What's the difference between an indoor cat and an outdoor cat?
To some parasites, absolutely nothing. That's why parasite prevention is essential for every cat all year long. Even inside the home, cats are exposed to the outside world in many ways.
Mud on shoes can harbor roundworm and hookworm eggs or larvae. These parasites can be harmful to cats and can also be passed to their owners' children with potentially serious consequences.
Mosquitoes can transmit heartworm — a potentially lethal parasite that is often hard to detect. In fact, the first symptom of the disease can be sudden death. Fully 25% of infected cats are reported to be indoor cats.
Other animals in the house, from a family dog to an uninvited mouse, can harbor fleas, which cause painful itchy bites and carry organisms that can cause serious diseases. Other animals can also harbor ear mites, which are easily contagious and whose bites can lead to serious ear infections.