That dog weighs more than me. Anyhow, consider a groundcover such as liriope or creeping phlox. They should stand up to dogs, and may require less water and maintenance than a lawn.
Those are a couple of very handsome dogs, Debbie, but if they have free run of your lawn area, I don't held out much hope of even a ground cover surviving. In addition to the ones Steve mentioned, you could try blue star creeper (Isotoma fluviatillis), but for any of them it is crucial you keep the dogs off until the plants are very well established. Good luck!
Debbie, I have seen a few companies offering a good looking artificial pet turf that is pet urine resistant. It takes some work for installation (a base material etc) but you can get some "grass" look that they claim stands up. And of course, low maintenance. Here is just one website (but there are others): http://www.easyturf.com/pet-grass-dog-grass...»
I don't have any personal experience to report on which may be better than others but it may be "cheaper" in the long run than fighting a losing battle with dogs in the yard. I always worry about pea gravel because I have seen a lot of it passing through a dog (it is used in some areas at Canine Assistants) but bigger stones have gotten lodged in a dog's intestine. Surgery can be done if that happens but we have unfortunately, as with any surgery there is risk and sometimes very sadly the worse happens.
We have found that the only thing that holds up to dogs is Artificial Turf. We have used it on many back yards for dog areas and all of our customers swear by it. It is a 5-6 year investment compared to sod but well worth it. You will always have beautiful green lawn that the dogs can run freely on with no damage or dirt tracking back into the house. Here is the link to the turf we use the most. They can even help you out with a contractor to install it if you need one. www.ecowaterlessgrass.com
My two dogs 87 & 103 lbs have had artificial turf in their 30' dog run/potty for about 8 years. It still looks great and we only use baking soda and water to clean it (after some manual pickup). I believe we have 5" of small stone and some sand underneath the turf.
Today they make even better artificial turf.