Allergic skin disease management Flashcards
A dog Underwent strict elimination diet trial for 8 weeks using a commercial hydrolysed diet (soy-hydrolysate (Purina HA)). His own food was used as treats, and he had water only to drink. No access to cat food!
Oclacitinib was used to control pruritus in the initial stages but could not be withdrawn without pruritus rapidly returning, even after 8 weeks
* What is your diagnosis?
* What is the prognosis?
* How will you manage this?
What is your diagnosis - Atopy due to Environmental allergens
What is the prognosis - Disease for life
How will you manage this - needs to be put on an antipruritic for life
What are the key things around atopic dermatits that you need to communicate to the owner?
- It’s not their fault!
- Disease will persist life long and will need ongoing management to control
- Lots of treatment options
- No guaranteed successful treatment and no ‘one size fits all’
- Usually need combination of therapies
- Need to establish tailor-made regime dependent on patient/owner factors
- Once regime established, changes may be needed as
- Disease not static – may have temporary flare-ups –> short-term adjustments
- Disease severity may generally increase with age –> adapt core regime long term
AD partly heritable so should not breed
What are the aims of managment of atopic dermatitis?
balance the three I’s:
Inflammation, itch, infection
- Control inflammation + pruritus
- Allergen avoidance & allergen-specific immunotherapy
- Control flare factors
- Improve skin barrier
And balance:
- Product efficacy/ speed of onset
- Risk side effects
- Treatment feasibility/ owner compliance
- keep regime as simple as possible
- Cost
What drugs can be used for the control of inflammation and pruritus?
- Anti-itch, anti-inflammatory - Glucocorticoids/corticosteroids - systemic or topical
- Anti-itch - Oclacitinib - JAK inhibitors
- Anti-itch: Lokivetmab - Anti IL-31 monoclonal antibody
- Anti-inflammatory and anti-itch: Ciclosporin - Calcineurin inhibitors -> T cell suppression
- Antihistamines? - very narrow spectrum of activity
What are the side effects for glucocorticoids?
how is this managed?
Short-term
* Polydipsia, polyuria, polyphagia
* Panting, lethargy
Long-term use, e.g.
* Systemic immunosuppression
* infections (often undetected in bladder)
* failed wound healing
* GI haemorrhage/ gastric ulcers
* Iatrogenic HAC
* Diabetes mellitus
* HPA axis suppression –> Addison’s disease
6-monthly serum biochemistry and urinalysis advised if used long term
What are the two types of systemic injectable GCCs?
What are the issues?
Short-acting solutions
* Useful for rapid onset short-acting effect – some licensed iv
* Occasionally dexamethasone solution used orally for fractious cats – off label - use with care and informed consent – see literature for dose/frequency
Depot suspensions
* Some products (methylprednisolone acetate) with action < 4-8 weeks but poor dose control. Most commonly used in fractious cats, ?never in dogs
* Diabetogenic and risk hypothalamic-pituitary-adrenal axis suppression with long term use
What are the prinicples of using oral glucocorticoids for atopic dermatits?
Usually prednisolone
Dose: anti-inflammatory dose needed for allergic disease
* start daily dosing
* Taper to lowest effective alternate day dose if needed for maintenance
Taper gradually – never stop suddenly! (risk of iatrogenic Addisonian crisis)
Tapering is NOT necessary if dosing is for less than 10 days & the animal has not recently received steroids
What are the risks of using topical Glucocorticoids?
- Risk of systemic absorption and skin thinning with long term use
- Gloves must be worn!
- Advise owner re licensed maximum duration of therapy, especially on thin-skinned areas
NB Some products also contain antibiotic (e.g. fusidic acid) – use only if antibiotic action actually required!
NB Hydrocortisone aceponate spray
* Steroid-only
* Potency equivalent to betamethasone but stated to cause less systemic absorption/skin thinning (still exercise caution!)
What are the benefits of oclacitinib for atopic dermatits?
What are the consideratinos when using it?
- Effective in approx. 70% cases
- Rapid-onset effect (24h), considered safe for long term use
- Excellent antipruritic, some anti-inflammatory effect
- dogs only, minimum 1yo!
