April 2008
Dermatology
Edmund J. Rosser, Jr., DVM, DACVD
Professor of Dermatology
Michigan State University
College of Veterinary Medicine
Diagnosis and Treatment of Food Allergy in Dogs and Cats
Prospective Clinical Evaluation of Food Allergic Dogs and Cats
Previous recommendation of a 3 week elimination diet trial was empirical
Initial recommendation in this study was to feed a home-cooked restricted diet for 60 days
In several instances the results were equivocal after 60 days and the diet was fed an additional 30 days.
Data Collected
Time elapsed before maximal clinical response on diet
Time elapsed before return of initial clinical signs when fed previous diet
Age, breed, sex, clinical signs
Responsiveness to glucocorticoids
Concurrent disease conditions
Final treatment diets
Diets Fed
Formulated based on known past exposure
Avoided any previously consumed foods
Consisted of home cooked foods
Canine diets
Protein sources - lamb, venison, moose, elk, rabbit, duck, goose, goat, ostrich, emu, alligator, kangaroo, pinto beans
Carbohydrate source - rice, potatoes, sweet potatoes (yams), rutabagas, oats, barley
Feline diets
Protein sources - rabbit, venison, lamb, duck, goose, ostrich, emu
Carbohydrate source - green peas, rarely rice
Results - Canine - Time elapsed before maximal clinical response
1-3 weeks - 13 dogs
4-6 weeks - 25 dogs
7-8 weeks - 10 dogs
9-10 weeks - 3 dogs
Results - Feline - Time elapsed before maximal clinical response
1-3 weeks - 4 cats
4-6 weeks - 7 cats
7 weeks - 1 cat, 9 weeks - 1 cat
Results - Canine - Time elapsed before return of initial clinical signs
1-2 hours - 9 dogs
1-3 days - 32 dogs
7-9 days - 3 dogs
14 days - 1 dog
6 dogs never fed previous diet
Results - Feline - Time elapsed before return of initial clinical signs
15-30 minutes - 2 cats
24 hours - 2 cats
2-3 days - 4 cats
6-8 days - 4 cats
10 days - 1 cat
Age At Onset of Clinical Signs - Canine
Range of 4 months to 11 years
<1 year old - 17 dogs (33%)
1-3 years old - 26 dogs (51%)
4-11 years old - 8 dogs (16%)
Age At Onset of Clinical Signs - Feline
Range of 3 months to 11 years
<1 year old - 3 cats (23%)
1-2 years old - 3 cats (23%)
4 years old - 2 cats (15%)
6-11 years old - 5 cats (39%)
Breeds Affected - Canine
Soft-Coated Wheaton Terrier, Dalmatian, Collie, West Highland White Terrier, Chinese Shar Pei, Lhasa Apso, Miniature Schnauzer, Cocker and Springer Spaniels, Labrador Retriever, Golden Retriever, German Shepherd, Bichon Frise
Breeds Affected - Feline
Siamese, Domestic Shorthair, Domestic Longhair
Clinical Signs - Canine
Non-seasonal pruritus
Most commonly affects the ears/pinnae, feet, inguinal region, axillary region, proximal foreleg, face, neck, perianal/perineal region
Chronic, recurrent otitis externa a common problem (Serous Otitis Media observed in 81/104 children from 1-9 years of age related to food allergy in 1 study)
May develop secondary staphylococcal pyoderma or Malassezia dermatitis
Possible history of seizures (Food Allergy and seizures in humans: seafoods and soybeans - increased dopamine in CNS)
Concurrent diarrhea rare, may have more frequent or softer feces
Only clinical sign on presentation:
Chronic recurrent pyoderma
Seborrheic dermatitis
Clinical Signs - Feline
Non-seasonal pruritus
Most commonly affects the ear/pinnae, pre-aural region, neck, periorbital region and face
Miliary type lesions most common ("Miliary dermatitis")
Eosinophilic plaques
Feline symmetrical alopecia
Severe excoriations can occur
Angioedema, urticaria, conjunctivitis
Response to Glucocorticoids
Complete cessation of pruritus
Dogs - 39% of cases
Cats - 64% of cases
Partial reduction in pruritus
Dogs - 44% of cases
Cats - 9% of cases
No reduction in pruritus
Dogs - 17% of cases
Cats - 27% of cases
Concurrent Primary Pruritic Skin Diseases
Flea Allergy Dermatitis
Atopic Dermatitis
Flea Allergy and Atopic Dermatitis
Flea Collar Hypersensitivity
DIAGNOSIS
Treat suspected food allergy cases symptomatically for first 6-12 months before recommending an elimination diet trial
Rationale For Initial Symptomatic Therapy For 6-12 Months
51 food allergic dogs followed for 3 years
Only 3 dogs re-developed pruritus
2 dogs became flea allergic
1 dog became atopic
None of the dogs became pruritic due to the new hypoallergenic treatment diet
All dogs had been eating the initial sensitizing diet for 6-12 months or longer
Dogs Started On Elimination Diet Prior To 6-12 Months Of Pruritus
2 cases initially on beef/soy based diets
Placed on lamb based diets after 3 months
Pruritus controlled for 2 months
Pruritus re-developed and dogs found to be reacting to lamb
Dogs Started On Elimination Diet Prior To 6 Months Of Pruritus
1 case initially on lamb/rice based diet
Placed on venison based diet after 2 months
Pruritus controlled for 3 months
Pruritus re-developed and dog found to be reacting to venison
Theory Of An Immunologic Window
Patient is genetically programmed to become sensitized to commonly exposed antigens in the diet after a certain age
At this age, sensitization begins over a 6-12 month time period?
