Self-Reported Utilization of International (ACVIM Consensus) Guidelines and the Latest Clinical Trial Results on the Treatment of Dogs with Various Stages of Myxomatous Mitral Valve Degeneration: A Survey among Veterinary Practitioners.

BACKGROUND: Myxomatous mitral valve degeneration is the most common canine heart disease. Several clinical trials have investigated various treatments. The latest recommendations are published in the ACVIM consensus guidelines (2019). Our study aimed to investigate how closely veterinary practitioners apply the treatment recommendations of these guidelines and the latest clinical trials. METHODS: An online survey was sent to Dutch and Belgian veterinary practices via digital channels. RESULTS: The data from 363 fully completed surveys were analyzed. For stage B1 disease, 93% recommended, correctly, no treatment. For stage B2 disease, 67% of the respondents recommended starting pimobendan as monotherapy. For chronic treatment of stage C disease, 16 different drug combinations were mentioned, but nobody recommended surgery. Only 48% of the respondents recommended the only evidence-based drug combination: a loop diuretic with pimobendan. A concerning finding was the simultaneous prescription of two loop diuretics, by 19% of the respondents. CONCLUSIONS: Treatment recommendations showed an increasing variation with more advanced disease stages from B1 through B2 to C. This reflects the increasing disagreement among the panelists who prepared the ACVIM consensus guidelines. Practitioners of our study seem to practice more evidence-based medicine than veterinary cardiologists, as it was reported in a recent survey-based study.

Self-Reported Utilization of International Guidelines for Staging Dogs with Myxomatous Mitral Valve Degeneration: A Survey among Veterinary Practitioners.

BACKGROUND: ACVIM developed and published guidelines for staging myxomatous mitral valve degeneration in dogs in 2009. An updated version was published in 2019. The present study aimed to investigate whether these guidelines are actually used by the intended public more than a decade after their first publication. METHODS: An online survey was distributed among Dutch and Belgian veterinarians through online channels and mailing lists. RESULTS: Of the 524 responses, only 363 complete surveys were analyzed. The ACVIM guidelines are used by 60% of the respondents. Veterinarians find it more difficult to differentiate stage B1 from B2 in asymptomatic dogs compared to diagnosing stage C. Three-quarters of the respondents would recommend echocardiography for an incidentally detected new murmur with an intensity of 3 out of 6 in an adult dog. Two-thirds of the respondents find coughing a convincing finding for stage C disease. Close to half of the respondents associate a horizontal, dull percussion line with pulmonary edema. For confirming cardiogenic pulmonary edema, 98% of the respondents used thoracic radiographs. CONCLUSIONS: Veterinary practitioners might not have the expected training and equipment to be able to apply the guidelines in their practices, especially in the differentiation of stage B1 from stage B2.

Preductal Segmental Tubular Aortic Hypoplasia in Perinatally Died Stabyhoun Puppies.

BACKGROUND: A high perinatal mortality rate in the Stabyhoun breed prompted one of the Dutch breeding organizations to start an investigation. Preductal segmental tubular aortic hypoplasia is an extremely rarely documented congenital vascular anomaly in dogs, and it is suspected to be the result of constriction of ectopic ductal tissue in the aortic wall at birth. METHODS: Over a period of 18 months, Stabyhoun puppies that were stillborn, died or were euthanized before 3 weeks of age were submitted to post-mortem examination at the reporting institution. Pathologic findings were documented. RESULTS: Eight Stabyhoun puppies were submitted during the study period. In five of them, a severe preductal segmental tubular aortic hypoplasia was found. Two of the five puppies were stillborn, and three died spontaneously or were euthanized. CONCLUSIONS: Preductal tubular aortic hypoplasia was found in an unusually high frequency in the examined Stabyhoun puppies. Because the condition is believed to cause clinical signs only after birth, this anomaly cannot explain the death of the stillborn puppies. However, it might be responsible for cardiogenic pulmonary edema in the postnatal period. Routine dissection of the great vessels in perinatally deceased puppies would help to establish the prevalence of congenital anomalies of the aorta.

