Cat and dog allergy and exotic pets 2024

Cat and Dog Allergy
and exotic pets
Topic: 8th March 2024
Tanatchabhorn Soponkanabhorn, MD.
Division of Allergy, Immunology and Rheumatology
Department of Pediatrics, King Chulalongkorn Memorial Hospital

Outline
• Cat and dog taxonomy
• Cat and dog allergens
• Immune responses to cat and dog
• Characteristic of sensitization to dogs or cats
• Usefulness of skin tests, determination of specific IgE and molecular diagnosis
• Environmental assessment and exposure control
• Immunotherapy
• Exotic pet allergy

• International survey from 22 countries:
• 57% of population has at least 1 pet at home
• Dogs and cats are most common
• Sensitization to furry animals (especially dog) increased
dramatically among allergic children and adolescents
between 2004 and 2016, reflecting a sedentary ‘indoor
lifestyle’
• Sensitization measured by SPT among adult Korean subjects
• Sensitization rate to cat (8.8%) and dogs (20.4%)
• Global Asthma and Allergy European Network
• European adults coming to clinic for suspected allergy
to inhalant allergens:
• Sensitized to cat (26%) and dog (27%)
Schoos AM, et al. J Allergy Clin Immunol. 2021 Apr;147(4):1164-1173.
Prevalence of pet allergy

http://www.dogica.com/dogvscat.html

Chan SK, et al. Allergy Asthma Immunol Res. 2018 Mar;10(2):97-105.
Fel d 1
Fel d 4
Fel d 7
Fel d 2
Fel d 3
Fel d 5
Fel d 6
Fel d 8

Cat allergen
• Secretoglobin Fel d 1
• Major cat allergen (95% of patients with cat allergy)
• Not cross-reactivity with other mammalian sources
• Sequence identity between Fel d 1 and Ory c 3 (rabbit) is very low
• Primiarily produced in sebaceous, anal and salivary glands
• Mainly present in the epidermis and fur
• Fel d 1 is spread to environment predominantly through airborne dander
• Can be detected in homes without a cat
• Allergenicity of inhaled Fel d 1 can be increased by its binding to mannose receptors
on dendritic cells
• Initiating the process of internalization and production of Fel d 1-specific IgE and IgG1
• High IgE levels to Fel d 1 could be a marker of increased asthma risk
Dávila I, et al. Allergy. 2018 Jun;73(6):1206-1222.
Konradsen JR, et al. J Allergy Clin Immunol. 2015 Mar;135(3):616-25.
Fel d 1

Cat allergen
• Lipocalins
• Found in dander, saliva, and urine
• Sticky and easily become airborne
• Fel d 4
• Found primarily in cat saliva and corss-reacts with lipocalin allergens from other animals
(Can f 6, and Equ c 1)
• High levels of IgE antibodies to Fel d 4 associated with atopic dermatitis in cat allergy
• Fel d 7
• Not yet widely available for IgE testing but has been reported to bind IgE in 38% of cat
allergic subjects
• Fel d 7 and Can f 1 share a high sequence identity (62%) and cross-reactivity
Fel d 4 Fel d 7

Cat allergen
• Cat albumin
• Fel d 2
• Minor cat allergen
• Cross-react with other mammalian albumins
• Discovered through detailed analysis in groups of patient who report
pork-cat syndrome
• Initial sensitization occurred through cat albumin, subsequently resulted
in pork albumin sensitization
Fel d 2

EAACI Molecular Allergology User's Guide 2.0. 2022
Fel d 2/4 -
Fel d 2/4 +
Fel d 2/4 +
Fel d 2/4 -

Dog allergen
Can f 1
Can f 2
Can f 4
Can f 6 Can f 7
Can f 3
Can f 5

Dog allergen
• ‘Major allergen’: only > 50% of allergic patients need to react
• No dog allergen has been identified to have the extent of reactivity compared
with cat allergic individuals and Fel d 1
• Older dogs produce more dander than younger ones
• Skin is drier and some breeds are more prone to eczeman and oily seborrhea
• Seasonal variation also affects the level of dog IgE antibodies

Dog allergen
• Currently, there are 7 named dog component allergens identified as Can f 1-7 by
the International Union of Immunological Societies

