Are some mares allergic to frozen semen extenders?
The inflammatory reaction of the uterus to semen and extender deposition is a normal antigenic response to the sperm cells themselves. Introduction of washed, separated sperm cells suspended in sterile saline causes the same reaction. A persistence of this inflammatory fluid may be due to the absence of seminal plasma in some frozen semen or due to delayed uterine clearance in older mares or mares with persistent endometritis. We do need to keep in mind though, that although very rare, any proteinaceous foreign fluid could have the potential to cause an allergic reaction in an individual mare.