A Novel Standardized Method for Aiding to Determine Left Atrial Enlargement on Lateral Thoracic Radiographs in Dogs.

BACKGROUND: Left atrial enlargement indicates severe cardiac disease. Although the gold standard for determining left atrial size is echocardiography, many veterinary practices lack the necessary equipment and expertise. Therefore, thoracic radiography is often used to differentiate cardiogenic pulmonary edema from primary respiratory diseases and to facilitate distinguishing dogs with stage B1 and B2 mitral valve degeneration. METHODS: The goal was to test a new standardized method for identifying radiographic left atrial enlargement. On a lateral radiograph, a straight line was drawn from the dorsal border of the tracheal bifurcation to the crossing point of the dorsal border of the caudal vena cava and the most cranial crus of the diaphragm. If a part of the left atrium extended this line dorsally, it was considered enlarged. Echocardiographic left atrial to aortic ratio (LA:Ao) was used as a reference. Thirty-nine observers with various levels of experience evaluated 90 radiographs, first subjectively, then applying the new method. RESULTS: The new method moderately correlated with LA:Ao (r = 0.56-0.66) in all groups. The diagnostic accuracy (72-74%) of the subjective assessment and the new method showed no difference. CONCLUSIONS: Though the new method was not superior to subjective assessment, it may facilitate learning and subjective interpretation.

Right atrial thrombus formation in a dog after successful electrical cardioversion for atrial fibrillation.

Right atrial masses in dogs are commonly diagnosed as malignant tumors. This report describes a dog with a right atrial mass that appeared after successful electrical cardioversion of atrial fibrillation and resolved with antithrombotic treatment. A 9-year-old mastiff was presented for acute vomiting, and occasional cough of several weeks' duration. Ultrasonographic and radiographic examinations of the abdomen and chest identified mechanical ileus, as well as pleural effusion and pulmonary edema, respectively. Echocardiography indicated a dilated cardiomyopathy phenotype. During anesthetic induction for laparotomy, atrial fibrillation developed. Electrical cardioversion successfully restored sinus rhythm. An echocardiogram performed 2 weeks later disclosed a right atrial mass, which had not been apparent before cardioversion. Repeat echocardiography after 2 months of clopidogrel and enoxaparin treatment failed to detect the mass. Intra-atrial thrombus formation is possible after successful cardioversion of atrial fibrillation and should be considered as a differential diagnosis for echocardiographically detected atrial masses.

Progressive Right Ventricular Obstruction Caused by a Double-Chambered Right Ventricle Resulting in Shunt-Reversal via a Concomitant Congenital Ventricular Septal Defect and Subsequent Erythrocytosis in a Dog.

A 3-year-old Chihuahua was presented because of exercise intolerance, respiratory distress, and syncopal episodes. At the age of 10 weeks, the dog was diagnosed with a congenital small left-to-right shunting ventricular septal defect and a mild right ventricular outflow tract obstruction via echocardiography. At that time, the dog was asymptomatic, but the breeder's veterinarian heard a murmur. Both cardiac defects were judged to be clinically non-relevant at that time. However, at 3 years of age, echocardiography revealed a severe right ventricular obstruction, known as a double-chambered right ventricle, along with right-to-left shunting via the ventricular septal defect. Because of chronic hypoxemia due to the right-to-left shunting, erythrocytosis developed. Flow reversal via the shunt was caused by a progressively worsening right ventricular obstruction leading to a supra-systemic right ventricular systolic pressure. Because of the poor prognosis, the dog was euthanized, and the heart was submitted for post-mortem examination. Gross pathologic findings revealed the close proximity of the right ventricular obstructive lesion to the ventricular septal defect. Histopathology revealed localized muscular hypertrophy and severe endocardial fibrosis. The suspected pathogenesis of the progressive obstruction was infiltrative myocardial fibrosis due to turbulent blood flow from the left-to-right shunting ventricular septal defect, as described in humans.