Dog allergen
• Can f 1 (50-90% of dog allergic patients)
• Secreted from canine sebaceous glands
• Found in dog hair, dander, and saliva
• It becomes airborne with minimal
disturbance, remains airborne for a long
time, and can be inhaled into smaller
airways more easily than larger particles
• Detectable in all homes with dogs and
home without a dog (30%)
• Dog lipocalin allergens
• Highly conserved single 8-stranded
continuously hydrogen-bonded
antiparallel beta-barrel which
encloses a ligand-binding pocket
• These proteins can bind a range of
small hydrophobic molecules and cell
surface receptors
Can f 1
Can f 2
Can f 4
Can f 6

Dog allergen
• Can f 2 (20-30% of dog allergic patients)
• Patients with antibodies specific for Can f 2
also reacted to Can f 1
• Similar structure of Equ c 1 but no cross-
reactivity
Can f 2
Can f 4
Can f 6
Can f 1

Dog allergen
• Can f 4 (30% of dog allergic patients)
• Can f 6 (38% of dog allergic patients)
• Similar structure to Fel d 4
• Cross reacts with Fel d 4 and Equ c 1
• Found 61% in patients with combined
sensitization to cats and dogs
Can f 2
Can f 4
Can f 6
Can f 1

Dog allergen
• Can f 5
• Found 70% of dog allergic patients
• Detected in urine of male animals
• Mono-sensitized to Can f 5 could be a highly
specific marker for allergy to male dogs
• No patterns of cross-reactivity to allergens from
other furry animals
• Cross-reactivity to human prostate-specific
antigen (major allergen in seminal plasma)
• Suggesting sensitization to Can f 5 could be relevant
to seminal fluid allergy
• KALLIKREIN
Can f 5

Dog allergen
• Can f 3 (16% of dog sensitized patients)
• Serum albumins: highly abundant proteins present in
blood, dander, milk and other secretions
• Considered minor allergens with low prevalence of IgE
reactivity among patients allergic to its source
• Cross-reacts with allergens from other furry animals
• Serum albumins may play a significant role as cross-
reacting allergens in individuals sensitized to dander of
multiple animal species
• May play a role in the progression to polysensitization and
clinical allergies to other animals
• May explain why some atopic patients develop allergic
sensitization to mammalian allergens in the absence of
contact with animals
• Serum albumins
• Bos d 6 (domestic cattle)
• Cav p 4 (guinea pig)
• Equ c 3 (domestic horse)
• Fel d 2 (cat)
• Sus s 1 (domestic pig)
Can f 3 (dog)

Dog allergen
• Can f 7
• Member of ML family (implicated in lipid recognition of
pathogen related product)
• Immunoglobulin-like beta-sandwich fold similar to Ig domains
• Can f 7 also known as Niemann-Pick disease type C2 protein
• The exact role of Can f 7 in dogs remains unclear
• Recombinant Can f 7 has been found to bind IgE in 14-17% of
dog sensitized individuals
• Dog MD-2 related lipid recognition (ML) family
Can f 7

Can f 3/6 +
Can f 3/6 -

Mammalian allergens
• Lipocalins
• Majority of mammalian allergens
• Small, secreted molecules of 150-250
amino acid
• Tertiary structure, composed of
central β-barrel shape formed of
eight anti-parallel-β strands
• Present in dander, saliva, and urine
• Stick to particle and become airborne
easily
• Considered ‘species-specific allergy
markers’
• Serum albumin
• Large globular protien synthesized in liver
• Molecular weight of 65-69 kDa, composed of
607-608 amino acids
• Present in dander, saliva, milk, and meat
• Minor respiratory allergen from animal dander

• 60 patients aged 10–18 years with sensitization to dog dander were
included
• Spirometry, methacholine challenge, fraction of exhaled nitric oxide,
nasal challenge with dog extract and questionnaires were performed
• Asthma: reported physician's diagnosis of asthma
• Troublesome asthma: asthma diagnosis in combination with
exhaled fraction of exhaled nitric oxide (FeNO) > 35 ppb,
Methacholine PD20 < 2 μmol and ACT score < 20
Results:
• Children with troublesome asthma had higher IgE levels to the
lipocalins Can f 2, Can f 4 and Can f 6 compared to the rest of
the study population
• Polysensitization to furry animal allergens and lipocalins is
associated with asthma in dog-sensitized children
• Children with troublesome asthma have higher IgE levels to
several dog lipocalins than other dog sensitized children
Käck U, et al. Clin Transl Allergy. 2022 May 2;12(5):e12149.

