Unpleasant and poorly localized sensation that elicits the desire of scratching. It is The most common complaint in veterinary dermatology! Biological response: probably originated as a defense mechanism against ectoparasites
what is PVAS?
pruritus visual analogic scale; a method to quantify pruritus according to the owners
Lesions/Clinical manifestations of pruritus--> Acute vs chronic?
Every individual is able to stand a certain degree of pruritus without scratching (threshold). Different individuals have different thresholds. Also, Different pruritic stimuli are usually additive--> Two stimuli on their own do not cause scratching can reach the threshold when present together.
3 main categories of DDx of pruritus in dogs? (subcategories within thesE?)
An allergic animal can be hypersensitive to multiple allergens. The most common cutaneous allergies in dogs are (in order): Flea allergy dermatitis, Atopic dermatitis, Food allergy
Flea allergy dermatitis--> what is going on in this condition?
Allergic reaction against flea (Ctenocephalides felis felis) bites. Not a simple flea parasitism! There are several allergens found in flea saliva (glycoproteins MWs 8-90 kD) which leads to Type I and type IV hypersensitivity
flea allergy dermatitis is what kind(s) of hypersentivity(s)?
Type I and type IV hypersensitivity
pic of flea lifecycle and flea pyramid
is flea allergy dermatitis seasonal?
Patients may be affected seasonally or non-seasonally depending on geography
what other condition is flea allergy dermatitis usually associated with?
Frequently associated with atopic dermatitis (pruritus threshold!)
what is clinical signs/distribution like for flea allergy dermatitis?
Severe pruritus predominantly in the lumbosacral area and caudal half of the body (“pants”). Primary lesion: papules. Secondary lesions: alopecia, erythema, scaling, crusts, lichenification, pyotraumatic dermatitis
are feet commonly affected with flea allergy dermatitis?
feet usually spared (think "pants")
flea allergy dermatitis-- "california triangle" distribution she called it. In pants area
how do you dx flea allergy dermatitis?
In most cases the diagnosis is based on history and clinical signs. Confirmation can be obtained with.....: Evidence of fleas or flea faeces (flea dirt), Good response to flea control program (8 weeks), Flea allergy test (serology/intradermal) (she said: Don’t do this!! This is really expensive and silly)
how long on a flea control program before the pruritus is gone?
how effective is a Flea allergy test (serology/intradermal)?
Don’t do this!! This is really expensive and silly
how do you tx flea allergy dermatitis? (2)
(1) Flea control (2) Anti-pruritic drugs (ex. Prednisone; short term)
you were beginning to think the itchy dog had flea allergic dermatitis, but you did an exam and you couldn't find any fleas or flea dirt. what do you think?
The absence of fleas or flea dirt does not rule out FAD!
what are the 3 principals of flea control?
(1) The main objective is to prevent flea bites (2) All animals have to be treated (dogs / cats, allergic or non-allergic) (3) Environmental treatment is very important if free roaming animals enter the house
which topical adulticide is NOT recc for tx of fleas for flea allergic dermatitis?
which topical adulticide are recc for tx of fleas for flea allergic dermatitis?
Imidacloprid, fipronil, indoxicarb, dinotefuran, q 3 weeks, or Imidacloprid collar
what are systemic adulticides which you can use to help tx flea allergy dermatitis? (4)
Spinosad q 3 weeks to monthly, Nitenpyram as needed, Afoxolaner q 4 weeks, Fluralaner q 3 months
how effective are IGRs (insect growth regulators) in tx of flea allergic dermatitis?
The use of IGRs alone for FAD is not appropriate ( doesnt kill adult so dont use in flea allergic pt)
what can you do for Environmental control for flea allergic dermatitis?
Vacuum daily! Use of environmental microencapsulated adulticides or IGR (sprays and foggers), In most households, control of the pets is enough to contain the infestation
No involvement of the immune system! Reactions are dose dependant (Histamine-rich foods). Gradual onset of clinical signs; never life-threatening
what is Food allergy?
Type I, III, and IV hypersensitivity reactions. Any amount of offending food will cause reaction. CAN be life threatening.
which is life threatening- food intolerance or food allergy?
what types of hypersensitivity does food allergy invoke?
Type I (allergies), III (immmune complex), and IV (Delayed-type hypersensitivity,cell-mediated immune memory response, antibody-independent aka contact HS) hypersensitivity reactions
allergy vs intolerance--> which reaction is dose-dependant?
Cutaneous adverse food reactions (CAFR)--> what is the usual signalment for this?
33-50% < 1 year of age, > 6 years of age, any age. No sex predilections. No breed predilections.
why is it like impossible to know the true incidence of Cutaneous adverse food reactions
Often occur in conjuction with other allergic diseases, therefore true incidence is unknown
Cutaneous adverse food reactions---> is this seasonal? How effective are steroids?
Non- seasonal pruritus!! Only partially responsive to steroids
how does Cutaneous adverse food reactions present? Distribution?
Erythema, signs of self-trauma. Can be 2* infections. Distribution: Face, neck, abdomen, perianal and perioral regions, paws. You can also see Otitis externa and Concurrent GI signs in 20% cases
in Cutaneous adverse food reactions, what is the most common offending allergins in dogs?
typically meat proteins: Beef, chicken, soy, dairy, corn, wheat
what are some "novel" proteins which OFTEN cross-react with already allergenic proteins?
Duck, turkey, venison, buffalo
how do you dx Cutaneous adverse food reactions?
8 week elimination diet followed by a challenge with the previous diet (2 weeks) (Serum allergy tests and saliva tests are not reliable!!!)
how useful are Serum allergy tests/ saliva tests for dx Cutaneous adverse food reactions?
NOT USEFUL. DONT DO
what are three options for dietary changes for the elimination diet for d?
(1) Home cooked diet following guidance of a veterinary nutritionist or BalanceIT.com (2) Prescription novel protein diet (Kangaroo, rabbit, fish, duck, venison) (3) Prescription diet based on hydrolyzed proteins (low molecular weight proteins, diets liek HA, HP, z/d, Anallergenic (Ultamino) )
what is important to know about over the counter novel diets?
over the counters arent regulated like the prescription ones, often still have contaminants. NOT APPROPRIATE to use for an elimination diet trial (they often switch foods they are making without cleaning the equipment)
how do you treat Cutaneous adverse food reactions?
(1) Maintain on a novel or hydrolyzed protein diet lifelong (2) Perform sequential dietary rechallenge to find what food sources are tolerated
flowchart for DIAGNOSTIC PROTOCOL FOR SUSPECTED CASES OF FOOD ALLERGY