With the 1992 and 1995 single pups, we caesared the bitches on the day he predicted. I found this difficult, because they showed no sign of going into labour and in all other respects were outstandingly healthy. My instinct was to wait, as one does with a natural mating until full term as we understand it, 63 days, or at least 59 when many of our own bitches whelo to natural matings. On both occasions, the placenta had already detached and any delay would have almost certainly resulted in the death of the se irreplaceable puppies and been potentially life threatening also for the bitch as she would no doubt have become toxic.
I thought my vet was God the first time, on the second occasion he admitted he was only human and had followed the scientific procedure that has been developed as a result of the increasing use and knowledge of frozen semen. Nevertheless, talking to other people who have lost puppies in similar circumstances, I feel he still does have an almost infallible instinct where this timing is concerned. As I said, you need a very talented veterinarian and to have nerves of steel ....
SEMEN COLLECTION
In order to get a sufficient quantity, i.e. enough semen to make the financial outlay worthwhile, two ejaculates - the correct terminolgy for semen collection - are recommended, our vet prefers 24 hours apart. Sometimes a dog will not be at all co-operati ve on the first attempt, and to be fair it is quite an intimidating experience for him to be in a confined space such as a veterinarian's office, have a "teaser" bitch in season introduced which is quite often of a totally different shape, size and person ality from those of his own breed, and then be expected to allow the veterinarian to handle him with plastic gloves, glass beakers etc. Proven dogs usually manage to sort this all out, and more often than not the second collection is superior to the first.
Personally, we will never collect from unproven dogs as we feel that using them artificially before they have had a natural mating is not a good thing, for either the dog himself or the breed in the long term. We are firm believers in insisting that our f uture studs are capable of managing bitches under natural mating conditions, good and bad, easy and difficult. After all, this is how the majority of their stud work will take place and it also ensures that they thoroughly enjoy their destiny as they shou ld.
I must say I am quite amazed by the number of breeders who don't bother to let their males mate naturally and just automatically do their matings by collecting fresh sperm and artificially inseminating their bitches, but I guess that is another matter as our topic, relates to working with frozen semen.
Sometimes a dog will burst a blood vessel and that semen must be discarded as it is contaminated and useless. This dog may perform better on a second collection and then perhaps the veterinarian will ask for a third collection. All this of course adds to the time and expense that you must be prepared for if you are going to take advantage of AI by frozen semen.
Semen is examined before freezing for motility, sperm density and sperm morphology. If all is in order, then a constant sperm density is achieved by use of a diluent. This is a liquid used to increase the volume of the sperm rich fraction, while protectin g and allowing reactivation on thawing. The earliest formulation for a diluent was known as Anderson's, and it contained glycerol for anti freeze protection, fructose for nutrition, citric acid, and other chemicals as it is essential to maintain a constan t acid-alkali balance, egg yolk, distilled water and antibiotics which were mainly penicillin and streptomycin.
Many advances have been made in this crucial area, and diluents used by the commercial organisations such as the well known ICG - International Canine Genetics - are subject to great secrecy and all the veterinarians belonging to this organisation use the same diluent, uniformity obviously being of considerable advantage when they handle shipments between each other.
The diluted semen is then chilled in a refrigerator for a few hours before being cooled down under controlled conditions to -196 degrees Centigrade.
Our veterinarian likes to send or receive an average of twenty straws, which gives a client sufficient for five surgical implants, four straws being the usual, although some successful pregnancies have resulted from using only three straws where the conce ntration and quality are very high.
For surgical inseminations, using more than four straws at one time is not recommended, because although it would initially seem as though you are increasing your chances, in fact you are decreasing them, because in addition to the semen fraction, each st raw also contains diluent as we have already pointed out, and this overall increase in volumetric liquid would flood the reproductive tract and lessen the chances of conception.
From here the topic becomes extremely technical and is basically out of the breeder's hands and totally in those of the veterinary profession. Apparently different freezing facilities may use different diluents and the concentration per straw can vary, n ot only from sire to sire but also within a single collection. When the semen and diluent are mixed, the concentration can also vary from straw to straw. Apparently there are also straws of differing diameters. Semen is also now being pelletised and packe d in rods as opposed to straws, but I am afraid I have no knowledge of this method.
The most common practice seems to be to freeze at 100 million sperm per millitre, and our vet normally uses four straws per surgical insemination, ie 400 million sperm. He was most concerned that my recently arrived American semen had been greatly over di luted. We received 49 straws but the four that were thawed for the insemination each contained lower than expected sperm content. Fortunately the bitch still managed to conceive one puppy. Now we have just used semen from that same batch on another bitch, and the concentration in these four straws was better than in the first four, although still far from optimal..
Post thaw motility of the sperm provides the critical evaluation of succesful freezing. It may vary between 20% and 90%, with the average being 50% to 70% - any less than this greatly decreases the chance of success and as a general rule semen with lower than 50% motility should not be shipped, or at the very least prior notice given to the client so that they can decide if they wish to take the chance. A straw is thawed at the freezing facility and when semen is shipped it is accompanied by certification as to its health and motility.
Immediately prior to insemination another straw is checked under a microscope for purposes of comparison.
Wendye Slatyer July 97
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