2 False Anestrum and its Types

Transcript

Hi! Friend’s greetings,

In the last session, we were discussing on introduction to Anestrum, Prevalence followed by Economic importance and Classification of Anestrum. In session 2, we’ll be continuing with the classification of False Anestrum, as we all know we have discussed in the last session also, the False Anestrum means there will be the presence of corpus luteum, the animal will not show any clinical signs of estrous. So what are the factors or what are the etiological factors which are being contributed to False Anestrum? The first one is Anestrus due to pregnancy. During pregnancy what happens, this ovary has a corpus luteum and the uterus is being occupied by the embryo or fetus, so what happened, this corpus luteum is kept on secreting progesterone, and progesterone is having negative feedback on the hypothalamus and suppress GnRH. So whenever the corpus luteum is there, it secretes progesterone, progesterone blocks, or suppresses the GnRH release from the hypothalamus by a negative feedback mechanism. So, during pregnancy, there will not be any clinical signs of estrum which is considered to be a normal physiological phenomenon. so, we need not worry about it. The second is Anestrum associated with corpus luteum of pregnancy, which has been terminated early and not recognized, so what it means, the animal would have been conceived, you could be able to find this is a slaughterhouse specimen of early pregnancy, you would able to find there will not be any major clinical changes or topographical changes in the uterine structures. The animal would have been pregnant but because of some reasons embryonic mortality would have happened and which results in the expulsion of the embryo which may be noticed, or which may be unnoticed also, but it has been not detected by the corpus luteum which is present in the Ovary. So, what happens, this corpus luteum will be kept on persisting in the ovary and it secreting progesterone. Even though the animal has lost its pregnancy during early stages, this corpus luteum is secreting key progesterone, as I said earlier, this progesterone is having negative feedback at the hypothalamus to suppress the GnRH, so till progesterone is there, GnRH will not be secreted and because of that there will not be any clinical signs of estrum, so this is not physiological phenomena, which are in pathological which we need to be intervened.

The next thing is under False Anestrum, which is due to Anestrum due to persistent Corpus Luteum, here the term ‘persistent’ is somewhat new. So, when this persistent corpus luteum will be there? persistence means it keeps on persisting, apart from the normal duration. The conditions such as associated with uterine pathology, so this persistent CL is almost associated with some uterine pathological conditions. For example, Pyometra means pus in the uterus. The second one is a Mummified Fetus, so what happened the fetus would have been dead for some reason, and it has been keeping on preserved in the uterus. So, you could able to find this in a mummified fetus that has been evacuated out, but this mummified fetus will keep on persisting in the uterus. Another condition is Fetal Maceration because, for some reason, the fetus would have been undergone death followed by autolysis by bacterial contamination, followed by cervical closure and only the fetal remanence will be keep retained in the uterus, which is also a pathological condition. And other disease conditions such as Mucometra, presence of Mucometra mucus or any kind of a liquid I can say mucometra or hydrometra, based on the change in viscosity, based on the uterine accumulation, prevents the release of prostaglandin and other condition is Pyometra, so I would like to insist that in all condition the uterus is being occupied with something either the fetus or dead fetus or fetal remanence or abnormal fluid in terms of the difference in viscosity or in terms of pus also. So uterus is occupied by something, which prevents the release of prostaglandin, so what happened unless the Prostaglandin F2 Alpha is being secreted, there will be no lysis of the corpus luteum, so what I would like to say is that in all conditions, the corpus luteum is persisting, so what happened this corpus luteum is kept on secreting progesterone and the animal is not showing any signs of estrum, these are all the different conditions where you can expect Anestrum because of persistent corpus luteum. So other than Anestrum due to persistent corpus luteum under the different mechanism. Usually what happens, in the ovary, the follicle keeps develops and this follicle secretes estrogen and estrous behavior will happen followed by ovulation and which results in the formation of the corpus luteum. This is a normal mechanism follicle growth proceeds undergo ovulation and there is the formation of corpus luteum, so after that in a normal mechanism what happens, this corpus luteum will undergo lysis and the animal will enter into the next period of Anestrum but in this condition after CL formation, the animal will enter into the period of Anestrum, due to failure of luteal regression. So what could be the cause for it, so usually what happened during the time of luteal regression, there will be one dominant follicle either it may be in the same ovary or the other ovary and this follicle secretes a little bit of estrogen and it potentiates the lysis mechanism but in this condition, the absence of estrogenic dominant follicle at the time of luteal regression favors the period of Anestrum. So till luteal formation, it is normal but luteal regression is not happening and because of that, the animal is entering into the period of Anestrum. Here I would like to insist that, persistent CL does not occur in the normal cyclical animal often many Vets are getting confused with the cyclical CL with the persistent CL, so here I would like to make it very clear how to differentiate persistent CL and normal CL. For example, if you want to declare the animal is having a persistent CL, you are requested to perform a rectal examination at least two times with intervals of a minimum of 10 to 11 days so when you perform two times rectal examination and you are finding same ovaries having a corpus luteum, then probably you can declare the animal is having a persistent corpus luteum. If suppose during your second examination you are not finding the same ovary that has this corpus luteum, then you should not declare that as in persistent CL, so that is a cyclical CL. So easy way to differentiate a persistent and cyclical CL, is you need to go for two repeated examinations at the interval of 10 to 11 days. So False Anestrumand.

