That was it, xylitol! Thank youSome peanut butter have xylitol in them which is extremely toxic to dogs.
If you use a peanut butter that is 100% nuts its absolutely fine. I tend to use Meridian as its what we have in the house anyway but Aldi and Morrisons do their own brands which are 100% nuts.
Palm oil isnt toxic to dogs, its just not good for the environment.
Peanut butters labelled for dogs are not any better for them than 100% nut PNB and often have palm oil in them.
I've been always buying peanut butter specifically labelled for dogs just to be 100% sure it would be safe but I'll have a look in aldi next time!