VetriScience Immune Plus Immunity Support for Dogs also includes bioflavonoids, including quercetin, rutin and hesperidin, which supports vascular and connective tissue health and maintain healthy collagen. Plus, it maintains healthy collagen levels and protects cell structures from damage caused by free radicals. 60 count is recommended for dogs under 30 lbs and 120 count is recommended for dogs over 30 lbs.