After this time period of programming, the sensitizing immunologic window closes
Immunology of Food Allergy
IgE mediated food allergy:
Common in children - peaks at 1 yr.
Consider skin testing and in-vitro serum testing in puppies?
Rare in adults
False negative skin tests in adults
Delayed hypersensitivity reactions to foods:
More common in adults
Consider patch testing with foods
ELIMINATION DIET TRIAL - MINIMUM 12 weeks in duration
Protein hydrolysate formulated diets:
Reducing the Molecular Weight (Daltons) of a specific protein in the diet
DVM Pharmaceuticals - Exclude - Hydrolyzed casein and chicken liver, oat groats, pinto beans
Purina CNM Diet - HA-Formula - Hydrolyzed soy, corn starch, canola/coconut oil
Purina Gentle Snackers - Hydrolyzed soy, corn starch, canola/coconut oil, oat fiber
Hill's Prescription Diets
Canine z/d Ultra - Hydrolyzed chicken and chicken liver, corn starch, soybean oil
Canine and Feline z/d Low Allergen - Hydrolyzed chicken and chicken liver, potato (canine), rice (feline), soybean oil
Canine and Feline Hypoallergenic Treats - Hydrolyzed chicken and chicken liver, corn starch (dogs), rice (feline) soybean oil
Royal Canin Veterinary Diet (Waltham)
Hypoallergenic HP19 Canine - Hydrolyzed soy, rice, chicken fat, beet pulp, vegetable oil
Hypoallergenic HP23 Feline - Hydrolyzed soy, rice, chicken fat, beet pulp, fish oil
Home-cooked Elimination Diet Trial
Restricted diet fed for up to 90 days
Formulate based on known past exposure
Avoid any previously consumed foods
Canine Diets
Protein sources
Lamb, venison, rabbit, duck, goose, goat, ostrich, emu, alligator, kangaroo, elk, moose
Cook by boiling, baking or broiling
Carbohydrate sources
Rice, potatoes, rutabagas - boiled, No instant or minute forms
Sweet potatoes - baked
Add nothing to the cooking water
Mix equal portions of protein and carbohydrate (50:50) to approximate the volume of the previous diet
1 cup of the cooked mixture per 10 pounds of body weight per day
Will need to increase the amount of carbohydrate 2-4 x for most dogs
Use carbohydrate and/or protein treat between meals
"Nothing else is to pass the dog's or cat's lips for the next 60 days"
Discontinue all:
Table scrapes
Dog and cat treats
Chewable heartworm preventative
Chewable vitamin supplements
Essential fatty acid diet supplements
Feline Diets
Protein sources
Rabbit, lamb, venison, duck
Cook by boiling or broiling
Carbohydrate sources
Green peas
Often refuse rice or potatoes
Most often feed protein source alone
Treatment Diets - Canine
Lamb, venison or vegetable and rice based dry diets (Nature's Recipe)
Rabbit and rice based canned diet (Nature's Recipe)
Duck, venison, or salmon and potato based dry or canned diets; lamb and rice based canned diet, egg and rice based dry diet (d/d, Hill's)
Venison, duck, rabbit, or whitefish and potato based canned and dry diets (Innovative Veterinary Diets - Royal Canin - Waltham)
Vegetable and potato/oat/rice based dry diet (IVD Select Care Vegetarian Formula)
Vegetable and rice/oatmeal/barley/potato based dry diet (Natural Balance Vegetarian Formula)
Fish and potato based dry diet (Eukanuba Response Formula FP for Dogs)
Salmon, trout and rice dry diet (Purina CNM Diet: LA-Formula); Menhaden fish meal and rice dry diet (Royal Canin - Skin Support SS21)
Kangaroo and oat based dry diet (Eukanuba Response Formula KO for Dogs)
Fish and sweet potato based dry diets
Wellness Fish and Sweet Potato diet - whitefish, barley, rye flour, menhaden fish meal, canola oil
California Natural Herring & Sweet Potato diet - herring, barley, oatmeal, herring oil, sunflower oil
Natural Balance Sweet Potato and Fish diet - salmon, menhaden fish meal, canola oil
