WTF? Seriously, old pets nobody wanted any more? For real pets like Rin Tin Tin, or tasty ones like Abner the family pig? What the hell kind of vet sells your put-down-puppy to the “meat byproduct” factory for like, twenty pounds of shitty meat?
The part about diseased and dying animals sounds reasonable but iffy, but this doesn’t sound plausible at all. Is this seriously even legal?
This wiki page indicates that, acording to the Association of American Feed Control Officials, it is only from slaughtered animals. The AAFCO has pet food regulation info on their site, but it’s in PDF and I don’t have pets so that’s as far as I got.
Animals that have been ‘put down’ by a vet can not be used for this, since the residue of the drugs the vet used to put them to sleep is still in their body.
Vets do not sell the remains of pets they put to sleep. Often, those are given to the owner so they can be buried at their home. Or the vet may dispose of them for you, but you generally pay an extra charge for this.
That website says “horses or other pets”. Here in Minnesota (and in most western states) horses are legally defined as livestock, not pets.
Finally, in claims like this, look to see if it makes economic sense. How could the cost of maintaining a system to collect dead bodies of small animals like cats & dogs from vet offices, and transporting them daily to a factory, be cheaper than just buying the less desirable parts of cows & pigs from the slaughterhouse?
Rather like the claim that McDonalds stretches the meat in their burgers by adding worm meat – when worms actually sell for about 3 times the price of ground beef!