I give ivermectin 1% injectible orally to cats, dogs, rabbits.
For dogs and cats it will deworm them as well as be your heartworm preventative (same drug as heartguard). A 50ml bottle will last people with a couple large breed dogs YEARS and cost between 30.00-40.00 from a local source, less if you order from Jeffers. Dose is .1cc (that is 1/10th of a cc, not 1 cc!) per 10lbs body weight for dogs, 1x per month. Can't recall it on cats, but I rarely use it. To dose accurately, I use a 1ml syringe from Jeffers to dose.
You can also use moxidectin as a heartwormer for dogs/cats (cydectin injectible) Can't remember the dose for that either, but I'm sure google would reveal answers. Orally or spot on from what I Understand. It's found in some new all-in-one spot on treatments for dogs/cats (they have the moxidectin as the heartworm preventative, as well as anti-flea meds) I do remember calculating the dose in mls for using cattle pour on for dogs/cats, and it was a bigger amount, so if I used it I'd use injectible orally. The cattle pour on leaves an oily, purple film on whatever you put it on, so not ideal for pets.
For rabbits, A vet on the ARBA FB page did the math for the multitudes of people asking, and the dose is .018 ml per pound, given orally.
Keep in mind some breeds/animals have avermectin drug class sensitivies (ivermectin and moxidectin included). Discussion on the rabbit groups described some issues in Dutch rabbits. Dogs such as collies/herding breeds are known to have genetic intolerance of the Avermectin class of dewormers. If your dogs are taking Heartguard with no problem, They should be able to use Ivermectin. I'd talk to your veterinarian to be sure. Animals that have high loads of worms or heartworms may be harmed by treatment as well when mass die-off occurs, so discussion with your vet is important.