Mite Derm objectives
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- Which parasitic mites have zoonotic potential?
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-Scabies (both Sarcoptes Scabiei var. canis and Notedres cati)
-Cheyletiella - Describe several diagnostic techniques that could be used to diagnose Cheyletiellosis.
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-Visualization of parasite:
-Larger than sarcoptes
-Prominent mouth hooks
-Visualization of eggs:
-Small and attached to hairs by fine strands
-Methods of parasite visualization:
-Direct examination of “walking dandruff†(w/ naked eye or hand lens)
-Superficial skin scrape
-Acetate tape preparation
-Fecal floatation
-Flea combing
-Vacuum tests - Which parasitic mite have a reputation of causing extreme prurititis?
- -Scabies (both canine and feline)
- What is the pathogenesis of canine generalized demodecosis?
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-Disease only occurs when mites are able to proliferate out of control
-Dysfunction of T-lymphocytes
-Hereditary predisposition (spay and neuter to prevent passing along unwanted traits)
-Immune suppression - What are the clinical features of canine generalized demodecosis?
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-NO standardized number of lesions is set to distinguish between localized and generalized
-Must know how to differentiate the two b/c it affects treatment
Rule of thumb:
->12 lesions or
-Involvement of entire body region or
-Involvement of two or more feet
Variable presentation:
-Pododemodicosis
-Very painful
-Often resistant to therapy
-Squamos form is the initial form
-Pusutular (bacterial) is the progression from squamos
-Bacterial folliculitis => furunculosis =>deep pyoderma
-Cellulitis => sepsis => death
Adult Onset:
-Usually have an underlying immunosuppressive disorder: relapsed juvenile form, iatrogenic cushings, natural cushings, DM, hypothyroidism, lymphoma, other neoplasia - What is the treatment for canine generalized demodecosis?
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-6-8 weeks of antibiotics
-Clavamox and Cephalosporin are good empirical options if there is no culture and sensitivity
-Weekly Benzoyl peroxide shampoo
-Identify and resolve the underlying disease
-Acaricidals:
-Amitraz dips
-Ivermectin
-Milbemycin
-Clinical cure will be achieved before parasitological cure
-Patients must be treated until 2 negative skin scrapes , 2-4 weeks apart
-Scrape the same area and record the number of mites each time - What is the prognosis of canine generalized demodecosis?
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-Good
-90% respond well w/ treatment (still a risk of relapse)
-Can be an extremely severe disease
-Long length (min. 4 month) of treatment and cost - What is the pathogenesis of canine localized demodecosis?
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-Disease only occurs when mites are able to proliferate out of control
-Dysfunction of T-lymphocytes
-Hereditary predisposition (spay and neuter to prevent passing along unwanted traits)
-Immune suppression - What are the clinical features of canine localized demodecosis?
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a.k.a. Juvenile Onset:
-<18 months of age
-Single to multiple (less than 6 lesions) of erythematous patches of alopecia
-Found on face and forelegs - What is the treatment for canine localized demodecosis?
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-Often a self-limiting disease
-Watchful neglect
-Benzoyl peroxide
-Follicular flushing action and anti-bacterial
-Recommend spay/neuter
-Decline treatment for show and breeding dogs
-Monitor monthly w/ skin scraping to ensure no progression - What is the prognosis for canine localized demodecosis?
- Good
- What are the clinical features of generalized Demodex cati?
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Even more rare than localized
-Siamese and Burmese are at risk
-Usually has an underlying condition (FIV, FeLV, DM, Bowen’s disease, neoplasia) - What is the treatment for generalized Demodex cati?
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-Generally much easier than canine treatment
-Manage pyoderma
-Lime sulfur dip
-Ivermectin - What is the prognosis of generalized Demodex cati?
- Good
- What are the clinical features of localized Demodex cati?
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Rare condition
-Eyelids, neck, head, periocular
-Differential for feline acne
-Usually responsive to lime sulfur or other mild parasiticides
-Often self-limiting - What is the treatment for localized Demodex cati?
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-Generally much easier than canine treatment
-Manage pyoderma
-Lime sulfur dip
-Ivermectin - What is the prognosis of localized Demodex cati?
- Good
- Where do Demodex canis mites colonize in the skin?
- Colonize the hair follicle and occasionally the sebaceous gland
- Describe the type of skin scraping that you would do to find Demodex.
- Must do a deep skin scraping to find them (scrape until capillary bleeding)
- What are the clinical features (types of lesions and distribution) of Sarcoptes scabiei var canis in dog?
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-Mite has predilection for sparsely haired areas:
-Ears, elbow, hocks
-Found predominatly ventrally distributed:
-Abdomen, chest, legs
-Initial primary lesion is erythematous papule +/- white, yellow crust
-Chronicity and self-excoriation can lead to:
-Alopecia
-Thickened skin
-Extensive crusting - How do you evaluate the treatment response of a dog w/ generalized demodicosis?