Flint River Ranch "Fish and Chips" Trout and Sweet Potato diet - trout, millet, herring meal, oatmeal, canola oil
Duck and sweet potato based dry diet - Fromm Duck and Sweet Potato Formula - barley, rice, oatmeal, egg, millet, tomato pomace, canola oil, cheese, carrots, broccoli, cauliflower, apples, green beans, cranberries, blueberries, chicory root, alfalfa sprouts, garlic, parsley
Venison based dog treats - Nature's Recipe Healthy Skin Venison Dog Treat - soy flour, molasses, garlic powder; Shaffer Venison Farms - Venison Dog Treats - 100% smoked venison
Sweet potato based dog treats - Sam's Yams Sweet Potato dog Chewz - 100% dried sweet potatoes/yams
Treatment Diets - Feline
Rabbit and rice based canned diets (Nature's Recipe)
Venison, duck, or rabbit and green pea based dry or canned diets (d/d, Hill's)
Lamb and barley based canned diet (Eukanuba Response Formula LB for Cats)
Venison, lamb, duck, or rabbit and green pea based canned and dry diets (Innovative Veterinary Diet - Royal Canin - Waltham)
Home Cooked Treatment Diets
Protein source
Lamb, venison, rabbit, chicken, turkey, beef, duck, ostrich
Carbohydrate source
Rice, potato, sweet potatoes, or rutabagas
Essential fatty acid dietary supplement
Derm Caps, EFA-Caps
Dicalcium phosphate
Non-flavored, additive free multiple vitamin and mineral supplement
Taurine for cats
EXclude DIET TRIALS
Introduction
Diagnosis of Food Allergy in Dogs Increasingly More Difficult
Exposure to a wide variety of common and novel proteins and carbohydrates
Finding a novel food source an extreme challenge
Study Purpose
"To evaluate the effectiveness of a novel carbohydrate and hydrolyzed protein diet in controlling pruritus in previously confirmed food allergic dogs".
Patient Selection
History of persistent, non-seasonal pruritus
Dogs initially exposed to numerous common and novel proteins and carbohydrates
Occurred prior to initiation of the home-cooked elimination diet trial
Initial home-cooked diets fed (19 dogs):
Venison and white potatoes (8 dogs)
Venison and sweet potatoes (4 dogs)
Duck and sweet potatoes (3 dogs)
Duck and white potatoes (1 dog)
Lamb and sweet potatoes (1 dog)
Rabbit and sweet potatoes (1 dog)
Pinto beans and white potatoes (1 dog)
Initally fed the home-cooked diet for up to 8 weeks
Then re-fed the previous diet for up 14 days until pruritus recurred
Again fed the initial home-cooked diet until pruritus resolved
Patient Selection - 19 dogs
All dogs on treatment diets for >6 months prior to entering study:
IVD - Venison/potato (8 dogs)
IVD - Duck/potato (4 dogs)
IVD - Lamb/potato (1 dog)
IVD - Rabbit/potato (1 dog)
Balanced home-cooked diets (5 dogs)
Study Design
Dogs initially examined and found to be free of any clinical signs or history of pruritus
All dogs fed the novel carbohydrate (pinto beans, oats) and hydrolyzed protein (casein = 99.7% < 1100 Daltons, chicken liver = 99.8% < 1400 Daltons) diet (EXcludeR) for 30 days
Owner to monitor each of the following:
Palatability
Gastrointestinal signs
Weight
Dermatologic signs and pruritus
RESULTS
All dogs re-examined in 30 days:
Palatability
Readily consumed (18 dogs); Refused diet after 9 days (1 dog)
Gastrointestinal signs
Diarrhea/soft feces (7 dogs)
Weight - diet fed at a rate of 1/2 cup per 20# body weight
Weight loss (11 dogs)
Corrected by increased volume of food for each feeding except 1 dog
Weight gain (0 dogs)
Maintained weight (8 dogs)
Dermatologic Signs and Pruritus
Pruritus well controlled (18 dogs)
Re-developed pruritus (1 dog)
Occurred within 7 days of feeding
Original treatment diet - Balanced home-cooked pinto beans and potatoes
Conclusions
EXcludeR adequate for controlling pruritus in a sizable number of known food allergic dogs
