Correlations between age, body size, sex, and conformation and ultrasound-measured femoral vessel diameter in the dog, with implications for transvascular procedural planning.

Transvascular interventional radiology procedures have advanced in veterinary medicine, but basic knowledge about expected vascular size and vascular imaging requires further exploration. A prospective analytical study of 230 client-owned dogs was carried out to investigate correlations between ultrasound-measured femoral artery (FA) and femoral vein (FV) diameter and various morphometric and demographic dog variables, compare ultrasound-measured femoral vessel diameter to diameter predicted by body weight, compare right- and left-sided femoral vessel diameter, and assess measurement repeatability. Internal diameter of the FA and FV was measured with ultrasound bilaterally. Allometrically scaled body weight had the strongest correlation with FA and FV diameter (correlation coefficients: 0.92 and 0.80, respectively), although thigh circumference (FA: 0.89; FV:0.78) and withers height (FA: 0.84; FV: 0.76) were also strongly correlated. Within the entire population, males had a smaller FA (P = .005), but not FV (P = .278), than females and age was negatively associated with FA (P = .031) and FV (P < .001) diameter. Compared to ultrasound-derived measurements, body weight-predicted diameter overestimated by at least one French gauge in 32.6% and 35.2% of dogs for the FA and FV, respectively. Comparison of left and right FA and FV diameter revealed minimal mean differences, though limits of agreement could encompass multiple French gauge sizes: (Mean difference [limits of agreement]: FA = 0.00 mm [0.85-0.84 mm]; FV = 0.04 mm [1.92-1.99 mm]). Intra- and interoperator repeatability coefficients of variation were <9%. Femoral vessel diameter in dogs is influenced by multiple factors, with potential for clinically relevant differences between right- and left-sided vessels. Ultrasound measurement of femoral vessels could improve transvascular preprocedural planning.

Myxomatous mitral valve disease in Labrador Retrievers and Golden Retrievers.

OBJECTIVE: To characterize myxomatous mitral valve disease (MMVD) in Labrador Retrievers (LRs) and Golden Retrievers (GRs). METHODS: 52 LRs and 20 GRs diagnosed with MMVD composed a retrospective study sample (February 1, 2010, to July 31, 2021). Stored echocardiograms were remeasured. Dogs were staged by 2019 MMVD consensus guidelines. RESULTS: Mean age was 9.9 years in LRs and 9.5 years in GRs, with 31 of 52 LRs (59.6%) and 13 of 20 (65.0%) GRs being male. Forty-six LRs were stage B1 (88.5%), 3 were B2 (5.8%), and 3 were C (5.8%). Fourteen GRs were stage B1 (70.0%), 2 were B2 (10.0%), and 4 were C (20.0%). Of LRs and GRs in stage B2/C, 50% had systolic dysfunction. Atrial fibrillation (AF) and ventricular arrhythmias were identified in 2 of 52 (3.8%) and 10 of 52 (19.2%) LRs at initial diagnosis versus 3 of 20 (15.0%) and 3 of 20 (15.0%) GRs, respectively. All 5 AF dogs were stage C, with intermediate to high probability of pulmonary hypertension. Two additional GRs developed AF during follow-up; thus 5 of 6 (83.3%) stage B2/C GRs ultimately experienced AF. Subjective mitral valve thickening was frequent in both breeds (41/52 LRs [78.8%]; 18/20 GRs [90.0%]), while mitral valve prolapse was more common in LRs (22/52 [42.3%]) than GRs (5/20 [25.0%]). Conclusions: In LRs and GRs, MMVD was relatively late onset, with males overrepresented. Both breeds exhibited mitral valve thickening in association with MMVD, while LRs more commonly exhibited mitral valve prolapse. CLINICAL RELEVANCE: While most LRs and GRs with MMVD were stage B1, those in stage B2/C had increased prevalence of systolic dysfunction and AF.

Echocardiographic values and prevalence of cardiac abnormalities in clinically healthy adult Borzoi dogs.

