The following interview was originally released as a podcast on March 27, 2014.
In this interview we are talking with Dr. Kit Kampschmidt of Brittmoore Animal Hospital in Houston Texas, about cryopreservation of canine semen. Dr. Kampschmidt received his DVM from Oklahoma State University in 1983. He has developed a special interest in canine reproduction and semen cryopreservation. He is a nationally recognized authority in these areas and serves as a consultant to other veterinarians through the Veterinary Information Network. He has been an invited speaker for national veterinary meetings, state and local veterinary associations, and many breed clubs. He has trained veterinarians from all over the United States and the world in canine semen freezing and artificial insemination techniques. He is a member of the Harris County Veterinary Medical Association, Texas Veterinary Medical Association, American Veterinary Medical Association, and American Animal Hospital Association and currently serves on the board of directors for the Society for Theriogenology.
This podcast is part of a special series of podcasts on canine reproduction in partnership with our corporate alliance, Zoetis.
AKC CANINE HEALTH FOUNDATION (CHF): If a breeder wants to cryopreserve semen it is likely they are saving it long term for artificial insemination or are going to ship it domestically or internationally. Shipping semen is a topic we will cover in the next podcast in our series, but can you tell us about basic health information a stud dog owner should have in place before they consider cryopreserving semen?
DR. Kit Kampschmidt: Any stud dog considered for long term preservation of his semen should of course be in good health and a good body condition. He should be current on all vaccinations, especially rabies vaccination. He should have all the health clearances recommended for his breed, this may include OFA, PennHIP, and CERF eye exams. It could also mean that he has had genetic testing performed for defects that are problems within his breed. All dogs should be tested for Brucellosis. The AKC requires that registered dogs must have a DNA profile on file with the AKC, this is performed on a cheek swab, and most stud dogs who have been producing litters already have one on file with the AKC. If not, this can easily be obtained at the time of semen collection. And I should mention that if the semen is going to be shipped internationally, or it is even considered that it may be shipped internationally, he should have testing done (or serum saved for testing) for diseases like rabies, Brucellosis, and Leptospirosis through a certified veterinary laboratory. Kim Hesler will explain in detail the ins and outs of shipping canine frozen semen internationally in the next CHF podcast. Suffice it to say that all these tests and preparations take time, so it is very important to plan well in advance for the collection and for an international shipment of frozen canine semen.
CHF: We recently did a very informative podcast with Dr. William Schultz of Schultz Veterinary Clinic in Okemos, Michigan who helped us understand semen collection. If we pick up where Dr. Schultz left off and we have semen we would like to preserve long term for shipment and artificial insemination, what do we do first to assess quality of semen to make sure it is worth preserving?
Kampschmidt: Once the semen is collected its quality is assessed in a number of ways. The first and most obvious is motility. A drop of the semen is evaluated on a microscope, usually within a few minutes of collection. The percentage of progressively motile spermatozoa is then estimated. Many laboratories may also utilize a computer assisted technology, known as CASA, to analyze the sperm. Once it is determined that sperm are present and that they are motile, the total number of sperm present in the ejaculate, or total sperm count, is determined. And finally a sample of the semen is stained and individual sperm cells are examined under high magnification by a trained technician to assess their morphology. Abnormally shaped or formed sperm cells may be motile but unable to fertilize an egg. These three factors, total count, progressive motility and sperm morphology; are then evaluated to determine if the semen sample is of adequate quality for freezing. All of these factors may change with each sperm sample collected so it is important that they be evaluated with every collection that will be frozen. These are also the criteria used, along with the physical examination of the dog and his reproductive organs, for Breeding Soundness Examinations we routinely perform on stud dogs, especially those showing any indication of infertility.
CHF: Why does the semen quantity and quality change from collection to collection?
Kampschmidt: That is an excellent question, while we can’t know all the factors that may affect sperm count and quality, we do know that certain external and internal factors can have short and long term effects. External factors such as the dogs housing conditions and husbandry, environmental changes such as exposure to extremely cold temperatures or extreme heat and humidity like we experience here in Texas in the summer months, certainly diet can have an effect, his exposure to females in heat, as well as the number and frequency of semen collections or natural breedings being performed.
The internal factors we consider are things such as his age, weight, body condition, and exposure to parasites and diseases. In general, a young mature dog (2-4 years of age) will have a higher sperm count and better quality semen than older or immature dogs. General health status is very important. An ill or stressed dog will rarely produce good quality semen. It can take as long as 3-6 months following recovery from illness or marked stress for the ejaculate to return to normal. Some medications, both prescription and over the counter, can affect sperm production.