Successful Clindamycin Therapy of an Infected Subcutaneous Permanent Pacing Lead in a Dog after a Failed Course with Potentiated Amoxicillin and Enrofloxacin.

Though permanent pacemaker implantation is the only effective therapy for certain bradyarrhythmias in dogs, it is not without risks. Bacterial infection of the device is one of the most common complications. Human guidelines recommend besides systemic antibiotics, surgical explantation of the pacing lead and pulse generator in case of device-infection. This report describes a 13.5-year-old dog that received a transvenous endocardial permanent pacemaker because of syncopal episodes resulting from paroxysmal third-degree atrio-ventricular block. Five days after an uneventful surgery, a painful swelling appeared around the subcutaneous part of the lead where this was inserted into the jugular vein. A 4-week course of amoxicillin and clavulanic acid combined with enrofloxacin failed to clear the infection on long-term. Ultrasound-guided puncture of the abscess was performed to gain a sample for bacterial culture and antibiogram. Oral clindamycin of 4 weeks' duration successfully resolved the infection with Staphylococcus aureus without having to explant the device. Repeated ultrasonographic examinations and fine-needle aspiration biopsies were used to evaluate for persistent local inflammation, guiding the length of the antibiotic therapy. Though the described approach has traditionally been ill-advised because of the risk of introducing bacteria and damaging the pacemaker lead, it was successful in our case.

Prevalence and Prognosis of Atenolol-Responsive Systolic Anterior Motion of the Septal Mitral Valve Leaflet in Young Cats with Severe Dynamic Left Ventricular Outflow Tract Obstruction.

BACKGROUND: Severe dynamic left ventricular outflow tract obstruction (DLVOTO) secondary to the systolic anterior motion of the septal mitral valve leaflet (SAM) can result either from congenital mitral valve disorders or left ventricular concentric hypertrophy of any cause, in cats commonly hypertrophic cardiomyopathy (HCM). Though HCM cannot be reversed, the question remains whether atenolol can cure cats with severe DLVOTO resulting from a presumed mitral valve dysplasia. METHODS: In this retrospective case series, client-owned asymptomatic cats younger than 1.5 years with echocardiographic evidence of SAM and severe DLVOTO were included. Oral atenolol therapy and recheck echocardiography after 2-3 months were recommended. The owners and referring veterinarians were called for long-term follow-up information. RESULTS: Of the 28 included cats, 23 were treated with atenolol. Recheck echocardiography performed in 17 cats showed a resolution of SAM in 47%. In the long term, SAM remained absent in only 9% of the treated cats. Cardiac-related death occurred in 26% of the atenolol-treated cats. CONCLUSIONS: The long term benefit of twice-daily atenolol therapy was documented in 9% of cats. Whether the cats where atenolol failed to resolve DLVOTO on long-term had HCM, or a therapy-resistant congenital primary mitral valve disorder remains unclear.

Information Provided by Breeders and Referring Veterinarians about the Presence and Meaning of a Murmur to Owners of Newly Purchased Puppies with a Later Confirmed Congenital Heart Disease.

Background: A recent study revealed that only 10% of puppies diagnosed with a congenital heart disease were referred for murmur investigation to a veterinary cardiology specialist while the puppies were in the breeders' possession. Whether the new owners had been informed about the presence of a murmur before purchasing a puppy was not investigated. Methods: New owners whose dogs were diagnosed with a congenital heart disease at the authors' institution in a 1-year period received a questionnaire during the consult after cardiac auscultation but before performing an echocardiogram. The main study aims were to reveal whether the breeders had informed the new owners about the presence of a murmur before purchasing the puppy, and whether the owners would have still chosen to buy that specific puppy if they had known about a potentially present congenital heart disease. Results: Of the 60 interviewed owners, 72% would have refrained from buying the puppy if they had known about the presence of a congenital heart disease. However, only 23% of them were informed about the presence of a cardiac murmur before purchase. Conclusions: Most owners would have chosen to buy a healthy puppy without a heart disease if they had been informed.