Cross-reactivity patterns between
cats/dogs
• Lipocalins have amino acid sequences with up to 60% identity
• Can f 6 (dog), Equ c 1 (horse), Fel d 4 (cat), Ory c 4 (rabbit), Mus m 1 (mouse),
Rat n 1 (rat)
• sIgE to Fel d 1 also present in other feline families:
• Tigers, jagaurs, pumas, and lions
• sIgE to Can f 6 present in patients sensitized to dogs (38%) and
appears in in patients sensitized to dogs and cats (60%)

Cross-reactivity patterns
Schoos AM, et al. J Allergy Clin Immunol. 2021 Apr;147(4):1164-1173.

Characteristic of sensitization to
dogs or cats and its influence on
allergic diseases

Factors predicting sensitization and development
of dog and cat allergy
• Timing of allergens exposure
• Exposure of dogs and cats during the first year of life, along with genetic and
environmental factors, may decrease the risk of developing allergic asthma
• Exposure occurs after first year of age, the risk of sensitization and
development of allergic disease seem to be increased

• Should assessment of exposure be based on pet ownership or allergen levels?
• Homes in the UK with cats contained very low levels of Fel d 1, and homes without cats
contained very high levels
• Is there a dose—response relationship between exposure to pet allergen (Fel d 1 and Can f 1) and
specific allergen sensitization?
• Some children (high risk?) become sensitized to cat with very low levels of domestic exposure
to Fel d 1
• Too few data on Can f 1 exposures
• Is there an association between cat or dog ownership and sensitization to cat or dog, or to atopic
status?
• Pet ownership in childhood seems to be associated with a reduced risk of atopy in adulthood
Simpson A, et al. Curr Opin Allergy Clin Immunol. 2003 Feb;3(1):7-14.

• Is there an association between pet ownership and asthma diagnosis?
• Lack of association between current pet ownership and asthma symptoms
• European Community Respiratoty Health Survey found that those who did not keep cats were more
likely to have the diagnosis of asthma
Conclusion
• Passive exposure, particularly at school, is important among non-cat owners
• The effect of pet exposure in the home may be markedly differenr for the
different relative risk groups, based on parental history
• ‘Modified Th2 response’
• Some individuals in the high exposed group were not sensitized to cat had
the evidence of IgG and IgG4 to Fel d 1 but not IgE
• Suggesting a different immunological response to allergen
Simpson A, et al. Curr Opin Allergy Clin Immunol. 2003 Feb;3(1):7-14.

• Nationwide population register comprising all children aged 1–4 yr (N = 4779) living in
the province of South Karelia, Finland
• Cross-sectional questionnaire data on pet exposure in infancy and physician-diagnosed
pet allergies were obtained
• sIgE and skin prick tests indicating allergic sensitization abstracted from all patient
records in the area
Results
• The incidences of dog or cat allergy were higher among children with early exposure to
pet at home
Pyrhönen K, et al. Pediatr Allergy Immunol. 2015 May;26(3):247-255.

Dog
Cat
Pyrhönen K, et al. Pediatr Allergy Immunol. 2015 May;26(3):247-255.

Custovic A, et al. Pediatr Allergy Immunol. 2023 Feb;34(2):e13915.
• The trajectory of the development of cat sensitization differed between children
exposed to cat (and high Fel d 1 levels) in pregnancy and infancy compared with
those not exposed
• When children were aged 1 year: frequency of cat sensitization was much higher
among cat owners
• After age 1 year: the increase in sensitization rate was 6% lower per year among
cat owners compared to children without a cat
• Adolescence: the prevalence of cat sensitization was the same in both groups
• No association was observed between early-life cat exposure and sensitization to
allergens other than cat or asthma

Custovic A, et al. Pediatr Allergy Immunol. 2023 Feb;34(2):e13915.
The analyses of the impact of cat exposure can reveal either an increase risk,
no effect or protection, depending on the age of studied

Course of sensitization to dogs and cats
throughout life
• Sensitization to Can f 1 or Fel d 1 and polysensitization to cat and dog allergens
during childhood have been associated to the development of subsequent allergy
to dogs and cats
• Some patient develop a lower clinical response when they are continuously
exposed to significant allergen levels
• Cat allergic patient: concentrations of Fel d 1 over 44 µg per gram of powder
may cause them tolerating the presence of their pets
• There is no studies comfirming

