Family pets, or companion animals, can sometimes bring unwanted pests, such as fleas and ticks, into your home. These bugs can be more than just an annoyance. Flea saliva can cause allergic reactions in both people and animals, and some ticks can transmit diseases. For example, blacklegged ticks can transmit the bacterium that causes Lyme disease. When using flea and tick control products on pets, it's important to use them carefully for the safety of dogs, cats and family members alike.