The breed does not determine the dog - significant differences in mentality both between and within breeds
News published:
02/10/2025
Carefully choosing a dog breed can give future owners a sense of security in knowing its typical appearance, needs, and temperament. But new research highlights that differences between individuals within the same breed can be just as significant—something many may not be aware of.
There are currently 371 registered dog breeds in Sweden, each with its own unique size, coat, heritage, and mental characteristics. Some have been used for hunting, others for guarding, herding, or companionship. It is wise to choose a dog breed that is typical of its breed (according to the breed description) and suits your family, in order to avoid conflict between the dog's needs and those of the family.
Many people who buy a dog therefore have expectations not only about what the dog will look like, but also about what it will be like, its mentality. Behavioral traits are partly determined by how the dog is trained, but also by its genetic inheritance. For example, a dog may be more or less social, protective, playful, curious, or fearful.
What fewer people may be aware of is that differences in characteristics between individuals, even within the same breed, can actually be very substantial. This has now been mapped out in dog research, providing further new perspectives to take into account.
This raises the question: is it really possible to know what you will get when you decide to welcome a puppy into your family?
The “puppy guarantee”: Does it exist?
Buying a puppy is always a bit of a gamble in terms of what you will actually get, begins Professor Erling Strandberg, continuing:
And what we have seen is that breed alone is no guarantee that the puppy will turn out to be like the breed's standard.
After almost 20 years in dog research, Erling Strandberg has in recent years devoted time to investigating how big the differences in mentality actually are between, but also within, dog breeds. He explains that the few studies previously conducted in this area have consisted solely of surveys, in which dog owners themselves have been asked to rate their dogs' characteristics.
And these have yielded quite different results. This made me interested in using Swedish mental descriptions to investigate the issue, Erling Strandberg continues.
Describing mental characteristics in dogs
Since the end of the 20th century, the mental characteristics of dogs have been described by the Swedish Kennel Club and the Swedish Working Dog Club through what is known as MH (mental description of dogs) and BPH (behavior and personality description of dogs).
Mentality
= The dog's personality traits. Traits that are more or less constant.
Mental descriptions mean that dogs undergo the same carefully planned tests. The aim is to be able to describe the dog's characteristics in a comparable way based on its reactions. The tests are selected so that they can always be repeated in the same way, which makes the results comparable between different dogs. In Sweden, all dog owners can have their dogs mentally tested – on a completely voluntary basis.
Within BPH, this is summarized into characteristics in four different areas: sociability, playfulness, environmental security, and threatening behavior. As a complement to the tests, dog owners can also answer a questionnaire with specific questions about things that cannot be tested in a practical way at a BPH. These may include, for example, the dog's behavior when meeting other dogs and in unusual situations such as riding an escalator or elevator. The descriptions are not intended to classify dogs as mentally “good” or “bad,” as traits can be evaluated differently in different dog breeds.
The collection of data from the mental descriptions provides a set of behavioral data for dogs that is completely unique in Sweden and can be used as both a breeding tool and a basis for studies, to give a few examples.
Using genetic indexes – mental index In recent years, the results of mental descriptions have also begun to be used as a way of measuring how dogs genetically pass on mental traits to their puppies – a mental index.
This is an important tool that breeders can use to further increase the likelihood that the next generation of dogs will develop in a direction that is desirable for the breed. Puppy buyers can also review the mental indices of the puppy's parents to gain a better understanding of how the puppy's behavior can be expected to develop.
Today, the mental index tool is used for breeds such as collies, Rottweilers, Staffordshire bull terriers, and Rhodesian ridgebacks. Over time, the idea is to apply the tool to more and more breeds.
How likely is it to get a "standard labrador"?
Four dogs of the breed Labrador Retriever. How similar or different are they mentally? Photo: Lisa Chröisty, SLU
So how likely is it that you will get a dog with the mental characteristics typical of the breed when, for example, you choose to buy a puppy of Sweden's most popular dog breed, the Labrador?
Well, it's not 100% in all cases, that's for sure, replies Professor Erling Strandberg.
Rather, it is a 50/50 chance that you will either get a typical Labrador – or an individual that certainly looks like a Labrador, but has mental characteristics that lean towards one of the “extremes” when it comes to personality.
... For example, it may become much more or much less social, playful, or threatening than one would expect a Labrador to be.
Why is it impossible to predict a puppy's mentality?
The idea is that the puppy consists of half of the mother dog's genes and half of the father dog's genes—in other words, a 50/50 mix of both. But just as diseases can affect some individuals in a family and not all, it is a matter of how the genes mix. This means that traits that have not been “visible” in either parent, but have been dormant, can appear in some of the puppies in a litter – which can then deviate from the breed standard. Quite simply, it is a genetic lottery.
“And then you also need to remember that not all traits are hereditary. There are some behaviors that don't come naturally to a dog, but which can be developed through training and encouragement. These will not be passed on,” adds Professor Erling Strandberg.
For example, through the study, researchers have been able to see that certain dogs of the guarding and hunting breed Rhodesian Ridgeback are more social and playful than certain dogs of the Labrador breed, which does not at all correspond to expectations of these two very different breeds.
This means that it is not always possible to say that there is always more variation between breeds than within the same breed; rather, it depends on the characteristics, which may differ, says the professor.
So what do we do with this knowledge?
How you can use this knowledge in your dog ownership
To begin with, instead of viewing the choice of dog breed as a fundamental “guarantee,” we need to think of it as a kind of optimization of probability for a certain type of behavior, appearance, coat type, and mentality. It increases the chances, but it is not a complete guarantee, says Erling Strandberg.
Practical tips: How to apply this knowledge to your dog ownership
Choose your dog breed carefully, but at the same time be prepared for the fact that your puppy will not necessarily correspond to the breed standard.
Remember that heredity is important, but that external factors such as home, owner, social interaction, and conscious training also have a major impact on how the puppy will grow up and develop.
As a breeder: Feel free to use mental indices to increase the likelihood that the breed will develop in the desired direction.
As a prospective dog owner: Choose a puppy from parents you like. If the parents have been mentally assessed, the results can be found at skk.se/avelsdata, which can give you a good idea of the characteristics your puppy may inherit.
It is also important to understand that not all behavioral traits are genetic. A dog that has received good training and encouragement may exhibit a range of traits that differ from those of the same dog if it had been exposed to frightening events.
But what we do know is that, for example, a tendency to be fearful is actually a trait that is genetically inherited, so investigating the extent to which fears exist in the parent animals may be a good idea in order to understand the risk that the puppy may inherit this genetically, says Erling Strandberg, continuing:
... And not knowing 100% what the puppy will be like is perhaps also part of the charm of welcoming a new member to the family, concludes the professor.
Photo: Lisa Chröisty, SLU
Facts
About this project:
The project has been funded by SLU and has been running at low intensity since autumn 2023.
