1 Introduction, Types, Incidence, Fertility and Normal Postpartum Events

Transcript

Greetings!

Happy to reach you all in this virtual media. I am Dr.S.Sathesh Kumar, professor in the subject of animal reproduction. Currently heading the Department of Veterinary Gynecology and Obstetrics at Veterinary College and Research Institute, Orathanadu, a constituent unit of prestigious Tamil Nadu Veterinary and Animal Sciences University, situated at Tamil Nadu. In this series of lessons entitled management of infertility in cattle, I am going to take classes on Endometritis and in this session, we are going to deal with the basic Introduction about uterine infections as well as the Types and incidences of various uterine infections. The fertility of dairy cattle is a gateway of production and the backbone of the dairy industry and rural economy. Our country stands first in milk production globally, but the bovine population behind this production scenario is also huge, ever-rising infertility problems seem to be the major hurdle in the production status of the animals, if these obstacles could be resolved, we can attain a mammoth structure of milk production, a real white revolution. One of the main factors that impact fertility, is the occurrence of uterine infections. The disturbed uterine environment, disrupts the Utero-ovarian function, leading to infertility. Hence, it is important to understand all the details about Endometritis condition in dairy cattle, right from its incidence, causes, diagnosis, treatment, and prevention in order to improve fertility. A parturition is an event of new life coming into being. At the same time, it’s also a period of high risk for the mother and the offspring as well, and cattle is no exception, we can expect all sorts of problems at the time of parturition also.

After parturition, there is often an upsurge of microbial infection in the cow that ultimately has a greater impact on the health and reproductivity of the animal. Most microbial contaminants are eliminated from the uterus during the first three weeks of pregnancy by uterine involution and activation of innate immune defenses. However, failure in this comeback mechanism leads to various degrees of uterine infections. Puerperal Metritis, is one of the serious conditions among uterine infections. It’s the inflammation of the inner lining and all the deeper layers of the uterus. It occurs within 21 days after parturition and it is also characterized by foetid reddish-brown uterine discharge and it’s also associated with signs of systemic illness like fever, decreased milk yield, dullness, and signs of toxaemia, in that way Puerperal Metritis is one of the serious conditions after the parturition.

Then comes a lesser degree of uterine infection, that is Endometritis, this is the Inflammation of the endometrial layer of the uterus, the superficial layer of the uterus. It is characterized by the presence of purulent or muco-purulent uterine discharge. About 15% of dairy cows have clinical signs of uterine disease, that persist beyond 3 weeks postpartum. Next is Sub-Clinical Endometritis, this is also the inflammation of the uterine endometrium but where lies the difference? Here, there will not be any overt signs because this infection is characterized by a clear uterine discharge and interestingly it affects 30-35% of dairy cows between 4 to 9 weeks postpartum. Since there are no signs to be found because of this Sub-Clinical Endometritis, this is considered to be the ‘Silent Killer’ of Fertility.

The major events that must be completed after parturition before a cow is likely to conceive again are:

Uterine involution,

Regeneration of the endometrium,

Elimination of bacterial contamination, and

Return of ovarian cyclical activity

The pre-requisite for all these normal postpartum events are the normal expulsion of the foetus, foetal membranes, and associated fluids at calving. Uterine Involution: Involution of uterus involves—

• physical shrinkage,
• necrosis and sloughing of caruncles and
• regeneration of endometrium.

Uterine caruncles are usually sloughed by 12 days after parturition. The sloughed caruncles along with the remains of the fetal fluids and blood from the ruptured umbilicus will be discharged as the lochial. This is a normal discharge in the postpartum period that is called lochial.

Epithelial Regeneration: Epithelial regeneration is completed about 25 days after parturition. Deeper layers of tissues require 6 to 8 weeks for a complete restoration, after parturition. It is followed by the Evacuation of Microbial Load: The postpartum environment of uterine lumen supports the growth of a variety of aerobic and anaerobic bacterias. Normally they are removed from the uterine environment by the defense mechanisms.

Ovarian Rebound: This is one of the important features for the animal to come into the next cycle. After parturition, the concentrations of the steroid hormones will decrease, the concentration of the follicle-stimulating hormone will increase, and it is very important in the stimulation of the first follicular wave emergence after parturition. The first dominant follicle that is selected from this follicular wave, will be around 10 to 12 days after calving. The fate of this dominant follicle decides the cyclicity or the onset of cyclicity of the animal, after the parturition.

The Clinical signs of Endometritis: The nature of vaginal discharge is a mirror of uterine health status, it’s always known, we can see that based on the nature of discharge, we can actually classify the conditions into Clinical Endometritis or Sub-Clinical Endometritis. First, we are going to see about Clinical Endometritis: here in the case of clinical endometritis the discharge will be purulent or muco-purulent, it will be readily detected from the vaginal discharge. The physical character and odour of vaginal mucus can be scored to assess the degree of infection. This is called the Clinical Endometritis Score. This score indicates the prognosis of the condition and the type of treatment we have to undergo. Basically, it has been characterized and scored as 0, 1, 2, and 3. If it is score 0, the discharge seems to be clear and translucent mucus. If the discharge is going to have some flecks of white pus, that can be graded as score 1, If the discharge is contained less than 50% white or yellowish pus, then it can be graded as score 2, If this discharge is going to have more than 50% of white, yellow or reddish pus, then it can be scored as 3. So, this will be given the various degrees of Clinical Endometritis condition.

Then we come to the Sub-Clinical Endometritis, as we have told in the last class itself, here the vaginal discharge is often clear, and the animal is not showing any signs of infection Typically copious clear discharge with thin consistency is a characteristic feature of subclinical uterine infection. The reproductive performance of these cows affected by subclinical endometritis is usually diminished, which will be reflected as repeat breeding syndrome. So, in this class, we have seen the various clinical signs and the various degrees of infection in the case of Clinical Endometritis as well as Sub-Clinical Endometritis. In the next session, we can see about the Etiology and Pathogenesis of the infected conditions. See you all.

Thank you!