Gridded, strand, or wire flooring in dog kennels does not promote either proper sanitation or adequate comfort and safety for dogs and puppies. Grid-style or wire flooring frequently leads to entrapment or injury, as dogs and puppies’ feet become wedged in openings intended for feces. Grid flooring is designed to allow feces to pass through, but unfortunately any gap large enough for fecal matter is large enough to entrap an animal’s foot or toe.
The Humane Society of the United States, "Problems with Grid Flooring in Dog Kennels" (2010). PUPPY MILL REPORTS. 1.