I worked for a vet that sold it.  His initial thought was no. but I talked
to the rep, and he said there was no reason why not, and that its even a
good idea to use the small dog one on larger cats.  You just need to ensure
you don't overdose, hence the dropper.

I have a dozen cats - no way can I afford to put the cat version on
all of them, and since they spend lots of time outside, I have to dose
them monthly (it works for fleas much longer, but not past a month for
ticks).  I buy the largest dog size and dose the cats with a 3cc
syringe without a needle: 0.5 cc/ml for the normal sized cats and 0.7
for the very large ones.  The listed ingredients are the same, except
that the dog version contains a bit less of the egg inhibitor.
Results over the last couple of years have been very good, though the
cats still bring ticks inside, they seldom get one attached and
feeding.