CARDIAC EXAMINATIONS OF ANESTHETIZED STELLER SEA LIONS (EUMETOPIAS JUBATUS), NORTHERN FUR SEALS (CALLORHINUS URSINUS), AND A WALRUS (ODOBENUS ROSMARUS).

Pinniped hearts have been well described via dissection, but in vivo measurements of cardiac structure, function, and electrophysiology are lacking. Electrocardiograms (ECGs) were recorded under anesthesia from eight Steller sea lions (Eumetopias jubatus), five northern fur seals (Callorhinus ursinus), and one walrus (Odobenus rosmarus) to investigate cardiac electrophysiology in pinnipeds. In addition, echocardiograms were performed on all eight anesthetized Steller sea lions to evaluate in vivo cardiac structure and function. Measured and calculated ECG parameters included P-wave, PQ, QRS, and QT interval durations, P-, R-, and T-wave amplitudes, P- and T-wave polarities, and the mean electrical axis (MEA). Measured and calculated echocardiographic parameters included left ventricular internal diameter, interventricular septum thickness, and left ventricular posterior wall thickness in systole and diastole (using M-mode), left atrium and aortic root dimensions (using 2D), and maximum aortic and pulmonary flow velocities (using pulsed-wave spectral Doppler). ECG measurements were similar to those reported for other pinniped species, but there was considerable variation in the MEAs of Steller sea lions and northern fur seals. Echocardiographic measurements were similar to those reported for southern sea lions (Otaria flavenscens), including five out of eight Steller sea lions having a left atrial to aortic root ratio <1, which may indicate that they have an enlarged aortic root compared to awake terrestrial mammals. Isoflurane anesthesia likely affected some of the measurements as evidenced by the reduced fractional shortening found in Steller sea lions compared to awake terrestrial mammals. The values reported are useful reference points for assessing cardiac health in pinnipeds under human care.

PERICARDIAL MESOTHELIOMA AND ASSOCIATED PERICARDIAL EFFUSION IN A TIGER RAT SNAKE (SPILOTES PULLATUS) TREATED WITH PERICARDIOCENTESIS.

A 1.5 kg, male, wild-caught tiger rat snake (Spilotes pullatus) presented with an externally visible distension of the body wall at the level of the heart. Ultrasound examination showed marked pericardial effusion. Pericardial fluid showed no bacterial or fungal growth, few leukocytes, and few suspected reactive mesothelial or neoplastic cells. Therapeutic pericardiocentesis was successfully performed, removing most of the fluid from the pericardial sac. The snake had mild lethargy and weakness immediately after the procedure but returned to normal behavior within 2 wk. Repeat pericardiocentesis was performed 6 mo after the initial presentation when moderate refilling of the pericardial sac was seen. The snake died 4 days after the second procedure with acute hemorrhage. Pericardial mesothelioma was diagnosed by histopathology after postmortem examination. This report provides the first documented case of mesothelioma in a tiger rat snake and the first description of the disease in colubrids.

Cardiac malposition (ectopia cordis) in a cat.

OBJECTIVE: To describe a case of cardiac malposition in a cat, and the successful management of the anomaly. CASE DESCRIPTION: A 2-year-old male neutered male British Shorthair cat weighing 7.58 kg was referred for bicavitary effusion. Ultrasonography and echocardiography demonstrated displacement of the heart into the abdomen through a diaphragmatic defect. Clinical signs of right-sided congestive heart failure were attributed to mechanical restriction of diastolic function by a constrictive segment of fibrous pericardium and to impaired venous return due to a kink in the caudal vena cava. Surgical repositioning of the heart into the thoracic cavity and a subtotal pericardectomy were performed, and the diaphragmatic defect was repaired. The patient recovered well postoperatively. NEW OR UNIQUE INFORMATION PROVIDED: The diagnosis and management of cardiac malposition has not been previously described in cats. With timely diagnosis and surgical intervention, a favorable outcome is possible.

