Syrian Hamsters are solitary and this makes mating particularly difficult as the male and female should only be introduced when the female is in season or serious fighting will occur.
A female Syrian hamster comes into season every 4 days (although this may vary from 3-5 days). When in season the female will be more active and will be receptive to the attentions of a male. Females come into season in the evening and can remain in season for between 4 and 24 hours. Prior to coming into season the female usually emits a strong musky smell and this is often more noticeable in summer months. The day after coming into season the female produces a thick, white discharge from the vagina and the white discharge can sometimes cause the urine to appear cloudy. The female will normally come into season again 3 days after this is noticed.
In the winter females may stop coming into season and this can be helped by extending their daylight hours by switching on a light for 12 hours each day for several days and feeding vegetables.
Syrian Hamsters should only be introduced for mating when the female is in season. Even if in season the male should not be introduced to the female on her territory as she will fiercely defend it. The female should be introduced to the male's cage or they should be introduced on neutral territory.
If a female is suspected to be in season she can sometimes be 'tested' by firmly stroking her back, and stroking her towards her tail. A female in season will 'freeze' with the body pressed to the floor, head pointing forwards and her tail in the air. The female should be placed in the male's cage or the female and male should be introduced on neutral territory for mating. If there is any doubt as to whether the female is in season or not it is usually a good idea to introduce them in a box in order that they can easily be separated should a fight occur. It is also wise to wear gloves or have an object handy that can be used to separate them if fighting does occur as trying to separate fighting male and female with bare hands is not recommended. If the female is not receptive to the male she should be removed and tried again the following evening until she is receptive.
When introduced the male should start to fuss around the female and if she is receptive she should 'freeze' with her tail in the air. A male that has not bred before may seem a little confused and try to mate from all sides but will usually get the idea before too long. Females that have not been mated before are not always tolerant of this confused attempt at mating from virgin males. Females that have mated before seem to be more tolerant of these attempts. Mating is often more successful if either the male or female has been mated previously and has experience. The male will mount the female and thrust a few times before dismounting and washing himself. He will then remount and mate again. The male will mate with the female several times and this should be allowed to continue for 20 minutes unless either the female or male loses interest before that time, in which case they should be separated and returned to their cages. It is not unusual for some males to gently bite the female and pull her skin but this is normal and usually nothing to worry about, although a female may get annoyed at a very over-enthusiastic male.
Not all unproven males will get a female pregnant after the first mating and some males may need to mate several times before a successful pregnancy occurs. Very occasionally males may show no interest in mating and this occurs most often in the winter when it is colder. Very rarely a male may not be interested in mating at all.
Pregnant females do not usually come into season once pregnant and so pregnancy can be "tested" by seeing if the female comes into season 4 days after mating, and that no white discharge appears 5 days after mating.
A female is usually sterile once she has reached 12-14 months of age but may continue to come into season.