Unspayed cats and dogs will have a period – or more correctly – come into heat. In female dogs, at the onset of heat, the vulva becomes quite swollen and will bleed. Some bitches bleed so much they will leave spots of blood all over the house. Others bleed so little you would hardly notice it. This portion of the heat will last for up to 3 weeks. When the swelling in the vulva reduces so that she looks normal – that is when the bitch will stand to be bred. This is the dangerous time! If you do not want your dog bred, you need to keep a close eye on her for at least 2 weeks after the bleeding stops. Dogs cycle anywhere from every 4 months to once every 12 -16 months.
The female cat’s vulva will also swell when she comes into heat but it isn’t always as noticeable as in the dog. There is no obvious bleeding either. A cat in heat will vocalize constantly, walk with her bum end in the air, roll around and just generally act bizarre to the untrained eye. This can last from a few days to a good week. Cats are seasonally poyestrus which means they’ll come into heat every 2-3 weeks for a few months in late winter/early spring and again in late fall/early winter.