the scientific study of pet nutrition by veterinary nutrition specialists and experts.

Dangers of Bully Sticks: Popular Treat Can Carry Bacteria and Add Calories

Dangers of Bully Sticks: Popular Treat Can Carry Bacteria and Add Calories
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Do you feed bully sticks (also known as pizzle sticks) to your dog?  If you do, you’re like 23% of dog owners in a survey we conducted.  And while this study completed several years ago, these treats don’t seem to be any less popular now.  But do you know what bully sticks are? A surprising number of owners (almost 50% in our survey) did not.  Bully sticks are, in fact, bull or steer penises.


I have always been surprised when talking to clients and even other veterinarians that many have no idea what bully sticks really are.  That’s one of the reasons my colleagues and I wanted to conduct a study on these popular treats.  Nearly 800 dog owners completed our online survey, and the results emphasize the confusion and misconceptions owners have about pet food and treats.  In addition to many not knowing what bully sticks are, 71% of people feeding bully sticks to their dogs said they avoided pet foods containing by-products, with most not being able to correctly identify what by-products really are.

Even if you can get past the issue of feeding your dog an uncooked, dried penis of a bull or steer as a treat, there are more potential problems with bully sticks.  One is that they may be contaminated with bacteria.  We tested 26 bully sticks for bacteria and found that one was contaminated with methicillin-resistant Staphylococcus aureus (MRSA), a type of staph bacteria that is resistant to certain antibiotics; one was contaminated with Clostridium difficile; and seven were contaminated with Escherichia coli (including one antibiotic-resistant sample).  This certainly doesn’t prove that all bully sticks are contaminated but does emphasize the importance of washing your hands after touching these treats, as you should with any raw meat or raw meat diets.  People at high risk (very young, elderly, pregnant, or immunocompromised individuals) should avoid all contact with raw animal-based treats and raw meat diets.


Finally, our survey found that 50% of dog owners underestimated the number of calories in bully sticks.  Our analysis of these treats showed that they contain between 9-22 calories per inch, which means than an average 6-inch bully stick is nearly 100 calories!  Since over half of all dogs in the US are overweight, it’s important for owners to factor in calories from treats and table food, in addition to those coming from dog food.  For healthier treat options, check out our post on safe and healthy treats for your pet.



This post provides a summary of our article: Freeman LM, Janecko N, Weese JS.  Nutritional and microbial analysis of bully sticks and survey of opinions about pet treats.  Canadian Veterinary Journal. 2013; 54: 50-54.


Dr. Freeman is a veterinary nutritionist and a professor at Cummings School of Veterinary Medicine at Tufts University. She is on the cutting-edge of science, with hundreds of articles in prestigious journals, speaking engagements at national and international conferences, and awards for her scientific achievements. However, she also is passionate about providing objective and accurate information on pet nutrition to veterinarians, pet owners, and other animal enthusiasts.

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