It can be very hard to get a dog to swallow a pill. Some act like they suspect that you might be trying to poison them. They're always reading too much into things.
My dog, Lucy, is easy. She takes her monthly heartworm/flea pill effortlessly. She likes the pill in a little dip of peanut butter. This is a good method for most dogs that spend their lives thinking about food, like Lucy. Sometimes we say that she's just a stomach with a face on it.
Placing the pill in a dish of food works for some dogs, though I have seen some that will gobble down all the food, and there will be that pill sitting on the bottom of the gleaming bowl. I don't know how they do it. It's like they have a food filter.
My mom's dog is a skittish suspicious little bitch. Nothing works. I have to cradle her body under my arm, wrap my hand around her head, pry her mouth open with a finger, then ram the pill down her throat while she fights and gags. After it's over and we're both shaken, I usually say, "it really doesn't have to be this hard". *sigh*