischisis totalis, cheiloschisis, palatoschisis, deviation of the right maxilla, prognathia, patent ductus arteriosus, 3 ventricular septal defects, and 4 great vessels. The lamb was born twin to a normal lamb. No definitive etiology was established.     

Effect of Angiotensin II Type 1 receptor blocker on cardiac angiotensin-converting enzyme and chymase-like activities, and cardiac fibrosis in cardiomyopathic hamsters

It has been reported that cardiac chymase has an effect on cardiac fibrosis through the Angiotensin (Ang) II formation and an Ang II-independent mechanism. In the present study, Ang II type 1 (AT1) receptor blocker (candesartan cilexetil) was administered to dilated cardiomyopathic (DCM; Bio TO2) hamsters for 4 weeks to study the effect of AT1 receptor blocker on cardiac chymase-like activity and cardiac fibrosis. Echocardiography, histological examination, and assessment of cardiac angiotensin-converting enzyme (ACE)/chymase-like activities were conducted. Hamsters showed cardiac dysfunction due to increased left ventricular dimensions and decreased ventricular wall thickness, significant increase in cardiac chymase-like activity, and fibrosis. This result indicates that the cardiac chymase-like activity is responsible for cardiac fibrosis. When candesartan cilexetil was administered to Bio TO2 hamsters, cardiac chymase-like activity increased significantly, whereas cardiac fibrosis decreased significantly. Cardiac ACE and chymase-like activities were unchanged in non-DCM hamsters with candesartan cilexetil. This suggests that the cardiac Ang II formation mechanism was stimulated by suppressing the effect of cardiac Ang II, and cardiac chymase-like activity could be increased. Moreover, this mechanism may be more highly activated if cardiac Ang II is activated in the heart. In conclusion, we demonstrated that AT1 receptor blocker reduced cardiac fibrosis, although cardiac chymase-like activity increased. Because the Ang II-forming pathway and the effect of chymase in hamsters is similar to that in dogs, the results of the present study may supplement the available information for dogs.     

Standardised exercise testing in 17 reining horses: Musculoskeletal,respiratory, cardiac and clinicopathological findings

Exercise testing can be useful to evaluate poor performance, as a preventative medicine tool, and in the assessment of training progression. A comprehensive exercise testing protocol that simultaneously evaluates common causes of poor performance has not been described in reining horses. The objective of this study was to describe the results of a standardised exercise testing protocol in reining horses. Seventeen reining horses that were part of a western performance intercollegiate team and had met the trainer's expectations during the athletic season were evaluated using a comprehensive standardised exercise test. Systems assessed included musculoskeletal system, upper respiratory tract, lower respiratory tract and cardiovascular system. These systems were assessed by means of historical questionnaires, general physical examinations, subjective lameness examinations, gait analysis using digital body mounted inertial sensors, resting and dynamic upper airway endoscopy, bronchoalveolar lavage fluid cytology, echocardiograms, resting and exercising electrocardiography, and laboratory tests (packed cell volume, lactate, creatine kinase and serum amyloid A). Subclinical abnormalities were detected frequently. The musculoskeletal system was the most commonly affected system, but cardiovascular and upper and lower airway abnormalities were also detected in some horses. These results suggest that exercise tests may be useful to detect subclinical abnormalities in horses used for reining. Further evaluation of both normally and poorly performing horses is necessary to determine if exercise testing can improve the health, performance and welfare of horses used for reining.     

Biochemical markers of cardiac injury in normal, surviving septic, or nonsurviving septic neonatal foals

The cardiac biomarkers cardiac troponin T (cTnT) and I (cTnI) and the cardiac isoenzyme of creatine kinase (CKMB) are used extensively in human medicine to diagnose and provide valuable prognostic information in patients with ischemic, traumatic, and septic myocardial injury. We designed a study to establish normal values for these markers in healthy, neonatal foals and to compare them with values obtained from septic neonates in a referral hospital population. The 25th, 50th, 75th, and 95th percentiles for cTnI and CKMB in the healthy-foal population were 0.08, 0.14, 0.25, 0.49 ng/mL and 1.4, 2.3, 4.0, 7.4 ng/mL, respectively. The values obtained for cTnT were frequently (43/52 foals; 83%) below the lower limit of detection of the assay (0.009 ng/mL), but the median and range were 0.009 and 0.009-0.041 ng/mL, respectively. In the septic foal population, the 25th, 50th, 75th, and 95th percentile values for cTnI and CKMB were 0.05, 0.12, 0.22, and 1.10 ng/mL and 2.0, 4.4, 7.8, and 24 ng/mL, respectively. The values obtained for cTnT were less frequently below the lower limit of detection (23/38 foals; 60%) compared with the healthy foal population, and the median and range were 0.009 and 0.009-0.20 ng/mL, respectively. Significantly higher values were observed for cTnT and CKMB in septic foals compared with the healthy neonatal foal population, but there were no differences among septic foals in survivors compared with nonsurvivors. These findings suggest that myocardial injury occurs during septicemia in neonatal foals but that the injury is not associated with survival among septic foals.     