Size has a big effect; large breeds produce more sperm cells than smaller breeds. Toy breeds will often need to have semen collections done several times to store enough sperm to breed one bitch, whereas a large or giant breed might produce enough sperm in one collection to inseminate multiple bitches. It is the number of sperm cells, not the volume of the collection that is important. Disposition and temperament also have an effect. In general an experienced stud dog produces better semen quality than one who doesn’t fully understand the collection process and what is expected of him. It may be advisable to have a young or inexperienced dog collected once or twice prior to having semen stored in order to acclimate him to the process. If the stud dog is shy or nervous, his semen numbers may be poor and freezing the collection won’t be recommended. In addition, a dog that is accustomed to having people around and being handled while breeding will fare better when having semen collected. We strive to imitate the natural breeding process for any semen collection attempt – a bitch in heat standing in front of the stud dog assists the collection process.
CHF: How does semen quality affect outcome of a breeding?
Kampschmidt: One thing I like to make sure that breeders understand is that poor quality semen does not produce poorer quality puppies. In the absence of the risk of infectious disease transmission, which is practically eliminated when using frozen semen, the only effect on outcome is the chance of a pregnancy and size of the litter. Poor quality semen has a lesser chance of fertilizing eggs. Once the sperm has successfully transferred its genetic payload into the ovum, its job is complete, the rest is up to the female and the quality of the genetic material transferred. When using good quality frozen semen, inseminated at the proper time and in the proper way, it is the female that determines the size of the litter by the number of eggs she ovulates.
CHF: If semen is not of high enough quality what do you recommend?
Kampschmidt: If a dog is producing motile sperm cells, it may be useful to attempt to freeze his semen. Generally, if semen numbers and/or quality are compromised, only a small quantity of viable sperm cells will be stored. While this will may give someone an “insurance policy” bank of semen, every attempt should be made to either breed the stud with fresh semen or improve semen quality and freeze again at a later date. If a reason for the poor semen quality is not obvious, as in the advanced age or condition of the dog, every attempt should be made to assess all the factors that may be affecting the stud’s fertility. A full veterinary and reproductive work-up may be recommended, and hopefully a successful treatment plan can be outlined.
CHF: What kind of paperwork and record keeping are required or recommended to store a dog’s semen?
Kampschmidt: A copy of the stud’s individual registration papers and positive identification including microchip or tattoo are usually required. All stud owner’s signatures must be obtained so that we may file appropriate paperwork with the stud dog’s registration body. We discussed the need for disease testing and having a DNA profile on record. Maintaining a record of your semen inventory and where it is stored is important. Record any transfers and uses of the straws. In addition to these things it is important to have a record of semen ownership, if the stud dog is co-owned it is important that the co-owners agree before freezing who will be the owner of the semen. If semen is transferred for breeding or changes in ownership occur, those records must be maintained by the storage facilities and by the semen owners.
CHF: Can you walk us through the steps of semen cryopreservation?
Kampschmidt: Immediately after the collection, the semen is evaluated microscopically as we discussed earlier. If the quality is acceptable for freezing, the sample is then extended with a buffer solution that protects the cells during the freezing and thawing processes. Basically, these buffers contain cryoprotectants which prevent ice crystals from damaging the cell membranes. They also contain ingredients that provide energy to the sperm cells during freezing and after the thaw. Most buffers also contain antibiotics. After the buffer is added, the sample is then placed into an equilibration unit in which is slowly cooled. A sperm count is then performed and the sample is further diluted to a uniform concentration. The refrigerated and diluted semen sample is then divided into multiple individually labeled straws – the number of straws is determined by the initial sperm count. After a gradual cooling the actual freezing process takes place over liquid nitrogen vapors. All the straws are then rapidly plunged into liquid nitrogen and packaged into goblets and onto canes for long term storage. Finally, one “partially filled” straw is thawed and examined for post-freeze motility and quality. An acceptable post thaw motility may be anywhere from 40 to 80 or even 90% – this means that 40-90% of the original sperm cells have survived the freeze and thaw process. From combining all these factors, we determine the number of straws needed for an individual breeding.
CHF: How much semen will be stored from each collection?
Kampschmidt: The number of straws stored is directly dependent on the stud dog’s sperm count. The quantity and quality of semen produced in one ejaculate can vary, sometimes considerably in a short period of time from dog to dog and collection to collection. The number of breedings obtained depends not only on the sperm count, but also on the quality and post-freeze motility. Therefore one individual breeding unit may use a different number of straws from one date than from another date the same dog was frozen.
CHF: How many straws should a breeder expect to need per breeding?
Kampschmidt: The quantity of straws required depends upon the quality of the collection including morphology and motility and the concentration of the sperm per ml. For the reasons we previously discussed, it can vary. But in general the range is from 2 to 6 straws per breeding. So on average, 4 straws are used per breeding. It is important when purchasing frozen semen for use in breeding a bitch to know all the criteria used in determining the number of straws per breeding and to remember that there are different packaging protocols and breeding recommendations used in the canine semen freezing industry. At this time we do not have a standardized protocol, so remember that a “straw” does not equal a “breeding” and that one “straw” does not even always equal another “straw”.
CHF: Dr. Kampschmidt, thank you so much for this valuable information.
For our listeners, our corporate alliance Zoetis provides many services discussed here today. Information about these services can be found at zoetisus.com/caninerepro.