Can Dogs Eat Big Macs Safely? + Which Part is Toxic!

can dogs eat big macs

My family and I will do the McDonald’s drive-thru once a month; the smell quickly gets our French Bulldog’s attention. As he sits in the back of the car with our son, and nothing gets his dog taste buds going more than a McDonald’s Big Mac.

Despite his pleading eyes, we’ve never let our dog eat McDonald’s Big Macs. We’ve always believed it wouldn’t be safe for him. But I did wonder if that was actually true, so decided to do an investigation into whether dogs can have Big Macs safely… and here’s what I found out.

Firstly, here’s the real short answer to the Big Mac question…

Can dogs eat Big Macs?

Dogs should not eat Big Macs as they have no nutritional value and have certain ingredients which will upset a dog’s stomach. For example, onions are toxic to dogs in large quantities and one Big Mac can account for up to 86% of a smaller dogs daily calorie intake.

But how did I get to this answer?

To start off with I looked at what professional vets recommend for a dog’s diet. There are two very key aspects which I think relate to whether you should let your dog McDonald’s burgers.

  1. Dogs should only eat 25 calories for each pound they weigh each day.
  2. Dogs should only have treats as 10% of their total daily food intake (the 90/10 rule).

As a French Bulldog owner, that means one Big Mac containing 540 calories would account for 86% of what my dog should be eating in one day! It also completely blows the 90/10 food to treat ratio out of the water!

Let’s take a closer look and dissect the ingredients of a Big Mac so you can understand whether this part of the McDonald’s menu is safe for dogs or not.

my dog ate a big mac
A dog will find this lot very tempting, but you should not let your dog eat your McDonald’s Big Mac meals. (Image copyright Mojo0306).

To help with this I took the average weight of two of the country’s most popular dog breeds. By doing so, it let me better understand how many calories an adult dog should be eating each day. I was then able to calculate how that relates to what percentage a McDonald’s Big Mac accounts for in a dog’s daily diet.

  • Average French Bulldog is 25 pounds: Should eat no more than 625 calories daily.
  • Average Labrador is 70 pounds: Should eat no more than 1,750 calories daily.

Big Mac ingredients

There are 540 calories in a McDonald’s Big Mac. That means just one serving will take up 86% of a French Bulldog’s daily calorie intake and 31% for a Labrador.

The Big Mac is made up of 7 core components:

  • Bun
  • Beef patty
  • Shredded lettuce
  • Big Mac sauce
  • Processed cheese slice
  • Pickle slices
  • Onions

The bun contains:

  • Enriched Flour (Wheat Flour, Malted Barley Flour, Niacin, Iron, Thiamine Mononitrate, Riboflavin, Folic Acid), Water, Sugar, Yeast, Soybean Oil, Contains 2% or Less: Salt, Wheat Gluten, Sesame Seeds, Potato Flour, May Contain One or More Dough Conditioners (DATEM, Ascorbic Acid, Mono and Diglycerides, Enzymes), Vinegar.

The beef patty contains:

  • 100% pure USDA inspected beef and prepared with salt and black pepper.

The Big Mac sauce contains:

  • Soybean Oil, Sweet Relish (Diced Pickles, Sugar, High Fructose Corn Syrup, Distilled Vinegar, Salt, Corn Syrup, Xanthan Gum, Calcium Chloride, Spice Extractives), Water, Egg Yolks, Distilled Vinegar, Spices, Onion Powder, Salt, Propylene Glycol Alginate, Garlic Powder, Vegetable Protein (Hydrolysed Corn, Soy and Wheat), Sugar, Caramel Color, Turmeric, Extractives of Paprika, Soy Lecithin.

The cheese slice contains:

  • Milk, Cream, Water, Sodium Citrate, Salt, Cheese Cultures, Citric Acid, Enzymes, Soy Lecithin, Color Added.

Which parts of a Big Mac are not safe for dogs to eat?

If we look at all of these ingredients closer there are items in a Big Mac McDonald’s burger which can be toxic to dogs. I decided to look at the main offending items.

Onions are not safe for dogs

Onions are not safe for dogs to eat. There is a lot of diced onion in McDonald’s Big Macs, making them not the safest of fast foods for our canine friends.

