What is the most common skin condition of dogs and cats?
flea allergy dermatitis
What is the most common flea species parasitizing cats AND dogs?
What two other species can parasitize companion animals?
Are they host specific?
Pulex irritans (human flea) and Echidnophagia gallinacea (the avian “sticktight” flea) can also infest these companion animals. Ctenocephalides canis is uncommon.
Not host specific
What pathogens can C. felis harbor?
Yersinia pestis (plague)
murine typhus and tularemia
Rickettsia felis (rickettsiosis)
Bartonella henselae (cat scratch disease).
What is the most common location to find avian stick-tight fleas (Echidnophagia gallinacea)?
margin of the pinnae
How long is the lifecycle of C. Felis?
21 days (3 weeks)
What are the ideal conditions for the survival of fleas?
Temp: 65-80 degrees F
low altitudes (does not do well >5,000 ft above sea level)
Which insecticides are the flea eggs susceptible to?
Instant growth regulators:
methoprene (just after laying)
pyriproxyfen for several hours
What is the food source for flea larva?
organic debris and blood filled flea feces
What are the flea seasons in FL?
spring and fall (temp 65-80 degrees)
What is the most resistant stage of the flea life cycle?
pupa (can be dormant for many months)
What causes fleas to emerge from their cocoon?
What is the first thing a young flea that has just emerged from its cocoon need to do?
mechanical pressure/vibration, body temp., low concentrations of CO2
Describe the lifecycle of the flea?
What are the predisposing factors for an animal to develop a flea allergy?
- lack of exposure neonatally or at a young age
- intermittent exposure
- small amounts
What are the possible phases of immune response to fleas?
1. Delayed hypersensitivity (Type IV) (24, 48 hours)
2. Combined delayed and immediate phase
3. Immediate hypersensitivity (Most FAD patients) (Type I; IgE)
4. Anergy or spontaneous desensitization (Non-allergic Animals) (tolerance)
also, Cutaneous basophil hypersensitivity
What is the primary lesion of FAD?
What is age and breed predisposition for FAD?
age 1-5 yrs (as early as 2 mo in FL)
T/F FAD is among the three most pruritic dz in dogs.
Where are the lesions most often seen d/t chronic self-trauma with a FAD?
back half of the dog: lower back, perineum, tailhead, hind legs, umbilical region
"racing stripe dermatitis"
If a patient comes in with intense itching but you cannot find any fleas, can you r/o FAD?
NO (only takes a couple of fleas to cause itching)
What secondary infection is common with FAD?
With a FAD, are signs constant?
no they wax and wane
worsen from year to year and are variable in severity
What are some behaviors dogs will show with a FAD?
corn cob biting of the paws
going under tables to scratch the back
What are the top three most pruritic skin diseases?
What are the ways FAD may present in cats?
1. Like the dog
2. tail-head or miliary dermatitis (scabby cat disease)
3. Alopecia w/ no dermatitis (feline symmetric alopecia)
4. associated w/ eosinophilic plaque or granuloma
What are the main DDX for a dog that presents for symptoms characteristic of FAD?
Differential dx dog - atopy, scabies, food allergy, drug hypersensitivity, bacterial folliculitis.
Remember there can be combinations of allergic diseases in an individual animal, and secondary folliculitis is common.
What is a parasite that can be tested for that would indicate the presence of fleas?
tape worms (DC)
Is histopath useful to DX FAD? What is the result of histo for FAD?
no, non-specific (use to r/o other conditions)
Primarily a superficial perivascular dermatitis with eosinophils
What types of diagnostics can be performed to determine FAD?
intradermal skin test (if neg, does not r/o)
animal carriers in the home
What are the key parts of tx for FAD?
eradicate fleas in the environment
eliminate fleas on all pets
Does hyposensitization therapy for FAD work?