Exposure to dogs and cats and risk of developing
sensitization or clinical symptoms upon exposure to
other mammalian allergens
• It is unclear whether sensitization to dogs or cats is a risk factor for sensitization
to other aeroallergens
• There seems to be an increased risk of sensitization to horse and mice in patients
previously sensitized to cats/dogs
• Could be related to cross-reactivity of lipocalins or albumins
• Mite allergic patients could have a higher risk of developing sensitization to dogs
if they own or previously owned a dogs

Dose exposure to dogs and cats have repercussions
for sensitization and clinical signs of exposure to
other allergens?
Evidence-based consensus recommendation statement
• In the case of patients who are allergic to dogs and cats that are
sensitized to albumin or lipocalins
• It is recommended that further exposure to other mammals be
avoided

Main food allergy syndromes in patients
sensitized to dogs or cats
• Pork-cat syndrome
• Secondary to cross-reactivity of Fel d 2 with other albumins from mammals
• Anaphylactic reactions after consuming pork (raw or undercooked)
• Alpha-gal syndrome
• Delayed anaphylaxis due to IgE to galactose-alpha-1,3-galactose
• Alphal-gal is present on cat IgA and IgM
• Evoking allergic symptoms after tick bites, cetuximan infusion, and in
mammalian red meat delayed allergic symptoms

Influence of dog or cat allergy on atopic dermatitis
• No definitive conclusions of role of dog and cat exposure in the development of
atopic dermatitis
• Some guidelines recommend avoiding or limiting contact with dogs and cats in
atopic dermatitis patients, depending on severity of signs and symptoms and
psychological stress getting rid of the pet

Quality of life in dog and cat allergy
• No specific studies have been found on the impact on the quality of life of
patients who are allergic to dogs and cats
• Recommendations are inferences from the quality of life of patients who suffer
from allergic respiratory diseases

What repercussions dose dog and cat allergy
have for quality of life?
Evidence-based consensus recommendation statement
• Given the potential effect of dog and cat allergy on quality of life,
its evaluation is essential for adoption the measures to improving
patients’s quality of life
• In dog or cat allergic patients, it would be appropriate to evaluate
quality of life by means of specific questionnaires to apply the
appropriate therapeutic/prophylactic measures

Immune response to cats and dogs

Immune response to cats and dogs: T-cells response
• T-cells response:
• Response to Fel d 1: Th2 type
• Evaluation of T-cell response to animal allergens is not part of routine
assessment of patients presenting with symptoms
• All studies on T-cell responses to Fel d 1 have focused on subjects with
positive skin test results

Immune response to cats and dogs: IgE and IgG
• The dissociation of allergen-specific IgE and IgG responses to cat, dog, and
horse was reported
• Indicating that nonsequential class-switch mechanisms are operative in
patients with animal allergy and might explain why naturally occuring
allergen-specific IgG is not always protective
• Measurement of IgG antibodies might also be relevant to understanding why
some subjects experience increased symptoms on entering a house with an
animal after a period of decreased exposure

• Participants 18 years of age were included
• Serum was assayed for cat and dog sIgE and
sIgG4 compared between symptomatic and asymptomatic
teens
Results:
• Teens experiencing allergic symptoms with cat exposure had
significantly higher cat sIgE and higher cat sIgG4, but a lower
ratio of cat sIgG4/sIgE than teens who did not report symptoms
• These relationships did not differ by current cat exposure
• This study do not confirm that sIgG4 is a strong predictor of
tolerance. The higher ratios of sIgG4/sIgE seen in participants
without allergic symptoms suggest that IgG4 may be associated
with tolerance to some degree
Burnett M, et al. J Allergy Clin Immunol Pract. 2013 Jul-Aug;1(4):350-3.

• Retrospective chart reviews, 28 patients sensitized to dogs in
early life
• Evaluated specific IgE to dog component allergens and
aeroallergens using microarray
Results:
• Can f 1 was positive in 77.8% of young children sensitized to
dogs and cosensitization to house dust mite was the most
common
• The symptomatic group tended to be poly-sensitized to Can f
1, Can f 2, and Can f 3
• Most of patients have been exposed to dogs not living with
• Can f 1 is detected in 1/3 of houses that do not own a dog
• Indirect exposure to dog allergens at low concentrations might
be disadvantages to obtaining tolerance
Lee J, Jeong K, et al. Asia Pac Allergy. 2020 Jul 27;10(3):e33.