By just eating 0.5% of their body weight in onions, dogs can become very ill, leading to anaemia and possibility fatalities in the worst cases.

However, I don’t want to panic you too much.

Handy Hint: I also looked into other items on the menu and published a guide to what your dog can eat at McDonald’s including the calories values of each meal.

If your dog has eaten a Big Mac, it would need to eat a lot of burgers to lead to potential onion poisoning. There are 7 grams of onion in one Big Mac, and onion toxicosis is typical in dogs that eat more than 0.5% of their body weight in onions at one time.

That would mean a dog weighing 45 pounds would have eaten 0.03% of their body weight in onion from one Big Mac. To get to the dangerous level of 0.5%, a dog would need to eat 16 Big Macs to develop onion poisoning.

Whilst this is re-assuring, even a little bit of onion in your dog’s diet can lead to diarrhoea and an upset stomach (read more on… so avoid Big Macs with onion.

Salt is not safe for dogs

Then there’s the salt content in the bun, meat, sauce and cheese.

Dogs should not eat more than 1.5g of salt a day. Anything more than that can lead to dehydration and sodium ion poisoning.

There’s 2.3g of salt in a Big Mac. That’s way too much for a dog to be eating in one day. However, I don’t believe there’s any salt in the actual meat burger part of a Big Mac… but more about that in a moment.

Bread isn’t great for dogs

And what about the bun part of the Big Mac? Surely the bread part is safe for your dog to eat safely?

Well, yes and no.

McDonald’s burger buns are made from processed flours which are never going to be great for your dog’s digestive system.

Breads also contain lots of unnecessary calories that aren’t overly healthy and could lead to weight gain.

Cheese isn’t great for dogs

McDonald’s burger cheese is processed. Many dogs will be lactose intolerant, and the thing is… you won’t know until the eat it and get sick.

Plus, if a dog eats large quantities of cheese on a regular basis, they can develop pancreatitis.

Trans fats are bad for dogs

And lastly, unsaturated fats in a McDonald’s Big Macs is not safe for dogs to eat at all.

This is why you should not really let your dog have a Big Mac, particularly with all the trimmings.

The bottom line is this; McDonald’s Big Macs are not safe for dogs when consumed in their entirety (with bun, onion, sauces, and salt) and can lead to health issues when eaten in large quantities.

Handy Hint: I wrote a similar guide to the Burger King Whopper. The calories of this rival burger are far more than the humble Big Mac.

Can my dog eat just the meat part of the McDonald’s Big Mac safely?

But… what about just the meat part of the burger? Surely the Big Mac patty is safe for dogs to eat?

To be honest, it’s not as bad when the Big Mac patty (beef part only) is eaten in isolation.

There are 90 calories per beef patty, and with two patties in a Big Mac, that means your dog will be taking on 180 calories in total – for most dogs that an acceptable meal range.

However, despite the lack of salt, it still will be fatty meat.

To conclude, can dogs eat Big Macs from McDonalds? Well, yes, they can. Do I recommend it; absolutely not.

My dog ate a Big Mac, should I worry?

Whilst I don’t recommend you let your pooch munch on a Big Mac, sometimes people make mistakes… or dogs can actually steal one straight out of your hand!

No matter how it happened, please don’t worry as chances are your pup will be fine. There isn’t enough onion in a Big Mac to poison a dog. He might get a bad belly and become very thirsty due to the salt content, but other than that he should be fine.

However, as with anything of this nature, I always recommend that you consult with your vet if your dog eat something they shouldn’t have.


Whilst you might cave into your dog’s pleading and let him eat a Big Mac, I don’t advise it. Yes, the health issues will only really mount up with a regular diet of Big Macs or lots eaten in one sitting, but that’s not really the point here.

Ultimately, it’s fast food with lots of fat, cheese, ketchup, mustard, onions and salt all of which will give your dog a bad belly and possible diarrhoea.

 Big Macs also have no nutritional value… if you love your dog, don’t let him or her eat Big Macs.

Marc Aaron

I write about the things we've learned about owning dogs, the adventures we have, and any advice and tips we've picked up along the way.

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