Small Dogs Are Less Likely to be House Trained than Big Dogs

But small dogs are more likely to be fully house trained if they have attended training, study shows.

Why small dogs are more likely to make house training mistakes, and the effects of training
Photo: Jakkrit Orrasri/Shutterstock

By Zazie Todd, PhD

It has often been suggested that small dogs are more likely to have accidents in the house than large dogs. New research in press in the Journal of Veterinary Behavior finds that small dogs are significantly more likely than big dogs to have house-training mistakes. The research was conducted by Dr. Amy Learn (resident in Clinical Behavioral Medicine at Florida Veterinary Behavior Service) with veterinary behaviourists Dr. Lisa Radosta and Dr. Amy Pike.

It’s an important topic because when dogs have house training issues, their owners may surrender them to an animal shelter, or resort to punishment (which is associated with risks such as fear and anxiety).

The study looked at differences between small dogs (up to 9kg) and big dogs (18kg or more). Dogs in the 9-18kig range were excluded from the analysis as there was some overlap with breeds in other categories.

67% of small dogs and 95% of large dogs were completely house-trained. (This was defined as having always eliminated only in locations the owner thought appropriate during the previous 2 months).
Amongst both small and large dogs, the most common signal reported to mean the dog needed to go was if they stood by the door. For large dogs, staring at the owner was the second most common signal, whereas for small dogs the second most common was the ‘other’ category of miscellaneous signals.

Small dogs were more likely to be house trained if they had some kind of formal training. As well, there was a correlation between the amount of training small dogs received and the likelihood of them being successfully house trained. This correlation did not hold up for large dogs, perhaps because of the smaller number who were not completely house trained.

Small dogs are less likely to be house trained than big dogs. Here's why
Photo: NJ photograph

These results are in line with other research that found little dogs are less likely to receive training, and are also treated differently, than big dogs.

The authors suggest several possible reasons why small dogs may not be completely house-trained, including:
  • Small dogs have a higher metabolism but a small bladder and so need to pee more often
  • Small dogs produce smaller amounts of urine and so owners are more tolerant of mishaps
  • Small dogs are more likely to live in apartment buildings where it’s harder to get the dog outside in time to toilet
  • Small dogs are more likely to still have ‘babylike’ features and so may be spoiled or forgiven for mistakes
  • Small dogs are less likely to receive training, and their owners may be less aware of house training practices

The owners of 735 dogs (235 small, 500 large) took part in the survey. The most common small dog breeds were Chihuahuas, dachshunds, and schnauzers, while the most common large breeds in the survey were Labrador retrievers, German shepherds, and "pit bulls".

This is a convenience sample of participants who were recruited online (mostly via social media) and so is not representative of dogs overall, although it is a nice large sample. We don’t know if the percentages for house-training mishaps are the same as in the general population, as it’s possible people whose dogs have issues may have been more likely to complete the survey.

Further research is needed to understand why these differences between small and large dogs were found. It would be particularly interesting to know more about the training methods people use and how those relate to house training success.

The findings will be of interest to anyone who works with dogs, and suggest that it is especially important to ensure owners of small dogs have good information about how to house train their dog.

For more information on house training, see don’t punish your dog for peeing in the house. I also have a page with information on general dog training.

Don’t forget to check out the Companion Animal Psychology t-shirt - a portion of all proceeds goes to the animals at the BC SPCA Maple Ridge.

Zazie Todd, PhD, is the author of Wag: The Science of Making Your Dog Happy. She is the founder of the popular blog Companion Animal Psychology, where she writes about everything from training methods to the human-canine relationship. She also writes a column for Psychology Today and has received the prestigious Captain Haggerty Award for Best Training Article in 2017. Todd lives in Maple Ridge, BC, with her husband and two cats.

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Learn, A., Radosta, L., & Pike, A. (2019). Preliminary Assessment of Differences in Completeness of House-training Between Dogs Based on Size. Journal of Veterinary Behavior.

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  1. Fascinating research that makes complete sense.

  2. We have a beagle which I think is considered a medium size dog. By far the best method for us is to ensure he gets enough time during the day outside to do his business. You should be able to eventually predict when they will need to go. Puppies obviously need to go more often due to smaller bladders. As they get older they need to go less. He's now like clockwork - an hour after eating he needs to go out for a number two for example... you can set your clock by him.

    1. I love Beagles! It's great that you are so clued in to when he needs to go. Thanks for sharing your tips!

  3. I've always had big dogs - Afghans, Weimeraner, Gordon Setter, English Springer (Show Type - a biggie!) but our daughter wanted a Bichon for her 21st which, of course, we ended up with. She, much as we loved her, was never housebroken properly - she pee'd EVERYWHERE, despite our best efforts. She'd been with daughter for 6 months before we ended up with her and much as we loved her, she ruined every carpet and laminate in the house. We put it down to her early life with daughter. When daughter finally took her, we replaced all the flooring and, as our Springer had finally passed to rainbow, we rescued a Miniature Poodle, mainly because we usually rescued big dogs but now had a tiny granddaughter so felt we should down-size. Poodle was fab. After his neuter, he never marked or messed anywhere. Sadly, he got to daughter's Bichon the day before he was neutered ( he was 7 months old and we'd had him three days...!) and she had a litter. We kept one - a girl, who has carried on her mother's tradition of peeing in the conservatory at every opportunity! She's not as bad as her Mum but she's now nine and still not bomb-proof. PITA.......!

    1. Thanks for sharing your story. I'm sorry about all the ruined flooring! The Poodle sounds like a great dog. I am sure the girl is a lovely dog too despite this issue!

  4. As a dog trainer and behaviourist I have seen tons of small dogs with house training problems. The majority of these dogs came to their families as pups. The only bigger dogs I have had as customers or own dogs were never house trained as they were raised in shelters, labratories, barns, ... I know it's not representative, but most of the small dogs were not trained, were treated more like a doll then a dog and/or were sunshine and sidewalk dogs as their owners did not like to go out in the rain. Owners tend to look at me as if I am a Martian when I promise them that their dog will enjoy walking in the rain or on wet grass if only they show and teach them that it is worse it.

    1. It made me smile when you said some owners look at you like you're a Martian, but I'm glad they come to you for advice. Good training advice is so important! I find it really interesting how (some) people treat little dogs so differently from big dogs, but I wonder how much is due to different kinds of people being interested in different types of dogs, too.

  5. I have a 20 pound dog. I take him for a walk twice a day and he does fine. We both get exercise and he relieves himself. What's the problem?

  6. Love this post! Very interesting read.


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