False Pregnancy After Ovariohysterectomy (Spay)

An female dog that ovulates will remain under the influence of the hormone progesterone for approximately 2 to 3 months. Regardless if she is pregnant or not. Progesterone is a hormone that maintains pregnancy and causes mammary development. If the dog is pregnant, the concentration of progesterone declines sharply about 1 to 2 days before delivery. The concentration of another hormone, prolactin, increases. Prolactin is the hormone that stimulates milk production.

It is thought that the drop in progesterone levels and the increase in prolactin in dogs that are not pregnant may be the cause for a false pregnancy.

If an animal undergoes an ovariohysterectomy (spay) during the time when progesterone levels are high, the sudden drop in progesterone following surgery may cause false pregnancy. This drop may tell the prolactin to increase too, causing the milk production. It is a normal response to the hormone changes brought upon by the surgery. This hormonal change is similar to delivery.

In medium/larger dogs, various studies have shown that 12 weeks after the start of the first heat or 8 weeks after the end (when swelling and discharge have gone away) is the best time to spay. These studies take various cancer risks and growth into consideration. This puts the spay towards the end of the Diestrus stage.

Stage 1: Proestrus Cycle (lasts +- 9-10 days): vulval swells, blood stained discharge. (note: swelling may come the day before or a few days prior to bleeding.
Stage 2: Estrus Cycle (lasts +- 5-9 days): discharge changes from blood stained to straw colored. Ovulation occurs during this phase. This stage last about a week.
Stage 3: Diestrus (last +-9 weeks): progesterone levels will remain high for 2-3 months. (a womb infection called pyometra can happen at this phase as well as false pregnancy (pseudocyesis) )

Signs Include:

Nesting (includes digging and positioning blankets, going into closest, under tables, spending time in their kennel
Decrease Appetite
Mammary glands enlarge and may secrete milk and/or watery fluid
Aggression, commonly centered on protecting or "mothering" objects such as socks, gloves, and toys. She may also growl and not want others near her "nest".

Treatment

Remove all toys, she pry is still in recovery from her spay so remove asap.
Do not allow any stimulation along her abdomen. This will increase milk production
Some will cut food back to 1/2 the normal amount (minimal carbohydrates) and pull water up overnight to decrease milk production.
Do not allow her to nest, or encourage any of the "odd" behavior. If she digs at a blanket, just say "no" and put the blanket up. Block off "secret" areas she would not normally attempt to go, but does at this time. Telling them "no, out", then block access.
Note: Notify your vet, treatment is usually not needed, but talk to them to be sure

Since the spay causes a similar hormonal drop to delivery, symptoms usually do not persist longer than one week. You most likely will see an increase in nesting and aggression 2 or 3 days after she is home from her spay. This will go on for about 2 or 3 days. Her aggression can become severe. After these few days, she will begin to go back to her old self. Once given the doctors ok (from the spay), start exercising her. Exercise will help decrease milk production too. 2 to 3 weeeks after her spay, her personality will slowly return to normal. Milk will stop, and a clear fluid will be seen. Then eventually nothing at all, and they will be normal again :).

**** I'm not a vet or even close to an expert on this. I've just spent a lot of time reading online trying to figure out what I can do for my dogs, and my friends dogs. Above is the best information I could find.