Yes, dogs can get fleas from grass. Fleas are small, wingless insects that feed on the blood of mammals and birds, including dogs. They can jump onto your dog from grass, bushes, or other outdoor areas where fleas are present. When a dog walks or plays in an area where fleas are present, the fleas can jump onto the dog's fur and begin feeding. Once on the dog, fleas can quickly multiply and cause irritation and discomfort.