Ultrasonographic measurement of flow-mediated vasodilation in dogs with chronic valvular disease

Circulating hyaluronan as a marker of endothelial glycocalyx damage in dogs with myxomatous mitral valve disease and dogs in a hypercoagulable state

The endothelial glycocalyx (eGlx) lines the luminal surface of endothelial cells, maintaining vascular health. Glycocalyx damage is pathophysiologically important in many diseases across species however few studies have investigated its breakdown in naturally occurring disease in dogs. The aims of the study were to investigate eGlx damage in dogs with myxomatous mitral valve disease (MMVD) diagnosed on echocardiography, and dogs in a hypercoagulable state diagnosed using thromboelastography (TEG), by measuring serum hyaluronan concentrations. Serum hyaluronan was quantified in dogs with MMVD (n = 27), hypercoagulability (n = 21), and in healthy controls dogs (n = 18). Serum hyaluronan concentrations were measured using a commercially-available ELISA validated for use in dogs. Hyaluronan concentrations were compared among groups using Kruskal-Wallis tests, and post-hoc with Dunn’s tests. Serum hyaluronan concentrations (median [range]) were significantly increased in dogs with MMVD (62.4 [22.8–201] ng/mL; P = 0.031) and hypercoagulability (92.40 [16.9–247.6] ng/mL; P < 0.001) compared to controls (45.7 [8.7–80.2] ng/mL). Measurement of serum hyaluronan concentration offers a clinically applicable marker of eGlx health and suggests the presence of eGlx damage in dogs with MMVD and dogs in a hypercoagulable state.

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Few studies have investigated endothelial glycocalyx breakdown in disease in dogs.

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Serum hyaluronan is a clinically applicable marker of endothelial glycocalyx health.

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Serum hyaluronan was significantly increased in dogs with mitral valve disease.

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Serum hyaluronan was significantly increased in dogs in a hypercoagulable state.

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Increased serum hyaluronan may indicate glycocalyx shedding in these diseases.

Increased serum C-reactive protein concentrations in dogs with congestive heart failure due to myxomatous mitral valve disease

Cardiovascular disease in humans and dogs is associated with mildly increased circulating concentrations of C-reactive protein (CRP). Few studies have evaluated associations between circulating CRP and canine myxomatous mitral valve disease (MMVD) and the results reported have been divergent. The aim of this study was to investigate whether serum concentrations of CRP, determined using a novel automated canine-specific high-sensitivity CRP assay (Gentian hsCRP), were associated with severity of MMVD and selected clinical variables in dogs. The study included 188 client-owned dogs with different severities of MMVD. Dogs were classified based on ACVIM consensus statement guidelines (group A, n = 58; group B1, n = 56; group B2, n = 38; group C, n = 36). Data were analysed using descriptive statistics and multiple regression analysis. Dogs with congestive heart failure (CHF; group C) had significantly higher CRP concentrations (median, 2.65 mg/L; quartile 1-quartile 3, 1.09-5.09) compared to dogs in groups A (median, 0.97 mg/L; quartile 1-quartile 3, <0.50-1.97; P = 0.001), B1 (median, 0.78 mg/L; quartile 1-quartile 3, <0.50-1.73, P <0.0001) and B2 (median, 0.60 mg/L; quartile 1-quartile 3, <0.50-1.23; P <0.0001). Other variables reflecting disease severity, including left atrial to aortic root ratio (P = 0.0002, adjusted r(2) = 0.07) and left ventricular end-diastolic diameter normalised for bodyweight (P = 0.0005, adjusted r(2) = 0.06), were positively associated with CRP concentration, but the association disappeared if dogs with CHF were excluded from analysis. In conclusion, slightly higher CRP concentrations were found in dogs with CHF whereas severity of asymptomatic MMVD showed no association with CRP concentrations.

Biopterin status in dogs with myxomatous mitral valve disease is associated with disease severity and cardiovascular risk factors

BACKGROUND

Endothelial dysfunction (ED) has been suggested to be associated with myxomatous mitral valve disease (MMVD) in dogs. Tetrahydrobiopterin (BH4) is an important cofactor for production of the endothelium-derived vasodilator nitric oxide (NO). Under conditions of oxidative stress, BH4 is oxidized to the biologically inactive form dihydrobiopterin (BH2). Thus, plasma concentrations of BH2 and BH4 may reflect ED and oxidative stress.

OBJECTIVE

To determine plasma concentrations of BH2 and BH4 in dogs with different degrees of MMVD.

ANIMALS

Eighty-four privately owned dogs grouped according to ACVIM guidelines (37 healthy control dogs including 13 Beagles and 24 Cavalier King Charles Spaniels [CKCSs], 33 CKCSs with MMVD of differing severity including 18 CKCSs [group B1] and 15 CKCSs [group B2], and 14 dogs of different breeds with clinical signs of congestive heart failure [CHF] because of MMVD [group C]).

METHODS

Dogs underwent clinical examination including echocardiography. Plasma concentrations of BH2 and BH4 were measured using high-performance liquid chromatography with fluorescence detection.

RESULTS

Higher plasma BH4 and BH2 concentrations were found with dogs in CHF compared with all other groups (control, B1 and B2; P ≤ .001). Females had higher concentrations of BH4 and BH4/BH2 (P ≤ .0003). BH4/BH2 was found to decrease with age (P < .0001). Cardiovascular risk factors in humans such as passive smoking (P ≤ .01) and increased body weight (P ≤ .009) were associated with lower BH4 concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

Age, sex, body weight, passive smoking, and cardiac status are associated with plasma biopterin concentration in dogs. Additional studies should clarify the clinical implications of the findings.

Systolic arterial blood pressure in small-breed dogs with degenerative mitral valve disease: a prospective study of 103 cases (2007-2012)

The objective of this prospective observational study was to assess systolic arterial blood pressure (SABP) in small-breed dogs with degenerative mitral valve disease (MVD) from different International Small Animal Cardiac Health Council (ISACHC) heart failure classes. For this purpose, 103 client-owned dogs weighing <20 kg (mean ± standard deviation, 8.5 ± 3.0 kg; aged 9.8 ± 2.9 years) and presenting with MVD diagnosed by echo-Doppler examination were enrolled. Nineteen healthy dogs (9.9 ± 2.3 years; 8.7 ± 4.2 kg) were concurrently recruited as controls. SABP was measured in unsedated dogs using the Doppler method according to the recommendations in the American College of Veterinary Medicine consensus statement. SABP was significantly increased in dogs in ISACHC class 1 (n=53; median, interquartile range 140 mmHg, 130-150 mmHg) and class 2 (n=21; 140 mmHg, 130-150 mmHg), compared to the control group (n=19; 130 mmHg, 120-140 mmHg; P<0.01 and P<0.05, respectively), but remained within the reference interval (≤ 160 mmHg). Conversely, dogs in ISACHC class 3 showed a significantly lower SABP (n=29, 120 mmHg, 110-130 mmHg) than those from all other ISACHC classes (P<0.001) and the controls (P<0.05). Additionally, SABP<120 mmHg was recorded in 13/103 dogs (13%). The 13 dogs were all ISACHC class 3 (3a or 3b) and were under medical treatment for heart failure. In conclusion, MVD was often associated with SABP values that were within the reference interval, but at its upper end. However, a significant decrease in SABP was observed in dogs with ISACHC heart failure class 3. Whether such low SABP values resulted from an MVD-related decrease in cardiac output, an afterload reduction owing to cardiac treatment, or both, remains to be determined.