Phantom pregnancy in dogs – symptoms, duration and treatment

Overview

Phantom pregnancy is associated with the normal reproductive cycle and does not mean that a dog has previously been pregnant. Similar hormonal changes occur after a season even in females that have not met a male.

Some females show hardly any outward signs. In clinical phantom pregnancy, physical or behavioural changes are more apparent.

Estimates of clinical phantom pregnancy frequency include both 10–20% and 50–75%. Symptoms often begin 6–8 weeks after a season.

The possible onset also extends from 4–9 weeks after the previous season. Mild symptoms usually last about 14–21 days.

Causes

After a season, the ovaries produce hormones whether or not fertilisation has occurred. These hormones prepare the womb for a possible pregnancy.

If pregnancy does not occur, hormone levels usually fall after 4–6 weeks. A rapid fall in progesterone is associated with the onset of phantom pregnancy signs.

Prolactin, which regulates milk production, also contributes to symptoms. Tissue sensitivity to prolactin may influence how strongly an individual dog is affected.

Hormonal changes can trigger mammary gland growth and behaviour resembling labour without puppies. The precise mechanism of phantom pregnancy is not yet fully understood.

The phase after oestrus lasts about 2.5 months and ends in the birth of puppies or phantom pregnancy. Removing the ovaries during the luteal phase can trigger phantom pregnancy because of the sudden fall in hormone levels.

The season itself often lasts about 3–4 weeks before the post-oestrus phase begins. Normal seasonal bleeding stops after the early part of that phase.

Risk factors

The condition is most commonly seen in unspayed females after a season. Signs can occur in females of different ages that have had a reproductive cycle.

The same dog does not necessarily show visible signs in every cycle. Severity can vary between different seasons in the same female.

A previous severe phantom pregnancy may be associated with recurrence after later seasons. Spaying a previously affected female during the post-oestrus phase can cause a more obvious or prolonged episode.

Older breed-specific estimates have described a frequency of 50–75% in Afghan Hounds, Beagles, Boxers and Dachshunds.

Females usually reach sexual maturity at about 7–15 months, but there are substantial breed and individual differences.

Typical symptoms

• Your dog collects toys, blankets or clothes into a nest.

• She mothers a soft toy or another object as if it were a puppy.

• The nipples or mammary glands enlarge and may produce milk.

• She guards toys or her nest more readily than usual.

• Appetite decreases without a corresponding fall in body weight.

• She is restless or less interested in exercise than usual.

Some dogs are unusually active during phantom pregnancy.

Fluid from the mammary glands may also be clear or brownish.

Licking around the abdomen may increase.

Fluid may accumulate in the body.

In a pronounced phantom pregnancy, the abdomen may enlarge.

Vomiting sometimes occurs.

Your dog may behave as though labour is starting.

Weight may increase with the physical changes of phantom pregnancy.

Swollen mammary glands do not always produce milk.

Complications and consequences

Milk production can predispose a dog to mastitis, an infection of the mammary glands. Mastitis can also develop in a milk-producing female that is not pregnant and has not given birth.

Intense guarding of a nest or toys may put a person or another dog at risk. Behavioural signs can be troublesome enough to need treatment even without visible mammary gland changes.

Persistent symptoms, or those lasting more than four weeks, need veterinary assessment to decide whether treatment is necessary. The outlook for mild phantom pregnancy is generally good.

Spaying during symptoms may prolong them for several more weeks.

Untreated severe mastitis can lead to an abscess or tissue death.

Mastitis may affect one gland or spread to several. A severe infection can progress quickly and cause sepsis, an infection affecting the whole body.

Mastitis is a bacterial infection of a mammary gland.

Untreated acute mastitis can eventually cause the gland to rupture.

Diagnosis at the vet

Timing of symptoms and ruling out other conditions

The vet assesses physical symptoms and behaviour changes in relation to the previous season. Mention any possible mating, because a true pregnancy can resemble phantom pregnancy.

A relationship between symptoms and recent spaying may also be an important clue. No specific blood test is available to confirm phantom pregnancy.

Prolactin and progesterone levels also change during true pregnancy, so they do not reliably distinguish the two situations. In a 2015 British survey, 397 first-opinion vets responded out of 2,000 who received the questionnaire.

In that survey, 96% of respondents had seen cases with behavioural signs alone during the preceding 12 months. If pyometra is suspected, ultrasound can reveal an enlarged womb filled with fluid.

With closed pyometra, a dog may be seriously ill without visible vaginal discharge. A milk sample from a painful mammary gland can be examined for cells and submitted for bacterial culture.

Culture can investigate an unclear mammary gland problem even if the milk looks normal. Aggression from another cause may need assessment by a vet with expertise in behavioural medicine.

Investigating true pregnancy

The placenta, which produces the hormone relaxin, develops only in true pregnancy, not phantom pregnancy. Relaxin can usually be detected in a pregnant dog's blood 22–27 days after mating.

