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Are Blueberries Bad for Dogs? (a Vet Answers)

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Are blueberries bad for dogs? It’s a good question I’ve been asked by well-meaning clients who know there are some human foods that cause big problems for canines.

The vast majority of dogs can eat blueberries with no problem. But some sources report blueberries to contain moderate to high amounts of oxalates (10). As a precaution, I advise my clients with dogs who have a history of calcium oxalate urinary crystals to avoid feeding blueberries. 

There are a few other things you should know before feeding your dog blueberries…

will blueberries hurt dogs? xray of a dog with bladder stones

Other Problems with Feeding Blueberries to Dogs

We’ve established that a fresh blueberry snack is fine for most dogs. But what about dehydrated blueberries?

There’s an unexpected danger to dogs who eat large quantities of dehydrated blueberries. The dehydrated berries draw water into a dog’s stomach and intestines. This water shift can cause diarrhea, dehydration and life-threatening increases in sodium levels.

If you like to snack on dried berries, make sure to keep them out of reach of your pup. He might find them so delicious he eats the whole bag and winds up in trouble!

Are Blueberries Bad for Dogs with Diabetes?

Cultivated blueberries contain about 15 grams of natural sugar per cup. Compared to other sweet fruits like watermelon, that’s not much.

Still, the natural sugar in blueberries could be a problem for diabetic dogs. Consult your veterinarian before introducing any fruit into your diabetic dog’s diet.

are blueberries bad for dogs? black dog waiting to eat a blueberry
Pretty please, may I have a blueberry?

Blueberries May Cause Black Dog Poop

The dark pigments in blueberries might not be broken down as they make their way through a dog’s digestive tract. Don’t be surprised if you see dark blue-black stools after your dog eats them.

But don’t automatically assume dark poop is caused by eating blueberries. Bleeding stomach ulcers can also make a dog’s stools black, so get your vet involved if you’re not sure what’s going on.

Dental Staining

The dark blue pigments in a fresh or frozen blueberry can also stain a dog’s teeth. 

While it’s not dangerous, you might be alarmed to see a greenish-purple tint on your furry friend’s teeth until you realize it’s from eating berries.

dog eating a blueberry

Wild Blueberries in the Canine Ancestral Diet

Multiple studies on wild wolves found they consume a significant amount of wild blueberries. Wolves may eat blueberries in large quantities as a last resort in times of food scarcity (7), but they also eat them as a regular part of their diet (1).

Contrary to what raw dog food enthusiasts claim, your dog’s ancestors are not strictly carnivorous! 

We know from extensive research that domestic dogs adopt an omnivorous diet when they live with humans. And the nutrients in fruit like blueberries can make up a beneficial and natural part of their diet.

Health Benefits of Blueberries for Dogs

If your dog doesn’t have a history of calcium oxalate urinary crystals and is not diabetic, blueberries can make a super healthy addition to his diet. 

Berries are nature’s vitamin pill. Whether it’s a blueberry, raspberry or strawberry, all these delicious fruits contain antioxidants. Antioxidants are super nutrients that may help prevent cancer, Alzheimer’s disease, Parkinson’s disease, hypertension and many other chronic diseases (8, 9).

Free radicals are cell-damaging metabolic waste products of all living organisms (4). Antioxidant nutrients protect cells from free radical damage.

Anthocyanidin is a pigment found in blueberries that acts as an antioxidant in a dog’s body. Anthocyanidins slow memory loss in humans, decrease the incidence of certain neurologic diseases and boost heart health (6, 2).

Blueberries contain a moderate amount of the antioxidant vitamin C. While dogs don’t require dietary vitamin C as humans do, it might still be beneficial for them to get a little extra from blueberries.Vitamin K is also present in moderate amounts in blueberries. This vitamin is instrumental in normal blood clotting function.

dogs pulling a sled
Antioxidants in blueberries could help dogs recover from exercise.

Blueberries Increase Blood Antioxidant Levels

In a study published in 2006 in Comparative Biochemistry and Physiology, scientists fed blueberries to sled dogs before they exercised. They found that dogs eating blueberries had higher antioxidant levels in their blood after exercise compared to those who did not eat the fruit before exercising (3).

A higher level of blood antioxidants could mean dogs are less sore and worn out after exercise.

Blueberries as a Hypoallergenic Dog Treat

If your dog has inflammatory bowel disease, food allergy or even food sensitivity you know how difficult it is to find a safe, healthy snack for them. Frozen or fresh blueberries just might fit the bill.

These berries contain zero allergenic animal proteins and have the slight sweetness most dogs love. Blueberries are a convenient, healthy treat for food-sensitive dogs. 

Go very slowly any time you’re introducing dog food and ask your vet first if your dog is particularly fragile.

Blueberries for Dog UTI

Chronic bladder infections make a dog’s life a real drag. I’m not surprised so many dog owners search for a natural way to break the cycle.

Cranberries and cranberry extract have been touted as a natural bladder infection cure and preventive measure. While there is some research around the topic, the evidence is not strong enough for veterinarians to make a wide recommendation to use cranberries to prevent UTIs in dogs.

