Prevalence of physiological heart murmurs in a population of 95 healthy young adult dogs.

OBJECTIVES: To determine the prevalence of physiological heart murmurs in healthy young adult dogs. MATERIALS AND METHODS: Healthy dogs aged between 1 and 5 years were enrolled prospectively. All participating dogs underwent physical examination, urinalysis, blood testing and blood pressure measurement. Cardiac auscultations were performed by three independent examiners. Dogs with heart murmurs underwent echocardiography, to exclude cardiovascular abnormalities. RESULTS: Of 109 dogs evaluated, 95 completed the study. Heart murmurs were detected in 22 dogs. Interobserver agreement for murmur detection was moderate to fair (weighted kappa 0 · 29-0 · 56). On the basis of two different sets of echocardiographic criteria, physiological heart murmurs were diagnosed in 6 and 11 dogs, respectively, giving a prevalence of 6-12%. All physiological heart murmurs were systolic and low-grade (I-III/VI). Most were louder towards the left heart base and some radiated up to the thoracic inlet. The epidemiological features of dogs with physiological heart murmurs did not differ significantly from those of dogs without murmurs (P > 0 · 10). CLINICAL SIGNIFICANCE: This study shows that physiological heart murmurs may not be limited to growing dogs or specific breeds, as they were commonly encountered in this population of healthy young adult dogs.

Transient tricuspid valve regurgitation following surgical treatment of cor triatriatum dexter in a dog.

Echocardiographically documented tricuspid valve regurgitation appeared immediately after surgical treatment of cor triatriatum dexter in a two-month-old rottweiler. Medical treatment was instituted with benazepril, spironolactone and furosemide. Pimobendan was added after five months, and all treatment was discontinued two months later when clinical signs of ascites and hepatomegaly had resolved and tricuspid valve regurgitation was markedly reduced on echocardiography. To the authors' knowledge, this is the first report describing the development and spontaneous improvement of haemodynamically significant tricuspid valve regurgitation following surgical treatment of cor triatriatum dexter in a dog. It is hypothesised that the increase in right atrial volume and pressure following cor triatriatum dexter repair and transient ischaemia of papillary muscles led to dilatation of the right atrioventricular annulus and subsequent severe tricuspid valve regurgitation in the face of an anatomically normal valve. Time and pharmacological preload reduction as well as normalisation of right atrial inflow and subsequent cardiac remodelling substantially reduced tricuspid valve regurgitation and eliminated clinical signs of heart failure. It is also possible that heart recovery has been spontaneous.

A model of mucopolysaccharidosis IIIB (Sanfilippo syndrome type IIIB): N-acetyl-alpha-D-glucosaminidase deficiency in Schipperke dogs.

Mucopolysaccharidosis III (MPS III) is characterized by lysosomal accumulation of the glycosaminoglycan (GAG) heparan sulphate (HS). In humans, the disease manifests in early childhood, and is characterized by a progressive central neuropathy leading to death in the second decade. This disease has also been described in mice (MPS IIIA and IIIB), dogs (MPS IIIA), emus (MPS IIIB) and goats (MPS IIID). We now report on dogs with naturally occurring MPS IIIB, detailing the clinical signs, diagnosis, histopathology, tissue enzymology and substrate levels. Two 3-year-old Schipperke dogs were evaluated for tremors and episodes of stumbling. Examination of the animals found signs consistent with cerebellar disease including dysmetria, hind limb ataxia and a wide-based stance with truncal swaying. There were mildly dystrophic corneas and small peripheral foci of retinal degeneration. Magnetic resonance imaging of the brain and skeletal radiographs were normal. Intracytoplasmic granules were found in the white cells of peripheral blood and cerebral spinal fluid, and in myeloid lineages in bone marrow. Electrophoresis of urinary GAGs indicated the presence of HS, while assays of cultured fibroblasts found N-acetyl-alpha-D-glucosaminidase (Naglu) activity of between 4.3% and 9.2% of normal. Owing to neurological deterioration, both dogs were euthanized, and post-mortem examinations were performed. Biochemical studies of liver and kidney from both animals demonstrated profound deficiency of Naglu activity and abnormally high GAG levels. Pathology of the brain included severe cerebellar atrophy, Purkinje cell loss, and cytoplasmic vacuolation in neurons and perithelial cells throughout the central nervous system. Pedigree analyses and Naglu levels of family members supported an autosomal recessive mode of inheritance. Using an obligate heterozygote, a breeding colony has been established to aid in understanding the pathogenesis of MPS IIIB and testing of potential therapies.