Pulmonary Artery Thrombosis in Experimental Angiostrongylus vasorum Infection Does Not Result in Pulmonary Hypertension and Echocardiographic Right Ventricular Changes

Background: Dogs experimentally inoculated with Angiostrongylus vasorum develop severe pulmonary parenchymal lesions and arterial thrombosis at the time of patency. Hypothesis: A. vasorum‐induced thrombosis results in arterial hypoxemia, pulmonary hypertension (PH), and altered cardiac morphology and function. Animals: Six healthy Beagles experimentally inoculated with A. vasorum. Methods: Thoracic radiographs and arterial blood gas analyses were performed 8 and 13 weeks postinoculation (wpi) and 9 weeks posttherapy (wpt). Echocardiography was done before and 2, 5, 8, 13 wpi and 9 wpt. Invasive pulmonary artery pressure (PAP) measurements were obtained 8 wpi. Two untreated dogs were necropsied 13 wpi and 4 treated dogs 9 wpt. Results: All dogs had patent infections at 7 wpi and clinical respiratory signs at 8 wpi. Moderate hypoxemia (median PaO₂ of 73 and 74 mmHg) present at 8 and 13 wpi had resolved by 9 wpt. Echocardiographically, no evidence of PH and no abnormalities in cardiac size and function were discernible at any time point. PAP invasively measured at 8 wpi was not different from that of control dogs. Severe radiographic pulmonary parenchymal and suspected thrombotic lesions at 13 wpi were corroborated by necropsy. Most histopathologic changes had resolved at 9 wpt, but focal inflammatory, thrombotic, and fibrotic changes still were present in all dogs. Conclusion: In experimentally infected Beagles, pulmonary and vascular changes induced by A. vasorum are reflected by marked radiographic changes and arterial hypoxemia. These did not result in PH and echocardiographic changes in cardiac size and function.     

Evaluation of red cell distribution width in dogs with pulmonary hypertension

ObjectivesTo compare red cell distribution width (RDW) between dogs with different causes of pulmonary hypertension (PH) and a control dog population to determine whether RDW was correlated with severity of PH as measured by echocardiography. A further aim was to determine the prognostic significance of increased RDW for dogs with PH.AnimalsForty-four client-owned dogs with PH and 79 control dogs presented to a single tertiary referral institution.MethodsSignalment, clinical pathological and echocardiographic data were obtained retrospectively from the medical records of dogs with PH, and RDW measured on a Cell-Dyn 3500 was compared between dogs with pre- and post-capillary PH and a control population. Referring veterinary surgeons were contacted for follow-up information and Kaplan–Meier analysis was conducted to investigate differences in survival time between affected dogs with different RDW values.ResultsThe RDW was significantly greater in dogs with pre-capillary PH compared to control dogs. There was no difference in median survival times between dogs with PH divided according to RDW values. The RDW was positively correlated with mean corpuscular volume and haematocrit in dogs with PH, but did not correlate with echocardiographic variables.ConclusionsAn association was found between dogs with PH and increased RDW; however there was considerable overlap in values between control dogs and dogs with PH. The RDW was not associated with survival in this study.     

Comparison of a computed tomographic pulmonary trunk to aorta diameter ratio with echocardiographic indices of pulmonary hypertension in dogs

