Subinvolution of placenta sites

Problems that can affect the dam after delivery include subinvolution of placental sites, acute metritis, acute mastitis, caked mammary glands, absent milk supply, and milk fever. Occasionally, a mother has problems accepting and caring for her puppies.

The uterus normally returns to near-normal size (a process called involution) by four to six weeks after whelping, and completes the entire process by 12 weeks postpartum. During the first four to six weeks, the dam will have a light pink to bloody vaginal discharge called the lochia.

A vaginal discharge that persists for more than six weeks is caused by subinvolution of placental sites (SIPS). These sites, where the placentas formerly attached to the wall of the uterus, are invaded by placentalike tissue called trophoblasts. The trophoblasts prevent the uterus from completing the process of involution. The associated vaginal bleeding is usually mild, but may be heavy enough to cause anemia.

SIPS tends to occur in bitches younger than 3 years old. There is no breed predisposition. The condition does not cause discomfort. SIPS can be complicated by acute metritis or perforation of the uterus, but this is not common.

The diagnosis is made by palpating the uterus and feeling lumpiness in the uterine horns. Ultrasonography shows the enlarged horns. Vaginal cytology may disclose trophoblastlike cells.

Treatment: The SIPS-related discharge usually resolves spontaneously. If it persists and you don’t plan to breed the bitch again, have her spayed. When SIPS disappears spontaneously, future fertility is not affected. There is no predisposition for developing SIPS after subsequent litters.