OBJECTIVE: To develop breed-specific echocardiographic values for normal Borzoi and to report the prevalence of structural cardiac abnormalities. ANIMALS: 146 clinically healthy, adult Borzoi dogs. METHODS: Cardiac auscultation and standard echocardiograms were performed. Longitudinal follow-up was described in a subset of dogs (n = 25). RESULTS: Most Borzoi were structurally normal (119/146, 81.5%), with breed-specific echocardiographic values generated independently for each sex, as females weighed significantly less than males (30.4 ± 3.8 kg vs 38.3 ± 4.1 kg, respectively; P < .001), and a significant impact of sex was found on most measurements. Physiologic heart murmurs were identified in 64/119 (53.8%) normal dogs. Thirty-six (30.2%) structurally normal dogs had trace or mild mitral regurgitation, and 43 (36.1%) had trace or mild tricuspid regurgitation. Structural cardiac disease was identified in 21 dogs (14.4%), including 9 dogs (6.2%) with dilated cardiomyopathy (DCM), 9 dogs (6.2%) with stage B1 myxomatous mitral valve disease (MMVD), and 3 (2.1%) dogs with congenital abnormalities. Seven dogs (4.8%) had equivocal abnormalities. During follow-up, new dogs were diagnosed with occult DCM (n = 3), equivocal DCM (1), and stage B1 MMVD (2). Two dogs originally diagnosed with DCM (1 occult and 1 equivocal) normalized after diet change. CLINICAL RELEVANCE: Borzoi dogs commonly have physiologic heart murmurs and mild atrioventricular valve regurgitation. Both DCM and MMVD were identified at similar frequencies in healthy Borzoi, although dogs with MMVD all had normal heart sizes. Echocardiographic screening for DCM in Borzoi should be considered, with breed-specific echocardiographic values now available for improved diagnostic confidence.

Pulmonary hypertension is associated with hypocoagulability in dogs: a retrospective analysis of 66 cases (2013-2021).

OBJECTIVE: To describe coagulation profiles in dogs with echocardiographic evidence of pulmonary hypertension (PH), to compare them to coagulation profiles in dogs without echocardiographic evidence of PH, and to determine the relationship between coagulation profiles and echocardiographic probability of PH. ANIMALS: 66 dogs with PH (cases) and 86 dogs without PH (controls). METHODS: Retrospective evaluation of records between 2013 and 2021 of dogs that had both an echocardiogram and a coagulation panel performed within 7 days. Dogs that received antithrombotics within 7 days of evaluation and dogs diagnosed with congenital or acquired coagulopathy or other severe systemic disease that could lead to coagulopathy were excluded. Dogs with a low echocardiographic probability of PH were also excluded. The dogs were divided into a PH group and non-PH group based on echocardiographic results. Demographic, clinicopathologic, and traditional coagulation parameters and VCM Vet (Entegrion) parameters were compared between the 2 groups. RESULTS: Dogs with PH were significantly older (median, 11 years vs 9.5 years, P = .02) and had a significantly lower body weight (median, 7.3 kg vs 19.3 kg, P < .001) than controls. Dogs with PH also had a significantly greater percent increase in prothrombin time (PT; P = .02), partial thromboplastin time (PTT; P < .0001), and fibrinogen (P = .045); however, their antithrombin concentration was lower (P = .005) compared to controls. Eight of 65 dogs (12.3%) in the PH group and 1/86 (1.2%) dogs in the non-PH group had an elevation of PT and/or PTT greater than 50% above the reference interval (P = .005). Dogs with PH had 11.9 times (95% CI, 1.5 to 97.9; P = .02) greater odds of being hypocoagulable than dogs without PH based on PT and PTT. CLINICAL RELEVANCE: This study demonstrated an association between a moderate to high echocardiographic probability of PH and a hypocoagulable state in dogs as determined by traditional coagulation assays. It underscores the importance of monitoring the coagulation status in canine patients with PH, particularly before initiating antithrombotic medications.

Analytical validation, sample stability, and clinical evaluation of a new high-sensitivity cardiac troponin I immunoassay for use in dogs, with comparison to a previous ultrasensitive assay.

