Pyometra, Canine - contd.
Diagnosis is based in part on the history, reproductive status, and clinical signs. Pyometra usually occurs one to two months after the heat cycle, or estrus. The clinical signs of vaginal discharge and a palpably enlarged, doughy-feeling uterus are helpful in establishing the diagnosis, especially if there are attendant signs of septicemia as well. Laboratory testing and imaging are frequently used to aid in the diagnosis.
The dog's complete blood count, or CBC, is influenced by the degree of drainage from the uterus. Patients with a closed cervix and limited uterine drainage are more likely to show significant elevations of, or reductions in, the white blood cell count. The white blood cells are also more likely to appear immature or unhealthy in those patients. Red blood cell counts are often reduced; patients with chronic disease frequently have low-grade anemia. Dehydration can mask this feature by reducing the amount of water in the bloodstream; consequently, the red blood count appears higher than it really is.
Blood urea nitrogen, or BUN, and creatinine reflect blood flow to the kidneys. The level of these nitrogenous waste products in the blood will frequently rise with dehydration and kidney dysfunction, which are common in patients with pyometra. Elevated blood protein levels and disturbed electrolytes will often reflect the state of dehydration.
The urine may be very dilute, reflecting toxic influences on the kidneys, or well concentrated as an appropriate response to dehydration. The urine may contain bacteria or inflammatory cells, if collected after voiding, due to contamination by the vaginal discharge. If pyometra is suspected, urine samples are rarely collected directly from the urinary bladder, via needle aspiration, because of worries about perforation of the distended, fluid-filled uterus. Urinary protein levels may be elevated if the kidneys have been damaged by the presence of chronic infection The vaginal discharge can be examined microscopically for the presence of white blood cells and bacteria.
Diagnostic x-rays of the abdominal cavity may demonstrate a fluid-dense tubular structure. A ground-glass appearance on the x-ray may suggest fluid accumulation around the diseased uterus if leakage has contributed to peritonitis. Ultrasound imaging will help to detect or verify the uterine enlargement, to define uterine size and wall thickness, and to differentiate between pyometra-related uterine enlargement and that of pregnancy. Ultrasound imaging is especially helpful in detecting stump pyometra, which occurs in spayed females; this condition consists of infected uterine remnants. Rarely, surgery is required for definitive diagnosis of a focal or stump pyometra.
