The word “repellent” when referring to the behavior of dogs commonly brings to mind the image of a timid mail carrier fleeing from an aggressive dog. For lawn care enthusiasts, the word refers to a plethora of mostly nontoxic products used to keep dogs out of gardens. The Humane Society of the United States (HSUS) writes in the Complete Guide to Dog Care that a number of products exist that have smells dogs don’t like but advises repellents aren't suitable for every case. They add that no matter how often these products are sprayed around plants, all repellents should be used with training techniques for your dog. If the dog is a stray, and its digging or urinating are not in your control, these ideas may prevent harm without putting up a fence.
Liquid Fence is just one brand of dog and cat repellent on the market and is made from all natural plant oils. It is recommended for flowerbeds, shrubs and trash containers that may give off familiar animal scents, frequented by wildlife or pets. This product comes recommended by the National Home Gardening Club, and is also safe to use around children and biodegradable. The effectiveness of this particular product is approximately one week, and the maker suggests using it frequently, initially to train and break patterns of behavior. The product can then be used sparingly to reinforce ground rules. Other brands include Grant’s Dog & Cat Repellent Granules, which are sold online and at some hardware stores in two pound shaker bottles. Granules contain methyl nonyl ketone (MNK), which according to the Pesticide Action Network North America (PANNA), is slightly toxic to humans and pets. So, the EPA cautions that for liquid applications, pets should not enter a treated area until the product has dried.
One quart of Liquid Fence costs approximately $12.99 on its website excluding shipping. If you are thrifty, homemade repellents that mask odors include red pepper, vinegar and crushed moth balls. Other brands are sold to repel gophers and squirrels, but they will be suitable for dogs and cats as well. David Deardorff and Kathryn Wadsworth, authors of What’s Wrong With My Plant?, weigh in on repellents commercially prepared for “hungry pest mammals” by cautioning that most contain rotten eggs, pepper oil and garlic. While rain typically washes these products off, some animals get used to the nastiest of flavors so alternating between different products may help. Electronic deterrents using ultrasonic technology are also available.
Finally, gardeners should be conscientious that, as the USHS reminds, “dogs do not use good judgment when eating things they shouldn’t,” so while repellents are generally safe, fertilizers, weed killers, snail and slug bait, several plants and berries, and garlic are all poisonous to dogs. If a dog gets a substance on its coat or in its stomach it should be rushed to a vet before the dog vomits, or you should call the Animal Poison Control Center at (800) 548-2423.