Transvenous cardiac pacing

Transvenous pacing therapy is a life-saving technique for patients with clinically significant bradyarrhythmias. For most symptomatic bradyarrhythmias in small animals, there is no effective substitute for cardiac pacing. The methods employed for pacemaker placement, although potentially time-consuming, are not technically difficult. This article discusses the indications, techniques, clinical decision-making, and potential complications associated with temporary and permanent transvenous cardiac pacing.     

Evaluation of hemodynamic measurements, including lithium dilution cardiac output, in anesthetized dogs undergoing ovariohysterectomy

OBJECTIVE: To measure cardiac output in healthy female anesthetized dogs by use of lithium dilution cardiac output and determine whether changes in mean arterial pressure were caused by changes in cardiac output or systemic vascular resistance. DESIGN: Prospective clinical study. ANIMALS: 20 healthy female dogs. PROCEDURE: Dogs were anesthetized for ovariohysterectomy. Ten dogs breathed spontaneously throughout anesthesia, and 10 dogs received intermittent positive-pressure ventilation. Cardiovascular and respiratory measurements, including lithium dilution cardiac output, were performed during anesthesia and surgery. RESULTS: Mean arterial pressure and systemic vascular resistance index were low after induction of anesthesia and just prior to surgery and increased significantly after surgery began. Cardiac index (cardiac output indexed to body surface area) did not change significantly throughout anesthesia and surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results provide baseline data for cardiac output and cardiac index measurements during clinical anesthesia and surgery in dogs. Changes in mean arterial pressure do not necessarily reflect corresponding changes in cardiac index.     

Characterisation and cardiac directed differentiation of canine adult cardiac stem cells

A multicentre study of 285 cases was performed to enhance the management of distal phalangeal fractures on the basis of clinical evidence. The outcome after treatment was available for 223 of the cases. Horses with a non-articular type I fracture had a better prognosis (91.7%) for return to original or expected level of use than horses with an articular type II or III fracture (69.6% and 74.1%, respectively). The prognosis for types IV and V fractures was fair (57.7% and 57.1%, respectively) and for type VI good (80%). Horses with a hindlimb fracture had a significantly greater chance of a successful outcome. No significant association between age or time to start treatment and success rate was noted. The best treatment option for types I-III fractures was a conservative approach (box rest). Type IV fractures were best treated by arthroscopic removal of the fragment. Immobilisation of the hoof did not seem to influence outcome. Radiological findings and clinical healing were not accurately correlated and the re-commencement of training should be based on clinical rather than radiological findings. Complete osseous union of the fracture was not essential for a successful return to athletic activity.     

Ventral abdominal, transdiaphragmatic approach for implantation of cardiac pacemakers in the dog

Surgical implantation of a sutureless myocardial electrode and pulse generator was performed in 18 dogs, using a ventral abdominal, transdiaphragmatic approach. Twelve dogs were greater than or equal to 10 years old. The 18 dogs weighed from 3 to 54 kg. Indications for permanent cardiac pacemaker implantation included complete (3rd degree) atrioventricular block, sick sinus syndrome, and sinus bradycardia. Few complications developed during or after surgery. One dog died during surgery from ventricular fibrillation, and hypertrophic cardiomyopathy was found at necropsy. Five dogs died 1 to 19 months after surgery (mean, 8.6 months) because of renal failure, hepatic cirrhosis, congestive cardiomyopathy, or idiopathic causes. Twelve dogs were alive 1 to 48 months after surgery (mean, 15.1 months). The surgical approach was used a second time in 3 dogs to replace the myocardial electrode wire and pulse generator 4, 16, and 26 months after surgery; technical complications were not associated with the second surgery in these 3 dogs. In 2 dogs that had initial pacemaker implantation via lateral thoracotomy, a transdiaphragmatic approach was used to replace the myocardial electrode lead and pulse generator 25.5 and 26 months after surgery. According to results of this study, the ventral abdominal, transdiaphragmatic approach for permanent pacemaker implantation in the dog is a simpler technique, with decreased surgery time, decreased time of tissue exposure, and decreased rate of infection, as compared with results described by investigators who used lateral thoracotomy or midline celiotomy and caudal one-third median sternotomy.     

Permanent transvenous cardiac pacing

Transvenous cardiac pacing is a commonly employed treatment for symptomatic bradyarrhythmias in dogs. Medical management of these conditions has not proven to be successful leaving pacing as the only viable alternative. The technique of pacemaker implantation is not difficult, but successful pacemaker therapy requires an understanding of electrophysiology, cardiac fluoroscopic anatomy, pacemaker instrumentation, and programming. Proper patient selection and identification of the underlying rhythm disturbance is essential to a successful clinical outcome. This article discusses the indications, equipment, techniques, complications, and outcome of permanent transvenous cardiac pacing.     

Non-invasive real-time measurements of cardiac vagal tone in dogs with cardiac disease

In dogs with spontaneous heart disease, an electronically generated measurement of cardiac vagal tone, the cardiac index of parasympathetic activity, was a sensitive, simple and inexpensive measure of the severity of heart failure. Dogs with cardiac disease and an index score less than 3 were at 15.8 (95 per cent confidence interval 2.9 to 87.2) times the risk of dying within a year than those with a score of 3 and over. The measurement of the index provided an objective and reliable beat-by-beat measurement of cardiac vagal tone, which was prognostically useful in dogs with heart disease.