You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Infertility is defined as an inability to produce offspring, but it is sometimes used to describe females that produce less offspring that would normally be expected for the breed. Sterility is the total inability of a female to give birth to offspring.

There are several possible causes of infertility, including the following :

Oestrus not occurring a frequently as expected :

• Late onset of puberty:
  • Absence of ovaries - rare, but does occur from time to time
• Prolonged periods between oestrus cycles
• Oestrus is occurring but the signs are mild and the owner is missing it

Mating is not occurring properly :

• Problems with the male :
  • Inexperienced
  • Unable to sustain an erection of the penis
• Problems with the female :
  • Inexperienced
  • Anatomical problem eg narrow vulva, vestibule or vagina
  • Thickening or prolapse of the vagina
  • Vaginal tumour obstructing the passage
• Behavioural problems - psychological , reluctance to mate 
• Timing of mating wrong and the female won't accept the male

The physical act of mating occurs normally but the female does not conceive :

• The mating may have occurred at the wrong time relative to ovulation of eggs from the ovaries
• Ovulation may be delayed beyond the survivability of sperm  for some reason
• The male may be infertile (eg abnormal or absent spermatozoa)
• The uterus may not be properly developed in the female
• There may be abnormalities of the fallopian tubes so that the eggs do not reach the uterus
• A failure of development of the male testicles (called aplasia - a congenital defect)
• Failure to ejaculate (not reported in male dogs)
• Atrophy of the testicles - often seen in association with hyperadrenocorticism (Cushings Syndrome) or following long term administration of corticosteroids in dogs
• Failure to produce sperm - due to aplasia or degeneration of the testicles
• Poor quality of the semen - abnormal spermatozoa, low numbers, poor motility of sperm

The female becomes pregnant, but the offspring are lost later :

• Resorption
• Abortion

Other causes of infertility that have been suggested include :

• Infections of the reproductive tract - probably not that common.

Veterinary investigation is necessary to determine the cause of infertility, and treatment depends upon the underlying cause.

Updated October 2013