Prevalence of Echocardiographic Evidence of Trace Mitral and Aortic Valve Regurgitation in 50 Clinically Healthy, Young Adult Labrador Retrievers without Heart Murmur.

Background-Though physiologic regurgitation of the right-sided cardiac valves is well recognized in dogs and other mammals, the prevalence of trace insufficiency of the mitral and aortic valves in clinically healthy, young adult dogs is unknown. Methods-In this observational cross-sectional study, 50 clinically healthy, young adult Labrador retrievers without an audible heart murmur were enrolled. All dogs were bred and owned by a single organization. Cardiac screening was requested for all dogs that were intended for breeding. These dogs underwent a cardiac auscultation and transthoracic echocardiography by a veterinary cardiology specialist. If mitral or aortic valve regurgitation was noticed, the jet size was subjectively assessed on color Doppler echocardiography. Pedigree analysis was performed to reveal a possible hereditary background of mitral valve regurgitation. Results-The prevalence of trivial mitral valve regurgitation was 52% with no significant predisposition to gender (p = 0.86) or haircoat color (p = 0.68). The prevalence of aortic valve regurgitation was 4%. Pedigree analysis for mitral valve regurgitation showed familial clustering, suggesting a hereditary background of the trait. Conclusions-The prevalence of silent trace mitral valve regurgitation in young adult Labrador retrievers was high. Because the regurgitant jet was trivial in all dogs, it is probably physiologic.

Genetic Basis of Dilated Cardiomyopathy in Dogs and Its Potential as a Bidirectional Model.

Cardiac disease is a leading cause of death for both humans and dogs. Genetic cardiomyopathies, including dilated cardiomyopathy (DCM), account for a proportion of these cases in both species. Patients may suffer from ventricular enlargement and systolic dysfunction resulting in congestive heart failure and ventricular arrhythmias with high risk for sudden cardiac death. Although canine DCM has similar disease progression and subtypes as in humans, only a few candidate genes have been found to be associated with DCM while the genetic background of human DCM has been more thoroughly studied. Additionally, experimental disease models using induced pluripotent stem cells have been widely adopted in the study of human genetic cardiomyopathy but have not yet been fully adapted for the in-depth study of canine genetic cardiomyopathies. The clinical presentation of DCM is extremely heterogeneous for both species with differences occurring based on sex predisposition, age of onset, and the rate of disease progression. Both genetic predisposition and environmental factors play a role in disease development which are identical in dogs and humans in contrast to other experimental animals. Interestingly, different dog breeds have been shown to develop distinct DCM phenotypes, and this presents a unique opportunity for modeling as there are multiple breed-specific models for DCM with less genetic variance than human DCM. A better understanding of DCM in dogs has the potential for improved selection for breeding and could lead to better overall care and treatment for human and canine DCM patients. At the same time, progress in research made for human DCM can have a positive impact on the care given to dogs affected by DCM. Therefore, this review will analyze the feasibility of canines as a naturally occurring bidirectional disease model for DCM in both species. The histopathology of the myocardium in canine DCM will be evaluated in three different breeds compared to control tissue, and the known genetics that contributes to both canine and human DCM will be summarized. Lastly, the prospect of canine iPSCs as a novel method to uncover the contributions of genetic variants to the pathogenesis of canine DCM will be introduced along with the applications for disease modeling and treatment.

Spontaneous closure of an isolated congenital perimembranous ventricular septal defect in two dogs.

