[Fertility problems in the bitch]

A short review of the oestrous cycle is given, followed by a more detailed look at fertility problems caused by husbandry aspects, anatomical abnormalities, hormonal disturbances and infectious aetiologies. One of the principal causes of fertility problems appears to be mating at an inappropriate time. The ovulation period and therefore the correct time of mating can however, be defined by measuring progesterone levels in peripheral blood three times a week. Vaginoscopy can also be used for this purpose, but is a subjective and less reliable method. Sterility is normally the single symptom of cystic endometrial hyperplasia(-mucometra). This probable major cause of sterility can sometimes be diagnosed with echoscopy but sometimes only during laparotomy. Additionally, hormonal disturbances can precipitate problems such as a persistent (pro-)oestrus, a split heat, or an abnormally long interoestrous interval. Bromocriptine, 15-20 micrograms/kg body-weight, twice daily orally, can be used to induce oestrus if no obvious abnormalities are diagnosed. Attention is paid to fertility problems with an infectious aetiology, such as herpes virus or Brucella canis. A vaginitis or abnormal bacterial growth in the vagina can also influence fertility. Unfortunately, little is known about bacterial growth in the vagina in relation to fertility problems. More research is needed in this field.