Sexual Behavior in Dogs

The urge to reproduce is strong in all higher animals, including dogs. This is because it is essential for the survival of the species and, in a manner of speaking, is driven by the “selfish genes” bent only on their own survival. Sexual drives and desires are absent in the early part of a dog’s life, intensify during puberty and early adulthood, and weaken as age advances, taking its toll.

Although a young puppy does not have the urge to procreate, males do engage in sexual play in the form of mounting as early as 5 weeks. At this stage, they probably have no idea what they are rehearsing, though successful mounting presumably establishes something about the relationship between two pups. Human observers ascribe the behavior to the establishment of dominance, which is true, but, then again, sex and politics are often intertwined. When puberty arrives, under the influence of a sea of hormones, dogs and bitches begin to get the true message about the joy of sex and, when opportunities arise, are driven to act on this compulsion. Dogs and bitches have different approaches to sexual behavior and are on different time lines. Males are always interested in an opportunity to mate, while the drive to mate is seasonal in bitches.

Sexual Behavior in the Female Dog

Bitches have their first estrus (“heat”) at the age of 6 to 12 months. Smaller dogs tend to come into heat at the earlier end of this spectrum while larger dogs take longer to mature. The onset of the first heat is heralded by the maturation of a wave of follicles within the bitch’s ovaries and a sudden rise in blood estrogen level. Initially, what transpires externally is referred to as proestrus, which is a stage of readiness for, and interest in, mating. Along with an interest in male dogs and flirtation with them (proceptive behavior), there is progressive vulval swelling and some bleeding.

If males try to mount a bitch in proestrus, she will often turn and growl or snap to rebuff their efforts. Ten days of proestrus lead to the climax, the internal release of ova, and the beginning of true or “standing” heat, in which the bitch will allow herself to be mounted by an interested male. Sometimes, bitches are well attended by competent suitors and, other times, their choice is limited. To attract the attention of a disinterested or otherwise distracted suitor, they will often back into him, deflecting their tail in a provocative way, so that he can hardly ignore what has been placed before him. When the dog mounts, the bitch stands firm, even moving her hips to accommodate him to ensure the success of his thrusting. Following introception, the bitch tightens her vaginal muscles around the male’s penis and settles in for the duration of copulation, which takes about 20 to 30 minutes.

Post-pubertal bitches come into heat cyclically and are thus receptive and fertile between one and four times per year. The average number of heats annually is two.

Sexual Behavior in the Male Dog

Testosterone levels climb in young male dogs, hitting a first peak at about 5 months of age. By this time, their mounting and thrusting behavior may be becoming a nuisance to their owners. At 7 months, dogs may seek to mate, attracted by pheromones put off by bitches. One such attractant is methyl p-hydoxybenzoate (methyl PHBA), a chemical found in high concentrations in the urine and vaginal secretions of bitches in estrus.

Mating usually occurs for the first time when the dog is around one year of age. During mating, the male first mounts and then intromits, sometimes with a little guiding help from his partner. An erectile section at the base of his penis, the bulbus glandis, expands and is grasped firmly by the bitch’s contracted vaginal muscles. The pair is now literally inseparable. At this point in the proceedings, the male may then dismount and turn to face the opposite direction while the couple is still tied. The bulbus glandis must shrink in size before the two dogs can separate.

Variations in Sexual Behavior

• Male dogs raised in isolation show abnormal mounting orientation for longer than other uninitiated dogs. This evidence demonstrates that dogs need social and pre-sexual experience in order to know which way is up when it comes to mating.
• Fear and subordinate status inhibits libido in male dogs.
• Masturbation occurs in “intact” and castrated domestic dogs. Apparently, brain centers that mediate sexual behavior are not completely inactivated by castration, but are merely muted.
• Inappropriate mounting of people’s legs and cushions, sometimes leading to ejaculation, is also expressed by some dogs and can occur despite neutering.
• Mounting can be used to signal dominance over other dogs and people.
• Some neutered dogs still show interest in the opposite sex and will mount, intromit, and tie as if they are still intact.

What Neutering (Castration) Does to a Male Dog

• Limits sexual interest.
• Reduces incidence of roaming in 90% of males.
• Decreases competitive aggression in 60% of males.
• Minimizes urine marking in 50% of males.
• Reduces mounting in 67% of males (especially mounting of people). Testosterone falls to very low levels immediately after neuter surgery, but behavioral changes, if they are going to occur, may take weeks or months.

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What Spaying Does to a Female Dog

Following ovariohysterectomy (“spaying”), a bitch will not come into heat and will show no interest in male dogs. She will also no longer be an object of attraction for male dogs.

A Neutered Dog Is a Healthier, Happier Dog

Unneutered dogs display a great interest in sexual behaviors. For males, this interest is more or less continuous, whereas for females it occurs during heat periods only. Sex hormones have an effect on sexual interest and behavior in both sexes, though the effect is more powerful in inspiring sexual behavior in bitches. Neutering is recommended to prevent unwanted, sexually-driven behavior in all males that are not to be used as studs.

Wanderlust, mounting, urine marking, and inter-male aggression are all unnecessary male behavioral baggage that need not be tolerated, except in a select few dogs to be used for breeding. Also, neutering is recommended for health reasons and to prevent unwanted puppies. Neutering females will prevent a bitch’s bi-annual heats, and the appearance of motley bands of wide-eyed, free-roaming would-be suitors. In addition, early neutering of bitches before the first heat virtually eliminates the risk of breast cancer. This healthful advantage is attenuated after the first heat and lost following the second heat.