There are limited criteria for the detection of pulmonary hypertension in dogs undergoing computed tomography (CT) for pulmonary disease. This retrospective analytical exploratory study compared a CT pulmonary trunk to aorta ratio with echocardiographic estimates of pulmonary hypertension. Dogs having both a contrast thoracic CT and echocardiogram were selected and maximal pulmonary trunk and descending aorta diameters were measured by two observers on a single transverse CT image. Computed tomographic diameter ratios were compared with the echocardiographic parameters of tricuspid regurgitation gradient, right ventricular acceleration time‐to‐ejection time ratio, pulmonary insufficiency gradient, and pulmonary artery to aorta diameter. A total of 78 dogs were sampled, with 44 dogs having one or more finding suggestive of pulmonary hypertension. A moderate positive correlation was shown between tricuspid regurgitation gradient and CT pulmonary trunk to aorta ratio (r = 0.61, P‐value < 0.0001). Mean CT pulmonary trunk to aorta ratio of dogs with moderate (P = 0.0132) and severe (P < 0.0003) pulmonary hypertension were significantly higher than normal dogs. There was no significant difference in mean CT pulmonary trunk to aorta ratio between normal and mild pulmonary hypertension dogs (P = 0.4244). The intraclass correlation coefficient (0.72) showed good reproducibility of the ratio. Findings indicated that CT pulmonary trunk to aorta ratio is a reproducible and potentially useful method to predict moderate and severe pulmonary hypertension in dogs, but not mild pulmonary hypertension. In dogs undergoing thoracic CT for pulmonary disease, an increased ratio should prompt follow up echocardiography.     

Predictive model for the detection of pulmonary hypertension in dogs with myxomatous mitral valve disease

Pulmonary hypertension (PH) often occurs due to a left heart disease, such as myxomatous mitral valve disease (MMVD), in dogs and is diagnosed using Doppler echocardiography and estimated pulmonary arterial pressure. Diagnosis of PH in dogs requires expertise in echocardiography: however, the examination for PH is difficult to perform in a clinical setting. Thus, simple and reliable methods are required for the diagnosis of PH in dogs. The purpose of this study was to develop models using multiple logistic regression analysis to detect PH due to left heart disease in dogs with MMVD without echocardiography. The medical records of dogs with MMVD were retrospectively reviewed, and 81 dogs were included in this study and classified into PH and non-PH groups. Bivariate analysis was performed to compare all parameters between the groups, and variables with P values of <0.25 in bivariate analysis were included in multiple logistic regression analysis to develop models for the detection of PH. In multiple logistic regression analysis, the model included a vertebral heart scale short axis of >5.2 v, and a length of sternal contact of >3.3 v was considered suitable for the detection of PH. The predictive accuracy of this model (85.9%) was judged statistically adequate, and therefore, this model may be useful to screen for PH due to left heart disease in dogs with MMVD without echocardiography.     

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.

Caudal pulmonary artery to vein ratio on radiography can predict pulmonary hypertension in dogs with mitral regurgitation

Pulmonary hypertension (PH) is an important predictor of poor outcomes in dogs with mitral regurgitation (MR). The feasibility of radiography to predict PH in dogs with MR is unknown. This retrospective, observational, and analytic study aimed to identify a radiographic parameter to predict PH in dogs with MR. A total of 302 dogs diagnosed with MR on echocardiography were enrolled. Medical record and radiographic findings such as the size of the main pulmonary artery, left atrium, left ventricle, and right chamber, and cranial and caudal pulmonary arteries and veins were evaluated according to the presence of PH. The diameters of the cranial and caudal pulmonary vessels were compared to the fourth rib and the ninth rib, respectively, and the ratio of the pulmonary artery to the corresponding vein (CdPA/CdPV) was calculated. Pulmonary hypertension was diagnosed in 77 dogs (25.5%) and the prevalence of PH increased with MR grade. The CdPA/CdPV was significantly higher (P < 0.001) in the presence of PH. Multivariate analysis showed that the CdPA/CdPV was the only independent radiographic parameter that had a significant association with PH in dogs with MR (P = 0.028). The cut-off value of the CdPA/CdPV = 1.10 showed 90.6% specificity and 31.1% sensitivity for detecting PH in dogs with MR. In dogs with MR, PH can be predicted with high specificity when the caudal pulmonary artery is 1.1 times larger than the corresponding vein on radiographs.     

