When I sold some of my Labrador puppies I was amused by the number of people wanting a male dog, “because girl dogs destroy the lawn with those big yellow spots”. Well our male dogs have taken out their share of grass, as well as some trees and expensive perennials of mine. As both an avid gardener and a veterinarian let me pass on what meager advice I can give.
Urine contains nitrogen, potassium, and phosphorus, all three ingredients of fertilizer. Thus, a urine spot with the dead grass is always surrounded by dark green rapidly growing grass, too much of a good thing. Urine would make a great fertilizer if you could catch it and dilute it before spreading it over your lawn. Not me!
The nitrogen content of urine scalds grass more severely than the urine acidity. Nitrogen breaks down to ammonia and “burns” the grass. This is the same as over-fertilizing your lawn. Salinity or salt content of urine rises in concentrated urine. Large amounts of nitrogen and salt are impossible for the natural buffering of the soil to overcome and the grass dies.
The urine pH or how acid or alkaline the urine is can also kill the grass. This varies with the individual dog’s metabolism and diet. Baking soda and commercial products available at pet stores and veterinary clinics will alkalinize or acidify the normally slightly acid canine urine. Products include tablets and dog rocks or water pucks to put in the pet’s water bowl. These products as a rule are safe in most dogs, but unfortunately some may be harmful in individual dogs inclined to form stones in their bladders. I have not found a product that I think works. Most soils are slightly alkaline and can readily withstand the normally slightly acid canine urine. Certainly, Calgary’s clay soil tends to be alkaline as a rule.
Diluting the urine immediately with large amounts of water is effective but impractical if your dog is loose and alone in the backyard. You can build up the soil’s natural buffers by leaving grass clippings on the lawn or by spreading compost, peat moss, or wood ashes on the grass.
Train your dog as a puppy to piddle in one place in the yard. It is more difficult to train an adult dog used to using the entire lawn but you can with persistence and patience.
Garden centers have products that may help you repair or prevent those yellow spots. I have found most of these products too labour intensive for my taste.
A friend sent me an e-mail saying Martha Stewart swears that by giving her chows two tablespoons of tomato juice in their food twice daily their urine never causes lawn spots. Never tried it, give me some feedback if you try it and it fails or works. Adjust the amount of juice to your dog’s size.
My solution is to train my dogs outdoors like I do indoors. Since I like a nice green lawn, I trained my four large dogs on my last property to use one section of the lawn and I promoted the growth of crab grass in that area. Nothing kills crab grass for long and from a distance it looked same as the rest of the lawn. Now I have trained my dogs to use the gravel dog run and one pees on gravel more readily than grass.
Be positive, it might be possible to have a happy dog and a beautiful lawn. Good luck!