Anne-Christine Merveille

CCDC39 is required for assembly of inner dynein arms and the dynein regulatory complex and for normal ciliary motility in humans and dogs

Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by recurrent infections of the upper and lower respiratory tract, reduced fertility in males and situs inversus in about 50% of affected individuals (Kartagener syndrome). It is caused by motility defects in the respiratory cilia that are responsible for airway clearance, the flagella that propel sperm cells and the nodal monocilia that determine left-right asymmetry. Recessive mutations that cause PCD have been identified in genes encoding components of the outer dynein arms, radial spokes and cytoplasmic pre-assembly factors of axonemal dyneins, but these mutations account for only about 50% of cases of PCD. We exploited the unique properties of dog populations to positionally clone a new PCD gene, CCDC39. We found that loss-of-function mutations in the human ortholog underlie a substantial fraction of PCD cases with axonemal disorganization and abnormal ciliary beating. Functional analyses indicated that CCDC39 localizes to ciliary axonemes and is essential for assembly of inner dynein arms and the dynein regulatory complex.

Breed Differences in Natriuretic Peptides in Healthy Dogs

Background Measurement of plasma concentration of natriuretic peptides (NPs) is suggested to be of value in diagnosis of cardiac disease in dogs, but many factors other than cardiac status may influence their concentrations. Dog breed potentially is 1 such factor. Objective To investigate breed variation in plasma concentrations of pro‐atrial natriuretic peptide 31‐67 (proANP 31‐67) and N‐terminal B‐type natriuretic peptide (NT‐proBNP) in healthy dogs. Animals 535 healthy, privately owned dogs of 9 breeds were examined at 5 centers as part of the European Union (EU) LUPA project. Methods Absence of cardiovascular disease or other clinically relevant organ‐related or systemic disease was ensured by thorough clinical investigation. Plasma concentrations of proANP 31‐67 and NT‐proBNP were measured by commercially available ELISA assays. Results Overall significant breed differences were found in proANP 31‐67 (P < .0001) and NT‐proBNP (P < .0001) concentrations. Pair‐wise comparisons between breeds differed in approximately 50% of comparisons for proANP 31‐67 as well as NT‐proBNP concentrations, both when including all centers and within each center. Interquartile range was large for many breeds, especially for NT‐proBNP. Among included breeds, Labrador Retrievers and Newfoundlands had highest median NT‐proBNP concentrations with concentrations 3 times as high as those of Dachshunds. German Shepherds and Cavalier King Charles Spaniels had the highest median proANP 31‐67 concentrations, twice the median concentration in Doberman Pinschers. Conclusions and Clinical Importance Considerable interbreed variation in plasma NP concentrations was found in healthy dogs. Intrabreed variation was large in several breeds, especially for NT‐proBNP. Additional studies are needed to establish breed‐specific reference ranges.

Clinical Findings and Prevalence of the Mutation Associated with Primary Ciliary Dyskinesia in Old English Sheepdogs

Background Primary ciliary dyskinesia (PCD) is generally a recessively inherited disorder characterized by dysfunction of motile cilia. A mutation in a new causative gene (CCDC39) has been identified in the Old English Sheepdog (OES). Objectives To describe the clinical findings and the molecular changes of affected dogs and estimate the worldwide prevalence of the mutation in a large cohort of OES. Animals 578 OES, including 28 affected and 550 clinically healthy dogs. Methods This retrospective study reviewed the data of OES diagnosed with PCD and OES tested for the mutation. Clinical data including results of physical examination and further investigations were obtained on 11/28 dogs. CCDC39 expression was assessed by qRT‐PCR and Western blot analysis in affected dogs and healthy dogs. DNA was extracted on 561/578 dogs and a genetic test by Taqman technology was developed to genotype the CCDC39 mutation in these dogs. Results Clinical findings were recurrent nasal discharge and cough, pyrexia, leucocytosis, and bronchopneumonia. Ultrastructural defects were characterized by central microtubular abnormalities and decreased number of inner dynein arms (IDAs). Molecular analysis revealed a reduced expression of CCDC39 RNA and an absence of CCDC39 protein in affected dogs compared to healthy dogs. The mutation was more frequent in nonrandomly selected European OES population with a higher proportion of carriers (19%) compared to non‐European dogs (7%). Conclusion and Clinical Importance CCDC39 mutation is dispersed in a worldwide population and is responsible for PCD in this breed. Genetic testing might enable control of this disease.

The Shepherds' Tale: A Genome-Wide Study across 9 Dog Breeds Implicates Two Loci in the Regulation of Fructosamine Serum Concentration in Belgian Shepherds.