Diagnosis and management of
allergy to cats and dogs

Diagnosis
• Diagnosis of dog and cat allergy based on
• Consistent medical history
• Physical examination
• Comfirmed with
• Positive skin test results or sIgE
• It is often necessary and advisable to perform molecular diagnosis, especially
in polysensitized patients
• Goal: acheiving short and long term symptom management

Usefulness of skin tests, determination
of specific IgE and molecular diagnosis
• Skin prick testing
• Inexpensive, simple and quick
• Different commercial dog SPT extracts, founding a 20-fold to 1000-fold variation
regarding the total protein content
• Commercially available dog extract used in skin testing is composed of multiple proteins and
their potency in extracts can vary considerably
• Dog component allergens have been identified in serum, dander, pelt, hair, saliva, and urine
• Extract prepared from dog liver, serum, salivary glands and keratinocytes contain fewer IgE
binding allergens compared to dander
• Can f 1 and Can f 2 varied considerably between the extracts
• Dander is the preferred source of commercial dog allergen extract preparations

• Serum-specific IgE extract
• Not reliable enough to predict whether the patient is allergic or sensitized
• Should be particularly used when patient’s symptoms and skin test results are
contradictory, especially before recommending allergen-specific
immunotherapy
• In case of cats, the determination of sIgE is highly sensitive tests, there is a
likelihood of false positives (less accurate than skin prick tests)

• Molecular diagnosis
• Using purified or recombinant allergens
• Usefulness in polysensitized individuals
• Sensitization specific to singular species VS sensitizations due to cross-reactivity
• Usefulness for predicting clinical symptoms and severity
• Dogs:
• Can f 1, Can f 5, Can f 4, and Can f 6 could be clinically significant
• Cats:
• Fel d 1 is predictive marker of allergy to cats

Usefulness of specific exposure tests
• To assess the clinical significance of sensitisation to an allergen
• Whenever there are discrepancies between medicatl history and diagnostic skin or serum
tests
• Assessment of the aetiological study of allergic respiratory diseases of
occupational origin, in medical/legal situations
• Assessment of drug efficacy
• Follow-up and monitoring of clinical response to allergen-specific IT

Usefulness of specific exposure tests
• Specific exposure tests in the case of inhaled allergens:
• Conjunctiva provocation
• Nasal provocation
• Bronchial provocation
• Confirm or rule out the involvement of an allergen in asthmatic patients
• May be needed in individuals who have persistent symptoms with exposure who are skin
test and specific IgE negative
• Available only in large research settings
• Very few publications have dealt in particular with specific exposure tests in allergy to
epithelia

• First strict avoidance
• Second combination of other measures
Environmental control
Goal: removing the animal from home

Measures of avoidance
• Washing dogs and cats regulary
• At least twice a week
• Reduction in the quantity of Fel d 1 from
cats and Can f 1 from dogs
• Keeping the pet out of the bedroom
• Applying topical lotions to the animal’s fur
• Encapsulated the allergens on the fur
• Spraying and neutering dogs and cats
• No specific recommendations
Mammalian allergens are
very stable and persist in house
dust up to 6 months

Measures of avoidance
• Air purifying using HEPA filters
• Regulary using and maintaining of high-efficiency
vacuum cleaners
• Using night-time temperature-controlled laminar
airflow
• Using covers and cases for mattresses and pillows
• Pore size equal to or less than 6 µm
• Removing pillows and other items that may act as a
reservoir
• Using bleach (sodium hypochlorite), tannic acid for
washing pillows and other reservoirs

Measures of indirect avoidance
• Changing their clothes when travel from places with a high
allergen concentration to places with a low concentration
• Reducing the dispersion of animal epithelia allergens
• If people who live with an allergic patient work with or have
been in contact with animals, they should change their
clothes and shower before returning home
• Family members and friends who have animals should
refrain from bringing them to the home of patient who is
allergic to epithelia
• In school, it would be advisable for students who live with
pets to wear clothes that have not come into contact with
these pets
• The presence of animals in classes should be avoided