Cardiac troponin I (cTnI) is considered the gold standard biomarker for myocardial injury and shows a high degree of homology between humans and dogs. The ADVIA Centaur XP High-Sensitivity Troponin I (AC-cTnI-HS) assay has been validated for use in humans but not dogs. The study objectives were to analytically validate the AC-cTnI-HS assay in dogs, to assess correlation between the AC-cTnI-HS and a previous ADVIA Centaur TnI-Ultra (AC-cTnI-U) assay, to assess cTnI sample storage stability, and to clinically evaluate the AC-cTnI-HS assay in healthy dogs and dogs with cardiac disease. Canine serum samples were used for analytical validation. Intra- and inter-assay variability, dilutional parallelism, and spiking recovery were assessed. Samples from 196 client-owned dogs were evaluated (healthy dogs (n = 39) or dogs with congenital heart disease (n = 54), myxomatous mitral valve disease (n = 68), dilated cardiomyopathy (n = 15), or myocarditis (n = 20)). Inter- and intra-assay coefficient of variation (%CV) was between 2.8-41.4% and 3.8-30.2%, respectively, with pools with concentrations >20 pg/mL all having %CVs <10%. The observed to expected ratios for dilutional parallelism and spiking recovery experiments ranged between 92.3 and 266.7.0% and 84.3 and 108%, respectively. A strong correlation between the AC-cTnI-HS and AC-cTnI-U assays was observed (Spearman's ρ = 0.927), though a proportional bias existed, with AC-cTnI-HS assay concentrations being proportionally lower than AC-cTnI-U assay concentrations. Serum samples stored at -80°C had stable cTnI measurements for up to 2.7 years and after a single freeze-thaw cycle. Healthy dogs and dogs with congenital heart disease had significantly lower cTnI concentrations than dogs in the other three groups. The AC-cTnI-HS assay precisely, reproducibly, and accurately measures cTnI concentrations in dog serum with cTnI concentrations >20 pg/mL.

A masked, placebo-controlled, randomized clinical trial evaluating safety and the effect on cardiac function of low-dose rapamycin in 17 healthy client-owned dogs.

Introduction: Geroscience studies of low-dose rapamycin in laboratory species have identified numerous benefits, including reversing age-related cardiac dysfunction. Cardiovascular benefits have been observed in dogs with 10 weeks of treatment, raising questions about possible benefits and adverse effects of long-term use of low-dose rapamycin. The objectives of this study were to assess the impact of 6 months of low-dose rapamycin on echocardiographic indices of cardiac function in healthy dogs and to document the occurrence of adverse events. Methods: Seventeen client-owned dogs aged 6-10 years, weighing 18-36 kg, and without significant systemic disease were included in a prospective, randomized, placebo-controlled, masked clinical trial. Low-dose rapamycin (0.025 mg/kg) or placebo was administered three times per week for 6 months. Baseline, 6-month, and 12-month evaluation included physical examination, cardiology examination, and clinicopathology. Three-month evaluation included physical examination and clinicopathology. Owners completed online questionnaires every 2 weeks. Results: There were no statistically significant differences in echocardiographic parameters between rapamycin and placebo groups at 6 or 12 months. No clinically significant adverse events occurred. In 26.8% of the bi-weekly surveys owners whose dogs received rapamycin reported perceived positive changes in behavior or health, compared to 8.1% in the placebo group (p = 0.04). Discussion: While no clinically significant change in cardiac function was observed in dogs treated with low-dose rapamycin, the drug was well-tolerated with no significant adverse events.

A multicenter, retrospective study of cardiac disease in Borzoi dogs.

Borzoi are large, relatively uncommon sighthounds anecdotally reported to suffer from sudden death. This multicenter retrospective cohort study aimed to describe the sample of Borzoi presenting to veterinary cardiologists for evaluation, with records searched from 14 centers across a study period of up to 20 years. The study sample was comprised of 152 client-owned Borzoi, with dogs most commonly presenting for pre-breed screening in 87/152 (52%), followed by evaluation of an arrhythmia in 28/152 (18%). Of the 131/152 (86%) dogs that had an echocardiogram performed, 85/131 (65%) were structurally normal, with 40/85 (47%) structurally normal dogs having trace or mild atrioventricular valve regurgitation. Tricuspid valve dysplasia was the most commonly diagnosed congenital cardiac disease (n = 6). Myxomatous mitral valve disease (n = 12) and dilated cardiomyopathy (n = 13) were diagnosed at similar frequencies, though 92% of valve disease cases were mild. Only 48/152 (32%) Borzoi had a diagnostic electrocardiogram (ECG) and/or a Holter monitor for arrhythmia screening. Despite this, ventricular arrhythmias were identified during the entirety of the available cardiac evaluation including diagnostic ECG, contemporaneous ECG monitoring during the echocardiogram, and/or Holter monitor in 25/131 (19%) dogs in which an echocardiographic diagnosis was available. Of these 25 Borzoi, 76% had minimal or no structural cardiac disease identified, and five had a family history of sudden death. A sudden death outcome was reported in 3/55 (5%) Borzoi with long-term outcome data available. In conclusion, Borzoi commonly have trace or mild atrioventricular valve insufficiencies, and may develop ventricular arrhythmias and dilated cardiomyopathy.

