do all mammals undergo menstural cycle. if no why?

Answer 1

Most animals have periods of heat (female fertility) only about twice a year, so there is no need for the uterine lining to build up and then slough off constantly. It would be very dangerous for wild animals to bleed regularly, as that would attract predators, so at the end of a heat cycle, most animals reabsorb the uterine lining if not impregnated.

Answer 2

I do not think all mammals menstruate like humans do and some do not bleed at all, but most mammals go through a similar cycle called estrus. Ahhh here I found some info it seems only a few mammals go through a "menstrual cycle" the same as ours most have an "estrous cycle"...
Excerpt from Wikipedia... The estrous cycle (also oestrous cycle; originally derived from Latin oestrus) refers to the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females; humans and some primates, bats, and shrews are the only mammals who undergo a menstrual cycle instead. Estrus cycles start after puberty in sexually mature females and are interrupted by anestrous phases. Typically estrus cycles continue until death. Some animals may display bloody vaginal discharge, often mistaken for menstruation.

However, species vary significantly in the detailed functioning. One difference is that animals that have estrous cycles reabsorb the endometrium if conception does not occur during that cycle. Animals that have menstrual cycles shed the endometrium through menstruation instead. Another difference is sexual activity. In species with estrous cycles, females are generally only sexually active during the estrous phase of their cycle (see below for an explanation of the different phases in an estrus cycle). This is also referred to as being "in heat." In contrast, females of species with menstrual cycles can be sexually active at any time in their cycle, even when they are not about to ovulate.


So the answer to your question is No, not all mammals have a menstrual cycle, most go through estrous instead. From what I have read, I would guess the reason for this is because most animals do not need to reproduce as often otherwise it would get over populated.......since females that have a menstrual cycle can be sexually active at any time, whereas animals that have an estrous cycle only become sexual active when they are "in heat". Less mating=less reproduction. The short explanation is evolution....

Answer 3

I want to say i read somewhere that though dogs have monthly cycles, they don't have the necropsis (sloughing off or bleeding) part -- I read that they reabsorb the unused material that builds up in the uterus. Ask a vet, though -- they would probably know.

Answer 4

I'm not sure but my guess is that a platypus does not. It lays eggs, yet is still a mammal.

Answer 5

Monotremes, such as platypuses and echidnas lay eggs, and thus don't menstrate.