Allergens at home: cat, dog, dust mite, mouse, cockroach
Pet ownership predicts pet-allergen levels less reliably than most people think. Bedroom dust, HVAC return air, and the couch tell a more accurate story than "do you have a cat" does. That's mostly what Canary's allergen panel measures.
The two-sentence summary
Mainstream allergy and asthma practice (AAAAI, NHLBI EPR-3 / 4) endorses environmental allergen avoidance as a first-line intervention for sensitized patients. The intervention only works if you know which allergens are actually present and where — which the NIH Inner-City Asthma Study (1997 onwards) established cannot be assumed from the obvious household questions alone.
The Inner-City Asthma Study, briefly
NIH's Inner-City Asthma Study followed pediatric asthma in seven US cities over decades. One of its most-cited findings: cockroach allergen (Bla g 1, Bla g 2) in bedroom dust was a stronger predictor of asthma severity and ER visits than tobacco-smoke exposure or housing condition alone. Pet allergen (Fel d 1, Can f 1) often appeared at clinically-relevant levels in homes with no pet (carried in on clothing, carried over from prior owners) and was sometimes absent at clinically- relevant levels in homes with pets but careful management.
The allergens we measure + their thresholds
| Allergen | Source | Sensitization threshold | Symptomatic threshold |
|---|---|---|---|
| Fel d 1 | Cat (saliva, sebum, dander) | 2 µg/g | 8 µg/g |
| Can f 1 | Dog (saliva, dander) | 2 µg/g | 10 µg/g |
| Der p 1, Der f 1 | Dust mite | 2 µg/g | 10 µg/g |
| Mus m 1 | House mouse (urine) | 0.5 µg/g | 1.6 µg/g |
| Rat n 1 | Rat | 0.05 µg/g | 1.0 µg/g |
| Bla g 1, Bla g 2 | Cockroach (frass, body parts) | 2 U/g | 8 U/g |
Thresholds are reservoir levels in settled dust (µg or U per gram of fine dust collected). The literature on these levels is mature — most are from the AAAAI Practice Parameters and the NIH Inner-City Asthma Study. The pet-allergen thresholds in particular have been replicated across multiple cohorts.
How we sample
Inspector uses a high-volume vacuum with a Mitest or DUSTREAM collector to pull 2-4 grams of settled dust from each target location. Sampling locations follow the AAAAI / Indoor Biotech recommendation: bedroom bedding + bedroom carpet, family room couch, kitchen floor, HVAC return air filter face.
Samples ship to an AIHA-LAP-accredited allergen lab. Analysis is by sandwich ELISA against the established reference standards for each allergen. Results in µg / U per gram of fine dust.
What we report
- Per-allergen result at each sampling location.
- Each result flagged sensitization-threshold, symptomatic- threshold, or below-detection.
- Inspector's plain-English interpretation: which allergen is most likely driving symptoms, which sampling location matters most for which sensitization, and what avoidance interventions the literature supports.
- If applicable: referral guidance for allergen immunotherapy candidacy (your treating allergist's call, but our report supplies the environmental data).
Why bedroom sampling usually drives the result
The single most-validated avoidance intervention for dust mite and pet allergen sensitization is bedroom-specific (allergen- impermeable mattress + pillow encasings, weekly hot-water bedding wash, HEPA-filtered air in the bedroom). The reason: ~30% of a 24-hour day is spent in the bedroom, in close contact with the highest reservoir surfaces. Bedroom-specific avoidance gets disproportionate clinical return.
Pet allergen in homes without pets
Cat allergen (Fel d 1) is one of the stickiest molecules in indoor air. It rides on clothing, transfers from house to house, and persists in carpet and upholstery for years after a cat is removed. Bedroom samples in no-pet homes routinely show measurable Fel d 1; in homes with prior cat ownership, the level can stay above sensitization threshold for 4-6 years after the cat leaves.
This explains a lot of clinical confusion. Patients say "we don't have a cat," the allergist trusts that, and the relevant allergen exposure stays missed for years.
When to test
- Diagnosed allergic rhinitis or asthma with unclear or multiple suspected triggers.
- Allergy testing (skin or specific-IgE) positive but symptoms don't track the obvious exposures.
- Recent move to a new home; symptoms started or worsened.
- Considering or undergoing allergen immunotherapy and want to confirm bedroom-level exposures.
- Chronic eczema flares in a child without clear dietary correlation.
- Suspected mouse / cockroach infestation in a multi-unit building.
When NOT to test (yet)
- You haven't done a basic allergy workup with your clinician. Specific-IgE or skin testing is much cheaper than environmental testing and clarifies what to look for.
- You know what's there (recently acquired pet, visible mouse droppings). Implement avoidance + treat the source. Re-test if the avoidance doesn't move symptoms in 4-6 weeks.
Selected references
- Eggleston PA, et al. Cockroach allergen exposure as a risk factor for asthma in inner-city children. JACI 1998.
- Phipatanakul W, et al. Mouse allergen exposure and sensitization in inner-city asthma. JACI 2000.
- NIH National Heart, Lung, and Blood Institute. Expert Panel Report 3 (EPR-3): Guidelines for the Diagnosis and Management of Asthma. 2007 (updates 2020).
- AAAAI / ACAAI / JCAAI Joint Task Force. Allergen-Specific Immunotherapy Practice Parameter. 2011.
- Custovic A, et al. Distribution and transport of indoor allergens. Allergy 2003.