May be a suitable substitute for a home-cooked elimination diet
Problems encountered are similar to those when feeding a home-cooked elimination diet
Treatment of Diarrhea/Soft Feces
Submit fecal sample ASAP for direct exam
Diff-Quik stain - Clostridial overgrowth
Change to a home-cooked bland diet - Usually chicken and rice or potatoes
Plain cultured yogurt added to diet
Pepto-Bismol tablets - adult dosage
Metronidazole (Flagyl) - 10 mg/kg BID x 7 days
Foods Associated With Exacerbation of Clinical Signs
Any food items being prepared in the kitchen
Meats, cheeses, cooking oils, margarine, breads, odors from various cooked foods
Peoples favorite snack foods
Popcorn, pretzels, peanuts, cookies (Oreo), potato chips, corn chips, doughnuts, pizza, french fries
"The Hoover Hound"
New Dilemma
Many patients with a possible food allergy that have already eaten and been exposed to "everything but the kitchen sink"
Possible cross contamination of commercial diets during processing
Prescription and non-prescription hypoallergenic diets
Patients reacting to various ingredients used in the processing of commercial diets
Treatment of Food Allergy
Breast feeding exclusively for > 6 mos
Decreased food allergy, atopic dermatitis, allergic rhinitis
Oral cromolyn sodium (Gastrocrom)
Increased G.I. permeability
Enzyme potentiated desensitization
Beta-glucuronidase + food Ag intradermally
Enzyme treated foods - rice
Gut sterilization treatment protocols
Clostridium sp., Helicobacter sp.
Decreases bowel inflammation and thereby decreases GI absorption of dietary allergens
"Triple Therapy Regimen" - Canine
Metronidazole - 15 mg/kg BID x 28 days
Amoxicillin - 20 mg/kg TID x 28 days
Bismuth subsalicylate (Procter) - 1 ml/kg QID x 28 days
Food Allergy Potpourri
Food challenge can be dose dependent
Negative at small doses, positive after a large meal
Children with egg allergy can react to mother's breast milk after eating eggs
Cat with penicillin allergy can react to cow's milk containing penicillin
Unique Food Related Reactions
Onion powder in baby food
Heinz body anemia in cats
Allergenic food additives - Tartrazine (azo dyes), Na benzoate (preservative), MSG (flavor), Na bisulfate (anti-oxidant)
Cutaneous vasculitis - Potatoes, green beans, peas, eggs
Lupoid onychodystrophy, paronychia
Reactive cutaneous histiocytosis
Sterile granuloma/pyogranuloma
Footpad hyperkeratosis with eosinophils
Nasodigital hyperkeratosis
Pinnal vasculitis, urticarial vasculitis
Sebaceous adenitis
Obsessive/compulsive disorders - Separation anxiety, Kleenex shredders, Lick granulomas
Lethargy, depression, aggressive behavior
Unique Reactions to Foods
Food allergy to fish
Exacerbated by inhalation of fish odors/fumes
Food allergens in house dust
Egg, milk, sugars
Cross Reactions With Foods
Pork-cat syndrome
IgE reactions to pork meat and cat dander
Bird-egg syndrome
Bird feather allergy (asthma), followed by food allergy to eggs
IgE mediated oral allergy syndrome
Cross reactivity between pollens (birch, grass, mugwort) and foods (fruits, vegetables, nuts)
Atopic Dermatitis and Allergen-specific Immunotherapy (ASIT)
Hyposensitization
Environmental Allergies
Atopic Dermatitis (Atopy)
Allergic reactions to airborne, environmental allergens
Dust mites, storage mites, pollens, molds, cat dander, feathers
Allergens gain access to the immune system via percutaneous absorption, inhalation, ingestion
Allergens cause immune system to form excess IgE ("allergy antibody")
Problem is your dog's immune system
Inappropriate reaction to normal particles in our everyday environment!
Does not require your dog to come in direct contact with the allergen
Allergen may travel miles through the air!
