Sexual Maturity

Sexual maturity is the point in time at which a dog becomes physically capable of reproduction and hormone production exerts its full effect.

In small breeds such as Chihuahuas or Dachshunds, this phase usually begins between the sixth and eighth month of life. Medium-sized dogs such as Beagles or Cocker Spaniels reach sexual maturity between the seventh and tenth month. Large breeds such as German Shepherds or St Bernards take longer – here it can take up to the 18th month or even until the second year of life.

How do I recognise my female dog’s first heat?

With her first heat, your female dog reaches sexual maturity. Visible signs are a distinct swelling of the vulva and bloody discharge.

The discharge begins dark red and becomes lighter and more mucous after about a week – this signals the fertile phase. Your female dog now licks herself more frequently at the rear end and often behaves more restlessly than usual. Some become more affectionate, others rather withdrawn.

The entire heat lasts two to three weeks. The fertile days usually lie between the ninth and 15th day, but can vary individually. After the first heat, the cycle repeats every six to twelve months.

How does my male dog change with sexual maturity?

Male dogs begin producing fertile sperm between the sixth and twelfth month of life, even if they are not yet physically fully grown.

The first sign is usually increased marking behaviour. Your male dog now deliberately lifts his leg to leave small amounts of urine at prominent spots. In doing so, he marks his territory and communicates with other dogs.

He now shows more interest in other dogs, especially in females in heat. If he detects their scent, he can become restless and may try to escape or pull strongly on the lead in their direction.

When is my dog suitable for breeding?

Sexual maturity does not automatically mean breeding readiness – the body needs time to fully mature.

In female dogs, vets recommend waiting for at least the second or third heat. The pelvis must develop fully, and hormone cycles only stabilise after a few cycles. A pregnancy that is too early places considerable strain on the still-growing body.

Male dogs should also be at least 12 to 18 months old before being used for breeding. Their sperm quality improves with age, and character traits only become clearly apparent after development is complete.

How do I prevent unwanted pregnancy?

During heat, female dogs attract males magnetically – even through fences or from a great distance.

Only walk your female dog in heat on a lead and avoid dog meadows or parks. Males can detect the scent over kilometres and become inventive when they want to get to a female in heat. A normally peaceful male can turn into an escape artist.

Castration is the safest long-term solution. In female dogs, this completely eliminates heat; in males, it reduces marking behaviour and fixation on females in heat. The procedure should take place after physical development is complete – in small breeds at about eight to ten months, in large breeds later.

An alternative is sterilisation, in which only the reproductive organs are severed but not removed. Hormone production remains intact, as does heat in female dogs – but without the possibility of pregnancy.