Why component‑resolved diagnostics (CRD) matters for pet dander

CRD measures IgE to individual allergenic molecules (components) instead of only whole‑extract “cat dander” or “dog dander.” For pet allergy, the key components are:

• Cat: Fel d 1 (major), Fel d 2 (albumin), Fel d 4 (lipocalin).

• Dog: Can f 1 (lipocalin), Can f 2 (lipocalin), Can f 5 (prostatic kallikrein, male‑dog specific).

CRD can clarify cross‑reactivity, predict exposure patterns (e.g., male vs female dogs), and set expectations for environmental control and immunotherapy. Wyndly accepts existing CRD panels and incorporates them into your plan. If you already have results, upload them here: Existing Allergy Test Review.

How to read cat/dog CRD results

• Units and thresholds: Most laboratories report allergen‑specific IgE in kUA/L; results may also be mapped to “Class” scales (0–6). Newer assays often report values down to 0.10 kUA/L; historic “positive” cutoffs of 0.35 kUA/L are still commonly shown. Interpretation must match symptoms and exposure—IgE indicates sensitization, not severity.

• Multisensitization: Risk of symptoms generally increases as the number of positive components rises (e.g., multiple lipocalins and/or albumin), especially for asthma and rhinoconjunctivitis.

• Cross‑reactivity: Serum albumins (e.g., cat Fel d 2, dog Can f 3) often cross‑react across mammals; lipocalins cross‑react variably; Can f 5 (kallikrein) is immunologically distinct and linked to intact male dogs.

Pet allergen components at a glance

Notes: Ranges reflect multiple cohorts; your lab report may list additional components (e.g., Can f 3 albumin, Can f 4/6 lipocalins, Fel d 7). Always correlate with clinical history.

Example CRD report format (illustrative)

• Cat

• Fel d 1: 12.3 kUA/L (Class 4) — consistent with strong sensitization

• Fel d 2: 0.2 kUA/L (Class 0/1) — minimal albumin sensitization

• Fel d 4: 1.1 kUA/L (Class 2) — additional lipocalin sensitization

• Dog

• Can f 1: 3.6 kUA/L (Class 3)

• Can f 2: 0.5 kUA/L (Class 1–2)

• Can f 5: <0.10 kUA/L (Class 0)

Interpretation guide (typical, varies by lab):

• <0.10 kUA/L: undetectable; 0.10–0.34: very low/indeterminate; ≥0.35: positive; rising classes (1–6) reflect higher IgE but not necessarily worse symptoms. Use exposure history to judge clinical relevance.

When CRD changes management

• Dog allergy limited to Can f 5 (mono‑sensitization):

• Exposure: Symptoms often occur primarily with intact male dogs; many patients tolerate female or neutered male dogs.

• Counseling: Consider pet selection/neutering, urine hygiene, and cleaning strategies.

• Broad dog sensitization (e.g., Can f 1/2/4/6 ± Can f 5):

• Exposure: More likely to react to most dogs regardless of sex; focus on whole‑home controls (HEPA, bedroom exclusion, weekly bathing) and discuss immunotherapy.

• Cat allergy dominated by Fel d 1:

• Exposure: Strong indicator of clinical cat allergy when history aligns; prioritize cat‑specific controls and discuss cat‑directed immunotherapy.

• Albumin positivity (Fel d 2 and/or Can f 3):

• Exposure: Watch for cross‑species reactions (other mammals); this can explain “pet‑free” symptoms in mammal‑rich environments (farms, classrooms).

• Low‑level isolated positives (near cutoff) without symptoms:

• Action: May represent sensitization without clinical allergy—avoid over‑restricting; confirm with exposure history.

How Wyndly uses your CRD

• We accept and act on existing CRD: upload your results for physician review at Existing Allergy Test Review. Our doctors correlate components with your history to shape environmental advice and your immunotherapy plan.

• We treat environmental allergies (not food). Pet immunotherapy is available from home via sublingual drops or tablets with board‑certified oversight, 24/7 support, and transparent pricing. Learn more: Cat Allergy Immunotherapy and Dog Allergy Immunotherapy.

• Already tested only with whole extracts? That’s fine—CRD is helpful but not mandatory to begin care. We routinely create effective plans using extract‑based results and your clinical history.

Practical FAQs

• Are there truly “hypoallergenic” cats or dogs?

• No. All cats and dogs make allergens. Breed marketing doesn’t reliably predict allergen levels or symptoms. See Wyndly’s overview on “hypoallergenic” pets and why immunotherapy is the durable solution.

• If I’m positive only to Can f 5, should I choose a female dog?

• Many such patients do better with female or neutered male dogs. Confirm with your allergist, and continue standard controls (HEPA, pet‑free bedroom, regular bathing).

• Does a higher Class automatically mean worse symptoms?

• Not necessarily. kUA/L and Classes reflect IgE quantity, not guaranteed severity. Decisions should combine test results with your real‑world reactions.

References (selected)

• Fel d 1 prevalence and CRD in pet allergy: Konradsen JR et al., J Appl Lab Med. 2018;3(5):883–898 (review). Ichikawa K et al., data summarized in the same review.

• Cat component frequencies: Microarray study (Fel d 1 ~92.5%, Fel d 2 ~30%, Fel d 4 ~39%): PubMed PMID: 29228796.

• Dog component frequencies and Can f 5 biology: “Prostatic kallikrein: a new major dog allergen,” J Allergy Clin Immunol. 2009;123:376–383. PubMed PMID: 19135239.

• Clinical impact of Can f 5 and male‑dog exposure; cross‑reactivity with PSA: PubMed PMIDs: 29384112; 22653399.

• Multisensitization and symptoms with pet components: Pet exhibition cohort: PubMed PMID: 36321071.

• Reporting units and interpretation: ImmunoCAP/FEIA interpretation guidance (kUA/L, historical Class scales) summarized by Thermo Fisher Scientific interpretation guides and peer‑review (e.g., World J Methodology 2018 review of IgE immunoassays).

Get started

Have CRD already? Upload it for a physician review and fast start: Existing Allergy Test Review. No CRD? We can still help you begin care today with extract‑based testing and treatment. See Cat Allergy Immunotherapy and Dog Allergy Immunotherapy.