The majority of bitches that are brought to a veterinarian for reproductive evaluation are actually healthy. The causes of infertility in female dogs are variable due to many factors. The normal fertility of bitch requires the fertilization of sperm within the fallopian tube of female reproductive tract and implantation in uterus till the delivery. The common causes of infertility in bitch are structural, physiological, neoplastic and infectious.
The structural causes of infertility in bitch hamper in the fertilization or characterized by ambiguous genitalia in bitch. The second most important cause of infertility in bitch is physiological abnormalities. These abnormalities are manifested by unpredictable ovulation, split heat, si-lent heat and long anoestrus. e infectious
Common Causes of Infertility in Female Dogs
Mistimed Ovulation
Mistiming of ovulation is the primary reason for breeding to not result in pregnancy. The canine heat cycle has three stages: proestrus, oestrus and anestrous. Ovulation occurs during oestrus, which begins approximately nine to 12 days after the heat cycle begins and lasts approximately nine to 12 days. This is the time when the bitch should be bred.
Behavioral Factors
Behavioral factors may also contribute to a refusal to copulate. These factors include a dominant female dog refusing to stand for a submissive male, attempts to breed a female that is sexually immature, a stressful or otherwise unpleasant breeding environment, and inappropriate behaviors by either the male or female.
Silent Heat
This occurs in bitches where the ovary is active but swelling of vulva, vulval bleeding and attraction of male dogs are absent. Bitches that are thought to have silent heat can be diagnosed by taking monthly progesterone assays or conducting weekly vaginal smear investigations.
Male Infertility
Another common cause of infertility is male factor infertility. Too few sperm, poor motility or abnormal sperm may all result in poor fertility. Semen evaluation of the male prior to a breeding is always recommended. If this wasn’t done before breeding and the bitch fails to conceive, it should be done after the bitch is determined to be not pregnant. Sometimes this can be overcome by intrauterine insemination or multiple inseminations. In other cases, the infertility may be too severe.
Sexual abnormalities
A dog may appear as a female but has abnormal chromosomes (i.e. genetic materials) or have male gonads but with female external genitals (male pseudohermaphrodite). Such dogs can be determined via visual inspection of abnormal external genitals, biopsy of each gonadal tissue, measurement of hormone levels or assessment of karyotype.
Ovarian Cysts or Tumors
It is important to diagnose and remove these hormonally active cysts or tumors as quickly as possible for at least two reasons. First, it is necessary to cure them and try to restore fertility. Second, the secretion of high quantity of estrogens may act on the uterus. This is a potential factor towards the cystic endometrial hyperplasia–pyometra complex. Also on the bone marrow in creating progressive non regenerative anemia.
Other Infectious Diseases
Several viruses have been shown to play a potential role in canine infertility. Canine Herpes Virus (CHV), Canine Distemper Virus, Minute Virus of Canines (CPV1), are well known to have a pathogenic action on neonate pups.
The incidence of bacterial infections on canine infertility is better documented. Canine Brucellosis, which is well known as an abortive agent during late pregnancy,
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