False pregnancy, also known as Phantom pregnancy or Pseudo-pregnancy, is a condition of both dogs and cats, whereby the unsterilised female animal (regardless of whether she was mated or not) shows some or all of the typical signs of pregnancy but is not really pregnant. In other words, she shows mammary gland development (with or without milk production) but does not produce any offspring.
Symptoms appear usually about 1 to 2 months after oestrus (heat) has finished. Animals that have experienced a false pregnancy after a heat cycle may or may not experience the condition again after any future cycles.
Pseud-pregnancy is a fairly common condition and can be quite confusing and frustrating for the owner or breeder that wishes to breed with their animal. Although the astute pet owner or breeder may be able to correctly diagnose their animal as pregnant, non-pregnant or pseudo-pregnant, one should always consult a veterinarian if pregnancy is suspected.
A veterinary visit will help to ensure that the mother animal is healthy enough to support a pregnancy and that any potential complications are dealt with early. It will also ensure that you are adequately informed and correctly advised on how to care for both mum and babies during pregnancy and once they are born.
What are the typical signs of pregnancy in animals?
- Pregnant animals typically start showing a more pendulous belly as gestation progresses and weight gain may be the presenting complaint in animals that are found to be pregnant or pseudo-pregnant.
- Some animals will pour all their energy and body fat reserves into the unborn offspring and appear to be emaciated with muscle wastage in favour of a large developing belly. (This should not to be mistaken for parasitic causes of pot-belly).
- Some animals show signs of “morning sickness” such as vomiting/nausea/inappetance although appetite may increase in order to supply enough nutrients for the increasing energy demands of the growing offspring
- Nesting behavior may become apparent, whereby the pregnant female is more affectionate (motherly), scratches at bedding to make it more comfortable, or seeks a warmer environment in which to rest.
- Decreased activity levels or being less inclined to play/run may be noticed in pregnant animals which may be mistaken for depression.
- The female may become more agitated and restless and in some cases even aggressive.
- Mammary glands become enlarged and watery white or slightly brown-tinged fluid may be able to be expressed.
- Teats (or nipples) will become enlarged, usually during the first 3-4 weeks of pregnancy.
What is the length of the gestation period for dogs and cats?
Cats are pregnant for an average of 66 days, with a range of 62 to 67 days. Cats can have litter sizes of anywhere from 1 kitten in younger queens, to 4 or 5 kittens in older more mature queens.
Dogs are pregnant for an average of 65 days with a range of 58 to 65 days. Dogs can have litter sizes of anywhere from 1 puppy in smaller breeds e.g. Chihuahua, up to 15 puppies in some larger breeds e.g. Labrador.
What causes a False Pregnancy?
The un-sterilised female animal is continually under the influence of a number of hormones, including Oestrogen (feminising hormone), Progesterone (pregnancy maintenance hormone) and Prolactin (milk production stimulating hormone), which all play an important role in the recognition and maintenance of pregnancy.
The exact cause of pseudo-pregnancy is not currently known, but hormonal imbalances (mainly involving elevated levels of Progesterone and Prolactin) play a significant role.
After being “on heat” (oestrus) the female ovaries naturally produce more of these hormones in order to prepare the uterus and body for pregnancy in case she has been mated, and if pregnancy is recognised by the uterus (if embryos are present) the hormones will continue to be produced in order to maintain the pregnancy. If no embryos are present (the female is not pregnant), the Progesterone and Prolactin levels of a normal female animal will slowly decline in favour of a rise in Oestrogen in preparation for the next “heat” cycle.
Hormonal disturbances, whether due to inherent pathological conditions e.g. underlying infection or tumours that affect hormone production, or human intervention such as sterilisation (whereby the ovaries and uterus are surgically removed) have been known to occasionally result in false pregnancy-like symptoms.
I think my pet might be Pseudo-pregnant – what now?
A specific diagnosis of pregnant / pseudo-pregnant will need to be made by your veterinarian.
Once your veterinarian has collected a full, detailed history of your pet’s health, a number of diagnostic procedures will be performed which will usually involve a full clinical examination (temperature, pulse rate, respiration rate, capillary refill time of the gums, gum colour, general overall body condition score) and may also involve additional routine diagnostics such as a blood smear, blood testing, a faecal float, a vaginal smear and a urine analysis. This is in order to rule out any other potential illnesses which may be the cause of your dog’s apparent false pregnancy.
If your animal is suspected to be pregnant, your vet may need to take survey radiographs (abdominal X-rays) to assess the size, number and position of the foetuses. Foetal skeletal maturation occurs after the 49 days of pregnancy, so very young foetuses may not be visualised until after this point in gestation. In the case of early pregnancy, an abdominal ultrasound is more rewarding.
Where abdominal ultrasound is performed, pregnancy can be detected from 4 weeks after mating, and your vet will be able to assess the heart rate of the foetuses (which will indicate if the offspring are in fact alive and/or if they are stressed), as well as taking a closer look at the abdominal organs of the mother including the uterus and ovaries.
False pregnancy will quickly be diagnosed if there are no foetuses present. In this case, your vet may elect to run further diagnostic tests (such as routine blood testing involving a full blood count and biochemistry profile) to find out why your animal is showing signs of phantom pregnancy.
If the female animal suspected to be having a false pregnancy is suspected to be between 21 to 15 days pregnant, it may be possible to test your animal’s blood for a hormone called Relaxin which, if present in high enough quantity, may be used to confirm pregnancy.
Are there any dangers or adverse effects from Phantom Pregnancy?
If no underlying pathological condition can be found by your vet as the cause of the symptoms being displayed by your pet then no drastic intervention is usually required. Simple remedies such as the use of an Elizabethan Collar to prevent licking of teats, or hot/cold packs on the mammary tissue and even a reduction in food intake will help to reduce milk production.
However, if a disease process is found to be at the root of the problem (for example infection or cancer), intervention to remedy the condition (such as removal of the ovaries and uterus, called sterilisation or “spaying”) may be necessary.
If your pet is sick or physically ill, and if any behavioural changes are severe enough to cause concern, then medical treatment such as antibiotics, anti-inflammatories, anti-anxiety medication, and/or diuretics may be indicated. Hormonal therapy is rarely necessary.
Most dogs will improve or revert to normal within two to three weeks of the onset of symptoms without any intervention. If your pet is to be spayed, it is best to have the procedure performed after all pseudo-pregnancy symptoms have been resolved otherwise their resolution may be delayed.
Is there anything I can do to prevent False Pregnancy in my pet?
Although False Pregnancy is not a life-threatening condition (as long as it does not involve a disease process), early sterilisation or “spaying” of female animals will not only ensure that pets do not develop the condition again after the initial episode, but will also reduce the risk of other potentially life threatening conditions of the reproductive tract, such as pyometra (uterine infection), in future.
In addition, early sterilisation of females is proven to reduce the risk of mammary cancer and reproductive disorders, and all unwanted pregnancies or mis-matings will also be avoided if all non-breeding stock females are sterilised.