When doing an implant or artificial insemination, the leuteinizing hormone (or LH) test, is an important benchmark in the cycle. In its most general terms, the LH spike in the cycle initiates the onset of ovulation which, in most cases, does take place in four days, with, less than an approximate 24-hour window.

The following veterinarian summary is provided by George McKay, DVM. Dr. McKay is a reproductive vet in the coastal communities of Monterey and Santa Cruz and offers large animal mobile veterinary services. We thank him for providing us with a comprehensive summary  for breeding in natural, cool and frozen semen settings.

BITCH

1. Prior to breeding, the bitch should be in good health, brought up-to-date on vaccines and in good body condition. A bitch that is too heavy can easily lead to a dystocia, and a bitch that is too skinny has no reserves and may abort or have problems in the post parturient period. We want her immune system in top shape with acceptable antibody levels so she can pass on across the placenta and in the colostrum (first milk). Also, we don’t went to vaccinate during the pregnancy.

2. Pre-breeding culture. There is a controversy as to the efficacy of a pre-breeding culture. Certainly, you may pick up a hidden problem, but usually you only culture normal bacterial flora. It then clouds the issue because the presence of bacteria does not necessarily correspond to disease.

3. When the bitch comes into heat, she physically shows with bleeding, swelling of the vulva, and being attractive to male dogs. Some bitches will have quiet heats, some will have obvious heats. There is quite some disparity in how long it takes for a bitch to be fertile after she starts her heat (literature references are three-30 days). The average time is ten days from the first signs of heat. There are various tests that can be used to determine the optimum breeding time using either progesterone or leuteinizing hormone (a.k.a. LH).* Progesterone test is done every other day, usually starting at day six, while LH testing is done daily, beginning on day four to five.

* For the more technically-oriented person, here is a summary of the hormone cycle. In the bitch, estrogen levels begin to fall which triggers LH to spike (this is a quick event which is why you must test for it daily). After the LH surge, progesterone starts to rise, and it continues to stay high throughout the pregnancy regardless of whether or not fertilization occurs (this is why bitches can go through false or pseudo-pregnancies). Because progesterone stays high, we can afford to test every other day without missing the event. Forty-eight hours after the LH surge the bitch will ovulate, and it takes another 48 hours for the eggs to be ready to accept the sperm. Therefore, we suggest breeding on days three, five and seven post-LH surge, or if we are doing a surgical  implant, we do it on day four post-LH surge.

4. When it has been determined that the bitch has ovulated, either cool semen can be shipped or a natural cover scheduled or frozen ready to administer. 

5. Vaginal cytology can also be used as an aid In determining where a bitch is in her cycle. By taking a swab of the cervical tissue your veterinarian can assess the influence of estrogen and progesterone. In my opinion, this testing is not accurate enough for shipped semen,  however it may be adequate for a natural cover. Surgical Implant timing is best done by LH testing because there is only one chance to cover, and LH testing is the BEST method for testing when using frozen semen, because frozen semen is more fragile and does not survive as long in the bitch.

6. Fresh semen lasts up to four days In the bitch, while cooled semen will last about half as long. Frozen semen has the shortest longevity of approximately  24 hours. After ovulation, the eggs will last about 72 hours. The key is having healthy sperm waiting for healthy eggs.

   Failed pregnancies in the bitch are usually the result of Improper timing.

   STUD:

1. The stud should be in good health, and should be tested and found negative for brucella canis before breeding.

2. I advise that any male being used In a breeding program have his semen checked prior to needing his services. This allows the veterinarian to determine his viability and it gives time to work through any problems before the bitch's ovulation clock is ticking. A stud that has not been used for awhile will need to be collected prior to breeding to "clean out" the epidydimus where the sperm are stored.

3. A stud should be collected no more than every other day, as he needs time between collections to build up numbers of viable sperm. A typical collection requires one billion sperm cells with  approximately 80% motility.

George McKay, DVM
Mt. Madonna Veterinary Clinic
Monterey, California
mmadonna@ix.netcom.com
831-722-6800