Mysterious, Spontaneous Lactation in Dogs—What's the Cause?
Lactation (producing breast milk) in mammals is usually due to pregnancy. It doesn't matter if the mammal in question is a human, a giraffe, or a dog—lactation begins when a birth is imminent and continues until the baby is weaned. But this isn't always the case. Why is your dog producing breast milk when (as far as you know) she's not expecting puppies?
Make Sure She's Not Pregnant
Mystery lactation can be quite confusing—especially if your dog has been spayed. If her reproductive organs are intact, a pregnancy test will be helpful at this point. You can purchase a home test for dogs, but don't use a pregnancy test for humans, as the results will not be accurate. Alternatively, schedule an appointment with your dog's veterinary surgeon so that pregnancy (or lack thereof) can be confirmed with a blood test. If your dog has not been spayed, a phantom pregnancy (resulting in lactation) is a possibility, although this will not be the case when she has been spayed.
Check for an Abnormality With Her Thyroid Gland
Once pregnancy (actual or phantom) has been ruled out, your vet may need to run a few tests to get to the bottom of your dog's mystery lactation. An endocrine disease may be the culprit, specifically hypothyroidism. This condition reduces the functional abilities of your dog's thyroid gland, which can affect your dog's metabolism, and lactation can be one of these effects. Your dog may exhibit other symptoms (such as weight gain and lethargy). Untreated hypothyroidism can negatively impact your dog's health, but this is easily managed with appropriate hormone therapy. She will be prescribed medication, which must be taken daily, indefinitely.
Determine the Growth of Any Tumours
A tumour affecting the mammary glands can also lead to spontaneous lactation. In this case, your dog might not technically be producing breast milk, but a discharge caused by the growth of the tumour. The best treatment depends on your dog's age and general health, along with the size and severity of the tumour. Your dog is likely to need surgery (to remove the tumour), in addition to chemotherapy.
Mysterious, spontaneous lactation can be completely benign. It might even be an unexpected pregnancy! Yet sometimes the cause can be sinister, so it's crucial to have any instances of spontaneous lactation investigated by your vet. You will need to know if your dog needs important medical care, or if you need to start getting your home ready for puppies.