Good news for cats, there have been no studies indicating cats can get EEE. There has been some evidence in dogs but the cases have been exceedingly rare and the disease seems to only have a chance to cause disease in puppies. Even though EEE is a minimal threat to our pets, there are other diseases to worry about your pets getting from mosquito bites, the most important being heartworm disease. Any dog or cat that may have any exposure to mosquitoes should take a heartworm preventative every month. Other rare mosquito-borne viruses and diseases that affect pets exist but are nowhere near as common as heartworm. Also, mosquito bites are just not fun. They can be just as itchy for pets as for us and pets often do not resist the urge to lick and scratch, thus leading to a hot spot and requiring medical attention.
Dogs are more sensitive to DEET containing repellants than humans and can have neurological reactions if they are exposed to too much of it. Therefore, giving your dog a thorough spray-down with your own repellent before a walk is not a good idea. Every dog has a different sensitivity to these products. Some veterinarians have reported good results with a very minimal application of these products by spraying them on a towel and then wiping them onto the tips of the haircoat. We cannot recommend this method for all dogs as some dogs may be sensitive even to this small amount of exposure. However, if you have done this before (confession of a veterinarian that is an avid camper and hiker) and found that your dog had no problems then it is a reasonable thing to continue. Cats are very sensitive to DEET and should never be treated with DEET-containing products. Humans do generally tolerate DEET very well, so, for goodness sake, apply repellent to yourself.
For dogs there are products available that contain a chemical with repellent activity called permethrin. These products are safe and can help reduce mosquito exposure to your dog tremendously. Some of the products you may have heard of in this category are Vectra 3D and Canine Advantix. Your veterinarian can help you choose the best permethrin product for your dog. Unfortunately, cats are very sensitive to permethrins and it is very dangerous to use these products on cats.
Other, more “natural” and “herbal” products for mosquito repelling generally do not work as well and have not been studied for safety. One product, introduced as a moisturizer, but found to mildly repel mosquitoes is Avon Skin So Soft. This product does appear to be safe in dogs but is not enough of a deterrent to prevent all mosquito bites.