Dermatological therapeutic case discussion Flashcards
Dermatophytosis key points considering this case?
12mo NM Colourpoint
Lives in household with one other cat (4yo DSH) and a dog (2yo WHWT), neither of whom have skin lesions.
You have diagnosed dermatophytosis caused by Microsporum canis.
Treat effected animal topically and systemically and the in contacts ideally systemically and topically too but if just topical for in contacts ok too.
Important to treat cats and dog – cats often asymptomatic carriers
Zoonotic! Warn re avoiding handling animals and risk from fomites; esp if immunocompromised people. Go to doctors if they develop lesions. Avoid immunosuppressed people e.g elderly, children, HIV etc
Spores very long-lived in environment – essential to clear from here to prevent continuous reinfection
Clinical resolution reached before mycological cure – base assessment of progress on basis of cultures, not clinical appearance of animal.
Important to treat promptly and fully, as can be very difficult condition to clear, especially in multi-animal environment
Trim hair around lesions with scissors and dispose carefully of hair
Shave cats? Controversial… clipping may cause micoabrasions and exacerbate infection
Dermatophytosis topical and systemic treatments considering this case?
12mo NM Colourpoint
Lives in household with one other cat (4yo DSH) and a dog (2yo WHWT), neither of whom have skin lesions.
You have diagnosed dermatophytosis caused by Microsporum canis.
Topical Tx: rarely enough alone, but reduces environmental contamination
- Miconazole/chlorhexidine or MalAcetic shampoo (aka Malaseb bath twice weekly with contact time of 10 mins)
- Lime Sulphur dips (cheap/effective but staining, pungent)
- Enilconazole washes (dogs only) (aka imaverol)
Systemic Tx:
- Itraconazole: orally to cats: licensed for cats, not dogs. Treat daily for 7 days on 3 alternating weeks at least. Give with food. Not if hepatic compromise. Comes as an oral solution.
- Ketaconazole: licensed treatment for dogs. Less well-tolerated than itraconazole; unlicensed and minimally effective in cats. GI and hepatic side effects – monitor hepatic parameters. So dogs may be better on itraconazole even though it isn’t licensed diff decision.
- Lufenuron – ineffective
- Griseofulvin – unavailable for dogs/cats
Discuss dermatophytosis environmental treatments considering this case?
12mo NM Colourpoint
Lives in household with one other cat (4yo DSH) and a dog (2yo WHWT), neither of whom have skin lesions.
You have diagnosed dermatophytosis caused by Microsporum canis.
Environmental decontamination: Dermatophytosis lasts in the environment for years
- Disposal of hairs
- Physical cleaning (eg daily vacuuming, seal and burn bag)
- Chemical agents (eg sodium hypochlorite (bleach undiluted or 1:10), enilconazole, lime sulphur, others eg formaldehyde, glutaraldehyde, quarternary ammonium chlorides)
- Get rid of old bedding
- Lots of high temp washes
How should dermatophytosis treatment be monitored?
Monitor all animals with coat brushing weekly/2 weekly: treat until 2-3 negative cultures at least 7 days apart.
Discuss pemphigus foliaceus treatment when considering this case:
8yo NM Cocker Spaniel with extensive crusting.
Your skin biopsies have diagnosed pemphigus foliaceus.
Tinker is insured.
In this case get azathioprine up and running with a steroid and when you think it is starting to work you start tapering the steroid off!
Immunosuppression
Glucocorticoids
- Use immunosuppressive doses:
- eg prednisolone 2-4mg/kg/day in divided doses
- Gradual reduction to alternate day therapy (eg to 2mg/kg eod), then gradually reduce further to lowest effective alternate day dose (see Aiden Foster lecture)
- Alternatively use methylprednisolone? (Less mineralocorticoid effects? but more costly)
- NB 0.8mg methylprednisolone is equivalent to 1mg of prednisolone
+/- Azathioprine Not recommended for cats
- Wear gloves it is a cytotoxic drug and never split the tablets and be careful around secretions from animal
- Adverse effects
- myelosuppression, pancreatitis, and hepatotoxicity
- Complete haematology/platelet count and serum biochemistry initially monitored every 2 weeks for 2 months and then every 2 - 3 months
- Slow onset of action - three to six weeks to produce clinical effects so usually use concurrent corticosteroids initially, then gradually withdraw corticosteroids to lowest effective alternate day dose
Alternatively prednisolone + chlorambucil?
- Less toxicity than azathioprine, but ?slower to effect
- Monitor haematology every 2 weeks initially
Gold Salts?
Cyclophosphamide? Less nasty than azathioprine but a much more expensive drug
Adjunct therapy
- Chlorhexidine-based shampoo / product for the secondary bacterial component and to remove crust/scale
- Antibiotics for three weeks e.g. cephalexin 20mg/kg BID
- Gut protectants (e.g. cimetidine) to reduce risk of side effects of such therapy
Remember it’s our treatment that kills these dogs as you can’t leave pemphigus untreated but steroids have adverse effects causing pathology
How would you treat this case of atopic dermatitis considering the ownes financial limitations?
