it is a period in animals where they become sexually active
Oestrus
If you are talking about oestrus to do with female animals (e.g. the cow in oestrus) it means that that animal is in heat. They are ready and capable to mate.
Oestrus, also known as estrus, is the period in the sexual cycle of female mammals when they are sexually receptive and able to conceive. It is characterized by hormonal changes that result in behavioral and physical signs indicating fertility. Oestrus cycles vary in duration and frequency among different species.
On average, the menstrual cycle (oestrus) of a female goat occurs approximately every 17 to 23 days.
The estrus cycle is regularly occurring period of sexual receptivity in most female mammals, except humans, during which ovulation occurs and copulation can take place. In some animals it happens once a year and in some twice a year. This is not the same as the menstrual cycle in humans.
the relation between frequency and time period is ''t=1/f''
The period is independent of the mass.
Frequency = 1 / period
it means that your cat is not healthy
Oestrus is a word who's definition states among other things 'madness'.æ It is basically the period of time that some animal other than human is in heat.
about three weeks
Technically it's not a "period." Oestrus in female dogs can in fact be dangerous; they can develop an infection in their cervix, and it's possible for this to be fatal. The condition is called pyrometria, is similar in effect and symptoms to appendicitis, and usually happens at the close of oestrus. You may want to monitor your dog closely during this time for fever, lack of appetite, excessive thirst, or lethargy and take her to the veterinarian immediately if she shows signs of illness. It's more common in older dogs.