BACKGROUND: Though spontaneous closure of isolated congenital ventricular septal defects in humans is very common, it has been rarely reported in dogs. CASE PRESENTATION: A 4 month old Havanese dog and a 4.5 month old Chihuahua x Jack Russell terrier cross were presented for murmur evaluation to the authors' institution. Both puppies were clinically healthy and had a loud systolic murmur on the right hemithorax. Echocardiography in both dogs revealed a small, isolated, restrictive perimembranous congenital ventricular septal defect. No echocardiographic signs of left ventricular volume overload or pulmonary hypertension were present. Re-check auscultation in both dogs revealed the absence of a murmur, and echocardiography showed no flow through the interventricular septum. In the 9 kg Havanese dog and the 4 kg mixed breed dog, spontaneous closure occurred at 13-17 months and 12-30 months, respectively. CONCLUSIONS: In both dogs the spontaneous closure of a congenital perimembranous ventricular septal defect took place in a young adult age. The mechanism of closure remains unclear.

Sub-Antimicrobial Dosage Scheme of Doxycycline for the Chronic Treatment of Bronchiectasis in a Dog.

A 9-month-old German shepherd dog was examined because of a chronic cough, exercise intolerance and labored breathing, as well as recurrent episodes of lethargy with anorexia. Multifocal severe bronchiectasis and neutrophilic bronchitis was found with thoracic computed tomography and cytology of bronchoalveolar lavage fluid, respectively. While oral azithromycin was administered, clinical signs were absent. However, stopping azithromycin lead repeatedly to presumed bacterial pneumonia within 1-2 months. With sub-antimicrobial dosed oral doxycycline (initially 1.5 mg/kg once daily for 3 months, then 0.7-0.5 mg/kg once daily for 6 months), the dog remained free from clinical signs. Bronchiectasis is characterized by marked irreversible bronchial dilation. Accumulation of intraluminal mucopurulent material and neutrophilic inflammation cause chronic cough and recurrent bacterial pneumonia. For therapy, life-long oral antibiotics are recommended. Chronic antibiotic administration, however, can select resistant bacterial strains. Though both azithromycin and doxycycline possess anti-inflammatory effects, doxycycline has these off-target properties at a sub-antimicrobial dose. In this report, a chronic sub-antimicrobial dose of doxycycline resulted in the resolution of chronic cough, exercise intolerance and labored breathing, and prevented recurrence of suspected bacterial pneumonia in the long-term in a dog with severe bronchiectasis. Beneficial effect of doxycycline is probably related to its anti-inflammatory effects rather than its antimicrobial properties.

Temporal changes in the presence and intensity of innocent cardiac murmurs in clinically healthy Cairn terrier and Dachshund puppies between 4 and 8 weeks of age.

BACKGROUND: Spontaneous week-to-week variation in the presence and intensity of innocent cardiac murmurs in individual puppies is unknown. METHODS: Sixty privately owned, clinically healthy Cairn terrier and Dachshund puppies between 4 and 8 weeks of age were included. All dogs underwent weekly cardiac auscultation at the breeders' home by a veterinary cardiology specialist using an acoustic stethoscope. On each occasion, a phonocardiogram was recorded with an electronic stethoscope. Furthermore, all dogs were auscultated once at a first opinion veterinary practise and once at the authors' institution, where they also underwent an echocardiographic examination. RESULTS: Two-hundred and eighty-one auscultations were conducted on 32 Cairn terriers and 28 Dachshunds, at the breeders' homes. Innocent murmurs were detected in 19 puppies. Two of these puppies had a detectable murmur on each auscultation. In five of the puppies, the murmur became undetectable during the observation period and in 12 puppies the murmur was intermittently audible. Auscultation at the authors' institution had an unpredictable effect on murmur presence and intensity. Phonocardiography revealed murmurs in 42 puppies. Interpretation of phonocardiograms by two independent observers showed nearly perfect agreement (κ = 0.859). CONCLUSIONS: Remarkable and unpredictable spontaneous week-to-week variation was documented in the presence and intensity of innocent murmurs.