Hypoallergic animals
• Hypoallergenic animals
• Advertised that ‘they shed less fur or have been bred to produce lower quantity of Can f 1
and Fel d 1 in their dander’
• Decreased shedding dose not eliminate exposure to dog/cat saliva nor to minor
allergens to which the individual may have been sensitized and may also play a
role in allergy symptoms
• There is no scientific evidence to support labelling certain breeds of cats and dogs
as hypoallergenic
• Hypoallergenic pet shoud not be recommended to patients who are allergic to
dogs and cats

• Symptomatic management:
• The use of anti-histamine
• Localized steroids use
Pharmacotherapy
When avoidance strategies have been
utilized but symptoms still continue

• Subcutaneous immunotherapy (SCIT)
• Slow introduction of allergens to gradually larger doses and consistent
exposure to high levels of allergen during immunotherapy for 3-5 years
• Changes in T cell function:
• Shift a way from Th2 to Th1 phenotype
• Induction of regulatory T cells
• Data on dog allergen SCIT show evidence of effectivenss but is clinically less
effective than for cats
Immunotherapy

• Dog immunotherapy
• First Double-Blinded Placebo-Controlled Trial in 1984
• 27 children with asthma and dog allergy
• Dog dander extracts (15) and placebo injections (12)
• The patients' responses were evaluated by bronchial and conjunctival provocation challenges
and symptom scores
• After 12 months of immunotherapy:
• 80% of patients had improved tolerance to the conjunctival challenge compared with
17% who received placebo
• 40% of patients had improved tolerance to dog allergen bronchoprovocation compared
with 17% who received placebo
• 53% of patients had improved by subjective symptoms compared with 50% who received
placebo
• Specific immunoglobulin (Ig) E did not significantly change, but specific IgG increased
significantly
Immunotherapy
Smith DM, et al. Ann Allergy Asthma Immunol. 2016 Mar;116(3):188-93.

• In 2006, Lent et al. determine the most effective dose of dog immunotherapy
• Following immunologic markers at differing doses of Can f 1 up to 15 μg, a dose noted to be the most
effective dose in an antecedent study involving cat extract
• 27 patients received cluster immunotherapy for 5 weeks
• Outcomes: skin prick test positivity, nasal challenge, serum specific IgE, and IgG4
• After immunotherapy:
• Dose-dependent response was noted in suppression of skin prick testing and an increase
in IgG4
• There was no change in symptoms scores after nasal challenge
• Dog immunotherapy is “likely effective” because many of the same immunologic parameters
were similar as the antecedent Fel d 1 dosing trial (which did show clinical efficacy)
Immunotherapy

• SCIT with a complete dog extract in adults and children with
rhinoconjunctivitis, allergic rhinitis, and asthma
• Optimal dose: a dose containing 15.0 µg Can f 1 per 0.5 mL maintenance dose
• Reduction in the size of skin tests
• Increase in serum IgG and IgG4
• But not a significant clinical efficacy
• Systemic reaction rate: 0% to 0.3% in subjects receiving dog extracts
Immunotherapy

• Cat allergy
• SCIT with cat extract in adult patients with conjunctival, nasal and bronchial
provocation with cat with rhinoconjunctivitis and and asthma after 12 months
of treatment
• Optimal dose: a dose containing 15.0 µg Fel d 1 per 0.5 mL maintenance dose
• Reduction in the size of skin tests
• Dose-dependent increase in total IgG and IgG4
• Significant clinical improvement
• SLIT with cat extract has demonstrated significant improvement in nasal, eye
and bronchial symptoms in adult patients after 12 months of treatment
Immunotherapy

• Specific component can also be therapeutic targets
• Recombinant proteins, peptides, recombinant hypoallergens
• Mimic natural protein
• Modified to be less allergenic
• The use of allergy vaccination of Can f 1, Fel d 1
• Reduced ability to cross link IgE epitope, not initiate mast cell degranulation
cascade (less allergenic)
• Induce T cell tolerance through induction of regulatory T cells
• Side effects in clinical trials: exhibited late asthma reactions without
cutaneous response (overlapping of peptide treatment)
Novel therapies under
development

