Introduction

Which lab test actually answers “Am I allergic to cats or dogs?” Today’s gold standard for blood testing is serum specific IgE (sIgE) to inhalant allergens. IgE is the antibody that mediates immediate-type environmental allergy; IgG (including IgG4) reflects exposure/tolerance and is not diagnostic for allergy. Professional societies advise against using IgG panels and against indiscriminate IgE panels that aren’t guided by history.

The core test: s

IgE to cat and dog dander extracts

• What it shows: sensitization to cat (e1) or dog (e5) dander. A positive result indicates the immune system has made IgE to proteins in that animal’s dander/saliva/urine; correlation with symptoms and exposure completes the diagnosis.

• Why start with extracts: they contain the clinically relevant mixture of proteins and are widely validated for rhinitis/asthma due to pets. If the history and extract results don’t fully line up—or you need exposure guidance—add component testing (below). Guidance on when and how to use molecular (component) testing is detailed by EAACI’s Molecular Allergology User’s Guide (MAUG) 2.0.

Component testing 101 (molecular s

IgE) Component-resolved diagnostics (CRD) measures IgE to individual pet proteins. It helps distinguish genuine sensitization from cross-reactivity and can refine counseling and treatment decisions.

Cat components (key molecules)

• Fel d 1 (secretoglobin): the major cat allergen; up to ~95% of cat‑allergic patients have IgE to Fel d 1. It is produced mainly in salivary/sebaceous glands and becomes airborne easily. Sensitization is strongly associated with lower-airway symptoms.

• Fel d 4 (lipocalin): common and cross-reactive with other mammal lipocalins (e.g., dog Can f 6, horse Equ c 1). Helps explain “multi‑pet” triggers.

• Fel d 2 (serum albumin): can cross‑react with pork albumin (the “pork–cat” syndrome), useful when patients report symptoms with both cats and pork.

Dog components (key molecules)

• Can f 1 (lipocalin): one of the major dog allergens; common in classic dog allergy.

• Can f 5 (prostatic kallikrein): produced by male dogs (present in urine, dander, hair). Mono‑sensitization to Can f 5 can explain symptoms to male—but not female or neutered male—dogs, and it cross‑reacts with human prostate‑specific antigen (PSA).

When component testing changes care

• History doesn’t match basics: Extract sIgE is positive but symptoms occur only with certain animals (e.g., male dogs) or only in specific contexts (e.g., after pork ingestion with cat allergy). Use components to clarify exposures (e.g., Can f 5, Fel d 2).

• Multi‑pet households: Lipocalin profiles (Fel d 4, Can f 6, Equ c 1) help explain cross‑pet symptoms and guide environmental control.

• Counseling on pet selection and mitigation: Can f 5 mono‑sensitization suggests some patients react mainly to male dogs; this can inform discussions about pet sex/neutering and realistic expectations (not a guarantee of zero symptoms).

• Setting expectations for therapy: CRD is used to confirm genuine sensitization versus cross‑reactivity and to inform tailored immunotherapy strategies alongside clinical history.

Why s

IgE (not IgG) matters for pet allergy

• IgE mediates immediate respiratory allergy; positive sIgE indicates sensitization and is the laboratory signal used in guidelines and practice parameters.

• IgG/IgG4 to foods (and by extension “sensitivity panels”) is not recommended to diagnose allergy; elevated IgG generally reflects exposure/tolerance, not disease. Choose sIgE (and skin testing) guided by a compatible history.

A quick reference to common pet components

Source	Component	Protein family	Typical implication
Cat	Fel d 1	Secretoglobin	Major cat allergen; strong link to lower-airway symptoms; airborne and persistent.
Cat	Fel d 4	Lipocalin	Explains cross‑reactivity with dog/horse lipocalins (e.g., Can f 6, Equ c 1).
Cat	Fel d 2	Serum albumin	May cross‑react with pork albumin (pork–cat syndrome).
Dog	Can f 1	Lipocalin	Major dog allergen found in many dog‑allergic patients.
Dog	Can f 5	Kallikrein (PSA‑like)	Male‑dog–related sensitization; potential cross‑reactivity with human PSA; consider sex/neutering in counseling.

How to order testing (a practical sequence)

1) Start with sIgE to cat and dog dander. 2) Add components when the history or decisions require more precision (e.g., male vs female dog reactions, cross‑pet symptoms, suspected albumin cross‑reactivity). 3) Interpret results with exposure and symptom timing; sensitization ≠ clinical allergy. This stepwise, history‑first approach is consistent with allergy testing best practices and CRD guidance.

What Wyndly uses and why

• Wyndly’s at‑home blood test measures IgE to environmental allergens (including pet dander) using a simple finger‑prick collection, then a Wyndly physician reviews results alongside your history. When indicated, your doctor can discuss whether targeted component testing would add value. Allergy Test.

• If testing confirms pet allergy and you’re a candidate for immunotherapy, Wyndly offers sublingual immunotherapy (allergy drops/tablets) for long‑term relief from environmental allergies—including pet dander—without office injections. Pet Allergy Immunotherapy.

• We treat environmental allergies only; we do not treat food allergies.

FAQs

• Are there “hypoallergenic” cats or dogs? No. All cats and dogs make multiple allergenic proteins; Fel d 1 is produced by all cats (with wide individual variation). Manage exposure and treat the immune response rather than relying on breed claims.

• Can component results predict who will benefit from immunotherapy? Components help confirm genuine sensitization and refine counseling. Treatment decisions still integrate history, exposure, comorbid asthma, and patient preferences per guideline‑based care.

• Why did my “IgG sensitivity panel” list dozens of foods but not explain my pet symptoms? Because pet allergy is an IgE‑mediated inhalant condition; IgG panels are not validated for diagnosing allergy. Use sIgE (and/or skin testing) guided by history.