Contrast echocardiography in Boxer dogs with and without aortic stenosis

ObjectivesThe aim of this study was to investigate whether contrast echocardiography could enhance the subcostal Doppler signal for aortic flow measurements and achieve myocardial opacification, in Boxer dogs with and without AS.BackgroundIn evaluating dogs for aortic stenosis (AS) subcostal Doppler echocardiography was used for measurement of the aortic flow velocity, a measurement that can sometimes be difficult to perform in Boxer dogs.Animals, materials, and methodsCardiac auscultation, phonocardiographic and echocardiographic examinations, including a contrast study with Optison, were performed on 29 Boxer dogs selected based on previous examinations.ResultsThe initial subcostal Doppler signal was weak in 66% of the dogs and a marked improvement was seen in all dogs after contrast injection. The peak aortic flow velocity increased 5% from 2.58 ± 1.42 m/s before contrast to 2.71 ± 1.54 m/s after contrast (p = 0.003). This corresponds to a 2.8 mmHg increase in the pressure gradient from 26.6 mmHg before to 29.4 mmHg after contrast. A dose of 0.05–0.1 mL of Optison administered intravenously resulted in approximately 4 min of Doppler signal enhancement. With the present technique contrast echocardiography did not achieve myocardial opacification.ConclusionsSingle use of the contrast agent Optison can be recommended for enhancement of the subcostal Doppler signal in dogs, in which plain Doppler signals are difficult to obtain. Albeit statistically significant, the mild increase in peak aortic flow velocity after contrast was not considered biologically or clinically significant.     

Utility of N-terminal pro-brain natriuretic peptide for assessing hemodynamic significance of patent ductus arteriosus in dogs undergoing ductal repair

ObjectiveDetermine if plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) correlates with markers of hemodynamically significant patent ductus arteriosus (PDA) in dogs.AnimalsTen dogs with PDA and 30 healthy dogs of similar ages.MethodsProspective case series with control population. Dogs with PDA were initially evaluated with thoracic radiographs, transthoracic echocardiography, pulmonary capillary wedge pressure (PCWP) and NT-proBNP. Following ductal occlusion, NT-proBNP and echocardiography were repeated within 24 h and at day 90. PCWP was repeated at day 90. Correlation between NT-proBNP and hemodynamic measurements was assessed, and accuracy of NT-proBNP for identifying PDA severity was estimated.ResultsNT-proBNP was significantly higher (median; absolute range) in dogs with PDA (895; 490–7118 pmol/L) than controls (663; 50–1318 pmol/L) (p = 0.025). NT-proBNP decreased significantly 90 days post-ductal closure (597; 154–1858 pmol/L) (p = 0.013). Left atrial and ventricular size decreased significantly within 24 h and at day 90 as did PCWP (day 90 only). NT-proBNP correlated with vertebral heart size (VHS) and indexed left ventricular systolic diameter (iLVIDs); concentrations ≥ 1224 pmol/L distinguished dogs with elevated VHS and iLVIDs.ConclusionsNT-proBNP is elevated in dogs with PDA, decreases following PDA closure and correlates with select radiographic and echocardiographic markers of cardiac remodeling.     

First report of Angiostrongylus vasorum (French heartworm) in red foxes (Vulpes vulpes) on Prince Edward Island

Objective To identify first-stage nematode larvae (L1) recovered from a red fox scat sample and adult female worms recovered from 2 red fox lungs at necropsy, using published molecular methods to confirm a morphological diagnosis of Angiostrongylus vasorum (French heartworm).Animal Red fox (Vulpes vulpes).Procedure Nematode larvae recovered from a Baermann examination survey of wild canid scats (n = 101) conducted from January 2017 to August 2020, were identified by size and morphology and subjected to PCR and DNA sequencing of the small subunit (SSU) rRNA gene, the large subunit (LSU) rRNA gene, or the second internal transcribed spacer (ITS2). In addition, these techniques were applied to adult female worms recovered from the heart/lungs of 2 red foxes (obtained from PEI trappers and stored frozen at −20°C since December of 2018 and 2020).Results Size and morphology of L1 recovered by Baermann examination from a wild canid scat sample (presumed to be red fox) collected near Montague, PEI and adult female worms recovered at necropsy from 2 red fox carcasses were identified as A. vasorum. Molecular analysis confirmed the larvae and adult worms were A. vasorum.Conclusion These findings indicated that A. vasorum has become endemic in the red fox population on PEI.Clinical relevance Angiostrongylus vasorum infection is potentially fatal in dogs. Veterinarians and regional diagnostic laboratories in the Maritime provinces should consider the possibility of A. vasorum infection in dogs with clinical signs of cardiopulmonary and/or central nervous system disease or bleeding disorders.     