Etiology and Pathogenesis
Surface Lipid Barrier Abnormality
Decrease in lipid composition of stratum corneum - primarily ceramides (phytosphingosine)
TriCeram (humans), Douxo Calm (dogs)
Over-expression of sphingomyelin deacylase
Allows for increased aeroallergen contact with APC's
Allows for over-colonization of bacteria and yeast
Environmental Allergies
Atopic Dermatitis (Atopy)
Dog is born with this problem, but signs usually not present at birth!
Clinical signs usually observed between 6 mos and 3 years of age
Pruritus of face, ears, feet, foreleg, axillary and inguinal regions
Chronic otitis externa
Secondary infection common - Staph, yeast
Clinical Features
Age Predisposition
Usually less than 3 years of age
As early as 2 months of age:
Esp. Westies, Golden Retrievers, Labrador Retrievers, Cocker Spaniels, Shar Peis
Sex Predisposition
2.5:1 - female:male ratio
Breed Predisposition
All Terriers (Westie, Cairn, Scottie, WHFT, Boston Terrier), Golden Retriever, Labrador Retriever, Shar Pei, Dalmatian, Lhasa Apso, Irish Setter, Pug, Miniature Schnauzer, Bulldog, German Shepherd
Chief Complaint of Pruritus
+/- Erythema and papules initially
"An Itch That Rashes"
Distribution Pattern - any combination!
Face - periorbital region and muzzle
Ears - +/- secondary otitis externa
Feet - +/- secondary pododermatitis
Inguinal and axillary regions
Proximal anterior foreleg region
Secondary Lesions
Post-traumatic alopecia
Salivary staining of hairs
Excoriations and "hot-spots"
Post-inflammatory hyperpigmentation
Lichenification
HISTORY
Initially warm weather seasonal problem
50-75% of cases
Progressing to a non-seasonal problem
80% of cases
Hyperhydrosis - 10% of cases
Irregular estrous cycles
Temperament changes
More irritable
Side effects of steroids
Result of chronic discomfort
Rarely urticaria, rhinitis, coughing
Malassezia paronychia
Diagnosis
History - "Gold Standard" of diagnosis
Initially a warm weather seasonal problem
May become non-seasonal
Distribution pattern of pruritus
Intradermal Testing - "false positives"
In-vitro serum testing - "false positives"
Aeroallergen specific IgE
ELISA vs. RAST
Histopathology
Very non-diagnostic
Superficial perivascular dermatitis reaction - etiology unknown
+/- evidence of secondary superficial pyoderma, folliculitis, Malassezia dermatitis
Should You Do Intradermal Testing?
Needs to be done on a regular basis
At least one case/week
Need an adequate case load
Initial financial investment
Approximately $3,000
Selection of allergenic extracts
Consult with local veterinary and human allergist
National Allergy Bureau Counting Stations
Patient Preparation for Intradermal Testing
Rule out other causes of pruritus!
Flea Allergy, Food Allergy, Scabies
Appropriate drug withdrawals
Antihistamines, EFA's, NSAID's
14 day
Oral, injectable and TOPICAL steroids
30 days
Repositol steroids - 90 days!
Intradermal Testing
Best performed at the END of the allergy season
Proper sedation
Gently clip lateral chest
Mark each injection site
Negative (saline) and positive (histamine) controls
Read at 15-20 minutes post-injection
Treatment
Treat any concurrent secondary problems
Bacterial pyoderma, Seborrhea, Malassezia dermatitis
Client Education
Heritability of the disease
Sources of the Aeroallergens
Avoidance when possible
Environmental Allergies
Treatment Options
Drugs
Steroids, antihistamines, essential fatty acid dietary supplements, cyclosporine (Atopica - $$$)
Avoidance - rarely practical
Allergen-specific immunotherapy (ASIT) - Hyposensitization injections
Allergen-specific Immunotherapy (ASIT) -
Hyposensitization injections
Base on theory of "Blocking Antibodies"
Hyposensitization solution (allergen extract) contains what your dog is allergic to, mixed in sterile water
Injections will stimulate a new and "protective antibody" (IgG)
Compliant owners
Cooperative patients
Approximately 70% effective
Continued for the life of the dog
Instruct owners as to how to give SQ injections
1 ml Tuberculin syringe - 25 gauge, 3/8" needles
