A corn is a hard mass of keratin, the structural fibrous protein of skin, pads, horns, and hooves; and corns are found predominantly in the digital paw pads of sight hounds. It presents as a circular area of hard pad that can protrude from its surrounding and has a deep root that impinges on the underlying flexor tendon and its bony attachment.
Grit is really common in Greyhounds who live in urban environments and walk terrestrial pavements.
Dr Bec Goode at Port Phillip Animal Hospital reports they actually see more grit cases each week than corns. They are awfully painful for the dog, and difficult to treat with good outcomes in many Greyhounds. Mindful prevention is far better than the cure.