Age of puppies at referral to veterinary cardiology specialists for murmur investigation.

BACKGROUND: Cardiac auscultation is an important screening test at the first health examination of puppies because most clinically relevant congenital cardiac anomalies cause a loud murmur from birth. This retrospective study aimed to investigate the age at which dogs with suspected congenital cardiac anomalies were referred to a veterinary cardiology specialist for murmur investigation. A secondary aim was to establish the time interval between the visit to the cardiologist and the first available murmur documentation. The digital archive of a veterinary teaching hospital was searched for dogs with congenital cardiac anomalies and puppies with innocent murmurs during a 5-year period. Dogs had to be referred because of a murmur, and they had to undergo physical examination and echocardiography by a veterinary cardiology specialist. The health certificate section of the pet passport, and the medical records from the referring veterinarian, were reviewed to identify the date when the murmur was first documented. RESULTS: Of the 271 included dogs, 94% had a congenital cardiac anomaly and 6% had an innocent murmur. The dogs' median age was 190 days when they were examined by the cardiologist. Only 10% of the dogs were referred by the breeder's veterinarian, while 90% of the dogs were referred by the new owner's veterinarian. The median age of the first available murmur documentation by a first opinion veterinary practitioner was 95 days. CONCLUSIONS: Only 10% of the puppies in the present study were referred to a veterinary cardiology specialist for murmur investigation before they were sold to a new owner. Referral prior to re-homing would have been feasible if the murmur had been detected and documented by the breeder's veterinarian, if referral was offered by the breeder's veterinarian and the referral was accepted by the breeder.

Low profile vascular plug for transarterial occlusion of patent ductus arteriosus in small dogs.

BACKGROUND: Minimally invasive transcatheter occlusion using Amplatz canine duct occluder (ACDO) is the treatment of choice for dogs with left-to-right shunting patent ductus arteriosus (PDA). However, in small dogs the femoral artery diameter is often too small to accommodate the guiding catheter required for ACDO deployment. OBJECTIVE: Describe the effectiveness of transarterial implantation of Amplatzer Vascular Plug 4 (AVP-4), the only self-expandable nitinol mesh occlusion device which can be implanted through a 4 French diagnostic catheter, in small dogs with left-to-right shunting PDA. ANIMALS: Seven client-owned dogs. METHODS: Descriptive case series. Dogs with hemodynamically relevant left-to-right shunting PDA and a femoral artery diameter less than 2.0 mm measured preoperatively with ultrasonography were prospectively enrolled. RESULTS: Angiography after releasing the device showed complete immediate PDA closure in 5 dogs, where the manufacturers' recommendation were strictly followed (30%-50% device oversizing of the ductal ampulla's diameter). Trivial residual flow on angiography in the 6th dog, whose device was slightly undersized, had resolved on echocardiography within 2 hours after placement. Marked device undersizing in the 7th dog resulted in severe residual shunting, which necessitated the addition of a coil. In this dog, the AVP-4 embolized into the pulmonary artery within 2 weeks after placement. CONCLUSIONS AND CLINICAL IMPORTANCE: Transarterial implantation of AVP-4 is a safe, effective and technically easy procedure for PDA occlusion in small dogs and offers a valuable alternative to coil implantation. Accurate PDA measurement and device sizing is essential to prevent residual shunting, inadvertent device embolization, and protrusion of the device into the aorta.

False positive antigen test for Dirofilaria immitis after heat treatment of the blood sample in a microfilaremic dog infected with Acanthocheilonema dracunculoides.