Recent advances in the epidemiology,clinical and diagnostic features,and control of canine cardio-pulmonary angiostrongylosis

The aim of this review is to provide a comprehensive update on the biology, epidemiology, clinical features, diagnosis, treatment, and prevention of canine cardio-pulmonary angiostrongylosis. This cardiopulmonary disease is caused by infection by the metastrongyloid nematode Angiostrongylus vasorum. The parasite has an indirect life cycle that involves at least two different hosts, gastropod molluscs (intermediate host) and canids (definitive host). A. vasorum represents a common and serious problem for dogs in areas of endemicity, and because of the expansion of its geographical boundaries to many areas where it was absent or uncommon; its global burden is escalating. A. vasorum infection in dogs can result in serious disorders with potentially fatal consequences. Diagnosis in the live patient depends on faecal analysis, PCR or blood testing for parasite antigens or anti-parasite antibodies. Identification of parasites in fluids and tissues is rarely possible except post mortem, while diagnostic imaging and clinical examinations do not lead to a definitive diagnosis. Treatment normally requires the administration of anthelmintic drugs, and sometimes supportive therapy for complications resulting from infection.     

Assessment of the combination of spinosad and milbemycin oxime in preventing the development of canine Angiostrongylus vasorum infections

Angiostrongylus vasorum is an increasingly reported parasite in Europe that develops in dogs after ingestion of infective third stage larvae (L3) that reside in gastropod molluscs which are needed to complete the parasite's life-cycle. Infection can produce a diversity of clinical signs, determined by involvement of the respiratory, neurological, and/or coagulation system, with a likely fatal outcome in the absence of treatment. Few drugs have been shown to reliably prevent infection, and data on treatment of infections is limited. A controlled, randomized, partially blinded laboratory study was therefore executed to evaluate the efficacy and safety of a combination tablet of spinosad/milbemycin oxime in dogs inoculated with approximately 250 A. vasorum L3. Sixteen healthy nematode free adult dogs were randomly allocated to two study groups of 8 dogs each. Thirty days post inoculation (dpi) all dogs in the fed state were treated: dogs in group B were treated with spinosad and milbemycin oxime at the dose rates of 45–60 mg/kg and 0.75–1.0 mg/kg bodyweight, respectively, approximately the lower half portion of the expected full unit dose range; dogs in group A were treated with placebo tablets. All dogs were euthanized and necropsied 56–58 dpi. The heart and lungs were examined to determine the presence of A. vasorum. All placebo group dogs were infected at necropsy with counts ranging from 22 to 98 adult worms and a geometric mean worm count of 55.2. In contrast, the geometric mean worm count in the spinosad/milbemycin oxime group was 0.7 with worm numbers ranging from 0 to 8. The results of this study demonstrate that a single treatment with the tablet combination of spinosad and milbemycin oxime administered 30 dpi provided 98.8% preventive efficacy against development of adult A. vasorum infections. Monthly treatments with spinosad and milbemycin oxime have the potential to prevent the establishment of infections with A. vasorum in dogs.     