Summary of key factors in
cat and dog allergies
Key factor Cats Dogs
Dominant allergen Up to 96% of all cat
allergic patients react to
Fel d 1
Up to 64% of all dog
allergic patients react to
Can f 1
Identified named component allergens 8 7
Extract Standardized for skin testing and IT Yes,
based on Fel d 1
(5,000 BAU/mL)
No
Clinical effectiveness of IT Yes Possible
Routinely used for IT in clinical practice Yes Yes
Clinical study for peptide-based vaccines Yes Yes
Hypoallergenic animal No No

Exotic pet allergy
• Exotic mammals are the largest group of uncommon pets
• Most frequent symptoms presented after exposure to these
animals
• Rhinitis, conjunctivitis, and asthma affect the upper and lower
respiratory tract
• Prairie dog, chinchilla, guinea pig, ferret, gerbil, hamster, hedgehog,
rabbit, hare, and monkey
• Contact urticaria
• Chinchilla ferret, and hedgehog
• The owner was bitten by the animal, the subsequent symptoms
reported varied from urticaria or respiratory discomfort to
anaphylactic shock
• Gerbil, hamster, sunda slow loris, and mouse
https://www.npr.org/templates/story/story.php?storyId=129
198893
Díaz-Perales A, et al. Front Immunol. 2013 Dec 30;4:492.

Phillips JF, et al. J Allergy Clin Immunol. 2009 Feb;123(2):513-5.

Rabbit
• Rabbit allergens are identified in hair, dander,
and urine
• Lipocalin: Ory c 1, Ory c 2, and Ory c 4
• Secretoglobulin: Ory c 3
• Liccardi and Passalacqua reported rabbit dander
sensitization in 39 patients of 2329 undergoing skin-prick
testing
• 19 of the positive individuals reporting regular contact
with rabbits
• 4 of the patients were only sensitized to rabbit dander
• All had persistent respiratory symptoms
https://hypoallergenichomes.com/hypoallergenic-pets/rabbits/

Siberian/Dwarf hamster
• Case reports of anaphylactic reactions to hamster bites
• 2 cases involving the bite of a Siberian/dwarf hamster (Phodopus
sungorus), both patients developed finger swelling followed by
diffuse urticaria (1st patient) and palpitations and bronchospasm
(2nd patient)
• Both patients were negative to allergen-specific IgE derived from
common hamster (Cricetus cricetus)
• SDS-PAGE and IgE immunoblot on dwarf hamster saliva and
identified a 21-kd protein that was bound to IgE antibody in the
sera of 2 patients
• Several case reports of rhinoconjunctivitis possibly
secondary to aerosolized Siberian/dwarf hamster allergens
https://biologydictionary.net/dwarf-hamster/

Ferret (Mustela putorius furo)
• Domestic ferret (Mustela putorius furo)
• An individual presented with severe asthma exacerbation after
washing his ferret
• Extracts were prepared from ferret products, and the patient
demonstrated positive SPTs to ferret hair, male urine, and female
urine The patient’s serum IgE was also bound to 4 high-
molecular-weight protein bands in the male and female ferret
urine
• Another study identified a 66-kd protein in ferret extract prepared
from lyophilized antigen obtained from ferret hair, urine, feces, and
bedding material
• This protein was theorized to represent ferret albumin because of
its in vitro cross-reactivity with cat albumin
https://glurgang.com/ferret/

Iguana (Ergenia cunningami)
• A 32-year-old man with nasal congestion, rhinorrhea, cough, and wheezing occurring exclusively in his
home, which contained 2 dogs, 2 cats, and 2 iguanas
• He was found to be SPT-negative to the furred pets but positive to an extract of pulverized scale
harvested from the iguana
• The patient’s serum also demonstrated significant concentrations compared with healthy control of
radiolabeled antihuman IgE to proteins found in scale extract from both his iguana and other species of
iguana from a nearby zoo
• A case of cutaneous hypersensitivity to an iguana bite in a 13-year-old boy.
• He had been bitten several times on both of his fingers and wrists
• Biopsy of the lesions: focal epidermal spongiosis and lymphocytic infiltrate,
with occasional eosinophils and mast cells.
• Cultures were negative, the patient improved with oral antibiotics and topical
steroids
• The authors speculate that proteins in the iguana’s saliva or possibly plant
food in its mouth were the causative agent
http://blogs.thatpetplace.com/thatreptileblog/2012/05
/23/green-iguana-care-housing-diet-and-handling/

