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Latest health and behavior news and advice from the veterinarians at Tufts University.

Expert Advice December 2018 Issue

Dear Doctor: Not Even One Raisin?

Q. I know you’re not supposed to feed your dog any grapes, raisins, onions, or garlic, but is it really true that even one raisin or grape is poisonous? Or one slice of onion or a bit of garlic? I mean, after all, while they say not to feed your dog chocolate, I know anecdotally that a tiny piece of chocolate is not going hurt most dogs.

Carl Hiller

Canton, Ohio

Dear Mr. Hiller,

A. Let’s start with the fruit. Your suspicion that just one raisin or grape will not kill a dog is correct. Even a little dog can get away with it. But why court danger? A small amount of either fruit (raisins are dried grapes) can prove deadly by leading to sudden kidney failure and the inability to produce urine. That causes toxins to build up in the blood and make their way to every tissue in the body.

The exact mechanism by which the toxicity occurs is not well understood, but vomiting and diarrhea can begin within a few hours of eating these fruits. Other symptoms include weakness and abdominal pain. Death can ensue within just days. It’s for that reason that veterinarians suggest not getting your dog used to the taste of raisins or grapes by offering them one or two here and there when you’re taking some for yourself. There’s just too little room for error.

Interestingly, not all dogs are affected. But do you really want to find out if yours is one of them?

When it comes to onions and garlic — and chives, by the way — any amount is a bad idea. These foods can cause a form of something called hemolytic anemia, an illness that leads red blood cells to die prematurely. Without enough red blood cells, oxygen cannot get to all the body’s tissues, and the dog can become cyanotic. In this case, the effect can be cumulative. In other words, it’s not about how many onion slices your dog eats in one sitting. The damage can occur with a build-up.

The onions don’t have to be raw to do harm. Onion rings, the dehydrated onions in prepared soups, onions sautéed with mushrooms or hidden with garlic in spaghetti sauce — all of these can make a dog sick. Think twice before handing your dog a tiny piece of pizza or a plate with leftover sauce from pasta, no matter how much she loves it.

Comments (2)

I remember way back when, we were advised to put a little garlic powder in our dogs food to prevent fleas. It didn't help with the fleas, bit I did notice my dogs got some diarrhea so I quit doing it. All my dogs lived to a ripe old age, averaging 15 years, including a German Shepherd with a LOT of different health issues (prior to my taking possession of him). We also did not know about the problems with onions, so they got onions more than they should have, according to the new findings. Again, the issues with occasional tummy upset caused me to discontinue that practice. But it did not seem to cause any shortening of anybody's life, thankfully.

Posted by: Buzsaw7777 | December 11, 2018 6:46 PM    Report this comment

Most Australian dog foods have Garlic in them our Dry Kibble, Wet Can, Pre-Made Raw,
Loaves/Rolls, Cooked Balls & Treats....

Posted by: Sue | December 10, 2018 9:34 PM    Report this comment

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