The causes of infertility in female dogs are highly varied. Fertility requires a normal heat cycle and ovulation of normal eggs (ova) into a healthy reproductive tract, followed by fertilization of those eggs by normal sperm that are successfully introduced into the female. There also must be successful implantation of the embryos in the uterine lining, normal development of the fetuses, successful maintenance of the pregnancy and a successful delivery of live puppies.
Infections of the vagina or uterus can prevent conception and prevent the bitch from carrying her litter to term. Vaginal infections (vaginitis) are most frequently caused by bacterial microorganisms, especially by Brucella canis. Brucellosis is a venereal disease that causes infertility by either preventing conception or causing spontaneous abortion. Contrary to popular belief, the infectious microorganism, Brucella canis, can be transmitted sexually or orally with equal frequency and has the potential to infect people. Infection with the canine herpesvirus can also lead to infertility. Uterine infections can contribute to infertility, such as endometritis, pyometra/pyometritis and metritis.
Adrenal dysfunction or insufficiency can interfere with the production of sex hormones that are necessary for proper reproductive function. Two common adrenal disorders in domestic dogs, Cushing’s Disease (hyperadrenocorticism) and Addison’s Disease (hypoadrenocorticism), usually prevent female dogs from conceiving and carrying a litter to term. The tiny pituitary gland, located deep in the brain, is critically involved in producing and releasing hormones that start and regulate the estrous cycle. Any disease or disorder of the pituitary can cause canine infertility due to abnormal heat cycling. This can include failure to ovulate, abnormal ovulation pattern or timing, persistent heat cycle, primary congenital anestrus (never having a heat cycle), split heat, silent heat and false pregnancy/pseudopregnancy.
Inability to Reproduce in Female Dogs
Some of the common symptoms that appear in bitches which are unable to reproduce are abnormal cycling, failure to conceive, failure to copulate/mate, and pregnancy loss. Normal fertility in a dog, and the ability to reproduce puppies, requires a normal estrous cycle, with a healthy reproductive tract, normal ova (eggs), normal and stable levels of reproductive hormones, fertilization by normal spermatozoa, implantation of an embryo in the lining of the uterus (endometrium), normal placenta placement, and stable levels of progesterone concentration.
These conditions must be maintained for the entirety of the two month gestational period, or the process of reproduction will be altered, with resultant infertility. Symptoms
•Failure to copulate (i.e., an inability to successfully mate with a male dog)
•Normal copulation without subsequent pregnancy
•Too frequent cycling
•Failure to cycle Causes Infertility can affect dogs of all ages, but tends to be more common among older dogs. An underlying cystic endometrial hyperplasia -- uterine cysts -- is more common among dogs past the age of six. Dogs that have had previous uterine infections can also have subsequent difficulties with implantation. However, one of the most causes of seeming infertility is insemination during the improper time in the estrous cycle. Dog breeds that are predisposed to thyroids insufficiency have a higher prevalence of fertility problems. Breeds that are at particular risk of hypothyroidism are boxers, Doberman pinschers, dachshunds, golden retrievers, great Danes, Irish setters, miniature schnauzers, and poodles. Other conditions that may play a role in the dog's ability to reproduce include: •Male infertility factors
•Sub-clinical uterine infections
•Abnormal ovarian functions
•Systemic viral or protozoal infection
•Lack of sufficient copulatory stimulus in order to induce ovulation
Your vet will perform a thorough physical exam on your dog, taking into account the background history of symptoms and possible incidents that might have led to this condition. There are several diagnostic tests that can be conducted in order to find out if the symptoms are related to the infertility disorder. Some of the basis for the diagnosis will be related to whether your dog has conceived or given birth in the past.
If she has reproduced successfully before, your veterinarian will consider whether the male mate that has been chosen for breeding is of proven fertility, or whether the timing for the breeding was scheduled in accordance with your dog's ovulation cycle. Your dog's hormone levels will be analyzed, to be sure that she has the required levels for conception and a following pregnancy.
Progesterone concentration must remain steady throughout the pregnancy for it to be successful. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. These tests will show evidence of infections, either bacterial, viral, or parasitic. Viral infections that will be tested for include toxoplasmosis, protozoal parasite infection, canine herpesvirus, hypercorticolism, hypothyroidism, and Brucella canis. In addition, your doctor will be checking your dog's body thoroughly for any other chronic disease conditions.
Imaging techniques may be used to look for any abnormalities in the uterus, such as masses (indicating tumors), and anatomic abnormalities that would interfere with conception.
In a healthy dog, the ovaries and uterus will not be visible on X-ray imaging. If your veterinarian is able to view the ovaries or uterus, this would suggest that there may be an underlying condition of ovarian cysts, ovarian cancer, or uterine cysts. If it appears, on examination, that your dog has cysts or other masses of tissue in the uterus or reproductive tract, your vet will need to take a sample of tissue from the uterus for biopsy.