Weighed against that is the concern of possible cross contamination by potentially harmful pathogens of the stallion and other mares, and the lack of a suitable environment for the conceptus to grow in. Having established the absence of a potentially harmful STD, the next concern is the presence of a healthy growing environment within the mare. This can be established with reasonable accuracy by taking samples of the endometrium by way of guarded endometrial swabs. The generally accepted time to take these samples is when the mare is in mid estrus. At that time she has the maximum ability to defend her uterus to external infection, hence if bacteria are present in any numbers, the likelihood that the problem is significant is greater, and in addition, if an external bacteria is introduced into the uterus during sampling, the increased defense mechanisms will have a better chance of success in dealing with it.
Some technicians prefer to work with two swab samples, others only one.
If working with two samples, the first sample should be placed immediately in a suitable transport medium, the second sample being used to produce a smear for cytologic examination. If using only one sample, the cytology smear must be created on a sterile microscope slide and the swab then placed in the transport medium. If the cytology smear shows a high number of neutrophils, this is potentially indicative of a mare with a bacterial infection, and the sample in the transport medium should be cultured, the growth identified, and antibiotic sensitivity tests carried out to establish what treatment is likely to prove most successful. With thanks to the Atlantic Veterinary College, Ontario Veterinary College and the Western College of Veterinary Medicine for their help in compiling this response. May be used upon notification, and with accreditation.