Male or Female Dog? An Honest Guide to Choosing Your Puppy

For most families, whether you get a male or female dog matters far less than the individual puppy, its breed and how it is raised. The differences you can count on are practical ones: males are usually a little bigger, unspayed females have seasons, and entire males are more likely to mark and roam. Temperament varies more between individual dogs than between the sexes, so choose the puppy first and the sex second.

Male or female dog: does it really matter?

It matters less than the internet suggests. You will find plenty of confident claims that girls are sweeter, boys are goofier, or one sex is easier to train, but these are generalisations rather than rules. A review of research on sex differences in dogs found that, on average, males scored higher for boldness and aggressiveness in some studies, but it also noted that breeds differ so much that females of some breeds can score higher than males of others. In other words, a gentle male from a calm line can be far softer than a bold female from a working line.

What does change with sex is mostly about hormones, and much of that changes again if your dog is neutered. So the honest answer to "should I get a male or female dog?" is: think about the practical realities below, then choose the puppy whose personality suits your home.

Male vs female dog at a glance

Size: the most reliable difference

In most breeds, males are a little taller and heavier than females, but the gap is often small. The Royal Kennel Club breed standard for the Labrador Retriever, for example, gives an ideal height of 56 to 57cm for dogs and 55 to 56cm for bitches. That is a centimetre or two, not a different size of dog.

The difference can be more noticeable in larger and giant breeds, where males may also be broader and heavier set. If size matters to you (a smaller car, a flat, a child who will hold the lead), look at the breed's standard and ask the breeder how big the parents are. You can compare typical sizes across breeds in our breed guides.

Temperament and behaviour: small, average differences

Most of the behaviour differences between male and female dogs are averages across large groups, not predictions about the puppy in front of you. The research review mentioned above concluded that dogs broadly keep the sex differences seen in their wild relatives, such as males tending towards boldness, but only in the contexts that were studied. It is not a reason to assume a female will be calmer or a male will be harder to train.

Things that shape your dog's temperament far more than sex:

• Breed and working purpose. A Border Collie of either sex will need more mental work than a Cavalier King Charles Spaniel of either sex.
• The parents. Calm, friendly parents are a better sign than the sex of the puppy.
• Early socialisation. Puppies who meet people, sounds and other dogs in a positive way during their first months tend to grow into more confident adults.
• Training and routine. Consistent, kind training makes far more difference to trainability than whether you have a boy or a girl.
• Adolescence. Both sexes go through a challenging teenage phase, and our guide to adolescent dogs explains what to expect.

Living with an unspayed female: seasons

If you get a female dog and do not have her spayed, she will come into season (also called being in heat) once she reaches sexual maturity. This is the main practical difference between the sexes, and it needs some management twice a year.

Common signs include a swollen vulva, bloody discharge, more licking of her back end, weeing more often and changes in behaviour such as clinginess, restlessness or mounting. Some females show very few obvious signs.

During a season you will need to:

• Walk her on a lead, at quieter times and in quieter places, away from entire males.
• Never leave her alone in the garden.
• Keep her away from any entire male in your own home, including related dogs.
• Protect sofas and bedding, or use pants designed for dogs in season.

If an accidental mating happens, do not try to separate the dogs, as this can injure them, and contact your vet as soon as possible. Entire females are also at risk of pyometra, a serious womb infection that can be life threatening, and of false (phantom) pregnancy after a season. If she seems unwell after a season, for example off her food, drinking more, vomiting, lethargic or with a smelly discharge, contact your vet straight away.

Living with an entire male: marking, roaming and mounting

An entire (not castrated) male dog does not have seasons, but testosterone brings its own habits. The most common are urine marking, a strong urge to roam when he picks up the scent of a female in season, and mounting. Male dogs are strongly drawn to a female in season because her urine carries hormones and pheromones, so an escape artist male can be a real worry if there are entire females nearby, and an unintended litter is always possible.

What this means day to day:

• Secure fencing matters more, as a male following a scent can go a long way.
• Recall training is worth starting early, because distractions on walks can be strong.
• Marking usually shows up outdoors as cocking a leg on everything, but some dogs mark indoors. Patient, consistent training helps, and our guide on how to toilet train a puppy covers the basics.
• Health checks. Entire males can develop prostate problems later in life and are at risk of testicular cancer.

Females can mark and mount too, especially around a season, so neither habit belongs only to males.

Neutering: a decision to make with your vet

Neutering (castration for males, spaying for females) removes most of the hormone driven differences between the sexes, which is one reason the male or female question often matters less in the long run. It is not a simple yes or no, though. Current UK veterinary guidance is that the decision should be made for the individual dog after a proper discussion with your vet.

