Here's what you are using now: http://www.vethical.com/heartworm-treatment.html
Had to edit this message - it didn't come up on a google, but here's what your vet is moving to: http://www.vethical.com/comboguard.html
Looks like generic Triflexis: http://www.trifexis.com/
Some dogs seem to do fine on this, though several dogs online are reporting very serious reactions.
Personally, if a med has been working for so long, I'm hesitant to trade it in for something newer, until it's been on the market for a very long time - I'm not going to let my dog be the guinea pig for the medicine.
I don't like these combination products, but that is the trend.
Edit #2 - the tick collar - there is a new one out, but, it is new, again, we don't know much about side effects yet either (Seresto??? something like that, may also deal with fleas, you don't want double coverage). The Preventic tick collar has been effective, only deals with ticks, but everything has potential side effects for the susceptible dog.