Preparation of Vials
Standard Hyposensitization Protocol
Preferably select up to 12 allergens for initial treatment set
May add an additional treatment set after 6-12 months
Vial #3 (Maintenance Vial)
Equal volume of each "significant" allergen at 20,000 PNU/ml or 1:20 weight/volume
Vial #2 = 0.5 ml Vial #3 + 4.5 ml diluent
Vial #1 = 0.5 ml Vial #2 + 4.5 ml diluent
Hyposensitization Injections
Review hyposensitization injection protocol sheet with owner
Explain that most dogs will get noticeably more pruritic during the "early stages" of the injection protocol - first 1-3 months
If dog is extremely pruritic, concurrent drug treatment may be used without interference
Adverse Reactions to Injections:
Usually occur within 5-60 minutes
Overall increase in pruritus
Pruritus or swelling at the injection site
Urticaria ("hives"), angioedema
Panting, restlessness, and confusion
Vomiting and diarrhea, lethargy
Anaphylaxis rarely
Modified Injection Protocols
Based on patient's change in pruritus
Injection helps but effect wears off before next scheduled injection
Give injection more frequently
Injection helps but effect wears off in just a few days
Increase volume of injection
Injection causes transient increase in pruritus early in the protocol
Continue standard protocol
Injection causes increase in pruritus late in protocol
Decrease volume of injection by 50%
Owners are instructed to start a pruritus log on their calendar and to grade pruritus from 0-10
As volume of injection decreases, there is a tendency towards a need to increase the injection frequency
Examples:
0.5 cc Vial #3 q14-21d
0.4 cc Vial #2 q7-14d
0.2 cc Vial #1 q3-7d
Important Note
"If your diagnosis is correct, the degree of pruritus MUST change while the patient is receiving injections. If there is no observable change, then re-evaluate your own diagnosis."
AQUEOUS HYPOSENSITIZATION INITIATION SCHEDULE
Allergens:
|
| | Clinician:
|
| | Date Started:
|
| | Patient:
|
| | Case Number:
|
|
STORE ALLERGEN EXTRACTS IN THE REFRIGERATOR
- DO NOT FREEZE -
Give injections subcutaneously
VIAL #1
| Day
| Date
| Amount
| | 0
|
| 0.1 mL
| | 2
|
| 0.2 mL
| | 4
|
| 0.4 mL
| | 6
|
| 0.8 mL
| | 8
|
| 1.0 mL
|
VIAL #2
| Day
| Date
| Amount
| | 10
|
| 0.1 mL
| | 12
|
| 0.2 mL
| | 14
|
| 0.4 mL
| | 16
|
| 0.8 mL
| | 18
|
| 1.0 mL
|
VIAL #3
| Day
| Date
| Amount
| | 20
|
| 0.1 mL
| | 22
|
| 0.2 mL
| | 24
|
| 0.4 mL
| | 26
|
| 0.8 mL
| | 28
|
| 1.0 mL
|
Maintenance (VIAL #3)
| Day
| Date
| Amount
| | 35
|
| 1 mL
| | 42
|
| 1 mL
| | 56
|
| 1 mL
| | 70
|
| 1 mL
| | 91
|
| 1 mL
| | 112*
|
| 1 mL
| | 142
|
| 1 mL
| | Then 1 mL once monthly for LIFE
|
Observe for any abnormal reactions: swelling or redness at the injection site; worsening of itching; difficulty breathing; irritability.
Flea Biology, Flea Allergy Dermatitis, and Flea Control
FLEA LIFE CYCLE
EGGS
Laid on the host
Are non-sticky and roll off
Usually hatch within 1-10 days
Less than 50% relative humidity:
DESICCATION
Freezing temperatures: DEATH
Must hatch within 10 days or DIE!!
LARVAE
Motile and free living
Feed on organic debris, and adult flea feces
Negatively phototropic (photophobic): move deep into carpeting
Development completed in 5-11 days
Produces cocoon and pupates
PUPAE - PRE-EMERGENT ADULT
Silk-like cocoon is sticky
Camouflaged by debris in environment
Highly resistant to desiccation or ingestion
Stage last 7-10 days
Can survive up to 7 months
Adult fleas stimulated to emerge via: heat, vibration, exhaled carbon dioxide
ADULTS
Attracted by warmth, carbon dioxide, movement, changes in light intensity
Adult cat flea is a permanent ectoparasite
Is metabolically dependent on a constant blood source
Once fed, mating occurs within 12 hours
Egg production within 24 hours
Entire life cycle averages 3-4 weeks
Healthy pets harbor fewer fleas that unhealthy pets
Younger animals have more fleas
Homes with humidifiers MAY maintain fleas year-round (>50% humidity)
Primarily basements
Poor survival in high altitudes
2 Reasons Adult Fleas Leave Their Host
The Flea Dies!!