2yo English Bull Terrier with non-seasonal pedal pruritus. Atopic dermatitis with secondary Malassezia infection has been diagnosed.
Ellie’s owner is 75 and lives alone. She does not wish to pursue immunotherapy or further investigations into the allergens involved, as her budget for Ellie’s treatment is limited.
Allergen avoidance? High likelihood of involvement of dustmites (non-seasonality)
Oral EFAs to improve cutaneous barrier?
Local topical treatment of Malassezia: Topical shampoo initially every 2-3 days, then gradually reduce frequency to maintenance 2x/week (if owner able to manage)
- chlorhexidine 2%/miconazole 2% shampoo (Malaseb)
- chlorhexidine 3% shampoo (Microbex, Douxo Pyo)
- chlorhexidine 4% shampoo or spray (Clorexyderm)
- chloroxylenol/sodium thiosulphate/ salicylic acid (Coatex Medicated shampoo)
- piroctone olamine (PO) shampoo
- Sebomild: PO plus degreasing/keratolytic/keratoplastic properties
- Allermyl: PO plus mild antipruritic/moisturising /cutaneous barrier properties
- Topical wipes (Triz EDTA/chlorhexidine/climbazole (CLX wipes) or acetic acid/boric acid (MalAcetic wipes))?
- Chlorhexidine spray/foam.
Systemic treatment of Malassezia if topical not feasible?
- Eg Ketoconazole sid for 3 weeks, then reduce to maintenance dose eg 2-3 times weekly
Licensed in dogs for dermatophytosis
Possible hepatotoxicity: monitor liver enzymes. Give with food to reduce GI effects
- Itraconazole sid initially to control (eg 2 weeks) then maintenance 2 consecutive days/week but
Unlicensed in dogs
Costly
Possible side effects: hepatotoxicity (monitor liver enzymes), GI effects (giving with food helps reduce this), occasional cases of vasculitis
Reduce pruritus
Ideally assess response to clearing secondary microbial infection first. If inadequate effect, consider use of other drugs:
Antihistamines? May help but effect mild? Evidence base for use they have as good a response as a placebo?
Corticosteroids: oral prednisolone: start 0.5-1mg sid, then gradually reduce to lowest effective eod (every other day) dose
Oclacitanib (Apoquel)-may be too expensive. rapid, effective in 70% cases. Some pruritus may occur as dose reduced after 2 weeks. Longterm effects unknown –monitor haem/biochemistry regularly – some à leucopaenia, lipid disturbances.
Ciclosporin: slow to work but effective. Cost may preclude.
Hydrocortisone aceponate spray (Cortavance) (unlicensed for >7 days’ treatment): sid treatment to effect, then reduction of frequency to minimal effective (eg 2 days per week). Less skin-thinning/systemic effects than betamethasone (eg Isaderm) but these effects can still be seen.
Tacrolimus 0.1% ointment (Protopic) to localised areas? Unlicensed/costly but no skin-thinning or apparent systemic effects, cf topical corticosteroids. Slow to effect. Owner must wear gloves.
How would you approach this case of atopic dermatitis concurrent pyoderma infection:
Sadie is a 5yo NF Doberman who is known to suffer from atopic dermatitis.
Her owners have returned from holiday and found she has been rubbing her face excessively and developed an ill-defined ulcerated plaque on her right mandible.
Your cytology shows neutrophils and intracellular cocci, suggestive of a pyoderma.
Cytology indicative of pyoderma.
Severity of lesions à likely deep pyoderma. Biopsy for histopathology to confirm in light of lesion severity (d/d neoplasia/other inflammatory disease with secondary bacterial infection?)
All deep pyodermas need culturing. Take a tissue biopsy in this case good candidate for it.
- Will need to treat deep pyoderma with antibiotics for minimum 6 weeks (and 14 days post-resolution of pyoderma), on basis of tissue culture and sensitivity
Suitable antibiotics potentially:
- Cephalexin 20-25mg/kg bid (off-label)
- Potentiated amoxycillin
- Potentiated sulphonamide (TMPs)? Not Doberman have an immune reaction to them get polyarthritis, pyrexia blotches all over skin! All breeds: risk esp of KCS with longterm use. Poorer Staph sensitivity profile than others
- Clindamycin? bacteriostatic (bacteriocidal a/biotic better if deep pyoderma)
- Fluoroquinolones? – effective but only if no other option – use on basis of C+S only
If furunculosis on histopathology, may need longer antibiotics (eg 12 weeks?) as intradermal keratin may perpetuate inflammation so will continue to flare up after infection has been cleared
May need topical antinflammatories to control inflammation once infection resolved
Prevent further rubbing if necessary, eg Buster collar
Address underlying atopy.