Minimal interaction with other drugs, though unlicensed for concurrent use with prednisolone or ciclosporin (additive depressive effect on aspects of immune system)
do not use if patient immunosuppressed, has renal/liver impairment or suffering progressive neoplasia
What are the benefits of lokivetmab?
- Good safety profile and no effect on general immunity
- Rare anaphylaxis / anaphylactoid reactions
- Excellent antipruritic but minimal anti-inflammatory effect
- DOGS ONLY!
- Rapid onset of action, effective in 75% dogs
Risk - Occasionally efficacy lost with time
Can use
* in any age of dog
* with impaired liver/kidney function and neoplasia (cf many alternatives)
* in conjunction with the other therapies (steroids, ciclosporin, oclacitinib) if necessary – others not licensed to combine
In what species can ciclosporin be used in?
How effective is it?
When does it need to be stopped Temporarily?
When can it not be used?
What are the side effects?
- Licensed for dogs and cats, but costly
- Effective (80% cases) but slow to work (1-2mo)
–> initial concurrent use with 2-3 week of prednisolone or oclacitinib – off label
Oral product – q24h initially, but many can taper to q48-72h once stable
T-cell suppressor
* Avoid use 2 weeks before/after vaccination
* Test cats for FeLV/FIV/toxoplasmosis before commencing
Not < 6 months old or with neoplasia
Side effects
* Most commonly diarrhoea/vomiting, usually transient
* Others, e.g. anorexia, gingival hyperplasia, hirsuitism
What are the issues with antihistamines with atopic dermatits?
When are antihistamines useful?
- Block H1 histamine receptors of C neurones (+/- some central sedative effect) – but histamine has VERY limited role in canine and feline allergy.
- Efficacy low (?20%), but may allow reduction of dose of other drugs? – May provide small and limited benefit if given before flare?
- No use for chronic disease
- Unlicensed in animals
Most useful in acute urticaria and allergic conjunctivitis
What are the principles behind allergen-specific immunotherapy?
When is it used?
- Administer small amounts of relevant allergen to try to induce tolerance
- Only treatment that can potentially alter the long term course of the disease
Immunotherapy vaccines made by selecting clinically relevant allergens
* Based on positive results from IDT or serum IgE testing
* Administration: subcutaneous, intralymphatic,(sublingual)
* Unlicensed in UK – import licence required
For
* Environmental allergens (not food/fleas)
* Malassezia (Malassezia hypersensitivity recognised in some individuals)
What is the efficacy of allergen -specific immunotherapy?
What are the side effects?
Slow onset – trial 12mo+
* 20% highly effective (use as sole therapy)
* 30% ineffective
Side effects
Increased pruritus for few days after injection in ?10%
Rare local injection reactions
Systemic reactions < 1%. Anaphylaxis very rare (initial course given in surgery)
What methods can be used to improve the skin barrier?
Topical moisturisers, e.g.
* Colloidal oatmeal, aloe vera, glycerin, urea, propylene glycol, ophytrium, lactic acid, sodium or ammonium lactate
Systemic essential fatty acids
* Supplements or high EFA diets
NB 2-3 months to effect
Essential oils
What are the principles behind behind cortoling flare factors of atopic dermatits?
- Good ectoparasite control
- Avoid overheating
- Control microbial populations –
- e.g. antimicrobial shampoos/wipes/foams
- For treatment and prevention
NB good control of underlying CAD is best way to prevent recurrent secondary infection!
What are the challanges with dealing with feline atopic dermatits?
- Few licensed products
- GCCs and ciclosporin licensed
- Oclacitinib and lokivetmab unlicensed in cats (NB Oclacitinib not recommended; NEVER lokivetmab to cats)
- Administration of oral and topical treatments generally more difficult than dogs
- Vet visits more stressful
- Scratching can cause rapid and severe damage
What are the consideration with treatment regarding what phase the patient is in?
-
Reactive – initial rapid control of clinical signs required
- May require initial course of corticosteroids (oral +/-topical) if inflammation +++. Then change to more targeted therapy for longer term use
-
Proactive – ongoing maintenance therapy to prevent recurrence
- Use safest drug/regime that is effective
- Remember to consider all aspects of multimodal therapy
- Avoid systemic corticosteroids if possible
- But if needed, taper to lowest effective alternate day dose
