The Mad Cat? Shark Biter Catnip & Silvervine Cat Toy is an adorable plush-filled shark-shaped cat toy with a unique blend of premium catnip and silvervine that?s maximum potency, pure, and pesticide-free. Silvervine is an all-natural catnip alternative that cats love, it elicits a similar reaction to catnip and works for many cats who normally are not affected by catnip. Some cats LOVE catnip, but not all cats are affected by it. To solve this problem we developed our unique blend of catnip and silvervine. Silvervine is a non-toxic, all-natural catnip alternative that many cats prefer. This potent stimulant elicits a similar reaction to catnip and is safe and fun. Mad Cat toys are made of soft, high-quality plush with fun accents such as string, crinkle, and embroidery. Ideal for tossing, batting, kicking, and cuddling.