CANINE REPRODUCTION

The Rottweiler Bitch

The majority of breeding problems are very simply solved. Many females are given up on each year due to coming up empty after multiple breedings to a given stud. In the majority of these cases it simply a timing issue. Even though she has a three week-plus heat cycle, there is only a three to four day window of opportunity for conception to take place. The stud dog is not a reliable indicator, nor is the bitches receptivity.

Any reproduction issues should be considered as information only, and not a diagnosis nor prescription for treatment.  Always consult your veterinarian before acting on any information provided.

When we begin thinking about breeding we need to consider Dr. George Padgett's words:

"We need to quit whispering about defects, and gossiping about defects, and instead set up a sound program that allows the standard selection procedures to go on so that we breed good dogs and avoid major defects."

Evaluating the Rottweiler Stud

While the vast majority of fertility problems do surround the bitch, careful evaluation of the semen quality of the male is necessary to rule out male infertility.

In evaluating motility with most species, sperm are classified as non-motile, progressively motile or non-progressively motile. A progressively motile sperm swims forward in an essentially straight line, whereas a non-progressively motile sperm swims, but with an abnormal path, such as in tight circles.

There is considerable variability among species in what is considered normal or acceptable motility. For example, to pass a breeding soundness examination, it is recommended that bulls have greater than 30% progressively motile sperm, stallions greater than 60% and dogs greater than 70%. Example Rottweiler stud semen motility evaluation Micro Video.

Techniques for Evaluation of Sperm Motility

There are several means for evaluating motility. Which technique to use depends on experience of the operator, the desire for precision and repeatability, and availability of equipment. In almost all cases, motility is reported as the percentage of sperm that manifest motility (usually progressive motility).

Manual motility estimates (wet mount): This commonly-used technique involves placing a sample of diluted semen on a microscope slide, examining it with a microscope and estimating the fraction of the population that is motile.

More specifically, a sample of semen is diluted in warm extender or buffered saline, and about 10 to 20 microliters of this sample is pipetted onto a clean, prewarmed microscope slide. A coverslip is lowered onto the sample, avoiding formation of air bubbles if possible, and the slide is examined using a microscope with a 20X objective. At least ten widely-spaced fields are examined to provide an estimate of the percentage of motile cells. If estimating motility is a commonly required technique, a microscope warm stage may be worth purchasing.

A bright field microscope can be used for evaluating motility if the field diaphragm is closed to enhance contrast and ability to visualize sperm. A much better choice is a phase contrast microscope or a microscope equipped for differential interference contrast (DIC). Examine the images above to appreciate the difference in these three types of microscopy - clearly, unstained sperm are difficult to observe using bright field.

Manual motility estimates are easy to perform and require minimal equipment. In the hands of an experienced evaluator, manual estimates generally provide good estimates of motility. The chief limitation of this technique is its subjective nature. Samples with outstanding motility tend to be scored lower than they should be ("it can't be that good ..") and poor samples tend to be scored higher than they should ("it can't be that bad ..").

Track motility estimates: A wet mount of diluted semen is prepared as described for a manual estimate, and sperm are photographed using an exposure time long enough for motile sperm to leave tracks across the image (roughly 0.2 seconds). Using this technique, non-motile sperm appear .. well .. non-motile, and sperm with non-progressive motility leave tracks that are circular or otherwise abnormal. If a digital camera is used, the image can be displayed on a computer monitor for convenient tabulation.

The images below depict the track motility technique. On the left, three progressively motile sperm are represented by three straight tracks. On the left, a circular track is seen, representing a non-progressively motile sperm. Non-motile sperm are seen in both images.

Track motility estimates require more time to perform that manual estimates, but they are objective and repeatable. Additionally, one can save the images for a permanent record.

The articles and links provided here will provide you with all the knowledge necessary to fully understand a bitches estrus cycle.

VKW Rottweilers offers complete cytology, progesterone, and LH testing. (St. Louis area only)