Two-dimensional echocardiographic estimates of left atrial volumes obtained from two different views in dogs are similar but not interchangeable.

Left atrial (LA) volumes using a monoplane Simpson's Method of Discs (SMOD) can be obtained from the right parasternal long axis four-chamber (RPLA) or from the left apical four-chamber (LA4C) views in dogs; however, little information exists regarding the agreement of LA volume estimates using a SMOD on images obtained from LA4C and RPLA views. Therefore, we sought to examine the agreement between the two methods of obtaining LA volumes in a heterogenous population of healthy and diseased dogs. Additionally, we compared the LA volumes obtained by SMOD with estimates obtained from simple cube or sphere volume formulae. Archived echocardiographic examinations were retrieved and, where both RPLA and LA4C views were adequately recorded, included in the study. We obtained measurements from 194 dogs that were either apparently healthy (n = 80) or had various cardiac diseases (n = 114). The LA volumes of each dog was measured using a SMOD, from both views, in systole and diastole. Estimates of LA volumes obtained from simple cube or sphere volume formulae from RPLA-derived LA diameters were also calculated. We then used Limits of Agreement analysis to determine agreement between the estimates obtained with each view, and those calculated from linear dimensions. The two methods obtained by SMOD provided similar estimates for both systolic and diastolic volumes but did not agree sufficiently to be interchangeable. The LA4C view often slightly underestimated the LA volumes at small LA sizes and overestimated the LA volumes at large LA sizes compared to RPLA method, with increasing disagreement as the LA size increased. Estimates based on cube method overestimated volumes compared to both SMOD methods, whereas those based on sphere method performed reasonably. Our study suggests that monoplane volume estimates from the RPLA and LA4C views are similar but not interchangeable. Clinicians can also perform a rough estimate of LA volumes using RPLA-derived LA diameters to calculate the sphere volume.

Transthoracic echo-guided pacemaker implantation reduces fluoroscopic use in dogs.

Echocardiographic guidance provides an alternative method when fluoroscopy is unavailable, equipment or power failure of fluoroscopic equipment during a procedure occurs or to decrease radiation risk. Recently, transthoracic (TTE) and transesophageal echocardiography were reported as an alternative method to guide interventional procedures in dogs. Therefore, we hypothesized that TTE could be used as an alternative method to visualize endocardial leads during pacemaker implantation in dogs, largely avoiding the use of fluoroscopy. A prospective consecutive case series of pacemaker implantation was performed using TTE guidance. The endocardial lead was imaged by TTE during its intracardiac advancement until the lead tip was positioned at the right ventricular apex. Echocardiographic right parasternal views, optimized to visualize the pacing lead, were used, starting with a short axis image of the right atrium and ending with a long axis view of the right ventricle (RV) optimized to image the RV apex. Proper lead placement was confirmed by both capture threshold, impedance and fluoroscopy. Twenty-one pacemaker implantation procedures by TTE monitoring were successfully performed. The TTE guidance provided images of a quality sufficient to clearly monitor implantation in real-time and allowed for immediate corrections to pacing lead malpositioning or excessive looping. Fluoroscopy was used to confirm the correct placement of the lead that was guided echocardiographically in the initial three procedures, after which a single radiographic image (no cine-mode) was used to identify lead placement and redundancy in the remaining eighteen cases. Static imaging (radiography using the fluoroscope) was used to assess the proper lead redundancy in all procedures because this cannot be evaluated echocardiographically. Pacemaker leads were successfully implanted in the RV of dogs using TTE monitoring. A larger cases series is needed for validation of safety and effectiveness of TTE during this interventional procedure in dogs.

Mini-invasive approach for removal of iliopsoas migrating grass awns with an atraumatic wound retractor.

This case series describes a novel mini coeliotomy approach using a radial, atraumatic self-retaining retractor for the retrieval of migrant plant foreign bodies from the iliopsoas muscles of six male dogs under intra-operative ultrasonographic guidance. Four dogs had a history of pulmonary disease potentially compatible with inhalation of a foreign body approximately 2-4 months before presentation. Under ultrasonographic guidance, the grass awns were identified in the iliopsoas muscle and were completely removed. In this case series, the annular ring device provided an excellent view of the surgical field for intra-abdominal manipulations. Patient follow-up at 15 days and 6 to 12 months after surgery indicated a full recovery, and no grass awn fragment residues were identified.