The next etiology is, next type is, Subestrous or Silent Estrous or Quite Ovulation. so what it means, Sub, Silent, and Quiet? The term Sub means a little less, little less than the normal so what it means so usually the estrous signs will be exhibited but, in this condition, estrous signs are not getting exhibited properly, another one is Silent as the name indicates silently ovulation happens but there are no behavioral signs of estrum, that is Silent ovulation. Another one is Quite ovulation, quite ovulation is also almost similar meaning. So, the synonyms are Sub estrum, Silent estrum, or Quite Ovulation. So, what happens in this condition, is being characterized by the failure of overt symptoms of estrum, It means that there are no clinical signs of estrum, usually what happens, in this case, is the follicle development and ovulation occur without manifestation of overt signs of estrum. It is a beautiful condition physiologically ovulation takes place, follicular development takes place, lysis happens again next follicular development ovulation happens, but there are no behavioral signs of estrum under this condition. So, it is common during the post-pubertal period in heifers and early in high-yielding dairy cows, it happens. The reason could be the progesterone, which has been secreted from the regressing field of the previous cycle, potentiates the action of estrogen and seems to favors the manifestation of the estrous cycle in the next one. So what happens, the progesterone which is being secreted from the regressing CL of the previous cycle, potentiates the action of estrogen and probably I can say it is dominating and the animal is not showing any signs of estrum. so these all coming under silent. So one beautiful thing is after parturition, usually, the animal will show estrous signs, so whatever the estrous signs, which we are observing after parturition is not the first sign of estrous, it is usually the second sign. The reason behind this is, usually, the first estrum after parturition is a silent one, the reason behind this is the hypothalamus needs to get primed by the progesterone. Usually, what happens, the best example I can say is that during estrum little quantity of estrum is being secreted which results in the expression of estrum, but during calving, larger quantities of estrogen are being secreted for the relaxation of sacrociatic ligament, vulva, etc. Followed parturition during follicular development and ovulation, only a little quantity of estrogen is being secreted. So the animal could not able to differentiate between the larger quantity and the smaller quantity, so for which to differentiate that priming is required. So after parturition, the first ovulation happens, results in the formation of corpus luteum, and this corpus luteum secretes progesterone, and this progesterone primes the hypothalamus so that in the next follicular development, a follicle secretes estrogen, it could able to sensitize the hypothalamus properly and the expression of estrous seems to be in a better way. So Subestrum etiology, as I said the physiological basis is not exactly known, but it may be due to lack of estrogen and a potentiating action of Progesterone. So unobserved estrum may be due to managemental deficiencies in a short period of use. So other one is a managemental error, as the term indicates, the farmer/ the herdman, which has been involved in the farm is unnoticing the estrous signs, which are being exhibited by the animal. It is absolutely a man-made error, even though from the farm animal side everything is normal, even though the animal is showing the signs regularly or exhibiting the signs properly the farmer or the person who is involved in the farm activity is not able to observe these signs properly, it may be due to lack of awareness on estrous signs. For example, in the case of developed countries, there is only a short number of large farms are there but in the case of a developing country like India, we could able to find there are a large number of small farmers out there because of animal husbandry activity is part of our livelihood. So, each and every small family in the village is being involved in animal husbandry activity, especially a dairy activity and it is being a part of the livelihood. It is not that subsequent generation will be having awareness on the estrous signs and it is our duty to educate them in a better way to understand or brief about the clinical science of anestrum so that they could be able to understand and observe these signs properly and they could able to avoid this False Anestrum. We have come to the end of today’s session, so we have seen what is False Anestrum, so which means that the animal or the ovary will be having in CL, and because of that CL, the animal is not exhibiting signs of estrous and we have seen the etiological factors such as a normal physiological condition such as pregnancy and pathological conditions also. We have seen examples such as Mummified maceration, Pyometra, Mucometra, etc., and in addition to that we also had seen Sub estrum, Silent estrum also and these are all the factors which are being contributed for False Anestrum.

So, with this, we will conclude today’s session and we will continue the diagnostic and treatment protocols in the next session.

Thank you.