Management of allergic skin disease Flashcards
How can flea allergic dermatitis be managed?
–> rigorous year-round flea control to all pets and environment
How can cutaneous adverse food reactions (food-induced atopy) be managed?
restrict diet to tolerated ingredients
Describe the interrelationships of components of CAD?
What are atopy treatment options?
Illustrate the summation theory of pruritis?
How should bacterial pyoderma be managed?
Topical products
- Antimicrobial shampoo/wipes/foams (especially chlorhexidine products at 2-4%)
- use in preference to antibiotics where possible for surface/superficial pyoderma
Systemic antibiotics, if necessary
- Adequate length of treatment
- Superficial pyoderma for minimum 3 weeks and 1-2 weeks past clinical cure
- Deep pyoderma min 4-6 weeks and 2 weeks past clinical cure)
How can addressing barrier dysfunction help treat atopic dermatitis?
Important to
- reduce ingress of allergens/infections
- reduce trans-epidermal water loss (skin of atopic individual is deficient)
- Important in long-term control but measures slow to take effect – continue for long enough!
- Use in combination with other therapies, rarely used alone
- Examples of things that improve skin barrier function:
- Oral essential fatty acids (May exacerbate pancreatitis)
- EFA shampoos (e.g. linoleic acid shampoo)
- Topical skin lipid complex (Allerderm spot-on)
- Topical essential oils (Dermoscent)
- Topical phytosphingosine (Douxo range of products)
- Topical moisturisers - many
What should you look for in a topical moisturiser to help manage atopy?
Look for things that contain, e.g.
- Urea (works by drawing in water)
- Glycerine
- Linoleic acid
- Colloidal oatmeal
Some also anti-inflammatory
- Aloe vera extracts
- NB cooling effect of bathing and skin hydration can also contribute to the reduction of pruritus
What are the side effects of steroid treatment?
For atopic dermatitis how should glucocorticoids be used?
Use systemic glucocorticoids only when necessary – eg
- Short-term treatment of severe pruritic flare-up
- During early stages of immunotherapy
- Seasonal pruritus requiring only 3-4 months’ treatment per year
- When other treatments inadequate
- When financial constraints preclude other treatments
What are the side effects of long term injectables glucocorticoids?
- Sometimes cant use oral steroids so have to use injectable such as in the fractious cat.
- Greater risk of suppression of HPA axis.
- Don’t use lightly as can induce DM. Don’t be in a hurry to use it
One usually used: methylprednisolone acetate
(Depo-Medrone V)
Up to 6-8 weeks of action/efficacy
What is isaderm?
- Beta methasone (can cause skin thinning) and antibiotic (if you’re using it just to control inflammation this is not good stewardship of antibiotics)
- Always specify how long the treatment is for.
What is Hydrocortisone aceponate?
- spray - converted to more potent steroid in skin (with similar potency to betamethasone)
But
- less systemic absorption/HPA suppression
- less skin-thinning
than other topicals of similar potency
- Licensed for 7 days’ use but recent reports of longer-term use, off label (e.g. 2 days per week) in canine and feline allergic skin disease.
New treatment.
Hydrocortisone aceponate is converted to a more potent steroid in skin same potency as betamethasone but with less skin thinning effects and less HPA axis suppression and it does not contain an antibiotic.
Only licensed for 7 days use. Any longer is off label use.
What drug interaction should you be aware of when using ciclosporin?
CYP450 metabolises cyclosprorine so if you use in conjunction with other drugs metabolised by this pathway it increase bioavailability of it.
Systemic antifungal you need to half your ciclosprin dose.
What is cyclosporin?
- An immunosuppressant medication and natural product.
- Licensed for atopic dermatitis in dogs and cat
- Action: Calcineurin inhibitor
- Blocks release of inflammatory mediator molecules
- eg cytokines, interleukins
- Inhibits cells of allergic reaction
- eg T lymphocytes, eosinophils, mast cells
- –>Reduces pruritus & inflammation
- However supresses T cells across the board giving some significant side effects.
What are the side-effects of cyclosporin?
- Often initial vomiting/diarrhoea but usually settles (give with small volume of food to reduce GI side effects) Warn people of this beforehand.
- In dogs, occasional reversible anorexia, hirsuitism, gingival hyperplasia, papillomatosis
- Some risk of immunosuppression
- Bacterial infection, demodicosis, dermatophytosis
- Avoid use 2 weeks either side of vaccination
Ciclosporin (atopica) is not for use in?
- dogs <6 months old or <2kg in weight (no data)
- breeding, pregnant or lactating animals (no data)
- animals with history of malignant disorders (not proven in dogs but does happen in people)
- diabetics - may affect circulating insulin
Liquid oral ciclosporin for cats (Atopica Cat®)
- Need to test for FeLV, FIV and toxoplasmosis prior to commencement of treatment
- Mild GI signs and weight loss are most common adverse effects
Why toxo: if they get toxo on atopica or cyclosporin there is mortality associated they need to have a previous immune response evident to toxo before starting to ciclosporin
What is Oclacitanib (Apoquel)?