Pulmonary vein to pulmonary artery ratio in healthy and cardiomyopathic cats.

INTRODUCTION/OBJECTIVES: Recognition of congestive heart failure (CHF) in dyspnoeic cats is crucial for correct intervention. The pulmonary vein (PV) to pulmonary artery (PA) ratio (PV/PA) has been proposed as an index that might help discriminate dogs suffering from CHF but has never been studied in cats. We sought to determine reference intervals for various PV and PA variables in healthy cats. We then examined these variables in cats with subclinical and clinical cardiomyopathies to determine their diagnostic utility in identifying CHF. ANIMALS, MATERIALS AND METHODS: We took a sample of 114 cats: 51 healthy cats, 32 subclinical cardiomyopathy affected cats and 31 cardiomyopathic cats with CHF. PV and PA were measured at the minimal and maximal diameters using M-mode images obtained from a modified right parasternal long axis view. The aorta (Ao) and left atrium were measured using two-dimensional imaging employing the right parasternal short axis view. RESULTS: median PVmin/PAmin value in healthy cats was approximately 0.51 and the PVmax/PAmax value was 0.67. The median distensibility value of the vessels was 23% for ΔPA and 41% for ΔPV. Cats with CHF had higher PVmin/PAmin, PVmax/PAmax, PVmin/Ao, PVmax/Ao values and a smaller ΔPV value compared to subclinical and healthy cats (p < 0.0001). When evaluating the diagnostic performance of these variables (in cardiomyopathic cats), PVmin/PAmin and PVmin/Ao values had higher accuracy compared to the LA:Ao value when identifying cats with CHF. CONCLUSIONS: Our study provides reference values for PV and PA variables in cats. Moreover, PV/PA variables were better factors than LA:Ao for discriminating cardiomyopathic cats with and without CHF.

Right ventricular outflow tract fractional shortening: an echocardiographic index of right ventricular systolic function in dogs with pulmonary hypertension.

OBJECTIVES: To create reference intervals for right ventricular outflow tract fractional shortening (RVOT-FS) in healthy dogs and examine diagnostic performance of this index in dogs with pulmonary hypertension (PH). In addition, we examine the impact of myxomatous mitral valve disease (MMVD) without PH on RVOT-FS. ANIMALS, MATERIALS AND METHODS: The study population included 52 healthy adult dogs, 51 dogs with MMVD but without PH, and 51 dogs with PH. This is a prospective study. Complete echocardiographic evaluations were performed on all dogs. Right ventricular outflow tract fractional shortening was obtained by two-dimensional guided M-mode recordings from the right parasternal short axis view. Right ventricular outflow tract fractional shortening was evaluated in healthy dogs of various breeds, and reference intervals were generated. We examined the effect of PH on RVOT-FS with receiver operating characteristic analysis and evaluated the effect of MMVD on RVOT-FS in dogs without PH. Intraobserver and interobserver reproducibility was calculated. RESULTS: Healthy dogs had RVOT-FS > 44%. Right ventricular outflow tract fractional shortening values of healthy dogs and MMVD dogs without PH did not differ (p=0.84). In dogs with PH, RVOT-FS decreased with increasing tricuspid regurgitation velocity (p<0.0001). Pimobendan use in dogs with PH increased RVOT-FS as PH worsened. Right ventricular outflow tract fractional shortening was acquired with clinically acceptable intraobserver and interobserver reproducibility. CONCLUSIONS: Right ventricular outflow tract fractional shortening is a novel, easy applicable, and repeatable index for evaluating RV systolic function. Studies comparing this index with common echocardiographic indices used to assess RV function in dogs are needed.

Low-energy ablation of anteroseptal accessory pathways in two dogs.

