Figure 1.

Plots of plasma tetrahydrobiopterin (BH4) concentrations and three different measurements of myxomatous mitral valve disease severity. Red symbols indicate dogs from homes with smoking. ▲, males; ●, females. Medians are indicated with horizontal lines. Horizontal bars indicate statistically significant comparisons and their P values. Plasma BH4 concentrations were significantly higher in group C compared with all other groups and in group B1 compared with the control group. Males and dogs from homes with smoking had significantly lower plasma BH4 concentrations. ACVIM, American College of Veterinary Internal Medicine.