Determining the best moment for stud (English version)

DETERMINING THE BEST MOMENT FOR STUD 

One of the most reoccurring questions I’m asked in my office of reproduction assessment is:  ‘when is the best time to mate the female?’ 

Although it depends on if the stud is natural or done through artificial insemination with fresh, refrigerated, or frozen semen, as they change slightly, here exist some basic principles that serve us for any of these techniques. The success of our job is, at a basic level, to access when exactly ovulation happens and the time period in which the bitch is fertile. Ovulation occurs in the female dog 48hours after the peak leves of a hormone called LH (luteinizing hormone) is produced. At this moment, the first ovocyte appears and matures after another 48 hours. At that time the secondary ovocytes are present.  What this means is that the female dog, contrary to other animals, is not fertile at the time of ovulation. Rather, the eggs need time to become fertile once they are released. After that, they remain fertile for 48-72 hours within the fallopian tubes where insemination occurs.

In order to achieve our goal, we are going to evaluate a series of techniques: 

– Vaginal Cytology

This technique is useful to understand about in the phases of the bitches cycle. This method allows us to know when to do hormonal testing to dectect ovulation and to detect if there is any type of genital infection that might impede successful reproduction. In this sense it is a test that is indespensable in managing the female’s reproduction. 

– this test will determine for us an approximation when peak levels of LH will be produced. Luteinizing hormone is key in determining the bitch’s fertile time period that usually occurs between 4 – 6 days from the peak levels of LH. Moreover, it can tell us with accurate precision the moment of birth that is usually an estimated 65 days after that peak. Knowing the exact moment of birth is an important fact for any dog breed.  However, if one could say, even more important for the American Bully as they are a breed known to have complications during birth. The complication is what we know in the veterinarian world as dystocia. That is, an elevated percentage of the cases that have been brought to us have had to have cesarean sections and including having a  planned cesarean section.  

–  The test can determine the moment of ovulation, that is usually two days after the peak of LH levels.

– It allows us to determine what type of ovulation has occurred; wheather it has been a heat ovulation or an anovulatory, that is the cycle when no egg is produced.

– It can identify the next birth of the litter and put a value on the progesterone levels which can tell us when birth will happen within the next 12 to 48 hours.

Progesterone is a hormone that can be identified by a blood test and is usually measured in a quantitative manner (the test gives us a numerical value) or a qualitative manner (usually with a test that uses a color-meter made up of some small dishes that show a series of colors given the level of progesterone). Without a doubt the quantitative method is the best choice due to the fact that it gives us a numerical value that can be studied in each case. 

 

– direct determination of peak LH levels: it is a very valuable test as it is exact in determining ovulation and labor. However, it can present a few inconveniences.

– The elevation of LH maintains its peak levels for a short time (6-48hours).

– difficulties with processing the test in the laboratory, unavailability of laboratories to perform tests

Due to these these possible obstacles, we usually turn to indirect determination of peak LH levels through testing progesterone levels. 

– Ecografia:

This is a useful method to follow the heat cycle and detect ovulation. One can monitor the size of the fallopian tubes and ovaries and compare their growth as the heat cycle progresses. With this method it is possible to observe of the rupturing of the eggs and the changes that are produced in the ovaries following ovulation. The biggest problem with this technique is that it requires daily tracking in order to achieve accurate precision.  One must take into account the economic cost that one would supposedly take on and that, in many cases, the dogs require other support tests for quality assurance.

– Other tests: we can continue to evaluate other techniques that could be useful to help us in determining when ovulation occurs or in what phase of the reproductive cycle the dog is in but with less importance than the tests previously mentioned:

– Vaginoscopy

– Electrical conductivity of the vaginal discharge

– Crystallization and Arborization of vaginal fluid

– Measuring estrogen levels through blood tests

– female’s reproductive behavior in respect to the presence of the male

All female dogs that are destined to reproduce should be in a healthy state and in good nutritional health. To achieve optimal fertility one should consider the clinical signs, vaginal cytology, progesterone measurements, blood work, and if possible study an ultrasound of the dog. In order to achieve a higher chance of conception and a higher number of pups in the litter one must follow the dog 48-72 hours to determine the optimal moment to stud.