Diabetes mellitus is a serious health problem in both dogs and humans. Certain dog breeds show high prevalence of the disease, whereas other breeds are at low risk. Fructosamine and glycated haemoglobin (HbA1c) are two major biomarkers of glycaemia, where serum concentrations reflect glucose turnover over the past few weeks to months. In this study, we searched for genetic factors influencing variation in serum fructosamine concentration in healthy dogs using data from nine dog breeds. Considering all breeds together, we did not find any genome-wide significant associations to fructosamine serum concentration. However, by performing breed-specific analyses we revealed an association on chromosome 3 (pcorrected ≈ 1:68 × 10-6) in Belgian shepherd dogs of the Malinois subtype. The associated region and its close neighbourhood harbours interesting candidate genes such as LETM1 and GAPDH that are important in glucose metabolism and have previously been implicated in the aetiology of diabetes mellitus. To further explore the genetics of this breed specificity, we screened the genome for reduced heterozygosity stretches private to the Belgian shepherd breed. This revealed a region with reduced heterozygosity that shows a statistically significant interaction (p = 0.025) with the association region on chromosome 3. This region also harbours some interesting candidate genes and regulatory regions but the exact mechanisms underlying the interaction are still unknown. Nevertheless, this finding provides a plausible explanation for breed-specific genetic effects for complex traits in dogs. Shepherd breeds are at low risk of developing diabetes mellitus. The findings in Belgian shepherds could be connected to a protective mechanism against the disease. Further insight into the regulation of glucose metabolism could improve diagnostic and therapeutic methods for diabetes mellitus.

Crenosoma vulpis infection in two young dogs in Belgium

Two dogs were presented for chronic cough unresponsive to long-term treatment. Thoracic radiograph revealed diffuse bronchial pattern. Bronchoscopy revealed moving worms in the airway lumen, further identified as adults of Crenosoma vulpis. Additionally bronchoalveolar lavage fluid analysis and Baermann faecal analysis revealed the presence of larvae with a morphology compatible with C. vulpis first-stage larvae. In one dog, a first treatment with oral fenbendazole at 50 mg/kg during seven days failed to cure the infection then a single topical application of 10 per cent imidacloprid +2.5 per cent moxidectin at 0.1 ml/kg was given and was effective. The other dog was successfully treated with two administrations of milbemycin oxime at one-month interval. This lungworm infection might be underdiagnosed and should be excluded before initiating a long-term corticosteroid therapy. To the authors knowledge, this is the first time C. vulpis infection is reported in dogs in Belgium.

Pulmonary Vein-to-Pulmonary Artery Ratio is an Echocardiographic Index of Congestive Heart Failure in Dogs with Degenerative Mitral Valve Disease.

Background Early recognition of left‐sided congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD) is important because it influences medical therapy, timing of follow‐up, and outcome. Hypothesis Pulmonary vein diameter‐to‐pulmonary artery diameter ratio (PV/PA) measured by echocardiography can predict CHF. Animals Ninety‐eight client‐owned dogs, 37 controls, and 61 dogs with DMVD. Methods Prospective clinical cohort study. History, physical examination and Doppler‐echocardiography were performed. Dogs were classified as International Small Animal Cardiac Health Council class I, II or III. Congestive heart failure was identified in a subset of 56 dogs based on radiographic findings. The PV/PA was measured in bidimensional (2D) and M‐mode by 2 investigators blinded to the radiologists’ conclusions. Results Interobserver coefficients of variation for PV/PA acquisition and measurement were <10%. The PV/PA in control dogs was approximately 1 and increased with class of heart failure. The presence of CHF could be best predicted by measuring PV/PA in 2D echocardiography (cut‐off, 1.7; area under the curve, 0.98; CI, 0.97–0.98; P < .001) with a sensitivity of 96% and a specificity of 91%. Conclusion and clinical importance The PV/PA is a simple and reproducible echocardiographic variable that increases with class of heart failure and may help discriminate dogs in CHF from asymptomatic dogs with DMVD. Additional studies are required to determine whether PV/PA might provide additional information in the integrated interpretation of Doppler‐echocardiographic indices of left ventricular filling pressures and could be used for rapid assessment of CHF in dogs in a critical care setting.

Effect of Breed on Plasma Endothelin-1 Concentration, Plasma Renin Activity, and Serum Cortisol Concentration in Healthy Dogs

