Antipruritic treatments Flashcards
how common are skin issues in veterinary practice? how many are pruritis?
- skin disease is the second most common reason for consultation with the veterinarian
- Pruritus is the most common presenting complaint in dogs, accounting for 30 - 40% of dermatological consultations.
The best way to minimize side effects of any chosen treatment is to:
use multimodal therapy to minimize the side effects of any one treatment.
what factors contribute to persistent inflammation in chronic skin lesions?
Bacteria, yeast and self-trauma
how to control microbial ‘flare-factors’ in allergic dermatitis?
- judicious use of antibiotics, if at all
- Topical antimicrobial treatment is preferred for mild infections
> chlorhexidine or chlorhexidine + miconazole shampoos for local areas of bacterial infection - Yeast pododermatitis can also be treated with topical antifungal shampoos, sprays and ointments (miconazole, ketoconazole, clotrimazole, climbazole, terbinafine for example)
pruritus case - control of parasites
- how long should an antiparasitic therapeutic trial be? what type of product should we use?
6-week course is recommended
- products with flea adulticidal activity as well as activity against other ectoparasites such as Sarcoptes scabei (e.g., selamectin, selamectin+sarolaner, moxidectin-imidacloprid, afoxolaner, fluralaner, sarolaner, lotilaner)
first priority for itchy dog treatment
- control microbes (dont forget about yeast)
- also, parasitacide treatment trial
is “T-shirt” therapy effective for atopic dermatitis?
yup, of of the most effective
what has been the mainstay of treatment for pruritic pets for decades
corticosteroids
what diseases can steroids make ‘feel better’? which wont respond?
- Steroids will make almost anything “feel better” - including microbial skin infection, some cases of food allergies, contact allergic dermatitis/contact allergy, flea infestation. Partial responses are common to scabies and cheyletiellosis as well.
- Fungal and immune mediated diseases generally do not respond to anti-inflammatory doses of steroids.
principles of glucocorticoid use:
Glucocorticoids should be used
o as infrequently as possible,
o at the lowest possible “effective” dose (to lead to a tolerable level of discomfort) and
o In alternate day regimes (or less) whenever possible (to expose the adrenal gland to variable steroid levels).
Mechanism of Action of Steroids
o Passive diffusion through cell membrane
o Bind to high affinity glucocorticoid receptors in the cytoplasm
o Glucocorticoid receptor separates from its “chaperone proteins” and the glucocorticoid – glucocorticoid receptor
complex migrates across the nuclear membrane and into the nucleus of the cell and dimerize. The dimers bind to glucocorticoid response elements in the DNA; regions of the DNA that can either upregulate or down regulate transcription
o As monomers, they can interfere with other factors such as nuclear factor (NF)-κB and activator protein 1 (AP-1) and nuclear factor of activated T cells (NFAT) among others
actions of glucocorticoids
- repress inflammatory genes,
- decrease production of collagenase, elastase, and plasminogen activator and
- inhibit synthesis or release of inflammatory cytokines
> such as IL-1, IL-2, IL-6, IL-8, TNF-α, IFN-γ, and granulocyte colony stimulating factor (GCSF).
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They directly or indirectly affect leukocyte kinetics, having effects on: - eosinophils (e.g., decreased formation),
- neutrophils (decreased diapedesis into tissues, decreased chemotaxis, adherence and enzyme secretion leading to a neutrophilia),
- mast cells,
- lymphocyte and
- monocytes,
> thus affecting phagocytic defenses, cell-mediated and humoral immunity. - They upregulate lipocortin 1, which has potent anti-inflammatory effects
routes of admin for corticosteroids? preferred?
- available as topical treatment, injectable and oral systemic therapy
- topical and oral routes are preferred > easier to titrate and control
what type of steroids do most dermatologists prefer to use?
- short acting steroids administered orally, low potency
- (prednisone, prednisolone, methylprednisolone)
adverse effects associated with steroid use
- Polyuria, polydipsia and polyphagia (PU/PD/PP) - the most reported adverse event.
- Pilosebaceous atrophy
- Delayed wound healing
- Calcinosis cutis
- Thin skin/skin fragility syndrome
- Curled pinna in the cat
- Demodicosis
- Diabetes
- Bacteriuria
- Dry scaly skin
- Comedones/milia
- Osteoporosis
- Muscle atrophy
- Cruciate rupture?
- Steroid hepatopathy
- Decreased thyroid hormone synthesis
- Adrenal gland suppression