Pulmonary artery dissection following pulmonary balloon valvuloplasty in dogs

Introduction/objectivesPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. We sought to report the rate of this complication in dogs and describe the demographic, clinical, procedural, and outcome data in affected dogs.Animals, materials and methodsMedical records at a single academic institution between 2002 and 2021 were reviewed for dogs with pulmonic stenosis treated by a balloon valvuloplasty. Dogs were included for evaluation if there was evidence of pulmonary artery dissection on echocardiography or necropsy following balloon valvuloplasty. The demographic, clinical, surgical, and follow-up information were then recorded.ResultsSix dogs were included from 210 balloon valvuloplasty procedures for pulmonic stenosis giving a 3.9% rate of pulmonary dissection. There was a variety of signalment, pulmonary valve morphologies, and balloon catheter types used in each dog. All dogs had severe pulmonic stenosis (median pressure gradient of 208 mmHg, range 94–220 mmHg) with 5/6 dogs having a pressure gradient >144 mmHg. The median balloon to pulmonary valve annulus ratio was 1.35 (range 1.25–1.5). Three dogs died perioperatively, and three dogs were alive at follow up 3.3, 4.0, and 4.1 years postoperatively.ConclusionPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. Extreme elevations in preoperative pulmonary valve flow velocity were common. Prognosis is variable, with a potential 50% perioperative survival rate, but extended survival times were noted in those patients discharged from hospital.     

Tricuspid annular plane systolic excursion in dogs with myxomatous mitral valve disease with and without pulmonary hypertension

Objectives

To evaluate tricuspid annular plane systolic excursion (TAPSE) in dogs with myxomatous mitral valve disease (MMVD) with or without pulmonary hypertension (PH) and to study the correlations with clinical and echocardiographic parameters.

ACVIM consensus statement guidelines for the diagnosis,classification, treatment,and monitoring of pulmonary hypertension in dogs

Pulmonary hypertension (PH), defined by increased pressure within the pulmonary vasculature, is a hemodynamic and pathophysiologic state present in a wide variety of cardiovascular, respiratory, and systemic diseases. The purpose of this consensus statement is to provide a multidisciplinary approach to guidelines for the diagnosis, classification, treatment, and monitoring of PH in dogs. Comprehensive evaluation including consideration of signalment, clinical signs, echocardiographic parameters, and results of other diagnostic tests supports the diagnosis of PH and allows identification of associated underlying conditions. Dogs with PH can be classified into the following 6 groups: group 1, pulmonary arterial hypertension; group 2, left heart disease; group 3, respiratory disease/hypoxia; group 4, pulmonary emboli/pulmonary thrombi/pulmonary thromboemboli; group 5, parasitic disease (Dirofilaria and Angiostrongylus); and group 6, disorders that are multifactorial or with unclear mechanisms. The approach to treatment of PH focuses on strategies to decrease the risk of progression, complications, or both, recommendations to target underlying diseases or factors contributing to PH, and PH-specific treatments. Dogs with PH should be monitored for improvement, static condition, or progression, and any identified underlying disorder should be addressed and monitored simultaneously.     

Intramuscular alfaxalone and methadone with or without ketamine in healthy cats: effects on sedation and echocardiographic measurements

ObjectiveTo evaluate the effect of alfaxalone and methadone administered intramuscularly (IM), with or without ketamine, on sedation and echocardiographic measurements in healthy cats.Study designA randomized, blinded, clinical study.AnimalsA group of 24 client-owned cats.MethodsBaseline echocardiographic evaluation (bEchoCG) was performed. Cats were given IM alfaxalone (2 mg kg^–1) and methadone (0.3 mg kg^–1) with (AMK group) or without (AM group) ketamine (1 mg kg^–1). A sedation score (0–5, indicating none to good sedation) was assigned at 5 (T5), 10 (T10) and 15 (T15) minutes after IM injection. At T15, a second echocardiographic evaluation (sEchoCG) was performed. Data are shown as median (range). Significance was p < 0.05.ResultsFinally, 21 cats were included. Sedation score was significantly higher in the AMK (11 cats) than in the AM group (10 cats): 4 (1–5) versus 0.5 (0–4) at T5 (p = 0.003); 4 (1–5) versus 1.5 (0–5) at T10 (p = 0.043); and 4 (1–5) versus 2 (0–5) at T15 (p = 0.024). All echocardiographic measurements obtained were within reference ranges. Between the groups, aortic root area (p = 0.009) and end-diastolic aortic dimension (p = 0.011) were significantly higher in the AM group at bEchoCG and sEchoCG, respectively. Within each group, values at bEchoCG and sEchoCG showed no significant differences, except for pulmonary peak velocity (0.85 m second^–1; p = 0.028) in the AMK group and ejection time (154 m second; p = 0.03) in the AM group; both variables decreased after sedation.Conclusions and clinical relevanceIn this population of healthy cats, neither protocol produced clinically meaningful effects on the echocardiographic variables evaluated. Alfaxalone with methadone produced mild sedation, whereas the addition of 1 mg kg^–1 ketamine induced adequate sedation for diagnostic procedures.     