BACKGROUND: Dirofilaria immitis is responsible for heartworm disease in dogs in endemic areas worldwide. Screening for this infection is done by blood tests. Antigen testing is the most sensitive method to detect an infection with adult (female) worms. Microscopic examination of a blood smear or Knott's test can be used to detect circulating microfilariae, the infective larvae. To increase the sensitivity of the antigen test by decreasing the false negative test results, heating of the blood sample has been recommended in recent guidelines. Heating is believed to remove blocking immune-complexes. Circulating microfilariae are not specific findings for heartworm infection, as other nematodes (among others, Acanthocheilonema dracunculoides) can also result in microfilaremia. Although the type of microfilariae cannot be determined by microscopy alone, real-time PCR can reliably identify the infecting nematode species. Correct identification of the parasite is of major importance, as an infection with D. immitis requires antiparasitic therapy, whereas A. dracunculoides is thought to be a clinically irrelevant coincidental finding. The present case report describes a microfilaremic dog where the initial antigen test for D. immitis turned positive after heat treatment, whereas real-time PCR revealed that the microfilariae were A. dracunculoides (syn. Dipetalonema dracunculoides). RESULTS: A circa 5-year old, asymptomatic Spanish mastiff dog was referred for heartworm therapy because microfilariae were found via a screening blood test. The dog was recently imported to the Netherlands from Spain, where it had been a stray dog. Antigen tests on a plasma sample for D. immitis were performed with three different test kits, which all turned out to be negative. However, heat treatment of two of these samples were carried out and both of them led to a positive antigen test result. Real-time PCR showed that the circulating microfilariae belonged to A. dracunculoides species. Three administrations of moxidectin spot-on at monthly intervals resulted in a negative antigen and a negative Knott's tests one month after the last treatment. CONCLUSIONS: We conclude that heat treatment of initially negative blood samples for D. immitis could lead to false positive antigen test results if the dog is infected with A. dracunculoides.

Spontaneous tricuspid valve chordal rupture in a dog with severe, irreversible pulmonary hypertension caused by Angiostrongylus vasorum infection.

BACKGROUND: The adult worms of Angiostrongylus vasorum reside in the pulmonary artery of dogs and can lead to cardiac, respiratory, and central neurologic signs. Due to luminal obstruction and perivascular inflammation of the pulmonary artery branches, pulmonary hypertension can arise. Pulmonary hypertension, in turn, can lead to severe damage of the right-sided cardiac structures, leading to right ventricular remodeling and tricuspid valve regurgitation. CASE PRESENTATION: An 8-year-old neutered female English Cocker Spaniel was presented to the author's institution because of abdominal distention and exercise intolerance. Ascites caused by congestive right-sided heart failure was found to be responsible for these problems. The underlying etiology of the right-sided heart failure was a severe pulmonary hypertension caused by Angiostrongylus vasorum infection. Echocardiography revealed, in addition to a severe concentric and eccentric right ventricular hypertrophy, right atrial and pulmonary trunk dilation, severe tricuspid valve regurgitation, and a systolic flail of the anterior leaflet of the tricuspid valve, resulting from ruptured chordae tendineae. As a coincidental finding, a congenital mitral stenosis was found. Oral therapy was initiated with daily administration of fenbendazole for 2 weeks along with daily administration of oral sildenafil until the re-check examination. At the 6-week re-check the dog showed full clinical and partial echocardiographic recovery, and both the blood antigen test for Angiostrongylus vasorum and the fecal Baermann larva isolation test were negative. When the sildenafil therapy was ceased after tapering the daily dosage, the owner reported recurrence of abdominal distension. Re-starting the sildenafil therapy resulted in resolution of this problem. The dog was reported to be clinically healthy with daily sildenafil administration 7 months after the initial presentation. CONCLUSIONS: The present case report describes a dog where angiostrongylosis led to congestive right-sided heart failure resulting from severe pulmonary hypertension. The secondary right ventricular eccentric hypertrophy together with suspected papillary muscular ischemia were the suspected cause of the ruptured major tricuspid chordae tendineae, which led to a severe tricuspid valve regurgitation. Despite eradication of the worms, the severe pulmonary hypertension persisted. Treatment with daily oral sildenafil, a pulmonary arterial vasodilator, was enough to keep the dog free of clinically apparent ascites.