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

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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.

If you liked this post, check out my book Wag: The Science of Making Your Dog Happy. Modern Dog magazine calls it "The must-have guide to improving your dog's life."

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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