Associations between thoracic radiographic changes and severity of pulmonary arterial hypertension diagnosed in 60 dogs via Doppler echocardiography: A retrospective study

Doppler echocardiography is a noninvasive method for estimating and grading pulmonary arterial hypertension. No current literature associates significance of radiographic findings with severity of pulmonary arterial hypertension. We hypothesized that the number and conspicuity of radiographic findings suggestive of pulmonary arterial hypertension would be greater based on the severity of pulmonary arterial hypertension. Dogs with pulmonary arterial hypertension and normal control dogs were included in this retrospective, case control study. Three radiologists blinded to echocardiographic results scored thoracic radiographs for right ventricular and main pulmonary artery enlargement and pulmonary lobar artery enlargement, tortuosity, and blunting by multiple methods. Presence or absence of each finding was scored in an additive fashion and averaged for each grade of pulmonary arterial hypertension severity. Seventy‐one dogs (60 dogs with pulmonary arterial hypertension and 11 control dogs) of which some had multiple studies were included: 20 mild, 21 moderate, 25 severe, and 11 absent pulmonary arterial hypertension. The following radiographic findings were significantly associated with increasing pulmonary arterial hypertension severity: right ventricular enlargement by “reverse D” and “3/5–2/5 cardiac ratio” methods, main pulmonary artery enlargement, and caudal lobar artery enlargement by the “3rd rib” method. Mean scores for severe pulmonary arterial hypertension and normal dogs were significantly different (P‐value < 0.0001). Mean scores between different pulmonary arterial hypertension grades increased with severity but were not statistically significant. Individually and in combination, radiographic findings performed poorly in differentiating severity of pulmonary arterial hypertension. Findings indicated that thoracic radiographs should be utilized in conjunction with Doppler echocardiography in a complete diagnostic work‐up for dogs with suspected pulmonary arterial hypertension.     

Angiostroneylosis in Cornwall: Clinical presentations of eight cases

Clinical signs in eight dogs with Angiostrongylus vasorum infection included chronic cough, dyspnoea, lumbar pain, hindleg paresis/paralysis, abdominal pain, weakness and collapse; two of the dogs were asymptomatic. Thrombocytopenia was present in two dogs and a mild anaemia in one. Thoracic radiographs showed mild right heart enlargement in two out of three dogs and a pneumothorax in one. At post mortem examination in three dogs, the lungs were swollen with a mottled appearance and there was dilatation of the right ventricle. Adult A vasorum were found in the right heart, the pulmonary artery and its branches. Adult worms were also found in the systemic vasculature in one dog, associated with thromboembolism. Treatment with ivermectin in two dogs and fenbendazole in three dogs resulted in the resolution of clinical signs and no demonstrable larvae in the faeces one to two weeks later.     

Quadricuspid aortic valve and associated abnormalities in the dog: Report of six cases

ObjectivesTo describe the clinical and echocardiographic findings in dogs with quadricuspid aortic valve (QAV).BackgroundQAV is a rare canine congenital heart disease which has been reported only three times in the young dog.Animals, materials and methodsSix dogs (0.3- to 13-year-old) with QAV diagnosed by two-dimensional echocardiography were retrospectively evaluated. Medical records, echocardiograms, and follow-ups were reviewed.ResultsAccording to aortic cusp morphology, QAV was classified as type A (n = 1), type B (n = 4) or type C (n = 1). QAV was associated with at least one other heart disease in all of the dogs including, ventricular septal defect (n = 1), enlarged left coronary ostium (n = 4), degenerative mitral valve disease (MVD, n = 1) and patent ductus arteriosus (PDA, n = 3). Mild to moderate aortic regurgitation was also detected in all dogs by continuous-wave and color-flow Doppler echocardiography. QAV was diagnosed in four asymptomatic dogs referred for evaluation of a heart murmur. The remaining two dogs had QAV and PDA with evidence of mild exercise intolerance and moderately retarded growth. The PDA was surgically corrected in both dogs and at the time of writing, 1–2.5 years after the initial diagnosis, none of the six animals shows evidence of clinical signs.ConclusionQAV is a cause of aortic insufficiency. It may incidentally be found by two-dimensional echocardiography in dogs of various ages in association with other congenital or acquired cardiac abnormalities.     