Background There are breed differences in several blood variables in healthy dogs. Objective Investigate breed variation in plasma endothelin‐1 (ET‐1) concentration, plasma renin activity, and serum cortisol concentration. Animals Five‐hundred and thirty‐one healthy dogs of 9 breeds examined at 5 centers (2–4 breeds/center). Methods Prospective observational study. Circulating concentrations of ET‐1 and cortisol, and renin activity, were measured using commercially available assays. Absence of organ‐related or systemic disease was ensured by thorough clinical investigations, including blood pressure measurement, echocardiography, ECG, blood and urine analysis. Results Median ET‐1 concentration was 1.29 (interquartile range [IQR], 0.97–1.82) pg/mL, median cortisol concentration 46.0 (IQR, 29.0–80.8) nmol/L, and median renin activity 0.73 (IQR, 0.48–1.10) ng/mL/h in all dogs. Overall, breed differences were found in ET‐1 and cortisol concentrations, and renin activity (P < .0001 for all). Pair‐wise comparisons between breeds differed in 67% of comparisons for ET‐1, 22% for cortisol, and 19% for renin activity, respectively. Within centers, breed differences were found at 5/5 centers for ET‐1, 4/5 centers for cortisol, and 2/5 centers for renin activity. Newfoundlands had highest median ET‐1 concentration, 3 times higher than Cavalier King Charles Spaniels, Doberman Pinschers, and Dachshunds. Median renin activity was highest in Dachshunds, twice the median value in Newfoundlands and Boxers. Median cortisol concentration was highest in Finnish Lapphunds, almost 3 times higher than in Boxers. Conclusions and Clinical Importance Breed variation might be important to take into consideration when interpreting test results in clinical studies.

Effect of physiological determinants and cardiac disease on plasma adiponectin concentrations in dogs.

Background In humans, a high concentration of adiponectin is associated with a favorable cardiovascular risk profile whereas, in patients with heart failure (HF), a high concentration of adiponectin is associated with a less favorable prognosis. Hypothesis/Objectives To evaluate the physiological determinants of plasma adiponectin concentration in dogs and the influence of heart disease, myxomatous mitral valve disease (MMVD), and dilated cardiomyopathy (DCM). Animals One hundred and fourteen client‐owned dogs and 9 Beagles from the research colony of the Clinical Veterinary Unit of the University of Liège. Methods We prospectively measured circulating adiponectin concentration in healthy control dogs (n = 77), dogs with MMVD (n = 22) and dogs with DCM (n = 15) of various degrees of severity. Diagnosis was confirmed by Doppler echocardiography. Plasma adiponectin concentration was measured by a canine‐specific sandwich ELISA kit. Results An analysis of covariance showed an association between adiponectin concentration and age, neuter status, and heart disease. No association between adiponectin concentration and class of HF, sex, body condition score, body weight, circadian rhythm, or feeding was found. Plasma adiponectin concentration was negatively correlated with age (P = .001). Adiponectin was lower in neutered (P = .008) compared to intact dogs. Circulating adiponectin concentration was increased in dogs with DCM compared to healthy dogs (P = .018) and to dogs with MMVD (P = .014). Conclusions and Clinical Importance Age and neutering negatively influence circulating adiponectin concentration. Plasma adiponectin concentration increased in dogs with DCM. Additional research is required to investigate if this hormone is implicated in the pathophysiology of DCM and associated with clinical outcome.

Establishment of reference values of the caudal vena cava by fast‐ultrasonography through different views in healthy dogs

Background Clinical assessment of intravascular volume status is challenging. In humans, ultrasonographic assessment of the inferior vena cava diameter, directly or as a ratio to the aortic diameter is used to estimate intravascular volume status. Objectives To ultrasonographically obtain reference values (RV) for caudal vena cava diameter (CVCD), area (CVCa) and aortic ratios using 3 views in awake healthy dogs. Animals One hundred and twenty‐six healthy adult dogs from clients, students, faculty, or staff. Methods Prospective, multicenter, observational study. Two observer pairs evaluated CVCD by a longitudinal subxiphoid view (SV), a transverse 11th‐13th right hepatic intercostal view (HV), and a longitudinal right paralumbar view (PV). Inter‐rater agreements were estimated using concordance correlation coefficients (CCC). For body weight (BW)‐dependent variables, RVs were calculated using allometric scaling for variables with a CCC ≥ 0.7. Results The CCC was ≤0.43 for the CVC/aorta ratio at the PV and ≤0.43 in both inspiration and expiration for CVC at the SV. The RVs using allometric scaling for CVCa at the HV for inspiration, expiration, and for CVCD at the PV were 6.16 × BW0.762, 7.24 × BW0.787, 2.79 × BW0.390, respectively. Conclusions and Clinical Importance The CVCD, measured at the HV and PV in healthy awake dogs of various breeds has good inter‐rater agreement suggesting these sites are reliable in measuring CVCD. Established RVs for CVCD for these sites need further comparison to results obtained in hypovolemic and hypervolemic dogs to determine their usefulness to evaluate volume status in dogs.

Congenital Venous Aneurysm of the right external jugular vein in a great dane

An 11-month-old entire female great dane was presented for a painless swelling on the ventral right side of its neck. Fine needle aspiration of the mass revealed the presence of blood. Ultrasonographic examination revealed an anechoic subcutaneous tubular structure consistent with a jugular aneurysm. Surgery consisted in ligature of the right external jugular vein and excision of the aneurysm. No intraoperative complication occurred. Jugular aneurysm has been rarely reported in dogs. Venous aneurysms may be the result of several processes including tumours, inflammation, trauma, or may appear spontaneously or congenitally. Surgical excision is the treatment of choice due to the risk of thrombosis or possible rupture.