A test performed too early can be negative even in a genuinely pregnant dog. In unclear cases, a negative relaxin test may be repeated after one week.

In a small dog carrying only one or two puppies, relaxin may remain below the test's detection level. Embryos may be visible on ultrasound from about three weeks after mating.

Ultrasound also helps assess whether developing puppies are alive. Their bones generally only begin to show on X-rays 43–45 days after mating.

A positive relaxin test does not by itself confirm that the puppies are alive. Relaxin testing is sometimes repeated at 31–34 days after mating.

Treatment

Managing mild symptoms at home

Medication is not usually needed for mild phantom pregnancy if symptoms start settling on their own. Exercise and play can redirect attention away from nesting and mothering toys.

Do not express milk or massage the mammary glands, because handling increases milk production. Your dog's own licking of her nipples can also maintain milk production.

A suitable protective collar or recovery suit can prevent licking. Toys being treated as puppies can be removed calmly from the environment without confrontation.

For example, another person can remove the toys while your dog is out on a walk. Avoid punishing mothering behaviour, because it is part of the dog's natural behaviour.

Avoid unnecessary touching of the mammary glands or brushing the abdomen to reduce stimulation of milk production. As well as play and walks, offer activities that your dog will not start mothering as a puppy.

When is medication needed?

Treatment choice considers the combination of physical signs, behaviour changes and symptom duration. Medication is considered when the dog is physically unwell or behaviour changes are pronounced.

The vet prescribes medication according to an individual examination and symptoms. Milk production can be reduced with a medicine that inhibits prolactin secretion.

Severe anxiety may sometimes be relieved with a sedative chosen by the vet. When choosing it, the vet considers that phenothiazines can increase prolactin secretion.

Previous episodes and other health conditions also affect the choice of medicine. Mastitis is treated as a separate complication that may require antibiotics.

Bacterial culture from the mammary glands helps select a suitable antimicrobial for infection.

Physical and behavioural signs may resolve at different rates, both in treated dogs and those recovering without medication.

Prevention

Removing the ovaries prevents future episodes of phantom pregnancy associated with the reproductive cycle. Surgery is usually planned during anoestrus, the resting phase, after the active luteal phase has ended.

Planned spaying during active phantom pregnancy is usually postponed until symptoms have settled. The stage of the reproductive cycle therefore affects surgical timing.

In the British survey, 96% of vets delayed spaying an affected female until symptoms had disappeared. Some females have repeated episodes if ovarian function continues.

Spaying may help manage intense mothering behaviour and aggression associated with phantom pregnancy.

Important for dog owners

Monitoring also needs information about behaviour, because visible mammary gland changes may be absent.

Record the start and end of the season and when symptoms began. Monitor eating, drinking, activity, nesting and toy guarding. Mention any possible mating, previous phantom pregnancies and recent spaying. Show the practice a video of behaviour changes if helpful.

Forcibly taking away a toy being mothered can make your dog agitated or aggressive.

Keep children and other animals away from a dog that is guarding intensely. Provide a quiet resting place and plan how to move toys safely. If safe handling is not possible, ask your vet for guidance before the situation escalates.

Milk production alone does not show that a dog is pregnant.

Conversely, an enlarging abdomen and mothering behaviour do not rule out true pregnancy if mating has been possible.

Contact a vet promptly about pain or suspected mastitis.

Assess symptom changes after later seasons too, because episodes in the same dog can vary in severity.

Frequently asked questions

Can a dog have a phantom pregnancy without mating?

Yes. Phantom pregnancy can occur even if the dog has never mated. After a season, her body undergoes physiological changes resembling pregnancy. Record the dates of the season and symptoms so that the vet can assess the overall picture.

How long does phantom pregnancy last in dogs?

Mild signs usually settle within about 14–21 days. Severe signs or those lasting more than four weeks need assessment for treatment. Track duration from the first sign and also record changes in eating and behaviour.

Should I express milk from a dog with phantom pregnancy?

No. Expressing milk and massage can increase milk production. The female's own licking can also maintain it. A protective collar or recovery suit may be used to prevent licking when necessary. A painful, hot or hard mammary gland needs examination. With infection, the milk may contain pus.

Does phantom pregnancy show on a blood test?

There is no specific blood test that confirms phantom pregnancy. A relaxin test can be used to investigate true pregnancy. However, a negative result obtained too early may be false. The vet chooses a suitable test and timing. Ultrasound helps assess a possible pregnancy.

Can a spayed dog have a phantom pregnancy?

Yes. If the ovaries are removed during the active luteal phase, the hormone change can trigger symptoms. Spaying during symptoms may also prolong the episode by several weeks. Tell your vet the surgery date and exactly when signs began. Planned spaying is usually scheduled during anoestrus.