Pruritis In Dogs

Question 1

Causes of pruritis

Answer 1

Allergic: atopic derm, food allergy, urticaria, drug reaction
Ectoparasites: scabies, mites, Cheyletiella, lice
Infectious: bacteria, fungi
Neoplasia: cutaneous lymphoma

Question 2

Canine atopic dermaitis

Answer 2

Genetically predisposed inflammatory and pruritic skin disease with characteristic clinical features, associated with most commonly IgE antibodies to environmental allergens

Question 3

Breeds predisposed to CAD

Answer 3

Golden retrievers, WHWT, GS, cocker spaniels, boxers, frenchies
Vary between countries and continents

Question 4

Defect of CAD

Answer 4

Multi factorial disease. Defective skin barrier
Allows absorption of allergens through epidermis

Question 5

Pathogenesis of CAD

Answer 5

Could be
-overactive immune system
- failure to regulate immune system

Question 6

Regulatory T cells

Answer 6

Tregs- keep the immune system balanced so every chance for assault isn’t a dramatic shift but better managed

Question 7

Characteristic clinical features of CAD

Answer 7

1. Pruritis
2. Alopecia
3. Excoriation
4. Erythema
5. Hyperpigmentation
6. Lichenificiation
7. Recurrent otitis externa
8. Recurrent bacterial /yeast skin infection

Question 8

Common locations for CAD

Answer 8

Face, eyes, throat, ears, armpits, axillary stomach, paws

Question 9

Distribution of similar clinical signs - CAD

Answer 9

Sarcoptic mange and demodicosis have the closest distribution
Sarcoptic mange: ears, hocks, elbows and axillary stomach
Demodicosis: under eyes, chin, splotchy dispatch on legs and paws

Question 10

Perianal pruritis

Answer 10

Similar % seen in dogs with CAD and food allergy
Clinical signs for both - only itchy near anus no where else

Question 11

Role of IgE in CAD

Answer 11

1. Percutaneous penetration of allergens
2. Langerhans cells (APC) capture allergens
3. APC presents processed allergens to naïve T lymph to LN
4. Naive t lymph stimulated into Th2 whcih secrete IL-4,5,13
5. B cells stimulated become plasma
6. Plasma produce IgE antibodies in the circulation
7. IgE bind to surface of mast cell (sensitization stage)
8. Re-exposure to allergen = cross link w IgE bound to mast
9. Mast cell degranulate & release inflammatory mediators (histamine, serotonin, eosinophil chemo tactic factor)

Question 12

Favrots criteria

Answer 12

Guidelines for CAD
1. <3yrs
2. Mostly indoor (eh)
3. Corticosteroid responsive pruritis
4. Chronic or recurrent yeast infections
5. Affected front feet
6. Affected pinnae
7. Non-affected ear margins
8. Non-affected Dorso-lumbar area

Question 13

DX CAD

Answer 13

The clinical DX is only given AFTER ruling out pruritic diseases via serum allergy test and intradermal test
Other pruritic diseases
1. Ectoparasites, scabies, Cheyletiellosis
2. Infection
3. Cutaneous adverse food reaction (food allergy)

Question 14

Tx approach for recurrent skin or ear infections

Answer 14

Skin/ear infection —> recurs after successful treatment —> investigate underlying cause
- allergic disease: parasite, endocrine, chronic steroids
- no underlying: idiopathic recurrent pyoderma

Question 15

CAD DX

Answer 15

Seasonal pruritis —> canine AD
NON seasonal pruritis —> canine ad? Or food allergy? —> elimination diet trial —> no response —> canine AD

Question 16

Elimination diet trial

Answer 16

ONLY reliable method to rule in/out food allergy
Serum allergy test is NOT reliable method to diagnose food allergy
Proteins are likely allergen
GI signs +/- but does not rule out food allergy

Question 17

Hydrolyzed diet

Answer 17

Does not contain intact proteins - only peptides
Allow skin to reset. Diagnosis of food allergy is confirmed when pruritis resolved via elimination diet—>relapse on old diet —> resolve with hydrolyzed diet

Question 18

Duration of elimination diet

Answer 18

5weeks: 80% of dogs w food allergy can be diagnosed
8 weeks: >90% of dogs w food allergy can be diagnosed
Management and prognosis is usually good

Question 19

CAD management

Answer 19

Cannot be cured - life long therapy
1. Allergen specific immunotherapy
2. Cyclosporine/ciclosporin
3. Oclacitinib (apoquel)
4. Lokivetmab (cytopoint)
5. GC’s
6. Antihistamine

Question 20

Pros and cons of ASI

Answer 20

Allergen specific immunotherapy -
Ideal Tx in dogs, injection of allergens to de sensitize
Serum tests can help ID for injections
Works in 50-70% of dogs show 50% improvement
May take up to 12 months

Question 21

Pros and cons of cyclosporine (ciclosporin)

Answer 21

Advantages:
Highly effective long term treatment (80%)
Cons:
Expensive, 4wk to see benefit

Question 22

Pros and cons of oclacitinib

Answer 22

Pros:
Highly effective, rapid speed, cheaper than cyclosporine

Question 23

Pros and cons of lokivetmab

Answer 23

Antibody that neutralized interleukin-31, pruritogenic cytokine in dogs
Convenient - injection last 4weeks, up to 70% respond, rapid speed of action
Cons: expensive

Question 24

Pros and cons of GC’s

Answer 24

Pro:
Highly effective Tx, rapid speed, cheapest drug
Cons:
MANY adverse effects
Long term Tx of CAD w GC’s is NOT recommended unless other Tx fails

Question 25

Pros and cons of Antihistamines

Answer 25

Pro:
Cheap, no major ADR
Con:
Ineffective as sole therapy in most CAD