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-Evaluate based on the results of skin scrapings (looking for 2 negative skin scrapes 2-4 weeks apart)
-Watch for signs of toxicity on some of the drugs (i.e. Amitraz (mitaban) dip)
-If unable to achieve resolution, recommend long-term maintenance therapy:
-Oral ivermectin (2 days/week) –OR- Monthly amitraz dips - Which mite is the walking dandruff mite and how would you treat an animal infected w/ it?
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-Cheyletiella
Treatment:
-Treat all contact animals for min. 4wks
-Treat environment (pyrethrin spray)
-Keratolytic shampoo
-Topical therapy (Lime sulfur dip, mitaban dip, paramite)
-Avermectins are effective
-Fipronil (frontline) - In which disease is the use of corticosteroids contraindicated and why?
- -Demodex (animals are already immunocompromised esp. w/ the adult onset)
- How does a fecal floatation help you identify mange mites?
- -Some animals may excessively groom and ingest the mites and pass them in their feces
- What are the side effects and contraindications to the use of Amitraz?
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-Toxicity
-Hypoglycemia
-Don’t use in small dogs (at very high risk for toxicity)
-Don’t save the bottle (potency and toxicity increase when exposed to oxygen)
-Can interact w/ other drugs and potentiate its toxicity:
-Hydroxyzine (Atarax)
-Behavioral drugs (Prozac)
-Sedatives (Diazepam, Acepromazine)
-MAO inhibitors (problem in humans) - What are the side effects and contraindications to the use of Ivermectin?
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-Toxicity
-Hypersaliviation
-Mydriasis
-Lethargy
-Ataxia
-Tremors
-Coma
-Death - Which mite may be extremely difficult to find?
- -Canine sarcoptes (a negative scrape does not rule out a diagnosis)
- What are some Differential diagnoses for Canine Demodicosis?
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Bacteria pyoderma
Dermatophytosis
Muzzle folliculitis & furunculosis
Canine impetigo
Abrasions
Contact dermatitis
Pemphigus diseases
Lupus erythmatosus
Facial lesions of dermatomyositis - How would you treat Sarcoptic mange?
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-Treat all contact animals
-Environmental management
-Clip if using dip
-Keratolytic shampoo
-Miticidal therapy : topical and systemic
-Corticosteriods (animal may get itchier after starting treatmet)
-Treat for 2 life cycles (6 weeks)
-Lime-sulfur dips (6 weekly dips)
Topical therapy:
-Paramite
-Organophosphate (watch for toxicity related problems)
-Resistance occurs
-Amitraz
-Potential for toxicity
-Dip q. 2 weeks for 3 treatments
Systemic therapy:
-Selamectin (Revolution)
-Only FDA approved therapy for sarcoptes
-Spot on therapy
-2 applications q. 30d,
-Wide safety of margin (even in collies)
-Ivermectin
-Watch for signs of toxicity (avoid in collies)
-q. 7 days if PO and q.14 days of SQ
-Milbemycin
-Easy to use
-q. 7 days for 6 weeks
-Safer to use (even in susceptible breeds) - What is the pinnal-pedal reflex, and which mite is this associated with?
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Pinnal-Pedal Reflex = scratch the ear and the rear leg starts scratching
-Seen w/ canine sarcoptes - What are the three common species of Cheletiella mites?
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1. C. yasguri (dogs)
2. C. blakei (cats)
3. C. parasitivorax (rabbits) - Why does demodicosis develop in some dogs and not in other (even among litermates)?
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-It is part of the normal flora of canine hair follicle
-Animals who develop demodicosis are immunosuppressed, predisposed genetically, or have dysfunctioning T lymphocytes - What are the two major species of feline Demodex mites?
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Demodex cati
Demodex gatoi - What is the clinical presentation for localized and generalized Demodex cati infestations?
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LOCALIZED FOLLICULAR DEMODICOSIS:
-Rare condition
-Eyelids, neck, head, periocular
-Differential for feline acne
-Usually responsive to lime sulfur or other mild parasiticides
-Often self-limiting
GENERALIZED:
-Even more rare than localized
-Siamese and Burmese are at risk
-Usually has an underlying condition (FIV, FeLV, DM, Bowen’s disease, neoplasia) - What are some characteristics of Demodex gatoi?
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-Short bodied
-Found in the stratum corneum
-Contagious
-Pruritic
-Hairs don't epilate easily - What is the distribution of Demodex gatoi lesions?
- -Head, neck, elbow
- What are the signs of Demodex gatoi infestations?
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-Alopecia
-Scale, erythema
-Excessive grooming
-More puritic than D. cati