In humans, accessory pathways (APs) in an anteroseptal and midseptal position are often challenging to ablate because of their close proximity with the conduction pathways of the atrioventricular junction. The use of low-energy ablation techniques can be useful to reduce the risk of permanently damaging the atrioventricular node and the His bundle. This report describes the use of low-energy radiofrequency catheter ablation to successfully and permanently ablate anteroseptal APs in two dogs with orthodromic atrioventricular reciprocating tachycardia. In the first dog, a transient first degree atrioventricular block persisted for 30 s after radiofrequency energy delivery. In the second dog, transient paroxysmal atrioventricular conduction block was observed during the procedure but resolved within 3 days. First degree atrioventricular block was again identified 2 months later. In conclusion, anteroseptal APs can be effectively treated by low-energy radiofrequency catheter ablation with minimal and transient damage to the atrioventricular junction.

Left atrial deformation and phasic function determined by two-dimensional speckle-tracking echocardiography in dogs with myxomatous mitral valve disease.

INTRODUCTION: Left atrial (LA) function can provide useful information in dogs with myxomatous mitral valve disease (MMVD). Recently, we have demonstrated the feasibility of measuring LA longitudinal deformation using speckle-tracking echocardiography (STE) to estimate LA function in healthy dogs. Whether LA strain and strain rate variables provide additional information about LA function and clinical cardiac status in dogs with MMVD remains unexplored. ANIMALS: Ninety-six client-owned dogs of different breeds with MMVD were prospectively enrolled. METHODS: LA longitudinal deformation was evaluated in each dog by STE and different STE variables were used to assess LA function. RESULTS: No STE variables differed between American College of Veterinary Internal Medicine Stage B1 and B2 dogs but were lower in Stage C dogs. Peak atrial longitudinal average strain < 27.9%, left-atrial-to-aortic ratio > 2.2 and peak atrial contraction average strain < 7.25% discriminated symptomatic MMVD dogs by receiver operating characteristic analysis with sensitivity and specificity of 100% and 100% (95% confidence interval [CI] 91-100%), 92% (95% CI 78-98%) and 98% (95% CI 87-100%), 100% (95% CI 91-100%) and 95% (95% CI 83-99%), respectively. In 12 dogs with similar left-atrial-to-aortic ratio, peak atrial longitudinal average strain and peak atrial contraction average strain differentiated dogs with subclinical disease from those with congestive heart failure (CHF). CONCLUSION: Dogs with MMVD in CHF appear to have lower LA longitudinal strain and strain rate variables compared with dogs with subclinical disease. Further studies are needed to establish if our initial findings can provide useful information for the diagnosis, treatment, and prognosis of dogs with MMVD.

Canine pulmonary vein-to-pulmonary artery ratio: echocardiographic technique and reference intervals.

OBJECTIVES: The size of the pulmonary veins (PVs) and pulmonary arteries (PAs) changes in response to hemodynamic alterations caused by physiological events and disease. We sought to create standardized echocardiographic methods for imaging the right ostium of the pulmonary veins (RPVs) and the right pulmonary artery (RPA) using specific landmarks and timing to quantify vessel diameters and phasic changes during the cardiac cycle. ANIMALS: Fifty client-owned healthy dogs prospectively recruited. METHODS: M-mode and 2-dimensional images were obtained from modified right parasternal long and short axis views. Right ostium of the pulmonary veins and RPA measurements were timed with electrical [peak of the QRS complex (RPVQRS and RPAQRS) and end of T wave (RPVT and RPAT)] or mechanical events [RPV and RPA vessels at their respective maximal (RPVMAX; RPAMAX) and minimal (RPVMIN; RPAMIN) diameters]. Right ostium of the pulmonary veins and RPA measurements were also indexed to the aorta. RESULTS: In normal dogs regardless of the echocardiographic view or time in the cardiac cycle, the RPV/RPA ratio approximated 1.0. Mechanically timed fractional changes (distensibility indices) in RPV and RPA diameters did not differ (p=0.99; 36.9% and 36.8%, respectively). ECG-timed fractional changes (distensibility indices) in RPV and RPA diameter were at least 50% smaller than mechanically timed changes (p<0.05). RPV:Ao and RPA:Ao ranged between 0.3 and 0.6, with lower values obtained in diastole and larger values in systole (p<0.0001). Multiple positive and negative deflections were identified on the RPV and RPA M-mode tracings. CONCLUSION: This study provides detailed methodology and 2D and M-mode reference intervals for the RPV and RPA dimensions and the phasic changes during the cardiac cycle of the dog using echocardiography.

Transthoracic ultrasound guided balloon dilation of cor triatriatum dexter in 2 Rottweiler puppies.

