Subinvolution of Placenta Sites
The uterus normally returns to near-normal size (a process called involution) by 4 - 6 weeks after whelping, and completes the entire process by 12 weeks after birth. During the first 4 - 6 weeks, the dam will have a light pink to bloody vaginal discharge called the lochia.
A vaginal discharge that persists for more than 6 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 placenta-like 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 female dogs 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.
The SIPS-related discharge usually resolves spontaneously. If it persists and you don't plan to breed the dog again, your best option is to have her spayed. When SIPS disappears spontaneously, future fertility is not affected. There is no predisposition for developing SIPS after subsequent litters.
There is no prevention for this condition. Spayed females will not suffer this condition.
Please contact your veterinarian for more information regarding this condition.
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