In June, we rehomed a lovely little black girl dog called Taxi to a very nice family. The family loved her to bits and since winter was approaching, they decided to get her a lovely warm winter coat.
They duly called in at a pet shop to buy a suitable coat. While in the pet shop Taxi saw, fancied and stole a fat ball. Everyone in the pet shop thought that this was hilarious.
However a short time later Taxi became very ill, was rushed to the vet, but sadly died. It turned out that she had taken a massive allergic reaction to the fat ball. The family were completely devastated.
We do not know if this was an allergy that this particular dog had but, for safety reasons, we must assume that all greyhounds may be fatally allergic to fat balls.
A lot of the commercially made fat balls are fruit ones and contain sultanas, currants etc which are poisonous to dogs.
Also, as someone who makes their own fat bricks for our wild bird feeders, I'm always very sceptical of the ingredient listing on the commercial versions as the texture does not tend to correspond to the supposed mix.
That's pretty shocking, especially since my own greyhound has stolen countless fat balls from the garden. Greyhounds (in general) are not allergic to fat, and I doubt there were enough raisins in it to constitute a lethal dose. I would guess, as someone else mentioned, that possibly not all ingredients are accounted for in these sort of products (especially as they are cheapish and intended for wildlife = can't keep track of its safety), and that it probably contained a chemical which was the cause of the toxicity. If the fat ball was made in a factory were other foodstuffs are made there is a chance of contamination. Often feeds (especially for farm animals) are mixed with medication such as antiparasitic treatments; there have been cases of horse deaths following contamination with cattle and sheep feed that were treated for anthelmintics.