Structure and Function of the Female Canine Reproductive Tract

Structure and Function of the Female Canine Reproductive Tract

By: Virginia Wells


What Are the Common Diseases of the Female Reproductive Tract?

Disorders of the reproductive tract may affect the ovaries, the uterus, the vagina, the vulva or the mammary glands. Each individual area is prone to different disorders.

Disorders of the Ovary

  • Ovarian cysts may develop from the accumulation of fluid within the follicles. These cysts may cause no clinical signs, the animal may fail to come into estrus (heat), or may show signs of continuous estrus.

  • Ovarian remnants may sometimes occur when a portion of the ovary is cut and left behind during the spaying surgery. These dogs show recurrent signs of coming into heat at some time after the surgery has been performed.

  • Tumors may develop in the ovaries and may be either benign or malignant.

    Disorders of the Uterus

  • Metritis is inflammation of the uterus. This term is most commonly used when uterine inflammation develops after a pregnancy.
    It usually develops because of a bacterial infection that ascends up the vagina and gains entrance to the uterus through the open cervix.

  • Pyometra disease is a complex problem of older female dogs that have not been spayed. The glands and the endometrium of the uterus become enlarged and predispose the uterus to infection. Bacteria may enter the uterus through the cervix and begin to grow in the uterus. The uterus gradually increases in size, filling with purulent material. If the cervix is open, discharge (pus) may drain from the vagina. If the cervix is closed, no discharge will be seen. Pyometra often occurs within eight weeks of the dog's last heat cycle due to increased levels of the hormone progesterone. All unspayed dogs are susceptible.

  • Uterine prolapse is the protrusion of the uterus through the cervix into the vagina. Portions of the uterus may be exposed at the vulva. It is an uncommon condition in the dog. It usually occurs during or immediately after giving birth, most often after the delivery of the last newborn, but can also be seen following spontaneous abortion.

  • Tumors may develop in the uterus. There are many different types of tumors that can develop in this organ, both benign and malignant. Spaying, with removal of the uterus, prevents the development of uterine tumors.

    Disorders of the Vagina

  • Vaginitis is inflammation of the vagina. It may occur in any age of dog, but a juvenile form is seen in dogs less than one year of age. The juvenile form of vaginitis often resolves after the first estrous cycle. Other causes of vaginitis include congenital defects, urinary tract infections; vaginal infections (bacterial, viral), vaginal tumors, and vaginal trauma. The primary clinical sign is vaginal discharge.

  • Vaginal hyperplasia or edema is an exaggerated response by the vaginal tissue to estrogen during certain phases of the estrus (heat) cycle. The vaginal tissue becomes swollen and may protrude through the vulva, and appear as a donut-shaped mass. Vaginal hyperplasia is most common in young intact female dogs and is more common in the boxer, English bulldog, Saint Bernard, German shepherd dog, and certain other breeds.

  • Tumors may also develop within the vagina. One form of tumor, the transmissible venereal tumor (TVT) is caused by a virus. TVT is a contagious condition and is often spread during breeding.

    Disorders of the Mammary Glands

  • Disorders of milk production include galactorrhea (milk production that is not associated with pregnancy), agalactia (the failure to secrete milk at appropriate times), and galactostasis (the abnormal collection of milk in the mammary glands).

  • Mastitis is inflammation and/or infection of the mammary glands. In most cases, bacteria are believed to travel up the mammary ducts into the glands. The glands then become painful, red, and sometimes swollen.

  • Mammary gland tumors are the most common tumor to develop in female dogs, particularly in those that have not been spayed. Mammary gland tumors are frequently malignant, although some do not behave very aggressively. Spaying the dog before its second heat cycle can effectively prevent these tumors.

    What Types of Diagnostic Tests Are Used to Evaluate the Female Reproductive Tract?

  • A complete blood count, organ profile, urinalysis, and urine culture are often used to look for evidence of infection or other related organ abnormalities (e.g. bladder infection, kidney disease, etc.).

  • X-rays of the abdomen are useful to identify enlargement of the uterus. If the ovaries and uterus are a normal size, then they usually do not show up on plain X-rays.

  • Chest X-rays may be indicated if a tumor is present, in order to search for metastasis.

  • Vaginoscopy is the examination of the vulva and vagina by introducing a scope through the external genitalia directly into the vagina to examine the area for evidence of tumors and inflammation.

  • Vaginal cytology can be performed by retrieving cells of the vagina using a sterile cotton swab and examining those smears under the microscope. Vaginal cytology is helpful to identify where in the heat cycle the dog might be and to search for signs of inflammation and infection.

  • Cytology can also be performed on milk samples.

  • Ultrasonography of the abdomen is very helpful in evaluating the internal organs of the abdomen using high frequency sound waves. Ultrasonography can often identify organ changes that do not show up on X-rays. It can also be used to confirm the presence of a pregnancy.

  • Bacterial culture and sensitivity testing may be performed. Material is retrieved using a special culture swab or collection tube, and attempts are made to grow the bacteria and identify them. Several antibiotics are then tested on the bacterial culture to determine which antibiotic works best to kill the bacteria.

  • A fine needle aspirate and examination of the cells is often useful when assessing masses or tumors.

  • Biopsy of masses and abnormal tissue may also be performed.

  • Removal of the organ and submitting it for biopsy may be needed in some cases to identify the underlying problem and its cause.

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