Balloon dilation was performed in two Rottweiler puppies with cor triatriatum dexter and clinical signs of ascites using transthoracic echocardiographic guidance. The dogs were positioned on a standard echocardiography table in right lateral recumbency, and guide wires and balloon catheters were imaged by echocardiographic views optimized to allow visualization of the defect. The procedures were performed successfully without complications and clinical signs were resolved completely in both cases. Guide wires and balloon catheters appeared hyperechoic on transthoracic echocardiography image and could be clearly monitored and guided in real-time. These two cases demonstrate that it is possible to perform balloon catheter dilation of cor triatriatum dexter under transthoracic guidance alone.

Left atrial deformation and phasic function determined by 2-dimensional speckle tracking echocardiography in healthy dogs.

INTRODUCTION: Feasibility, intra- and inter-observer variability of measuring left atrial (LA) longitudinal strain and strain rate (SR) variables using speckle tracking echocardiography (STE) have not been reported in the dog. Reference intervals for these variables which can be useful to estimate LA function have been provided. ANIMALS: Forty-eight healthy adult dogs. MATERIALS AND METHODS: Left atrial longitudinal deformation was evaluated in each dog by STE, and different combinations of STE variables were used to describe the 3 phases (reservoir, conduit and booster pump phase) of the LA function. RESULTS: Left atrial STE was possible in 40/48 dogs (83%). Strain and SR curves in healthy dogs were characterized, and reference intervals for several strain and SR variables are provided. Intra- and inter-observer variability, expressed as percent difference between observations or observers, was 3.58%-10.8% for indices of the LA reservoir function, 10.48%-15.82% for indices of the LA conduit function and 14.1%-34% for indices of the LA contractile function. Strain rate in early diastole and strain rate at atrial contraction variables were correlated significantly with age. No other relationships (body weight, heart rate or LA size) with any STE variables could be identified. CONCLUSION: Speckle tracking echocardiography provides quantitative measurements of LA longitudinal deformation and can be used to assess LA phasic function in healthy dogs. Further studies of these variables in dogs with cardiac diseases are needed to determine the clinical applicability and utility.

Acute undifferentiated leukaemia in a dog.

BACKGROUND: Acute undifferentiated leukaemia (AUL) is considered a separate entity in the context of acute leukaemias. AUL is extremely rare in both humans and dogs, has a rapid clinical course and does not respond to treatment. It is characterised by the presence of blast cells within the bone marrow and/or peripheral blood at levels ≥ 20% and even up to 100% of all nucleated cells. Blast cells are unable to be differentiated on morphological, cytochemical and phenotypic criteria into myeloid or lymphoid lineages because of their immaturity and/or atypia. CASE REPORT: An 8-year-old German Shepherd dog was referred for depression, asthenia, mild anaemia, thrombocytopenia and marked leucocytosis. Abdominal ultrasound showed hepatomegaly, splenomegaly, bilateral nephromegaly and enlargement of mesenteric lymph nodes. Echocardiography revealed biventricular hypertrophy with abnormal tissue density of the myocardium. Blood and bone marrow smears were composed of 95% unclassifiable and/or atypical blast cells and signs of dysplasia of the erythroid and thrombocytic/megakaryocytic lineages were present. Blast cells were negative for all cytochemical stains used and flow cytometry of peripheral blood revealed 85% of total leucocytes consisting of small-to-medium-sized cells, negative for all lymphoid and myeloid markers except CD45 and CD34. After necropsy, cytology and histology revealed that blast cells had diffusely infiltrated all tissues examined. Both erythroid and megakaryocytic extramedullary haemopoiesis was also detected in the spleen, lymph nodes and liver. All immunohistochemical stains used were negative. CONCLUSION: On the basis of all the results, a diagnosis of acute leukaemia involving a very primitive haematopoietic precursor was made.

Transesophageal echocardiography as the sole guidance for occlusion of patent ductus arteriosus using a canine ductal occluder in dogs.