Pharmacokinetics of oral pimobendan in healthy cats.

OBJECTIVE: To describe the pharmacokinetics of oral pimobendan in healthy cats. ANIMALS: 18 purpose-bred cats. METHODS: In 10 cats, blood samples were collected before, and at multiple time points after, a single oral dose of pimobendan (0.28 ± 0.04 mg/kg). In 8 cats, blood samples were collected at 3 various time points on the first and third days of twice daily oral dosing of pimobendan for a total of 7 doses (0.31 ± 0.04 mg/kg). Plasma concentrations of pimobendan were quantified by high pressure liquid chromatography coupled to tandem mass spectrometry. RESULTS: A 1-compartment open model with first order absorption in and elimination from the central compartment with a lag time best describes the disposition of pimobendan. Two cats were removed from final pharmacokinetic descriptive analysis due to delayed minimal absorption from gastrointestinal adverse effects. After a lag time (0.3 ± 0.06 h), pimobendan was rapidly absorbed (absorption half-life = 0.2 ± 0.08 h) and eliminated (elimination half-life = 1.3 ± 0.2 h). Maximum plasma concentrations (34.50 ± 6.59 ng/mL) were high and were predicted 0.9 h after drug administration. Apparent volume of distribution at steady state (per bioavailability) was large (8.2 ± 2.5 L/kg). The multi-dose study showed the pharmacokinetic model to be robust. CONCLUSION: When administered a similar dose on a per weight basis, pimobendan has a substantially longer elimination half-life and maximal drug plasma concentration in cats as compared to those previously reported in dogs.

Use of contrast echocardiography for quantitative and qualitative evaluation of myocardial perfusion and pulmonary transit time in healthy dogs.

OBJECTIVE: To evaluate reproducibility of ejection fraction (EF), myocardial perfusion (MP), and pulmonary transit time (PTT) measured in a group of dogs by use of contrast echocardiography and to examine safety of this method by evaluating cardiac troponin I concentrations. ANIMALS: 6 healthy dogs. PROCEDURES: 2 bolus injections and a constant rate infusion of contrast agent were administered IV. Echocardiographic EF was determined by use of the area-length method and was calculated without and with contrast agent. The PTT and normalized PTT (PTT/mean R-R interval) were measured for each bolus. Constant rate infusion was used for global MP evaluation, and regional MP was calculated by use of a real-time method in 4 regions of interest of the left ventricle. Cardiac troponin I concentration was analyzed before and after contrast agent administration. Intraoberserver and interobserver variability was calculated. RESULTS: EF was easier to determine with the ultrasonographic contrast agent. For the first and second bolus, mean ± SD PTT was 1.8 ± 0.2 seconds and 2.1 ± 0.3 seconds and normalized PTT was 3.4 ± 0.3 seconds and 3.5 ± 0.3 seconds, respectively. A coefficient of variation < 15% was obtained for global MP but not for the regional MPs. No differences were detected between precontrast and postcontrast cardiac troponin I concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Contrast echocardiography appeared to be a repeat-able and safe technique for use in the evaluation of global MP and PTT in healthy dogs, and it improved delineation of the endocardial border in dogs.

Infectious endocarditis and chylothorax in a cat.

A 6 yr old domestic longhair cat was evaluated for progressive weight loss, weakness, and dyspnea. Results of a physical examination and electrocardiogram were suggestive of cardiac disease. Thoracic radiographs revealed pleural effusion, which thoracocentesis revealed was consistent with chyle. An echocardiogram was performed, and aortic valve endocarditis with secondary aortic insufficiency was presumptively diagnosed. The cat was treated with broad-spectrum oral antibiotics and palliative cardiac medications. Two days after discharge, the cat's dyspnea returned, and it died suddenly. Histopathology and culture confirmed Pseudomonas bacterial endocarditis of the aortic valve. Bacterial endocarditis in the cat has rarely been reported in the literature. This case described heart failure and chylothorax resulting from bacterial endocarditis.

