Lex is starting to growl...

  How do I stop this before it escalates?

growling is just communication. It will only escalate if the kittens persist in being extremely rude- in which case he'll probably just air-snap at them to ensure they leave him alone. You shouldn't expect him to put up with rude behavior from other animals. You should have stepped in before- the cats shouldn't have been allowed to get at his food or crawl into his mouth to steal his treats. Like a toddler- you hopefully would teach a child how to treat the dog respectfully. Think of what would happen to your cats if they learn that "dogs let us do anything" and they pulled these stunts with some other dog- dead cat. Think about their long-term safety instead of trying to make your dog super-tolerant.

While I agree that the growl is just a form of communication, I still am of the opinion that training a cat NOT to do something, is a bit like trying to climb up an icy slope barefoot, and probably a lot less enjoyable.

Yes, of course the cats should be fssst away or whatever it takes, but, we ALL get to be distracted by other things in life and it's simply easiest and safest to crate a dog with a yummy treat.  And I say that having to crate six dogs.

glenmar

we ALL get to be distracted by other things in life

And thats why you cant always remember to create a dog when he is eating something, we will have to disagree on whats the easiest way, for me teaching a cat to respect boundaries is the easiest and no body can convince me otherwise since thats my experience and worked for me

Lets just make the OP decide whats the easiest for him/her 

If that's what is easier for you, by all means, go for it.

I personally find that crating for special treats and bones is a no brainer.  When I suggest a bone, everyone heads for their crates in a hurry.  There is no forgetting since they know where they are to go for bones.

I have never had a great deal of interest in training cats to NOT do something unless it in some way annoyed me, such as getting on the counters or table.

but, of course it is up to the OP to choose which methods works best for them.

I've noticed Misty doing this with Tabitha (my very tiny Maltese), but she doesn't even curl her lips back, she just gives that low grrrrr.  Of course, I wonder if it isn't something she was tought from down at the boat being around the older dogs.  When they would have a stick, or bone, and Misty not knowing any better and being curious, 'cause well she's just a baby, the black lab "Max", would "grrrrrr" no teeth, just a low "grrrr", of course she didn't know to leave him alone, and I didn't want him to actually bite, even though the owner said he wouldn't, I just called her away.  I do this w/ Tabitha too.  I just call her away.  After all it's her food, and if anything, Misty loves to EAT!!!!  She's the dominant one, since she's the biggest!  LOL  I also, correct Misty and tell her to "be nice"!  I guess it's just a territorial thing.  It happens to all of us!  You wouldn't believe the growl that comes out of me, when someone eats MY CHOCOLATE!!!!