Thickening of the Uterus Lining and Fluid-filled Sac in Dogs

Normally the cervix remains closed until the estrus cycle (heat). When a female dog is in the heat cycle, hormonal changes occur that allow the preparation of the body for mating and the reception of sperm. After the heat cycle, hormone levels stay elevated for some time, which causes a thickening of the uterine lining. After several estrus cycles without a pregnancy there is sometimes the chance that the lining will continue to thicken. Additionally, cysts form and the continued hormonal influences of progesterone (which can interfere with the regular immune system of the uterus) promote the growth of bacteria. With a proliferation of bacteria, pyometra can easily result which if left untreated, can result in shock or death.

The abnormal thickening in the lining of the endometrium (uterus lining) is called cystic endometrial hyperplasia (CEH). Cysts filled with fluid accompany this condition. Secondary to CEH is pyometra which occurs when bacteria becomes part of the equation and pus subsequently develops.

A canine who has cystic endometrial hyperplasia may not have noticeable symptoms until the condition has evolved into pyometra. Any time that we notice our pets have changed their demeanor or normal habits, a visit to the veterinarian is in order so that if there is a condition present it can be diagnosed before complications arise.

• Your pet may seem lethargic and listless
• She may have no appetite
• There may be increased thirst (polydipsia) and increased urination (polyuria)
• Your dog may be vomiting
• There could be fever
• She might have diarrhea
• With pyometra there can be pus and discharge in the vaginal area
• If the cervix is closed and pus or bloody mucus are accumulating, there can be abdominal distention due to an enlarged uterus
• The abdomen can be painful

Pets who have reached a severe stage of pyometra may be dehydrated and in a state of shock or collapse because of bacterial contamination throughout the body.

Types

Cystic Endometrial Hyperplasia

• Lesions and cysts are present on the endometrial lining
• The proliferation of bacteria that results can develop into pyometra

Pyometra

• Is most often secondary to CEH
• It can become severe and lead to death

• Hormonal changes (progesterone and estrogen) allow for the bacteria naturally found within the body to multiply
• The uterine secretions that normally occur during estrus accumulate and build up
• Immunosuppression can be a factor
• Unspayed females may be more prone
• Older females are more likely to develop the condition though both young and very old dogs have been recorded
• Repeated estrus (heat) cycles without a pregnancy can cause thickening of the uterus lining and the growth of fluid-filled sacs
• Estrogen shots during the heat cycle could be a factor
• There is a predisposition to pyometra: Bernese Mountain Dogs, Rottweilers, Rough Coat Collies, Miniature Schnauzers, Golden Retrievers, Cavalier King Charles and English Springer Spaniels

Your pet may be more uncomfortable than is obvious if the abdomen is distended. Do not delay in bringing your dog to the veterinarian as she may have pain but is being stoic and quiet. Upon palpation of the abdomen, your veterinarian may be able to determine the severity of the situation, especially if your dog vocalizes her pain. There may or may not be evidence of discharge.

A urinalysis could show that the concentration is abnormal pointing to the fact that there is bacteria present and the kidney function is slow. Blood tests markers may reveal elevated liver enzymes, blood urea nitrogen, creatinine, white blood cell count, and more. Cytology of the uterine secretions may indicate the nature of the discharge. X-rays could show an enlarged abdomen but the most accurate way to see the true extent of the problem is with an ultrasound of the abdomen which could show thickening of the uterine lining, and the presence of fluid filled cysts.

Treatment for thickening of the uterus lining and the presence of fluid-filled sacs will depend on how severe the condition is at time of diagnosis. When your dog is admitted to the hospital care will be taken to immediately stabilise her through the use of intravenous and antibiotic administration.

The typical treatment for complications arising from a thickened and enlarged uterus and pyometra is an ovariohysterectomy. This procedure does become more delicate if the dog is in the advanced stages of pyometra, but it remains the best choice because not only does an ovariohysterectomy remove the problem, it also prevents it from recurring again. The veterinary team will take the utmost care as this procedure takes place, carefully monitoring your pet though the entire surgery as well as after, with continual fluid and antibiotic therapy. If the uterus has ruptured or if there is leakage of any kind, a flushing out of the abdomen with a warm saline solution will be necessary. 

For pet owners who have hopes of breeding their female in the future there are options, such as the use of prostaglandins to cause contractions which may expel the fluid, pus, and bacteria from the uterus. However, many considerations must be discussed with the veterinarian before opting for alternative procedures due to adverse effects plus the chance that the condition can recur in the future.

No matter whether the choice for therapy is medical management or surgery, your pet will need extensive monitoring at the clinic until she is considered to be restored to health. Her appetite and bathroom habits need to be adequate and safe before she can be released from the hospital. As well, testing will be done to ensure that the bacteria is no longer able to cause a problem. Once home, your dog will need your care and attention. She will be on antibiotics for one to four weeks. Continue the medication until it is finished, even if your dog appears to be feeling well. Provide a quiet place for her to rest, with water, food and a soft bed. Your veterinarian will schedule a follow-up visit, most likely within the next two weeks to a month.