The
scent of a female in heat can carry for considerable distances making it extremely difficult to contain a male pet that smells a female in heat.
Male dogs can smell the
urine of a female in heat several feet away, and once detected, they may temporarily lose interest in food.
Even though pet dogs rarely have the opportunity to reproduce, intact male dogs will still vie for the
attention of females in heat, and females will still compete for access to a male.
Most dogs have a strong urge to reply by pmail to certain odours: a
whiff of a female in heat will warrant a squirt in most males, and the smell of any dog urine is a pretty reliable trigger for both sexes.
This is mainly to protect her from an unwanted breeding because males can detect the scent
of a female in heat from some distance away, and they'll travel from blocks away to find her.
Male cats tend to lay off of the nasty habit of spraying their turf, and both dogs and cats seem to lose their desire to respond when they catch the
whiff of a female in heat.
Castration reduces the male's tendency to wander in search
of females in heat, his need to mark every corner of his territory, and his penchant for aggression and dominance.
Unneutered male dogs and cats are prone to wander in search
of a female in heat.