The valid reasons for using artificial insemination include the following:  

      1. Use of frozen or fresh-extended semen.  
      2. Protection of the stud dog from infection by the bitch  
      3. An inexperienced stud dog  
      4. A stud dog with a physical disability.  
      5. Size incompatibility of the dog and the bitch.  
      6. An overly aggressive or dominant bitch.  
      7. Need to evaluate the semen before insemination.  
      8. Splitting an ejaculate between 2 bitches.  
 

 The most frequent circumstance in which an artificial insemination is requested, is that the stud dog doesn't wish to breed the bitch on a given day. The fact that it is day 10, or 12, or 14, or 18 of the bitch’s season is often the basis for the breeder deciding that this is the correct day for the breeding. It may be thought to be the time that "all" bitches of this particular breed are most receptive; it may be the day, counting back from a prior litter, 
that the most effective breeding was done. It may be that for reasons of time constraints of the people or the dogs involved, show tments, travel opportunities, and so on, it is desirable to cover a period of three or four days when it will be impossible for the two to mate, even though it is likely to be early. Sometimes, less frequently, it is done toward the end of true estrous, when the dog’s interest, once again, has dropped to a less than willing level, and due to the generally held belief that the later breedings are most likely to yield a litter, or a large litter, so one last attempt is desired.  

 There are many ways of estimating the proper day. An experienced and reliable stud dogs nose is the finest instrument for this. A ‘smear’, which is more properly termed a vaginal cytology, can be read with good success by an experienced reproductive veterinarian, and is best done every day,  or every other day, from day 8 on. The next step up from this, and a tool which can be used by a  relatively inexperienced veterinarian with good success, is the progesterone elisa test, or even  better, the LH elisa test. When properly interpreted, any of the various kits available will provide useful information. These tests are useful only when performed routinely over several days. The  technique I find most reliable, is the endoscopic examination of the cervix. I find this gives me the  very best information on a bitch which hasn't been available for repeated exams all through her  cycle, or where the correct date isn't known for the beginning of her season. Even this technique,  however, works better when repeated exams are done. This gives a sense of the progression of  hormonal events in a particular bitch. Progression through the estrous cycle generally follows a  pattern which is similar in most bitches; however, like everything else in nature, is not universally  applicable to a particular bitch. The most common reason for failure of artificial insemination is  breeding at an inappropriate time, and lack of follow up inseminations over the correct time later in the bitch’s season.  

 The bitch which never appears to stand for breeding, or to swell and loosen up enough to 
admit the male comfortably, is often simply not cycling properly. Instead of going into 
artificials every season,  it would be more useful to check on the bitch’s hormone levels 
through one complete cycle, trying  to identify a correctable problem. Often such problems respond to thyroid supplementation, and frequently, with younger bitches, once one cycle has been corrected in this way, and a pregnancy achieved, it is not necessary to continue the thyroid supplementation in later cycles. Sometimes, the bitch just needs a jump start. A frequent cause of failure to conceive by artificial insemination is the lack of a fully developed season in the bitch, and the failure to ovulate.  

 A dog which hasn't been bred for a period of months or years may be an unknown quantity as far as fertility is concerned. Ideally, an ejaculate would be evaluated before the actual day of breeding. If this hasn't been done previously, an artificial insemination offers the opportunity to do a semen examination before being committed to a breeding with a sub-fertile male.  

 Young males often suffer from ‘performance anxiety’. Sometimes they can be helped with the bitch and a tie achieved. When this isn't possible, rather than letting him lacerate or fatigue himself unduly without any success, a skillfully managed collection can help the dog gain confidence and actually train him for a natural breeding career, rather than spoiling him for breeding. Some very dominant bitches can simply be too much for a more reserved or young male.  

 When managing the virgin or young and underdeveloped male, care must be exercised not to force  the dog beyond his comfort zone. Dogs of the same breed and age, may differ significantly in the size and apparent physical maturity of the reproductive apparatus. Underdeveloped physical development is often accompanied by an immature libido as well. An experienced veterinarian can collect semen from such a dog, and help to stimulate him and condition him for future natural breedings. However, if he just isn't ready, it is better not to give him a bad experience which could later on result in an impotent adult. These individuals are easily identified by their lack of physical  development and response to manipulation. It is very important to know when to stop with this dog, whether trying to force him to breed naturally, or artificially.  

 A dog with a missing limb or an injury to a rear leg may not be able to stand on his rear to tie  bitches. As long as the disability doesn't reflect a genetic or structural unsoundness, artificial inseminations can keep this dog producing.  

Given the absolute certainty of the ‘dormitory effect’ in kennels, it is possible to encounter the need to breed more than one bitch on a given day. In order to legitimately cover both bitches from one ejaculate very good semen quality must be present. This practice requires an experienced evaluation of the semen if it is to be ethically attempted.