The ability to achieve meiotic maturation in the dog oocyte is linked to glycolysis and glutamine oxidation.

We tested the hypothesis that meiotic competence of dog oocytes is tightly linked with donor follicle size and energy metabolism. Oocytes were recovered from small (<1 mm diameter, n = 327), medium (1-<2 mm, n = 292) or large (≥2 mm, n = 102) follicles, cultured for 0, 24, or 48 hr, and then assessed for glycolysis, glucose oxidation, pyruvate uptake, glutamine oxidation, and nuclear status. More oocytes (P < 0.05) from large follicles (37%) reached the metaphase-II (MII) stage than from the small group (11%), with the medium-sized class being intermediate (18%; P > 0.05). Glycolytic rate increased (P < 0.05) as oocytes progressed from the germinal vesicle (GV) to MII stage. After 48 hr of culture, oocytes completing nuclear maturation had higher (P < 0.05) glycolytic rates than those arrested at earlier stages. GV oocytes recovered from large follicle oocytes had higher (P < 0.05) metabolism than those from smaller counterparts at culture onset. MII oocytes from large follicles oxidized more (P < 0.05) glutamine than the same stage gametes recovered from smaller counterparts. In summary, larger-sized dog follicles contain a more metabolically active oocyte with a greater chance of achieving nuclear maturation in vitro. These findings demonstrate a significant role for energy metabolism in promoting dog oocyte maturation, information that will be useful for improving culture systems for rescuing intraovarian genetic material.

Asymptomatic Canine Degenerative Valve Disease: Diagnosis and Current and Future Therapies.

Degenerative valve disease (DVD) is the leading cause of heart disease and heart failure in the dog. The first consensus statement published in 2009 by the American College of Veterinary Internal Medicine was updated in 2019 and provides guidelines for the diagnosis and treatment of DVD. These updated guidelines recommend treatment with pimobendan in stage B2 DVD characterized by sufficient left heart enlargement. Asymptomatic dogs with DVD that do not meet or exceed the definition of stage B2 are considered stage B1. No treatment is recommended in stage B1 DVD. This article discusses the relevant scientific background and practical application of the updated DVD guidelines related to stage B. In addition, management of common sequelae of DVD that can result in clinical signs unrelated to congestive heart failure will be reviewed. The impact of new evidence on current recommendations and a glimpse into novel diagnostic approaches and possible future therapies will also be addressed.

Whole blood and plasma taurine reference intervals in adult Cavalier King Charles Spaniels and correlations between taurine concentration, diet and mitral valve disease.

OBJECTIVE: To determine breed-specific reference intervals for whole blood (WB) and plasma taurine concentrations in adult, overtly healthy Cavalier King Charles Spaniels (CKCSs) and determine whether taurine concentrations differ across preclinical myxomatous mitral valve disease (MMVD) stages or between CKCSs eating diets that meet World Small Animal Veterinary Association (WSAVA) nutritional guidelines versus other diets. ANIMALS: 200 privately owned CKCSs. PROCEDURES: Clinically healthy adult CKCSs were recruited prospectively. Diet and supplement history was collected. Dogs were staged by echocardiography using MMVD consensus guidelines. Taurine concentrations were measured in deproteinized lithium heparin WB and plasma samples with the postcolumn ninhydrin derivatization method on a dedicated amino acid analyzer. RESULTS: There were 12 stage A (6%), 150 stage B1 (75%), and 38 stage B2 (19%) CKCSs. Seventy-eight dogs (39%) were reported by their owners to be eating diets meeting WSAVA nutritional guidelines; 116 (58%) were not. Taurine concentrations in plasma (P = .444) and WB (P = .073) were not significantly different across MMVD stages or between CKCSs eating diets meeting WSAVA nutritional guidelines versus other diets (P = .345 and P = .527, respectively). Reference intervals for WB taurine (152 to 373 µM) and plasma taurine (51 to 217 µM) concentrations in CKCSs were generated. CLINICAL RELEVANCE: In CKCSs, taurine concentrations do not differ significantly based on preclinical MMVD stage, nor do they differ significantly based on consumption of a diet that does or does not meet WSAVA nutritional guidelines.

