Go to the Farm store or you can order online and buy 1% Ivomec in a 50ml bottle. Same active ingredient (Ivermectin) that is in Heartguard. Costs roughly $30 give or take, but will last 1-3 dogs for 3+years, which is about what the expiration period is. Dosed at 1/10th of 1cc per 10 lbs of body weight once a month. This dosage also protects from other parasites as well. So as an example a 50-60 lb dog would get ½ (.5) a CC or you could even get by with ¼ (.2) of a CC and still protect from heartworm.
http://www.valleyvet.com/ct_detail.html?pgguid=30e07552-7b6a-11d5-a192-00b0d0204ae5
**** Note -- even though you use a syringe to measure the dosage, it is
NOT injected. You simply squirt it on a piece of food (I use a piece of bread) and give it to the dog.
You can ask your vet about this dosage, but your vet cannot recommend Ivomec by law as it is not marketed for dogs, but it's the same ingredient. Many, Many breeders use this for treating a kennel full of dogs.
For Flea and Ticks you have many to choose from. Frontline Plus, K9 Avantix, or what I use for ticks only, Preventic collars.