Blueberries contain some of the same antioxidant nutrients as cranberries and some people think they might help stop dog bladder infections. But we have even less scientific evidence to support using blueberries than we have for cranberries.

I think including a safe fruit like blueberries as a small part of the diet could improve a dog’s overall health. That’s a step in the right direction when you’re fighting chronic infections, so go for it!

Blueberries for Tear Stains

You may have heard of “blueberry facial” products for grooming dogs. You’ll find recipes for homemade facials as well as commercial products. Some of these contain blueberries as an ingredient but it’s not the blueberries that reduce the appearance of tear stains.

The commercial products invariably contain a small amount of synthetic ultramarine blue or violet dye. Ultramarine blue dye is also known as laundry bluing. It makes white fabric (and fur) appear whiter by dyeing it just a little bit blue.

White dogs show tear staining worse than dogs with dark coats.

While these dyes are not necessarily unsafe to put on a dog, they’re not natural substances. And don’t be fooled by the presence of blueberry fruit in a commercial or homemade product. It’s unlikely that actual blueberries do much to remove tear stains when applied topically.

Another internet fad suggests that feeding your dog blueberries will cure their facial tear staining. There is no evidence to back up this idea, but since blueberries are safe to feed your dog in small quantities, I see no reason not to try it.

The antioxidants in the fruit could theoretically change the chemical composition of the tears that spill onto a dog’s face. Perhaps the antioxidants could decrease excessive tearing that occurs as a result of allergies? 

How Many Blueberries Can You Give Your Dog?

It’s important to feed your dog a complete and balanced diet. As a rule of thumb, keep snacks to a maximum of 10% of your dog’s diet. I’ve calculated some reasonable amounts for different sizes of dogs:

Weight of Dog in PoundsMeasure of Blueberries/Day
102 Tablespoons
25¼ cup
50⅔ cup
751 cup

Organic Berries Are Best

Use organic blueberries in your dog’s diet whenever possible. This fruit is on the Environmental Working Group’s list of foods that contain large amounts of pesticides when they’re not grown organically (5).

Although the health implications of pesticides is a controversial topic, it’s easy enough to find organic berries these days. Why not be a little cautious and keep a few more chemicals away from your bestie?

blueberry muffins and bagels
Blueberry muffins and bagels might have other ingredients that are not dog-safe.

Can Dogs Have Blueberry Muffins, Bagels or Yogurt?

Want to share your own blueberry-flavored food with your dog? The blueberries themselves shouldn’t be a problem. But there could be other ingredients that could be disastrous for your dog!

Before you share your blueberry muffin, bagel or yogurt with your pup, carefully check the ingredient list. Watch out for the sugar substitute xylitol. Xylitol is highly toxic to dogs even in small quantities.

You should also avoid sharing anything containing macadamia nuts. These can cause temporary neurological problems when consumed by dogs.

Although it’s unlikely that a blueberry-containing food would also contain one of these, watch out for other potentially toxic ingredients:

  • Grapes
  • Onion
  • Chocolate


Most dogs can eat blueberries with no problem. Use caution before feeding them to dogs with calcium oxalate urinary crystals and diabetic dogs. 

Blueberries carry a high level of antioxidants that may improve a dog’s overall health. Blueberries should be fed as a limited portion of a dog’s diet, up to 10% of daily calories. 

Watch out for other toxic ingredients when sharing human blueberry-containing foods with your dog.

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  1. Bosch, G., Hagen-Plantinga, E. A., & Hendriks, W. H. (2015). Dietary nutrient profiles of wild wolves: insights for optimal dog nutrition? British Journal of Nutrition, 113(S1), S40-S54.
  2. Do, R., Xie, C., Zhang, X., Männistö, S., Harald, K., Islam, S., … & INTERHEART investigators. (2011). The effect of chromosome 9p21 variants on cardiovascular disease may be modified by dietary intake: evidence from a case/control and a prospective study. PLoS Med, 8(10), e1001106.
  3. Dunlap, K. L., Reynolds, A. J., & Duffy, L. K. (2006). Total antioxidant power in sled dogs supplemented with blueberries and the comparison of blood parameters associated with exercise. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 143(4), 429-434.
  4. Free radicals: How do they affect the body? (n.d.). Retrieved April 22, 2021, from
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  6. Higuera, V., Migala, J., Lawler, M., Palinski-Wade, E., Revelant, J., Bedosky, L., & Rapaport, L. (n.d.). What are Blueberries? Nutrition, health BENEFITS, RECIPES, MORE: Everyday Health. Retrieved April 22, 2021, from
  7. Homkes, A. T., Gable, T. D., Windels, S. K., & Bump, J. K. (2020). Berry important? Wolf provisions pups with berries in northern Minnesota. Wildlife Society Bulletin, 44(1), 221-223.
  8. In the news: Berries fight cancer. (2017, November 14). Retrieved April 22, 2021, from
  9. UK, P. (2012, April 26). A bowl of berries a day ‘keeps alzheimer’s and dementia away’. Retrieved April 22, 2021, from
  10. UPMC: Your Health Education, Low Oxalate Diet. (2018, August). Retrieved April 22, 2021, from

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