I use a horse worming paste called Zimectrin. This method was taught to us by other Bulldog breeders, and has been very effective. Be careful to notice the tube is marked in pound increments for horses. Simply estimate or weigh your dog (weighing is best) and squeeze it out onto your index finger. Then swipe the paste off of your finger onto the dogs tongue. This way you do not squeeze too much into the dog’s mouth.
From late fall through early spring, I de-worm the dogs every 2-3 months. During the late spring to early fall I will de-worm the dogs on the 1st of every month. I am told that doing this during the warm months prevents heart worms.
This however, does not replace having a veterinarian do a heartworm test on your dog. If your dog does have heart worms, the vet needs to do a simple but aggressive treatment to rid the dog of them.