Flea allergy

Question 1

Learner objectives

1. Flea life cycle
2. Areas of body affected by FAD
3. Primar lesion of FAD
4. Immunologic reaction types to FAD
5. Show signs of FAD with no fleas present
6. diagnoses/ rule outs FAD

Question 2

C. felis

Answer 2

• yersinia pestis
• murine typhus
• tularemia
• diplidium caninum
• rickettsia felis
• baronella heselae (cat scratch dz)

Question 3

Flea life cycle

Larvae

Pupa

Adult

Answer 3

1. Larvae: 3 stages, feed on organic debris and flea poop, neg phototactic
2. Pupa: cacoon env mat, resistent dessication, freezing, insectisides
   
   • adult stim by mech press, body temp, low conc exhal CO2
3. Adult: need blood meal to reproduce, AC/heat can kill, most live on host

Question 4

Duration flea life cycle and facts

Answer 4

• Can be completed in as little as 13 days
• don’t survive above 5,000 ft elevation
• somewhat dependant on humidity

Question 5

Fleas may be groomed off by host in …

Answer 5

flea allergy dermatitis

Question 6

Sand fleas

Answer 6

Common flea breeding outdoors in soil

Question 7

Four phases of immunologic response to flea exposure

Answer 7

1. Delayed hypersensitivity (Type IV) (24-48 hours)
2. Combined delayed and immediate phase
3. Immediate hypersensitivity (Most FAD patients) (Type I)
4. Anergy or spontaneous desensitization (non-allergic animals) (tolerance)

Question 8

Lack of exposure neonatally and/or intermittent exposure

Answer 8

may contribute to later development of flea allergy in the dog

Question 9

More than 50% of atopic dogs

Answer 9

are flea allergic in areas where fleas are plentiful

Question 10

Common age of onset for FAD

Answer 10

1-5 years, possibly later in dogs retired from flea naive environments

Question 11

Primary lesions of FAD

Answer 11

• 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

Question 12

Affected sites of FAD

Answer 12

• Bermuda triangle
  
  • Lower back
  • perineum
  • tail head
• hind lmbs
• umbilical region

*lesions usually spare the head

Question 13

three most pruritic skin diseases of dogs

Answer 13

1. FAD
2. Food allergy
3. Scabies

Question 14

Staphylococcal folliculitis

Answer 14

• common development secondary to FAD

Question 15

FAD symptoms

Answer 15

• May wax and wane
• difficult to manage
  
  • look out for iatrogenic cushings

Question 16

Cat FAD

Answer 16

• may present like in dogs
• possible generalized miliary dermatitis
  
  • scabby cat disease

Question 17

FSA

Answer 17

• Feline symmetric alopecia: alopecia with no dermatitis
• May be associated with eosinophilic plaque or granuloma

Question 18

Diagnosis of FAD

Answer 18

• based on clinical findings
• positive response to therapy is confirmatory

Question 19

FAD ddx dog

Answer 19

• atopy
• scabies
• food allergy
• drug hypersensitivity
• bacterial folliculitis

Question 20

FAD ddx cat

Answer 20

• miliary dermatitis
• alopecia sections

Question 21

Even minimal exposure to fleas in FAD

Answer 21

• 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

Question 22

Intradermal skin test

Answer 22

• positive reaction useful
• negative reaction does not rule out hypersensitivity

Question 23

Therapy for FAD

Answer 23

1. Flea control
   
   • eradicate fleas in environment
   • eliminate fleas on all pets
2. Antipruritic therapy
   
   • treat pyoderma
   • corticosteroids

Question 24

Hyposensitization

Answer 24

• immunotherapy
• Doesn’t work
• study found a solution but too expensive