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) is usually performed by fluoroscopy alone or together with transesophageal echocardiography (TEE). Transthoracic echocardiography (TTE) guidance has been used for deployment of Amplatz Canine Ductal Occluder (ACDO), but sometimes is limited by suboptimal acoustic windows. Transesophageal echocardiography can overcome such issues and provides higher image resolution at the level of the great vessels. OBJECTIVES: To determine if TEE without fluoroscopy could be used to successfully perform ductal occlusion for the treatment of PDA in dogs. ANIMALS: Twenty client-owned dogs with PDA. METHODS: A prospective consecutive case series of PDA occlusion was performed using only TEE guidance. Dogs were positioned in right lateral recumbency and the TEE probe was positioned to visualize the descending aorta, PDA, and pulmonary artery. The guide wire, long introducer sheath, and ACDO were imaged by TEE to direct deployment. RESULTS: Ductal occlusion was performed successfully without need for fluoroscopy and without complications in 19 dogs. One dog required a second larger ACDO because of embolization of the first device 18 hours after positioning. CONCLUSIONS AND CLINICAL IMPORTANCE: We have demonstrated that TEE monitoring without concurrent fluoroscopy can guide each step of transcatheter ACDO embolization thereby providing an alternate method of visualization for this procedure. Use of TEE alone can reduce radiation exposure or is an option when fluoroscopy is not available, and, therefore, should be evaluated in a larger case series to better assess procedural failure rates.

Ketamine as a part of anaesthetic management in a dog with twiddler's syndrome.

An 11-year-old male German shepherd dog was referred for possible pacemaker implantation. A routine 6-lead electrocardiogram revealed a third-degree atrio-ventricular block with a heart rate of 40 to 45 beats/minute. A transvenous pacemaker implantation procedure was scheduled. The dog was premedicated with 10 µg/kg acepromazine and 5 mg/kg pethidine. A dose of 5 mg/kg ketamine and 0·2 mg/kg diazepam were used for induction and isoflurane in O2 and a constant rate infusion of ketamine (20 to 30 µg/kg/minute) were administered for maintenance of general anaesthesia. Due to a twiddler's syndrome, the pacemaker had to be repositioned. For the second procedure, the same protocol was employed except for a lower dose of ketamine both for induction (3 mg/kg) and constant rate infusion (10 to 15 µg/kg/minute). Ketamine appeared to be useful for both management of anaesthesia and cardiac pacemaker implantation in the absence of a temporary pacemaker.

Monoclonal gammopathy associated with multiple myeloma and visceral leishmaniasis in the dog: a comparison of two cases.

The term monoclonal gammopathy (MG) suggests the presence of clonal immunoglobulins in blood serum that are recognized as narrow spikes in the beta and/or gamma region of the electrophoretic pattern of serum. In the dog, MG is rare and is associated with a heterogeneous group of diseases that include multiple myeloma (the most common source of MG) as well as infectious and chronic inflammatory diseases such as Leishmaniasis. In this paper, two cases of MG are described: the first case is associated with multiple myeloma of monoclonal component type IgA/lambda, with the latter rare in dogs, and the second case involves MG that developed 3 years after an initial diagnosis of Leishmaniasis.

Cardiac troponin I is elevated in dogs and cats with azotaemia renal failure and in dogs with non-cardiac systemic disease.

OBJECTIVE: To determine if dogs and cats with renal failure, or other severe non-cardiac disease, and no antemortem evidence of cardiac disease on basic clinical evaluation, have elevated levels of cardiac troponin I (cTnI). DESIGN: Cross-sectional study using 56 dogs and 14 cats with primary non-cardiac disease (39 dogs with azotaemic renal failure, 14 cats with azotaemic renal failure, 17 dogs with non-cardiac systemic disease); 7/25 dogs and 6/14 cats had murmurs detected on physical examination. Serum or heparinised plasma was collected and analysed for cTnI. RESULTS: Cardiac troponin I concentrations were elevated above reference intervals in 70% of dogs and 70% of cats with azotaemic renal failure and in 70% of dogs with a variety of systemic non-cardiac diseases. Cardiac troponin I concentrations did not correlate with the degree of azotaemia, presence of murmurs, hypertension or type of non-cardiac illness. CONCLUSIONS: Cardiac troponin I concentration is often elevated in dogs and cats with azotaemic renal failure and in dogs with other systemic non-cardiac illness, suggesting that these conditions often result in clinically inapparent myocardial injury or possibly altered elimination of cTnI.