Flea allergy Flashcards
Learner objectives
- Flea life cycle
- Areas of body affected by FAD
- Primar lesion of FAD
- Immunologic reaction types to FAD
- Show signs of FAD with no fleas present
- diagnoses/ rule outs FAD
C. felis
- yersinia pestis
- murine typhus
- tularemia
- diplidium caninum
- rickettsia felis
- baronella heselae (cat scratch dz)
Flea life cycle
Larvae
Pupa
Adult
- Larvae: 3 stages, feed on organic debris and flea poop, neg phototactic
- Pupa: cacoon env mat, resistent dessication, freezing, insectisides
- adult stim by mech press, body temp, low conc exhal CO2
- Adult: need blood meal to reproduce, AC/heat can kill, most live on host
Duration flea life cycle and facts
- Can be completed in as little as 13 days
- don’t survive above 5,000 ft elevation
- somewhat dependant on humidity
Fleas may be groomed off by host in …
flea allergy dermatitis
Sand fleas
Common flea breeding outdoors in soil
Four phases of immunologic response to flea exposure
- Delayed hypersensitivity (Type IV) (24-48 hours)
- Combined delayed and immediate phase
- Immediate hypersensitivity (Most FAD patients) (Type I)
- Anergy or spontaneous desensitization (non-allergic animals) (tolerance)
Lack of exposure neonatally and/or intermittent exposure
may contribute to later development of flea allergy in the dog
More than 50% of atopic dogs
are flea allergic in areas where fleas are plentiful
Common age of onset for FAD
1-5 years, possibly later in dogs retired from flea naive environments
Primary lesions of FAD
- Papules which may develop into small crusts
- rash is very pruritic
- symptoms noticed by owners usually self-inflicted/secondary lesions
- excoriation
- alopecia
- lichenification
- scaling
- crusting
Affected sites of FAD
- Bermuda triangle
- Lower back
- perineum
- tail head
- hind lmbs
- umbilical region
*lesions usually spare the head
three most pruritic skin diseases of dogs
- FAD
- Food allergy
- Scabies
Staphylococcal folliculitis
- common development secondary to FAD
FAD symptoms
- May wax and wane
- difficult to manage
- look out for iatrogenic cushings
Cat FAD
- may present like in dogs
- possible generalized miliary dermatitis
- scabby cat disease
FSA
- Feline symmetric alopecia: alopecia with no dermatitis
- May be associated with eosinophilic plaque or granuloma
Diagnosis of FAD
- based on clinical findings
- positive response to therapy is confirmatory
FAD ddx dog
- atopy
- scabies
- food allergy
- drug hypersensitivity
- bacterial folliculitis
FAD ddx cat
- miliary dermatitis
- alopecia sections
Even minimal exposure to fleas in FAD
- May be sufficient to perpetuate hypersensitivity
- hypersensitive patients may remove fleas
- animals may have been dipped before being seen
- look for flead dirt
- look for tapeworms or recent history
Intradermal skin test
- positive reaction useful
- negative reaction does not rule out hypersensitivity
Therapy for FAD
- Flea control
- eradicate fleas in environment
- eliminate fleas on all pets
- Antipruritic therapy
- treat pyoderma
- corticosteroids
Hyposensitization
- immunotherapy
- Doesn’t work
- study found a solution but too expensive