What the evidence says, in brief:

A few points worth knowing before you speak to your vet:

• Timing advice has changed. The British Veterinary Association and BSAVA policy from December 2025 says neutering should generally wait until after puberty, at around 12 months, or later for larger breeds, and that spaying before six months is no longer recommended. Older guidance often quoted around six months, so ask your vet what they recommend for your breed and size.
• For females, the balance favours spaying in that policy, mainly because of pyometra and mammary tumours. For males, the balance is finer, and breed, size and the individual dog carry more weight.
• Neutering is not a behaviour fix. It can reduce straying, mounting and marking in males, but it is not a reliable cure for behaviour problems and can sometimes make a fearful dog worse. If behaviour is the main reason, ask about a behaviour assessment first.
• Food needs drop. Neutered dogs often need around 30% fewer calories, so watch their weight afterwards.
• There is no health benefit to letting a female have a litter first.

On cost, the Royal Kennel Club gives a typical range of £100 to £400, with spaying usually costing more than castration. Prices vary by practice and by the size of the dog, and pet insurance does not usually cover routine neutering, so ask your vet for a quote when you register your puppy.

Living with another dog: does sex matter?

If you already have a dog, the sex of your new puppy deserves more thought. You will often hear that an opposite sex pair works best, and there is some evidence behind it: in a US veterinary hospital study of 38 households with fighting between their dogs, 30 of the 38 pairs were the same sex, and 26 involved at least one female. It was a small, specialist sample, so treat it as a pointer, not a rule. Most instigators in that study were also the younger dog or the newer arrival, which is a reminder that introductions and routine matter as much as sex.

Some practical points:

• Opposite sex pairs need a plan for seasons. An entire male and an entire female cannot share a home safely during her season without careful separation. Talk to your vet about neutering at the right age for each dog.
• Two females can be the trickiest pairing for some households, going by the study above, though many live together happily.
• Match personality and energy. A sociable, relaxed resident dog will cope with almost any puppy; a dog who struggles with other dogs may not want company at all.
• Plan the introduction on neutral ground, give each dog its own bed, food bowl and space, and supervise early play. Our guide to preparing for your puppy's arrival covers the first days.

Choose the individual puppy, not the label

The best advice for anyone torn between a male or female puppy is to keep an open mind until you meet the litter. If you set your heart on a girl, you might miss the calm, people focused boy who would have suited your family perfectly.

When you visit, look for:

• A puppy who is curious and recovers quickly from a surprise, such as a dropped set of keys.
• Interest in people without being frantic or very withdrawn.
• How the puppy plays with littermates: neither always flattening the others nor always hiding.
• How mum behaves. You should always see the puppy with its mother, and our guide to buying a puppy safely explains why.

Questions to ask the breeder

Before you decide on a male or female, these questions will tell you more than the sex alone:

• How big are the parents, and how big do males and females in this line usually grow?
• What are the temperaments of mum and dad like, with people and with other dogs?
• Which puppies are the boldest, the quietest and the most people focused?
• Which puppy would you suggest for a home like mine, and why?
• Has the mother had any problems with seasons, pregnancy or whelping?
• Have the puppies met other dogs, children and household noises yet?
• What health tests have the parents had for this breed?
• Will you take the puppy back if things do not work out?

When you have found the right breeder, our new puppy checklist helps you get everything ready before collection day.

Which one suits your household?

When you are ready, you can browse puppies for sale from breeders, rescues and rehomers, with every listing checked by a person before it goes live.

Frequently asked questions

Are female dogs easier to train than males?

Claims that one sex is easier to train are generalisations. Breed, the individual dog and consistent, reward based training make far more difference to how quickly a puppy learns.

Are male dogs friendlier than females?

Some owners say so and others say the opposite. Friendliness and affection depend on the individual dog, its early experiences and its bond with you, not on whether it is male or female.

Which is calmer, a male or female dog?

Neither sex is reliably calmer. Energy levels depend mostly on breed, age and the individual dog, and both sexes can be restless during adolescence before settling as adult dogs.

How do you tell if a puppy is male or female?

Look at the puppy's underside. A male has a small sheath on the belly a little behind the belly button, while a female's vulva sits just below the tail, near the bottom. Your breeder or vet can confirm if you are unsure.

Do female dogs bleed every month?

No. Unspayed female dogs usually come into season about every six to seven months, and the bleeding usually lasts about seven to 10 days.

Does neutering change a dog's personality?

A well socialised, confident dog is unlikely to change in personality after neutering, although some nervous dogs can become more fearful. Ask your vet about timing and your dog's temperament.

Is it better to get a male or female puppy if I have a female dog?

A male is often suggested, and a US study found most household dog fights were between same sex pairs, often involving females. Your resident dog's personality matters just as much. You will still need a plan for seasons, so discuss neutering with your vet.

Should I let my female dog have one litter before spaying?

No. There are no known health benefits to letting a female have a litter first.