Continued
Last week we dealt with the whole issue of the estrus cycle in dogs. One should understand that this ‘heat‘ cycle is influenced, to a large degree, by the hormones in the animal’s body. Hormones are chemical secretions produced by specific cells and transported by body fluids (in this case, blood) to other cells in the other parts of the body where their influence is exhibited. For example, a hormone produced in a part of the brain can have an influence on the activity of the ovaries of the reproductive system. Let’s look at these influences in more detail. As before, we will rely, to a large extent, on a text prepared by Drs Carlson and Giffin which is pretty easily understood and not encumbered by great and profound scientific utterances.
Pituitary influence
The heat cycle begins when the pituitary gland (in the brain) releases FSH (Follicle Stimulating Hormone) which causes the ovaries (female reproductive organs which produce eggs and hormones needed for the reproduction of offspring) to grow the egg follicles (small sacs) and begin to make estrogen (a sex hormone). Under the influence of another pituitary hormone called LH (Lutenizing Hormone) the egg follicle ruptures and releases eggs into the fallopian tubes (oviducts) which connect the ovaries with the womb (uterus).
When progesterone (for example, in the birth control pill Ovaban) is given during the