Q: I am allergic to cats, and I’m thinking about moving in with my girlfriend who has a cat. Antihistamines put me to sleep. Is there something we can give the cat instead?
A: At present, the answer is no. But that may change in the coming years.
Like most people who are allergic to cats, you probably are overly sensitive to a feline protein called Felis domesticus allergen 1, nicknamed Fel d 1. This protein is produced in the cat’s salivary glands and transferred from the saliva to the fur when the cat grooms; it’s also made in the skin’s sebaceous glands and the tear glands. Its role in the cat’s body is unclear.
Cats produce at least eight similar allergens; for example, Fel d 4 also is found in saliva. However, Fel d 1 is the most troublesome because it causes allergic reactions in over 90% of cat-allergic people, and it is present in high concentrations.
The Fel d 1 protein is small, so it remains airborne for long periods of time. Its molecular structure helps it adhere to fabrics, upholstery and carpet, so it easily makes its way into schools, offices and homes without cats.
A cat’s gender, weight, color and coat pattern do not affect Fel d 1 levels, according to a 2019 study of 64 indoor cats whose saliva was collected for a year. This study also showed that Fel d 1 levels vary considerably among cats and even within an individual cat over time.
It’s not clear that anything currently on the market that is applied to or given to a cat makes it easier for allergic humans to live with them. One study compared four treatments: Allerpet-C spray, acepromazine (a tranquilizer thought to help with this problem), bathing in water and no therapeutic intervention. None of the treatments decreased the cats’ Fel d 1 levels.
However, there is hope: Recent research evaluated a diet supplemented with an antibodythat binds the Fel d 1 protein. By the third week of the study, salivary Fel d 1 levels were significantly reduced in cats fed the supplemented diet compared with those fed the same diet without the antibody. The company, Nestle Purina, is continuing its research.
Another company, HypoPet, is studying a vaccine designed to decrease Fel d 1 levels. In research published this year, vaccinated cats produced antibodies that neutralized their Fel d 1. They also seemed to produce less Fel d 1, at least in their tears. Further research is needed to determine whether this approach is safe for cats and will actually help cat-allergic people.