False pregnancy

Some unneutered female dogs develop changes several months after a season. This is often referred to a ‘false pregnancy’ or ‘pseudopregnancy’. In most animals this is not a serious condition but it can be inconvenient for the owner and disturbing for the animal. Usually the condition resolves without any treatment but if you are not thinking of breeding from your pet then it is worth considering neutering to prevent this condition.

After oestrus (heat or season) in the female dog or cat the same hormonal changes occur whether or not she is pregnant. The phase of the heat cycle after oestrus is called dioestrus. During dioestrus levels of the hormone progesterone rise. In normal females dioestrus ends spontaneously if they are not pregnant. In pregnant females dioestrus ends as the female goes into labour.

All entire females undergo the same hormonal changes whether or not they are pregnant. This means that after oestrus changes occur in the body to support a pregnancy. For 2-3 months hormonal levels are similar to those in pregnant females. It is this part of the heat cycle that can result in a ‘false pregnancy’. ‘False pregnancy’ could be said to occur ‘naturally’ during dioestrus in all females (since they undergo the same hormonal changes whether or not they are pregnant).

At the end of this period (when a pregnant female would be giving birth) progesterone hormone levels drop and this can fool some female into thinking that they have given birth and need to care for their puppies. Sometimes behavioural changes develop and females may ‘adopt’ a cuddly toy and protect it like their young, in others physical changes may also occur including milk production.

Signs of false pregnancy usually develop around 2-3 months after the previous season. It can be very difficult to know whether a female is actually pregnant or is having a false pregnancy. If you are not absolutely sure that your pet could not be pregnant then you should visit your vet and ask them to check her over.

Each affected female will show different signs including:

  • Poor appetite, lethargy and depression
  • Nest building behaviour and ‘adopting’ toys
  • Behavioural changes, including aggression
  • Mammary development and milk production

In some animals the signs are very subtle, in others they can be dramatic. Signs of false pregnancy may develop after the first season and usually get more obvious with each heat cycle.

In the vast majority of cases false pregnancy is not a serious condition and you should not worry too much. Most females remain well throughout. Try to treat your pet the same as normal and don’t encourage her abnormal behaviour. If she shows a preference for a particular toy and tries to guard it, take this away from her for a few weeks. Encourage her to undertake her normal activities and try to distract her from any ‘strange’ behaviour with more interesting activities like play.

If your pet’s mammary glands develop and she starts to produce milk you should probably get her checked over by your vet. In most cases milk production dries up without any treatment but some females lick at themselves and stimulate more milk production. This can be uncomfortable for her and there is the risk of an infection (mastitis) developing.

You should also see your vet if your pet is off her food for more than 24 hours, if she has abnormal discharges from her nipples or vulva or she seems unwell in other ways. These may be the signs of more serious problems developing.

In females who have mild signs treatment may not be needed. In most cases the signs will resolve without any treatment as the hormone levels alter as the cycle continues. However in some cases (particularly where behavioural changes are very marked or a lot of milk is being produced) you may want to try to settle the signs more quickly.

There are a number of drugs that may help to reduce the duration of the signs but these will rarely stop the problems immediately. Many of the drugs used are hormones which may be given to stop milk production or affect hormone levels (cabergoline, bromocriptine, megestrol acetate or testosterone). These drugs can sometimes have significant side-effects and so are only used if signs are causing significant problems, or as a last resort.

The best way to control false pregnancy is to neuter the female. Preventing further seasons will prevent the problem happening again. However, if your pet has suffered from false pregnancy, it is important to let the signs abate before neutering. The operation should not be carried while she is still producing milk as it can then be very difficult to stop this.

Once a female has had a false pregnancy they tend to have recurring false pregnancies at every oestrus and signs may last for many weeks. Drug treatment can help during the false pregnancy, but the best solution is spaying, after the false pregnancy has ended. If your pet has suffered a false pregnancy discuss the options for treatment with your vet.