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Hormone Replacement Poisoning in Dogs

Toxicosis with Hormone Replacement Medidogions in Dogs

Hormone replacement therapy (HRT), commonly utilized by women in forms such as creams, gels, sprays, and patches, poses a significant risk to dogs if accidentally ingested. Dogs are particularly susceptible to poisoning from these hormone replacement products. Additionally, hormone replacement products can also be toxic to cats.

Symptoms and Types

The symptoms of hormone replacement poisoning vary based on the gender of the affected dog.

  • Female Dogs: Symptoms akin to being in heat, including a swollen vulva and bloody discharge, are observed in female dogs affected by HRT toxicity, even if they have been spayed.
  • Male Dogs: Male dogs may exhibit extreme attraction to female dogs, along with the potential for swollen mammary glands (breasts) and an unusually small penis. In intact dogs, there is also a risk of testicular atrophy (shrinking of the testicles).
  • Hair loss may manifest in both male and female dogs.

There is also a concern that prolonged exposure to HRT products could lead to bone marrow suppression, resulting in aplastic anemia (a severe blood disease), and potentially contribute to mammary tumors (breast cancer).


Hormone replacement therapies are administered to women to replenish estrogen levels and alleviate menopausal symptoms such as hot flashes, mood swings, and bone loss. These medications are typically available in forms such as creams, gels, sprays, or patches. Women are commonly instructed to apply the medication to their wrists, inner elbows, or legs.

Dogs often encounter exposure to HRT medication by licking it from a woman’s skin. Additionally, they may be exposed by chewing on or licking discarded patches.


The diagnosis hinges on recognizing the typical clinical signs and confirming known (or suspected) exposure to an HRT product. If needed, estrogen levels in the blood can be assessed to validate the diagnosis.


Symptoms can often be reversed by discontinuing further exposure to the medication. However, in some instances, it may take months for symptoms to fully resolve.


Women should apply hormone replacement therapy products to areas of their body that are unlikely to be accessed by the dog.

When using HRT products, women should wear gloves and dispose of them in a place inaccessible to the dog once finished. Any used patches or similar items should be disposed of in a location where the dog cannot reach them.

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