Esophageal dysfunction in four alpaca crias and a llama cria with vascular ring anomalies.

CASE DESCRIPTION: 3 alpaca crias and cadavers of an alpaca cria and a llama cria were evaluated for evidence of esophageal dysfunction. CLINICAL FINDINGS: All 5 crias were between 3 and 5 months of age when clinical signs developed, and all had a thin body condition when examined. Clinical signs included coughing, regurgitation, and grossly visible esophageal peristaltic waves. A barium esophagram was used to diagnose esophageal obstruction, megaesophagus, and a vascular ring anomaly (VRA). Fluoroscopy was used to evaluate deglutition, esophageal peristalsis, and the extent of esophageal dilation in 1 alpaca cria. A persistent right aortic arch was identified in 1 alpaca cria, and a left aortic arch with right ductus arteriosus or ligamentum arteriosum and an aberrant right subclavian artery were identified in the 4 remaining crias. TREATMENT AND OUTCOME: Surgical correction of the VRA was attempted in the 3 live alpaca crias. It was complicated by the conformation and location of each VRA and inaccurate anatomic diagnosis of the VRAs before surgery. Treatment was universally unsuccessful because of intraoperative complications and the persistence of clinical signs after surgery. CLINICAL RELEVANCE: Megaesophagus is typically an idiopathic condition in camelids. However, these findings suggested that camelids with esophageal dysfunction during the neonatal period may have a VRA. The prognosis is grave for camelids with VRA, and accurate anatomic diagnosis of the VRA via the use of advanced imaging techniques (eg, angiography, computed tomography, or magnetic resonance imaging) may improve the success of surgical intervention.

Doppler-derived deformation imaging in unsedated healthy adult dogs.

OBJECTIVES: To evaluate feasibility, repeatability and reproducibility (R&R) of Doppler-derived deformation imaging (DI) in healthy adult dogs. ANIMALS, MATERIALS AND METHODS: Forty-nine dogs underwent physical examination, ECG, blood pressure measurement and echocardiography. Doppler-derived DI parameters obtained from six selected Regions of Interest (ROI) within the left ventricle (LV) were: strain (S), systolic strain rate (SSR), strain rate E wave (SRE), and strain rate A wave (SRA). The averages of the six ROIs were calculated and labeled avS, avSSR, avSRE, and avSRA. Randomly selected dogs underwent two echocardiographic studies to evaluate intraoperator (n=14) and interoperator (n=17) variability. RESULTS: DI data were obtained in 87.2% of dogs and 77.2% of ROIs. Compared to controls, avSSR was significantly reduced in Doberman Pinchers (DP) and it was increased in dogs < 30 kg, compared to dogs > 30 kg. The intraoperator Coefficient of Variability (CV) for some ROIs was greater than 15% but for averaged measurements it was < or = 5.0%. Interoperator CV varied widely but were all < 15% for avSSR, avS, and avSRA. CONCLUSIONS: The CV for Doppler-derived DI varied widely. Averaging values from multiple ROIs improved R&R. DI may help elucidate differences in LV mechanics between canine breeds.

Analysis of weight uniformity, content uniformity and 30-day stability in halves and quarters of routinely prescribed cardiovascular medications.

OBJECTIVES: Congenital and acquired cardiac disorders are frequently diagnosed in small breed dogs and cats. In order to appropriately dose cardiovascular drugs for small patients, fractions of commercially available tablets must be prescribed. The aims of this study were to evaluate weight and content uniformity and 30-day chemical stability in halves and quarters of 11 drug formulations commonly prescribed to treat cardiovascular disorders in small breed dogs and cats. ANIMALS, MATERIALS AND METHODS: Fifteen tablets from 11 drug formulations were obtained within the same lot. Tablets were split by a single operator using a commercially available pill splitter. Whole tablets, halves and quarters were weighed and stored in plastic containers. High-pressure liquid chromatography or liquid chromatography with mass spectrometry were utilized to determine drug content and repeated 30 days later to estimate chemical stability. RESULTS: Statistically significant weight variability, content non-uniformity and chemical degradation were found for some formulations. Digoxin showed a significant degradation that should be considered in clinical practice. CONCLUSIONS: It appears that pill splitting is overall a relatively reliable practice; however tablets should not be split ahead of time but only immediately prior to intended usage.

