Ark Naturals Natural Products for Pets' Gray Muzzle products are formulated to meet the needs of senior dogs. Made in the USA in USDA/AFIS facilities, the line includes Old Bones! Happy Joints, Heart Healthy! Wags Plenty! and Brain's Best Mend, according to the manufacturer. The products contain no wheat, corn, yeast, soy or artificial colors, flavors or preservatives, the company reports.