Flat-faced dogs like Pugs and Frenchies may seem extra friendly, but new research shows size, training, and “spoiling” often shape their behavior more than head shape – though some traits are likely hardwired.
Short- or flat-nosed, known as brachycephalic, dog breeds like Pugs and French Bulldogs are popular because of their “baby-faced” appearance and the general perception that they are affectionate. But is the perception accurate, or is it a case of dog owners projecting their beliefs onto their pets?
In a new study, researchers from Eötvös Loránd University (ELTE) in Hungary wanted to know whether certain behaviors often linked to brachycephalic dogs are truly caused by their head shape, or whether other factors like body size, owner type, and how the dogs are kept are actually responsible.
The researchers surveyed more than 5,000 purebred dogs from 90 different breeds, and grouped them according to their head shape: brachycephalic, mesocephalic (medium-length), and dolichocephalic (long-nosed). They then compared these groups across eight behaviors, including four personality traits (calmness, trainability, sociability with other dogs, and boldness) and four problem behaviors (jumping up on people, pulling on the leash, overreacting when guests arrive, and not coming back when called). In addition, the researchers collected data on over 20 “confounding” variables, like dog size, training experience, owner demographics, and living conditions, to see if these explained behavioral differences.
Dog owners were given two large questionnaires (one on personality, the other on problem behaviors), and the dogs’ head shape was classified based on a “cephalic index” from breed averages, with clear separation between categories. The researchers used statistical testing to first look at raw differences, then they re-analyzed their data while controlling for confounding factors, using mediation models to see whether those factors explained (or hid) the link between head shape and behavior. They then re-ran all the analyses, excluding large-bodied brachycephalic breeds (such as Boxers), to determine if size influenced the results.
Raw differences before controlling for other factors
Brachycephalic dogs were found to be less trainable than medium- or long-nosed dogs and more reactive when guests arrived. They were less likely to come back when called. They were about as calm as mesocephalic dogs, and calmer than dolichocephalic dogs. Dolichocephalic dogs were less calm and bold. No differences were seen in leash-pulling or jumping up in the raw data.
Owner and keeping patterns that differ by head shape
Brachycephalic dogs tended to be smaller and younger and have less formal training (nearly half of the dogs analyzed had had no training). They mostly lived indoors, went on shorter walks and were more often allowed on the bed. They were more likely to be owned by younger, often first-time owners, more often women, and more often kept purely as “family members.”
What happened after controlling for confounding factors
Once size, training, and owner/keeping factors were accounted for, the difference in trainability disappeared; smaller size and less training explained why short-nosed dogs seemed less trainable. In terms of sociability towards other dogs, while there was previously no difference, after adjusting for age, brachycephalic dogs were actually less sociable than long-nosed dogs. Short-nosed dogs had fewer problems with jumping up and leash pulling, but this was hidden before because small, less-trained dogs tend to do worse generally. Higher reactivity to guests was partly explained by small size and being allowed on the bed. Differences in calmness, boldness, and recall stayed the same after adjustments, suggesting they may be more directly linked to genetics and head shape.
The study has limitations. The dogs’ behavior was owner-reported, which is subjective and may be biased (yes, “cute” dogs might have their faults overlooked by their owners). Additionally, head shape data were based on breed information, and the dogs weren’t measured individually. Because it was a volunteer sample, it may have been skewed towards happier owners with healthier dogs. Finally, how the owner’s personality influenced breed choice wasn’t measured.
Nonetheless, the study offers some interesting real-world implications for dog owners and potential dog owners, breeders, and researchers. Short-nosed breeds may have some genuinely positive behavioral traits, such as being calmer and less prone to nuisance behaviors, but these are easily masked by poor training or “spoiling.” Proper training can improve outcomes and help offset challenges with small-dog behavior.
Behavioral appeal might be part of why brachycephalic breeds stay popular despite serious health problems, which includes breathing problems, skin fold infections, and eye issues. Owner education should focus on training and realistic care needs, not just the dog’s appearance. The interplay of small size and brachycephalic shape creates a behavioral trade-off: small size tends to increase excitability and attention-seeking, while brachycephaly tends to promote calmness and dependence.
Future research should study head shape and size effects together, not separately. And it should include direct measurements, objective behavior testing, and an exploration of the role of chronic health problems in shaping temperament.
The study was published in the journal Animals.
Source ELTE