Gerbil (Meriones unguiculatus)
• Gerbil allergen:
• Mer un 23kDa (Lipocalin)
• Mer un 4 (Serum albumin)
• 3 patients with symptoms ranging from isolated nocturnal
wheezing to daily rhinorrhea and sneezing
• Each patient demonstrated positive SPTs to gerbil hair and serum,
with negative reactions to common allergens
• Two of these patients demonstrated specific IgE antibodies by
RAST to extracts prepared from gerbil hair and serum
https://th.wikipedia.org/wiki/มองโกเลียนเจอร์บิล

Monkey
• In 2004, 49-year-old man with a history of allergic asthma and positive
skin tests to cat and dog who subsequently developed rhinoconjunctivitis
and wheezing after long-term exposure to a pet macaque monkey
• Investigation:
• An extract from commercially available monkey hair
• Anti-monkey IgE in the test case
• However, they also demonstrated the presence of this same antibody in
another nonatopic exposed individual (the patient’s wife) and an atopic
individual (one of the study investigators) who were exposed during a
house visit
• Management:
• The patient demonstrated significant improvement on removal of the
monkey from the home Phillips JF, et al. J Allergy Clin Immunol. 2009 Feb;123(2):513-5.
https://en.wikipedia.org/wiki/Macaque

Díaz-Perales A, et al. Front Immunol. 2013 Dec 30;4:492.

• Burnett M, Wegienka G, Havstad S, Kim H, Johnson CC, Ownby D, Zoratti E. Relationship of dog- and cat-specific IgE and IgG4 levels to allergic symptoms on pet exposure. J Allergy
Clin Immunol Pract. 2013 Jul-Aug;1(4):350-3.
• Chan SK, Leung DYM. Dog and Cat Allergies: Current State of Diagnostic Approaches and Challenges. Allergy Asthma Immunol Res. 2018 Mar;10(2):97-105.
• Custovic A, de Moira AP, Murray CS, Simpson A. Environmental influences on childhood asthma: Allergens. Pediatr Allergy Immunol. 2023 Feb;34(2):e13915.
• Dávila I, Domínguez-Ortega J, Navarro-Pulido A, Alonso A, Antolín-Amerigo D, González-Mancebo E, Martín-García C, Núñez-Acevedo B, Prior N, Reche M, Rosado A, Ruiz-
Hornillos J, Sánchez MC, Torrecillas M. Consensus document on dog and cat allergy. Allergy. 2018 Jun;73(6):1206-1222.
• Díaz-Perales A, González-de-Olano D, Pérez-Gordo M, Pastor-Vargas C. Allergy to uncommon pets: new allergies but the same allergens. Front Immunol. 2013 Dec 30;4:492.
• Käck U, van Hage M, Grönlund H, Lilja G, Asarnoj A, Konradsen JR. Allergic sensitization to lipocalins reflects asthma morbidity in dog dander sensitized children. Clin Transl
Allergy. 2022 May 2;12(5):e12149.
• Konradsen JR, Fujisawa T, van Hage M, Hedlin G, Hilger C, Kleine-Tebbe J, Matsui EC, Roberts G, Rönmark E, Platts-Mills TA. Allergy to furry animals: New insights, diagnostic
approaches, and challenges. J Allergy Clin Immunol. 2015 Mar;135(3):616-25.
• Lee J, Jeong K, Jeon SA, Lee S. IgE recognition profile of aeroallergen components in young children sensitized to dogs. Asia Pac Allergy. 2020 Jul 27;10(3):e33.
• Phillips JF, Lockey RF. Exotic pet allergy. J Allergy Clin Immunol. 2009 Feb;123(2):513-5.
• Pyrhönen K, Näyhä S, Läärä E. Dog and cat exposure and respective pet allergy in early childhood. Pediatr Allergy Immunol. 2015 May;26(3):247-255.
• Schoos AM, Nwaru BI, Borres MP. Component-resolved diagnostics in pet allergy: Current perspectives and future directions. J Allergy Clin Immunol. 2021 Apr;147(4):1164-1173.
• Simpson A, Custovic A. Early pet exposure: friend or foe? Curr Opin Allergy Clin Immunol. 2003 Feb;3(1):7-14.
• Smith DM, Coop CA. Dog allergen immunotherapy: past, present, and future. Ann Allergy Asthma Immunol. 2016 Mar;116(3):188-93.
References

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