The Flea's Host Dies!!
FLEA LIFE CYCLE
INTERESTING FACTS
Some adults emerge spontaneously, when stimulated, attack in 1-5 seconds
No life cycle stage of the cat flea can survive freezing
Survive winters on raccoons, opossums, foxes, coyotes, and skunks
Over 50% of fleas on cats are digested
Female cat flea produces 50 eggs/day during peak production
Lays over 2000 eggs during lifetime
Consumes 13.6 ul of blood/day
220 female cat fleas can consume 10% of a 1 lb. kittens blood volume in a day
Record flea infestation: 5,300 fleas on 1 dog
THE CAT FLEA
Ctenocephalides felis
Most common flea of dogs and cats in the United States
Can parasitize humans, opossums, raccoons, ferrets, foxes, coyotes, and skunks
Wild rabbits and squirrels not parasitized
Intermediate host for Dipylidium caninum
FLEA ALLERGY DERMATITIS
An allergic hypersensitivity to salivary antigens deposited during feeding
Type I Hypersensitivity - involves IgE, mast cells, allergenic proteins (high molecular weight: 20,000-70,000 Daltons)
Type IV Hypersensitivity - involves hapten (incomplete allergen - low molecular weight: 1,000-10,000 Daltons), dermal collagen, cell-mediated immune response
Any dog or cat can become allergic
Intermittent flea exposure favors development of hypersensitivity
Continuous exposure favors tolerance
Allergic response is often life-long
Only requires 1 flea bite every 10-14 days
CLINICAL SIGNS
CANINE
Pruritus of the posterior 1/3 of the body
Rump, tail-head, ventral abdomen, posterior/medial thighs
Papules, post-traumatic alopecia
Excoriations and "hot spots"
Hyperpigmentation and lichenification
"Classic lumbo-sacral alopecic wedge"
"Pruritus of the post 1/3 of the body is a FLEA ALLERGY until proven otherwise and is RARELY proven otherwise"
"The diagnosis of a FLEA ALLERGY DERMATITIS DOES NOT REQUIRE the presence of FLEAS OR FLEA DIRT to make the diagnosis"
CLINICAL SIGNS
FELINE
Pruritus of the posterior 1/3 of the body, anterior 1/3 of the body, or both
Presence of "miliary lesions"
Symmetrical alopecia without lesions
Eosinophilic plaques, eosinophilic ulcers
DIAGNOSIS
History and distribution pattern of pruritus and lesions
Presence of tapeworm segments
Intradermal Testing with flea antigen
May present with concurrent pruritic skin diseases: atopic dermatitis, food allergy, scabies, allergic contact dermatitis
TREATMENT
ENVIRONMENT
Approximately $1 billion dollars spent on flea products annually
Thorough vacuuming of all floor surfaces and furniture
Dispose of vacuum cleaner bag when done
Wash bedding, throw rugs, etc.
PREMISE TREATMENT
INDOORS
Must treat the entire house
Must use spraying device, foggers ineffective (poor ground level coverage)
Insecticides with good adulticide action:
Permethrin
Chlorpyriphos (toxicosis in cats)
Microencapsulation for residual action
Insect Growth Regulators (IGR's)
Mimics activity of juvenile hormone
Affects larva to pupa, and pupa to adult
Pyriproxifin, methoprene
Very mammalian SAFE
Sodium polyborate, orthoboric acid
Fleabusters
Flea Eliminator, Flea Terminator
Larvacidal effect, prolonged residual
PREMISE TREATMENT
OUTDOORS
Concentrate on micro-environments
Moist shaded areas, dog houses, runs, garages, mulched areas
Do not WASTE time on shade free lawn
Microencapsulated chlorpyriphos or diazinon
Highly effective
Good residual activity
Malathion, methylcarbamate
PRODUCTS NOT RECOMMENDEDFOR PATIENTS WITH "FLEA ALLERGY
DERMATITIS"
Flea shampoos, Flea collars
Ultrasonic collars and devices
Systemic acting agents - only if used in conjunction with topical adulticides
Brewer's yeast, Vitamin B-complex
Garlic, Natural oils
Ivermectin
TREATMENT
SECONDARY PROBLEMS
Antipruritic drugs
Dogs: Prednisolone - 0.25 mg/# BID x 7 days,
0.25 mg/# SID for 7 days,
0.25 mg/# q48h x 1 week
Cats: Prednisolone - 0.5 mg/# BID for 7 days,
0.5 mg/# SID for 7 days,
0.5 mg/# q48h for 1 week
Antibacterial therapy
Systemic antibiotics for 21-30 days
Benzoyl peroxide shampoos (Oxydex, Pyoben, Benzoyl-Plus)
Antiseborrheic shampoos
Essential Fatty Acid Supplements
Derm Caps, EFA-Caps
TREATMENT
PATIENT
Treat all contact dogs and cats
"From when you see flies, until the snow flies"
Imidaclopird (Advantage)
Apply q14d
Fipronil + methoprene (Frontline Plus)
Apply q21d
Metaflumazone (ProMeris) - dogs and cats
Apply q??d
Hyposensitization - newer allergens
Dermatophytosis
Ringworm, Tinea
Etiology
Microsporum canis - Zoophilic
Most common isolate in dogs and cats
90% of feline ringworm
Minimal inflammation in cats
Microsporum gypseum
Geophilic - more inflammatory response
Trichophyton mentagrophytes
Zoophilic - most inflammatory
Wild rodents are the reservoir
"Beware of Zoonotic Potential of all Dermatophytes!"
