Flea allergic dermatitis

Question 1

Why are fleas important?

Answer 1

• Most common skin disease of dogs and cats in the world
• Fleas are contagious and zoonotic! Vectors for tapeworm (Dipylidium caninum) and other diseases

Question 2

What is Pruritic dermatosis?

Answer 2

• Pruritus associated with hypersensitivity to salivary proteins of flea (Type I +/or Type IV)
• Leads to self trauma by pet

Question 3

What are the clinical signs of FAD in the dog?

Answer 3

Affected areas - especially: caudal half of the body (tail base, thighs, inguinal area) , dorsum

• Scratching
• Biting skin
• Jumping up suddenly
• Excess licking/over grooming
• Alopecia
• Skin inflammation +/- skin infection
• Crusting
• Lichenification

Question 4

What are the clinical signs of fleas in the cat?

Answer 4

• Head & neck pruritus
• Miliary dermatitis
• Self-induced alopecia
• Eosinophilic granuloma complex lesions
  = Feline cutaneous reaction patters

Question 5

How can you demonstate the presence of fleas?

Answer 5

• Flea comb - Vigorous coat brushing – examine debris on moistened paper –> red/brown tinge

But
false negatives common
- cats may remove all evidence of fleas from their coat, particularly if flea allergic

Therefore failure to detect fleas, i.e. negative finding, is unreliable!

Question 6

What are the two methods are testing for hypersensitivity of fleas? (this is not done often)

Answer 6

Intradermal test
Inject flea salivary allergen intradermally
But
* up to 30% false +ve reactions
* FAD may involve Type I (immediate) or Type IV (delayed) hypersensitivity. But tests often not read after 48 hours, so Type IV reaction missed –> false -ve

In vitro/serological test
Measures antigen-specific IgE (Type I reaction) but not delayed (Type IV) reaction
* Negative result of limited value

Question 7

what is the best/most reliable method to diagnose prurutis when you are susspicious of fleas?

Answer 7

response to therapy:
* Range of effective and ineffective products – chose an effective one!
* Diagnosis is confirmed by response to thorough flea control trial

Question 8

What is the life cycle of a flea? And what is the principle behind flea control?

Answer 8

Flea life cycle usually 3-4 weeks but range 2 weeks - 6 months, depending on environmental conditions

Most of life cycle in environment:
Pupal window
* nothing kills the pupa so need to kill emergent adults before they bite – environmental control essential, initially at least
* May take 3 months+ before fleas fully eliminated
ensure your client is aware of this!

Question 9

What are the general categories of flea control products?

Answer 9

• Mechanical removal* (eg, flea combing, vacuum cleaning)
• Repellants
• Adulticides*
• Larvicides
• Ovicides
• Insect growth regulators*
  
  • Juvenile hormone analogues
  • Chitin synthase inhibitors

*most commonly used

Question 10

Name 4 active ingredients that are effective agaist fleas?

Answer 10

• imidacloprid
• Selamectin
• fipronil
• isoxazolines

Question 11

What are the prinicples behind chosing a product to treat fleas?

Answer 11

Fast-acting adulticide

• Which animals? Treat all susceptible in-contacts (dogs/cats/rabbits)
• Which product?
  
  • Products to optimise compliance
  • Products to suit patient’s lifestyle – e.g. systemic treatments if swim or bathed regularly
  • NB concern re environmental impact of non-systemic spot-ons (e.g. fipronil, imidacloprid)
  • Beware toxicity to patient!
    
    • Fipronil and rabbits
    • Cats and permethrins (except flumethrin)
    • Isoxazolines if history of seizures
• Consider toxicity to owner – spot-ons?

Question 12

Is it necessary to treat the environment when trying to remove fleas? Explain

Answer 12

yes - Essential with spot-on adulticides, even if product claims environmental activity against eggs/larvae, due to…
* more complete coverage of environment
* need to kill emergent adult before feeding

NB isoxazolines may be effective alone in uncomplicated cases of flea infestation, due to very rapid speed of kill. But still best to treat environment if possible

Question 13

How do you treat the environment when dealing with fleas?

Answer 13

Physical cleaning – e.g. hoover, hot wash bedding

Plus
Environmental spray – most common
containing
* IGR (lasts 1yr) and adulticide (permethrin-based – lasts 6-8 weeks)
* Repeat after 6-8 weeks if treating current infestation
* Read instructions, including re safe product use
* prevent contact with fish/birds/exotic pets; use carefully in household with cats

Treat anywhere fleas can hide - especially carpeted areas, soft furnishings (test inconspicuous area first!), under furniture/skirting boards, down arms of chairs etc. Remember cages, cars!

or
Other environmental treatments
* Dessicants – e.g. sodium polyborate powders
* Diatomaceous earth – physically disrupts flea exoskeleton
* Biological treatments – outdoors – ‘beneficial nematodes’ – available in granules

Question 14

Your pharmacy stocks 4 products that treat ectoparasites: Advantage (imidacloprid), Advantix (imidacloprid + permethrin), Frontline Combo (fipronil + S-methoprene), Simparica (sarolaner).
Which would you prescribe to an owner with a dog that has fleas but swims in the river daily?
1. Advantage (imidacloprid)
2. Advantix (imidacloprid + permethrin)
3. Frontline Combo (fipronil + S-methoprene)
4. Simparica (sarolaner)

Answer 14

4. Simparica (sarolaner)