Frontline Plus is generally considered safe for use on pregnant and lactating dogs when used according to the manufacturer's instructions. The active ingredients in Frontline Plus, fipronil, and (S)-methoprene, have been widely used in veterinary medicine for flea and tick control.
However, it's always best to consult with your veterinarian before using any flea and tick product, especially if your dog is pregnant or nursing. While Frontline Plus is considered safe for most pregnant dogs, individual circumstances may vary, and your veterinarian can provide personalized advice based on your dog's health status and gestational stage.
In some cases, your veterinarian may recommend alternative flea and tick control methods or may advise against using certain products during pregnancy. They can help you weigh the potential risks and benefits and make an informed decision regarding flea and tick control for your pregnant dog.