Sildenafil citrate therapy in 22 dogs with pulmonary hypertension

BACKGROUND: Pulmonary hypertension (PH) is a disease condition characterized by abnormally increased pulmonary artery pressures and often is associated with a poor prognosis. Sildenafil is a phosphodiesterase inhibitor that causes pulmonary arterial vasodilation and reduction in pulmonary artery pressures. HYPOTHESIS: Treatment with sildenafil will improve echocardiographic determinants of PH in dogs, while also improving quality of life and survival. ANIMALS: Twenty-two dogs with clinical and echocardiographic evidence of pulmonary hypertension. METHODS: A retrospective study evaluating the effects of sildenafil on physical examination, ECG and radiographic findings, blood pressure and echocardiographic findings of PH, clinical score, and outcome was completed. PH was defined as a peak tricuspid regurgitation flow velocity > or = 2.8 m/s or a peak pulmonic insufficiency flow velocity > or = 2.2 m/s. RESULTS: Sixteen of 22 dogs with PH were elderly females of small body size. Their clinical score was significantly improved (P = .0003) with sildenafil treatment, but physical examination findings remained unchanged. Heart rate, respiratory rate, vertebral heart size, ECG heart rate, and systolic blood pressure did not change significantly with sildenafil treatment (P > .05). Peak tricuspid regurgitation flow velocities did not change significantly with the treatment of sildenafil, but selected systolic time intervals were significantly improved. Survival times for all dogs ranged from 8 to > 734 days. CONCLUSIONS AND CLINICAL IMPORTANCE: Sildenafil did not significantly lower the degree of measurable PH in dogs. Clinical improvement and increased quality of life was seen with sildenafil treatment, despite lack of significant change in other variables.     

Diagnostic value of echo-Doppler and tissue Doppler imaging in dogs with pulmonary arterial hypertension

BACKGROUND: Diagnosis of pulmonary arterial hypertension (PAH) relies on Doppler measurement of pulmonic and tricuspid regurgitation (TR). However, these are not always detectable. HYPOTHESIS: Tissue Doppler imaging (TDI), a novel noninvasive ultrasound technique, provides indirect but sensitive and specific assessment of elevated systolic pulmonary artery pressure (SPAP) in dogs. ANIMALS: One hundred and five dogs with TR. METHODS: Prospective observational study. Dogs were categorized as presenting normal (group 1, n = 45), mildly increased (group 2, n = 19), or moderately to severely increased (group 3, n = 41) SPAP, based on TR peak velocities (< 2.5, 2.5-3.0, and > 3.0 m/s, respectively). Ten quantitative echo-Doppler- and TDI-derived variables were assessed, including the main pulmonary arterial diameter to aortic diameter ratio, pulmonary flow acceleration time, and acceleration-to-ejection time ratio, the Tei index of right ventricular function, and 6 longitudinal basal right ventricular TDI variables. RESULTS: A significant correlation was observed between SPAP and each of the 10 tested variables (P < .05). Conventional echo-Doppler variables were less discriminating than the TDI for predicting increased SPAP. The combined systolic and diastolic right TDI index had the highest sensitivity and specificity (89% and 93% respectively, for a cutoff of 11.8 cm/s) and could discriminate between dogs in group 1 from dogs in group 2. CONCLUSIONS AND CLINICAL IMPORTANCE: TDI provided effective predictors of systolic PAH and demonstrated that both alterations in right-sided systolic and diastolic myocardial function can occur with mild increases in SPAP.