Twenty years ago when I first started home made dog food i wanted to make the food as tasty as I could for my friend and happily added about one or two onions to every batch of meat that I cooked up for him (his name was Caesar). I never noticed any particular issues with him, though he would go “off” his food at times.

I’ve since learnt that onions are actually quite bad for dogs and that I may have (in ignorance) been harming him. You see there’s an ingredient called Thiosulphate in onions (and garlic to a lesser extent) that in sufficient quantity can attack red blood cells and cause a lack of oxygen carrying capacity in the blood; leading firstly to loss of appetite, vomiting and diarrhoea, later to breathlessness – and eventually if given a large enough dose or small doses over time; even to death.

Thankfully I must not have used sufficient onion in my recipes, because Caesar was OK – until the day someone let him out the back gate and he was never seen again! Read more on onions (and garlic) and lots more things that can be harmful for your dog including chocolate – Here.

Steve