Ground cover in your new dog run is one of the most important investments you can make. A dirt run quickly turns muddy in the rain, and natural grass fosters populations of parasites. But not all substrate is created equal: Some dogs eat wood chips, which can harbor dangerous fungus. Even concrete -- while easy to hose off -- has its downside, turning uncomfortably cold in the winter and hot in the summer.
Playing in the Sand
Sand is easy on a dog's feet and he can dig to his heart's content without doing any real damage. Sand makes an inexpensive base layer for your run and allows for easy removal of feces. Sand holds heat from the sun -- making it ideal for cold-weather basking -- but it can get hot enough to burn dog's feet when its in direct sunlight during summer months. It clings to dog's fur and ends up in indoor carpeting. You'll need to vacuum frequently to keep sharp edges on sand grains from making your carpet look worn.
The Gravel Pit
Pea gravel won't cling to your dog's fur when he heads inside, but you might find an occasional stone that finds its way between his toes. Gravel is easy to install and is easy to maintain by rinsing and raking. If you live in a wet climate, gravel will sink into the mud over time, requiring you to add more every year or two. It is easily displaced if your dog is active inside his yard. You may find it scattered outside the fence line. Gravel's light weight and small size is also easy to scoop up along with feces.
Durable and Decorative
Small river rock stays put better than gravel, and many dogs don't spend the effort needed to dig into it. The smooth stones hose off easily and are big enough that they won't get scooped up with fecal matter. Unlike gravel, dog's won't create a pathway when they trot along the rock. The rock isn't too comfortable to lie on, so provide your dog with a doghouse or other level platform to relax on. While river rock won't get so easily sucked up by the mud, they do get hot in the summer sun.
Mats or artificial turf can provide a surface that is unfriendly to bugs and parasites and is easily cleaned. Rollout mats can be custom cut to fit your run. You can use adhesive to secure it to a concrete base or roll it out on the ground and secure beneath the fencing so your dog doesn't chew the corners. Textured varieties provide extra traction so your dog won't slip or skid even when the mat gets wet. Special dog-friendly artificial turf made from soy lets water flow through without puddling on the surface. The grass contains an antimicrobial agent to discourage bacteria and other pests.