- JAK1 inhibitor
–> Prevents direct stimulation of nerves by IL-31 causing pruritus
- Reduces inflammation
For pruritus associated with allergic skin disease, particularly clinical manifestations of atopic dermatitis.
- Dogs only.
- Effective 60-70% cases
- Rapid onset (as fast as prednisolone in most cases)
- Side effects less than prednisolone (vomiting/diarrhoea most common)
- Does not interfere with intradermal testing/IgE serology
- Can vaccinate during treatment
How should oclacitanib be dosed?
- Dose 2x daily for 2 weeks, then once daily (every 12hours initially the every 24hr)
- (–> increase in pruritus as dose reduced but then effect should gradually return to previous level)
- Minimal interactions with other drugs
- Useful for short-term and? long-term use (need to monitor with periodic haematology/serum biochemistry)
- Lower price than ciclosporin
NB
- Not for dogs <1yo or <3kg
- May increase susceptibility to infection
- Not if immunosuppressed/ with progressive neoplasia (untested)
- Not in pregnancy/lactation/breeding males (untested)
What is Lokivetmab (Cytopoint)?
- A monoclonal antibody (mAb) therapy against IL-31 à block neuronal stimulation of pruritus by IL-31
(NB minimal anti-inflammatory effect)
- Injection every 4 weeks; DOGS ONLY! (Only for use in Dogs. Cats would have horrid reaction because it is a canine antibody.)
- Rapid onset of action, effective in 75% dogs
Can use:
- in any age of dog
- with impaired liver/kidney function and neoplasia (cf many alternatives)
- in addition to other therapies if necessary
- Malignancies
How do antihistamines work?
- Block H1 histamine receptors of C neurones (+/- some central sedative effect)
- Not very effective (?20%), but may allow reduction of dose of other drugs – recent EBM review questions efficacy
- Unlicensed in animals
- Examples
- Dogs: chlorpheniramine, hydroxyzine, cetirazine
- Cats: chlorpheniramine, hydroxyzine
Side effects
- Rare except drowsiness – care especially with cats!
- Reported: anorexia, vomiting, cardiac arrhythmias, excitability
How does Allergen-specific immunotherapy work?
- Immunotherapy vaccines made by selecting clinically relevant allergens
- Based on positive results from intradermal or serum IgE testing
- Not for fleas or dietary ‘allergens’
- Exact mode of action unknown, but causes reduction in allergen-specific IgE and increase in IL-10 and regulatory T cells
- Traditionally given by subcutaneous injection
- Initially dosed every few days - 2 weeks.
- Dose increases gradually to maintenance, then given every 2-4 weeks
- Occasionally can be weaned off treatment but usually need maintenance injections monthly for life (owner can be taught to give at home)
Describe the efficacy, side effects and cost of allergen-specific immunotherapy?
Efficacy:
- 25% can use as sole treatment
- 40% helped but require other concurrent treatment
- 35% ineffective
- Need up to 10-12 months to assess efficacy
Side effects:
- Some with increased pruritus for few days after injection
- Rare anaphylaxis (initial course given in surgery)
- Safe for longterm use
Cost
- Approx £300-400 per annum (plus vet’s fees)
What are some short-term aids for physical prevention of self-trauma?
How effective are the treatments for atopy?
Glucocorticoid tablets – effective in nearly 100% cases
Ciclosporin – effective in approx 80% cases
Oclacitanib – effective in approx 70% cases
Immunotherapy – effective in approx 65% cases
Antihistamines – ?effective in approx 20% cases
EFAs – effective in approx 20% cases (but benefit barrier function)
Medicated shampoos – helpful to treat/prevent infection, soothe skin
Antibiotics – effective when infection present
What is the risk of side-effects for different treatments for atopy?
Glucocorticoid tablets – can cause major side-effects when used for months-years (iatrogenic HAC, adrenal suppression)
Ciclosporin – can cause minor side effects, occasional major side effect
Oclacitanib – can cause minor side effects; long term side effects unknown
Immunotherapy – rarely causes side-effects
Antihistamines –rarely cause side-effects
EFAs – rarely cause side-effects
Medicated shampoos – may occasionally irritate skin
Antibiotics – may cause GI upsets; development of potential resistance, especially with long term use; major systemic side-effects rare
How much do the different treatment for atopy cost?
Ciclosporin capsules – approx £110-550/month
Oclacitanib – approx 50% cost of ciclosporin
Antibiotics – approx £22-110 for 3-week course
Immunotherapy – approx £25-30/month (+ injection fees)
EFAs – approx £17-£44/month
Medicated shampoos – approx £11-£33/month
Antihistamines – approx £11-28/month
Glucocorticoid tablets – £6-17/month
*dependent on size of dog, mark-up, inflation