Intracardiac heartworms in dogs: Clinical and echocardiographic characteristics in 72 cases (2010-2019).

BACKGROUND: Heartworms, a cause of pulmonary hypertension (PH) in dogs, can migrate from the pulmonary arteries into the heart resulting in life-threatening caval syndrome (CS). OBJECTIVES: To describe clinical and echocardiographic characteristics in dogs with intracardiac heartworms including estimated heartworm burden and frequency of PH and pigmenturia. ANIMALS: Seventy-two client-owned dogs with heartworms. METHODS: Retrospective study. Data collected from an electronic medical records search for dogs with intracardiac heartworms included clinicopathologic, echocardiographic, and procedural findings. Dogs with heartworms isolated to the pulmonary arteries were excluded. RESULTS: Estimated intracardiac heartworm burden was low in 14 of 72 (19%) and high in 58 of 72 (81%) dogs. The majority were small breed (54/72; 75%; 29/72; 40% Chihuahuas) and had a high likelihood of PH (67/72; 93%). Pigmenturia was the second most common clinical finding (31/72; 43%) after lethargy (32/72; 44%). Anemia (37/55; 36%), pigmenturia (30/58; 52%), and bilirubinuria (28/36; 78%) were significantly more common in dogs with a high worm burden (P < .05). Based on the presence of anemia, pigmenturia, and clinical signs, 18 of 72 dogs (25%) were considered to have CS. CONCLUSIONS AND CLINICAL IMPORTANCE: Although the majority of dogs with intracardiac heartworms had a high worm burden and high likelihood of PH, only 25% had clinical evidence of CS. Echocardiography is a useful tool to identify intracardiac heartworms, detect likelihood of PH, and could be useful for staging heartworm positive small breed dogs for intracardiac heartworm migration.

Anatomy, baseline characteristics, and procedural outcome of patent ductus arteriosus in German Shepherd dogs.

BACKGROUND: German Shepherd dogs (GSD) are predisposed to developing patent ductus arteriosus (PDA) and are reportedly prone to type III (tubular) PDA anatomy. Dogs with type III anatomy are not considered favorable candidates for device-based intervention. OBJECTIVE: To describe the PDA anatomy, baseline characteristics, and procedural outcome of GSD with PDA. ANIMALS: Twenty-eight client-owned GSD. METHODS: Retrospective review of medical records of 28 GSD diagnosed with PDA that underwent surgical ligation or transcatheter device closure between 2007 and 2017. RESULTS: German Shepherd dogs with PDA often presented with clinical signs (50%), concurrent congenital heart disease (35.7%), and arrhythmias (29%). Dogs were typically mature at presentation (median age, 12.1 months) and evenly distributed by sex (57% female). The PDA anatomy was classified in 24 of 28 GSD, with type II anatomy being most common (21/24). Three dogs had unusual anatomy (type IV in 1, type V in 2). Median minimal ductal diameter (MDD) in this population was larger than previously reported in a mixed population and ranged between 4.4 and 4.9 mm depending upon imaging modality. Successful closure was achieved using an Amplatz canine duct occluder (ACDO) in 22 dogs or by surgical ligation in 6 dogs. No cases of type III anatomy were confirmed. CONCLUSIONS AND CLINICAL IMPORTANCE: The majority of GSD in this population had type II PDA anatomy that was amenable to ACDO deployment. Predisposition for large MDD and occasional, unusual PDA anatomy suggests that transesophageal echocardiography may be beneficial for optimal procedural planning in this breed.

Asymptomatic Canine Degenerative Valve Disease: Current and Future Therapies.

Degenerative valve disease (DVD) is the leading cause of heart disease and congestive heart failure (CHF) in the dog. The first published consensus statement provided guidelines for the diagnosis and treatment of DVD. Although treatment was not recommended in stage B1 DVD, consensus was not reached regarding evidence-based recommendations for treatment of stage B2 DVD. This article addresses the impact of new evidence on historical recommendations for stage B DVD and gives the reader a glimpse into possible future therapies. Management of common sequelae of DVD that can result in clinical signs that are not attributable to CHF is also discussed.