Phantom pregnancy in dogs: is it really a psychological pregnancy?
It is important to start by highlighting that canine pseudocyesis, often incorrectly called phantom pregnancy, is not a psychological disease, but rather a physiological state in female dogs due to hormonal activity. Phantom pregnancy in dogs tends to occur 6–8 weeks after oestrus, even in females that have not been mounted by a male.
Reproductive cycle of female dogs: brief introduction
It is important to start by highlighting that canine pseudocyesis, often incorrectly called phantom pregnancy, is not a psychological disease, but rather a physiological state in female dogs due to hormonal activity.
Phantom pregnancy in dogs tends to occur 6–8 weeks after oestrus, even in females that have not been mounted by a male.
For a better understanding of this physiological situation, we will briefly explain the female dog’s reproductive cycle, which is typically monoestrous within each breeding season, so they have one or two oestrus cycles per year that are 5 to 11 months apart. All the remaining days in the cycle form the anoestrus stage, which courses without any signs of ovarian activity. This is followed by a period called proestrus where significant follicular activity is noted and which manifests as vulvar oedema, bloody vaginal discharge and male attraction. The next stage, oestrus, is notable for sexual receptivity and marked keratinisation of the vaginal epithelium. Ovulation and corpus luteum development usually start during the first third of oestrus; while the end of oestrus indicates that dioestrus has begun, during which progesterone (P) plasma levels remain high (> 5 ng/mL) for around 60–90 days. After oestrus, the corpus luteum continues to function and there is no significant difference between progesterone levels in pregnant and nonpregnant dogs.
When prolactinaemia increases above 3 ng/mL, especially during the second half of dioestrus, it triggers the onset of canine pseudocyesis and the clinical signs are directly related to these hormone levels (please see our post on the role of hormones to learn more).
Phantom pregnancy in dogs: clinical picture
The condition causes just as many physical signs as it does behavioural changes.The first observable sign of phantom pregnancy in dogs is milk let-down, which is known as false lactation. Progesterone and oestradiol levels increase to the same extent as they do in real pregnancies.
Affected females behave as if they have already had puppies, they may even adopt and take care of dolls or rags as if they were their offspring, as well as displaying signs of agitation and anxiety.
The clinical signs generally subside within 10 days and the patient returns to normal without any major physical consequences. A few cases present clinical problems; either due to behavioural changes or excessive milk production (see here more information on mastitis and its clinical signs).
Phantom pregnancy: treatment
Patients do not normally require pharmacological treatment; however, prolactin synthesis inhibitors, of which cabergoline is one of the most suitable, can be used to avoid complications. Patients must also be discouraged from licking their mammary glands to secrete milk, as this stimulates further milk production.
In addition, patients with pseudocyesis should be distracted through other activities.
To ensure puppies receive the best nutrition to help them grow for the first months of life, we recommend the Puppy Protect range.
