Will blueberries hurt dogs? It’s a good question, considering some human foods cause big problems for canines. The fact is that while blueberries are generally safe and even beneficial for most dogs, there are a few dogs who should stay away from them or eat them only in small quantities.
According to some sources, blueberries contain moderate to high amounts of oxalates (10). Dogs with a history of forming calcium oxalate urinary crystals should avoid eating fruit with significant oxalate levels. If your dog tends to produce oxalate urinary crystals, limit his intake of blueberries to a few berries once a week.
Oxalates are naturally occurring substances present in food. When oxalates are ingested, they can bind to calcium and form calcium oxalate crystals in urine. Some animals make more of these crystals than others. Calcium oxalate crystals sometimes clump together, forming kidney and bladder stones in dogs.
Dangers of 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. When eaten in extreme amounts, this water shift can cause diarrhea, dehydration and life-threatening increased sodium levels.
Sugar in Blueberries
Cultivated blueberries contain about 15 grams of natural sugar per cup. Compared to other sweet fruits like watermelon, that’s not much.
Still, this amount of sugar could be a problem for diabetic dogs. To be safe, consult your veterinarian before introducing fruit into your diabetic dog’s diet.
Health Benefits of Blueberries for Dogs
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.
One of the antioxidants in blueberries, anthocyanidins, is plant pigments. 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.
Another wonderful nutrient present in moderate amounts in blueberries is Vitamin K. This vitamin is instrumental in normal blood clotting function.
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 fed the supplement had higher antioxidant levels in their blood after exercise compared to those who did not eat the fruit before exercising (3).
Although not proven in this study, the assumption is that a higher level of blood antioxidants could mean dogs are less sore and worn out after exercise.
Organic Berries Are Best
Use an organic blueberry source in your dog’s diet whenever possible. This fruit is on the Environmental Working Group’s list of foods that may contain large amounts of unhealthy pesticides if not grown organically (5).
Wolves Eat Wild Blueberries
Multiple studies on wild wolves have found a significant consumption of wild blueberries. The argument that dogs are strictly carnivorous like wolves gets a bit hazy in this case!
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).
Dogs adopt an omnivorous diet when they live with humans. The nutrients in the fruit can make up a beneficial and natural part of a domestic dog’s diet.
Blueberries as a Hypoallergenic Dog Treat
If you have a dog with inflammatory bowel disease, food allergy or sensitivity you know just how nerve-wracking it can be to find a healthy snack they can tolerate. Well, frozen or fresh blueberries just might fit the bill.
With no source of animal protein and a delicious, slightly sweet flavor, blueberries make a convenient healthy treat for sensitive dogs. Go very slowly any time you’re introducing dog food and ask your vet first if your dog is particularly fragile.
Can Dogs Have Blueberry Muffins or Bagels?
Want to share delicious human food containing blueberries with your dog? Well, the blueberries themselves shouldn’t be a problem. But you should carefully check the ingredient list before giving your pup a bite.
When it comes to sharing your blueberry muffin, bagel or other baked good, look out for the sugar substitute xylitol. Xylitol is highly toxic to dogs even in small quantities.
You should also avoid sharing anything with macadamia nuts. These can cause temporary neurological problems when consumed by dogs.
Blueberries May Cause Black Dog Poop
Although blueberries won’t hurt most dogs, 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.
If your dog has an upset stomach, diarrhea or any other symptoms of illness, it might not be the blueberry fruit causing dark poop. Bleeding stomach ulcers can also make dog stools black, so get your vet involved if you’re not sure what’s going on.
The dark blue pigments in a fresh or frozen blueberry can also stain a dog’s teeth. While not dangerous, you might be alarmed to see a greenish-purple tint on your pup’s teeth until you realize it’s from his berry healthy treat!
What Is Blueberry Facial for Dogs?
You may have heard of giving a dog a “blueberry facial.” You’ll find recipes for homemade facials as well as commercial products. But it’s probably not the blueberries that help clean dogs’ faces.
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 dying it just a little bit blue.
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 blueberries do much to remove tear stains when applied topically.
Feeding Dogs Blueberries for Tear Stains
Another idea that’s popular on the internet is the notion that feeding your dog blueberries will cure him of 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? I doubt it, but it’s a theory!
Blueberries for Dog UTI
It’s a real drag when dogs get chronic bladder infections. 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. The research to support the use of cranberries in dogs with bladder trouble is tenuous at best.
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 this than we have for cranberries.
I think including a safe fruit like blueberries as a small part of a fresh dog food recipe 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!
Click to View References
- 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.
- 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.
- 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.
- Free radicals: How do they affect the body? (n.d.). Retrieved April 22, 2021, from https://www.medicalnewstoday.com/articles/318652
- Group, E. (n.d.). EWG’s 2021 Shopper’s Guide to Pesticides in Produce™. Retrieved April 22, 2021, from https://www.ewg.org/foodnews/full-list.php
- 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 https://www.everydayhealth.com/diet-nutrition/diet/blueberries-nutrition-health-benefits-recipes-more/
- 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.
- In the news: Berries fight cancer. (2017, November 14). Retrieved April 22, 2021, from https://www.drweil.com/health-wellness/body-mind-spirit/cancer/in-the-news-berries-fight-cancer/
- UK, P. (2012, April 26). A bowl of berries a day ‘keeps alzheimer’s and dementia away’. Retrieved April 22, 2021, from https://www.huffingtonpost.co.uk/2012/04/26/red-berries-slow-alzheimers-dementia-risk_n_1454638.html
- UPMC: Your Health Education, Low Oxalate Diet. (2018, August). Retrieved April 22, 2021, from https://www.upmc.com/-/media/upmc/patients-visitors/education/unique-pdfs/low-oxalate-diet.pdf