I have given my dogs Greenies for 5 years and currently give them about every other day -- the dogs love them; they are probably their single favourite treat along with dried tripe. There were a few reported early problems with dogs that gulped them or chewed off pieces, and in specific cases where small dogs were given a too large Greenie (the case with a chihuahua widely publicised -- it should not even have been eating a Greenie much less a large one, it should have been given just the bits) but they were reformulated and are quite soft now. I have never, ever seen a single chunk of an undigested Greenie in a poop (and I pick up poops right after they are done as I have to walk the dogs for toiletting, so I know my dog's poop :lol
. Nonetheless as with any treat or chew, there could be a problem for any given dog and impactions are scary and can be fatal.
By contrast though, I have had numerous shards of bone either vomited up or pooped out from both raw chicken wings and raw chicken necks
. Remember according to the raw gurus this is supposed to be impossible as the bone is supposed to be swiftly dissolved by the stomach acid. NOT TRUE as this happened with two different dogs of mine, Jaspar and Leo. I currently have on my shelf two very sharp pieces of chicken wing vomited up 12 hours later by Leo recently -- and he is a slow eater, not a gulper -- so that is the absolute end of me ever giving raw wings to the dogs.
Ask any vet and they will give a long list of items that have caused impactions and I think very few will cite Greenies. More likely objects include: socks, twine, bone (raw or cooked), dried jerky treats, pieces of chewed hard rubber dog toys, stones, sticks, pieces of leather, pieces of chewed cloth, bits of children's toys, pieces of rawhide, pieces of bully sticks -- in short, just about anything you might give a dog to chew on. Impactions are pretty rare but thy can happen as can many other unfortunate situations.
So it is really a matter of what people are comfortable with. There are plenty of raw advocates who say they have fed their dogs raw chicken carcasses for 20 years without any problem. But I have now had two very worrying instances of dogs vomiting back up very sharp undigested pieces of chicken bone over 12 hours after eating the wings, pieces that I was fortunate did not pierce a gut (a far more serious problem than an impaction) and to me that is way too risky. By contrast I've never had a single issue with Greenies, the old formula or the new one. Far more dogs have died from the food contamination issues recently.
So choosing treats or chews is always a matter of knowing your own dog and how that dog eats and weighing up the slight risks of practically anything your dog might eat. I've fed a wide variety of things over the past years and I am quit comfortable with
Greenies
Flat rawhide sheets
Rolled rawhide 'cigars'
bully sticks/pizzle sticks
dried tripe
Booda bones
chewable Nylabones
dried sinew
dried fish skins
I will not give my dogs
rawhide bones or shoes or other shapes -- they can chew off large pieces to easily
raw chicken wings
most other raw bones except marrow bones
cooked bones
On whether to give the 6k dog a petite Greenie for 7k dogs and above -- I have two dogs just over 6kg and give them this size. They are both slow chewers and not biting off pieces. But the recommendations are the recommendations so theoretically, you should not.