Camelid cardiology.

Cardiovascular disorders, although not thoroughly described in the literature, are frequently diagnosed in South American camelids, causing morbidity, mortality, and loss of production. Definitive confirmation concerning the heritability of cardiac defects in these species is lacking; however, this potential exists and should be taken into account when counseling breeders and owners. This article describes the diagnosis and treatment of cardiovascular diseases in llamas and alpacas and reviews the most recent literature. Unique aspects of the cardiovascular physiology in these species are also reviewed.

Evaluation of the presence of selected viral and bacterial nucleic acids in pericardial samples from dogs with or without idiopathic pericardial effusion.

Many viruses have been identified in pericardial fluid and in tissue samples from humans with pericarditis by means of molecular diagnostics. In canine idiopathic pericardial effusion there is as yet no conclusive evidence to support the involvement of an infectious agent. This study was designed to investigate a possible relationship between idiopathic pericardial effusion in dogs and viruses most commonly encountered in humans affected with viral pericarditis. Coxsackievirus B3 RNA, influenza virus type A RNA, human adenovirus type 2 DNA, human cytomegalovirus DNA, and parvovirus B19 DNA were investigated using PCR on pericardial effusion samples and pericardial tissue specimens collected from 14 dogs with idiopathic pericardial effusion. PCR was also used to test for two bacteria, Borrelia burgdorferi and Chlamydia pneumoniae. The same microorganisms were also looked for in pericardial effusions or pericardial washes from 10 dogs with neoplastic pericardial effusion, and in samples collected from 10 dogs which died of a non-cardiac disease. One pericardial effusion sample from a dog with the idiopathic form of the disease tested positive for influenza virus type A and sequencing of the amplicon confirmed the PCR result. In another dog from the same group a cytomegalovirus was detected by PCR in the effusion, but sequencing showed this to be a false-positive result. The genomes of the microorganisms investigated were not detected in neoplastic effusions or pericardial washes. The results indicate that viral and bacterial DNA/RNA of relevance for human pericarditis is rare in pericardial samples from dogs with idiopathic pericardial effusion. The finding of influenza type A viral RNA in pericardial fluid from one dog with the idiopathic form of the disease warrants further investigation.

Listeria associated mural and valvular endocarditis in an alpaca.

An alpaca presented for emergency evaluation of respiratory distress. Physical examination revealed weakness, pyrexia, and a grade V/VI left apical holosystolic murmur. Initial thoracic examination and radiographs were consistent with left sided congestive heart failure. Blood cultures, echocardiographic evaluation, and necropsy findings established a diagnosis of bacterial endocarditis associated with a Listeria monocytogenes infection. Left ventricular endocarditis is uncommon in ruminants, and to the authors' knowledge there are no other reports of L. monocytogenes being the causative agent in an alpaca.

Percutaneous occlusion of a muscular ventricular septal defect with an Amplatzer muscular VSD occluder.

Ventricular septal defects are a relatively common congenital cardiac disease that, when severe, can be associated with substantial morbidity and mortality. Several minimally invasive methods of repair have been described in the human literature. This report describes the first case of percutaneous closure of a naturally occurring muscular septal defect using an Amplatzer occluder in a dog affected by concurrent pulmonic stenosis. Based on this experience catheter-based occlusion of muscular ventricular septal defects is a feasible option in dogs. Further studies are necessary to identify the attributes and limitations of the technique.