What Is Fel d 1?

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Learn about the secretoglobin that can affect cat allergen-sensitized patients like yours.

 Fel D 1

The Major Cat Allergen

Sensitization to cat allergens is a global health concern. Fel d 1, a secretoglobin, is the major cat allergen that accounts for up to 95% of sensitization to cats.1,2 

image of cat looking up

All Cats Produce It

Contrary to common beliefs there are no allergen-free or ‘hypoallergenic’ cats or breeds.5,7 All cats, irrespective of the breed, age, hair length or color, sex, housing (indoors vs outdoors), or body weight, produce Fel d 1  at various levels and during different times of the year. 3,4,8

cat licking paw

It Starts In the Mouth

Fel d 1 is produced primarily in the salivary and sebaceous glands, and is transferred to cat hair and skin during grooming and eventually into the environment via hair and dander.1,6

cat fur close up

It’s Easily Airborne

Fel d 1 is light, so it easily becomes and remains airborne in dander and dust particles 1,2  where it can come into contact with cat allergen-sensitized individuals.

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  1. Bonnet B, Messaoudi K, Jacomet F, et al. An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen. Allergy Asthma Clin Immunol. 2018;14(14):1-9.
  2. Dávila I, Domínguez-Ortega J, Navarro-Pulido A, et al. Consensus document on dog and cat allergy. Allergy. 2018;73(6):1206-1222.
  3. Wentz PE, Swanson MC, Reed CE. Variability of cat-allergen shedding. J Allergy Clin Immunol. 1990;85:94-98.
  4. Nicholas C, Wegienka G, Havstad S, et al. Influence of cat characteristics on Fel d 1 levels in the home. Ann Allergy Asthma Immunol. 2018;101:47-50.
  5. Butt A, Rashid D, Lockey RF. Do hypoallergenic dogs and cats exist? Ann Allergy Asthma Immunol. 2012;108:74- 76.
  6. Kelly SM, Karsh J, Marcelo J, et al. Fel d 1 and Fel d 4 levels in cat fur, saliva, and urine. J Allergy Clin Immunol. 2018;142(6):1990-1992.
  7. Lockey RF. The myth of hypoallergenic dogs (and cats). J Allergy Clin Immunol. 2012;130(4):910-911.
  8. Bastien BC, Gardner C, Satyaraj E. Influence of time and phenotype on salivary Fel d1 in domestic shorthair cats. J Feline Med Surg. 2019;21(10):867-874.

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For questions or to learn more, please call our Veterinary Resource Center at 1-800-222-8387.