Adverse effects occurring in small dogs, cats, puppies and kittens have been reported in several European countries following repeated contact with hormone replacement therapy applied to their owner's skin. Most of these cases, affecting both females and males, have involved oestrogen. Medications are applied to parts of the body, such as the thighs, abdomen or arms, which can then potentially come into direct contact with the animal. Animals sleeping on the bed of the treated individual can also be exposed via bed sheets. No cases have been reported to date in France, but those described in other European countries reiterate the need to be vigilant when using these products.

Hormonal problems caused by the repeated exposure of animals

The exposed animals mainly develop signs suggesting a hormonal disorder, for example with swollen mammary glands and/or vulvas in females, as well as hair loss. Spayed females have also shown signs of going into heat. Moreover, the bone marrow toxicity of oestrogen can cause blood abnormalities in the long term that may be life-threatening to the animal. The time to symptom onset varies, ranging from a few weeks to several years. Symptoms generally improve or even disappear when the animal is no longer exposed to the hormones.

If you notice any swelling of the vulva or the mammary glands (in females or males), or if you see your spayed pet going into heat, you are advised to quickly take them to a veterinarian. You should tell them that someone in the household is taking a topical hormonal treatment.

Precautions to be taken when applying treatments

To avoid any effects on your pets, you should take all necessary precautions when using this type of human medicinal product:

• wash your hands after applying a gel or spray;
• cover the treated areas with clothes;
• don't let your pets lick the treated areas;
• don’t sleep with your pets;
• if your pet comes into direct contact with a treated area, don't let it lick itself, and use water to rinse any body parts that may have come into contact with the medication.

ANSES-ANMV reiterates that these precautions for use are valid for all medicinal products applied to the skin. Any adverse events occurring after an animal has been exposed to a medicinal product for humans should be reported to the national veterinary pharmacovigilance scheme, managed by ANSES-ANMV.