Pathogenesis
Keratinophilic
Affects the keratin layers of the epidermis, nails, and hair shafts
Infects actively growing hair
Stops at mitotically active matrix
Adamson's fringe or keratogenous zone
Therefore is a NON-scarring alopecia
Importance of Host-Response
Cell mediate immune response (CMI)
Most important
Good CMI - self cure in 1-3 months
Young, geriatric and immune compromised animals at risk
Humoral response ineffective
Clinical Features
Microsporum canis
Canine:
Annular areas of alopecia and scaling
Feline:
Circumscribed areas of alopecia, erythema, and mild scaling
Humans:
"Classical" ringworm reaction
Trichophyton mentagrophytes
Can become generalized
Produce mannins
Decreased CMI from host
Inhibits stratum corneum turnover
Dorsal planum of nose
Dogs that "root" into rodent burrows
Microsporum gypseum
Kerion Ringworm
Focal, raised lesions with draining tracts
Histiocytoma-like appearance
Hypersensitivity response?
Papular/pustular form
Looks like a pyoderma due to Staphylococcus intermedius
Non-responsive to antibiotics
Pseudomycetoma form
Nodular to diffuse granulomas
Only reported in Persian cats
Asymptomatic Carrier State
Most important from a zoonotic standpoint
Most problematic in adult cats
Usually Microsporum canis
Severe problem in catteries and multiple cat households
Sterile brush technique for fungal cultures
Diagnosis
Wood's Lamp
~50% of Microsporum canis
Fluorescent green - hairs only
Due to tryptophan metabolite
Trichogram
Ectothrix spores
All dermatophytes of domestic animals
Dermatophyte Test Media (DTM)
Dermatophytes preferentially metabolize protein in media
Results in an alkaline by-product
Turns phenol indicator RED
Occurs in < 2 weeks
At optimum incubation temperature of 81° F see color change in 3-5 days!
Histopathology
Treatment
Isolate affected animals
Especially children and elderly
Any immunocompromised people
Thoroughly vacuum weekly
Clip localized lesions with scissors
Clippers for generalized disease
Localized Form
Spontaneous remission
Topical Imidazoles
Miconazole (Conofite®, ResiZOLE®)
Clotrimazole (Veltrim®, Lotrimin®)
Systemic Therapy
Indicated in both localized and generalized disease!
Canine
Griseofulvin (Grifulvin-V®, Fulvicin-U/F®)
25 mg/lb divided BID
Administer with food + fat source
Treat for 2 weeks beyond apparent remission
Usually lasts 4-6 weeks
Ketoconazole - Griseofulvin-resistant cases
5-10 mg/kg SID-BID with food
Potential hepatotoxicity
Feline
Itraconazole - 5-10 mg/kg SID with food
Less hepatotoxic than ketoconazole
Fluconazole - 10 mg/kg SID with food
Topical Therapy
Generalized Forms
Lime Sulfur
LymDyp®, LimePlus Dip
Proven efficacy - aesthetically displeasing ("rotten-egg" odor)
Miconazole shampoos
Dermazole® (Virbac), Miconazole (Evsco), MalaSeb® (DVM) + chlorhexidine
Miconazole rinses/sprays
ResiZOLE® (Virbac), MalaSeb® (DVM)
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