Mange Flashcards
What species of Demodex mites infect dogs and cats? Where are each found?
DOGS - D. canis (follicular), D. injai (follicular)
CATS - D. cati (follicular), D. gatoi (surface swelling)
What are the 3 steps to the pathogenesis of demodicosis?
- mite-specific immuno-incompetency allows for proliferation of mites
- mites secrete factors that suppress T-cell function resulting in general immuno-insufficiency –> down-regulates CD4+ T-cells, elevated TGF-b and IL-10, inhibits TNF-a, mRNA expression
- this leads to secondary infection (pyoderma)
What dogs are predisposed to demodicosis?
- purebred
- shorthaired
- <1 y/o (may outgrow disease!)
What is localized demodicosis? What are some signs? What happens with treatment?
lesions restricted to one or two body areas
- alopecia
- erythema
- mild scaling
- 90% spontaneously resolve
not typically relevant, but if done it will make lesions look worse initially
Localized demodicosis:
- hair loss around mizzle and lips
- healthy skin, no secondary illnesses
Localized demodicosis:
What lesions are indicative of generalized demodicosis?
multiple lesions
- alopecia
- scaling
- crusts
- papules
- erythema
- draining tracts, folliculitis/furunculosis from secondary Staphylococcus pseudintermdius infection
- systemic signs - anorexia, lethargy, depression
Generalized demodicosis:
secondary, systemic illness common
Generalized demodicosis:
- neck crusting
- serosanguinous exudate = furunculosis draining tracts
Generalized demodicosis:
bruising + draining tracts = furunculosis
Trichogram, demodicosis:
long = D. cati
What are the first choices for diagnosing the 4 causes of demodicosis in dogs and cats?
- D. canis - scraping, trichogram
- D. injai - trichogram
- D. cati - trichogram
- D. gatoi - scraping
(when using the squeezing technique)
What are 3 treatments recommended in cases of localized demodicosis?
- tincture of time - typically resolves
- topicals - benzoyl peroxide, rotenone, amitraz
- flea control medications with efficacy in Demodex - Isoxasolines
What are 2 treatments recommended in cases of generalized demodicosis?
- treat underlying pyodermia - systemic antibiotics, topical antimicrobial/antiseborrheic shampoos
- hydrotherapy - cleansing, facilitates pyoderma treatment
What must be done first in cases of generalized demodicosis?
control secondary infection FIRST –> reduces pruitis and “yuck” factor
- commonly co-treated with parasite treatment
What are 5 traditional treatments of canine demodicosis?
- Amitraz
- Ivermectin (avermectin)
- Doramectin (avermectin)
- Milbemycin
- Moxidectin (milbemycin)
What is the typical treatment timeline when using Ivermectin to treat demodicosis?
- 90-120 days
- treat 30 days past second negative scraping
not as commonly done due to better treatments
What adverse effects are associated with Ivermecting use in dogs and cats?
DOGS - muscle tremors, dilated pupils, blindness, ataxia, seizures, sudden death
CATS - crying, anorexia, dilated pupils, blindness, hindlimb paralysis, muscle tremors, disorientation
due to ABCB-1 (MDR-1) gene mutation - P-glycoprotein pumps drugs out of the BBB –> genetic test available (EDTA blood sample, cheek swabs)
What 4 drugs cannot be used with Avermectins? Why?
- Ketoconazole (itraconazole)
- Spinosad
- Erythromycin
- Cyclosporine
these drugs act as P-gp inhibitors and can lead to toxicosis
What is the treatment of choice for cases of demodicosis? How do they work?
Isoxazolines - Bravecto, Nexgard, Simparica, Credelio
blocks insect GABA and glutamate-gated chlorine channels
What are 4 advantages to using Isoxazolines to treat demodicosis? What is a disadvantage?
- highly efficatious
- label doses are effective
- minimal adverse effects
- no contraindications in dogs with ABCB-1 mutation
not labeled for treating demodicosis
What treatment is contraindicated in cases of demdicosis?
glucocorticoids
- immunosuppression makes it worse
- search for underlying disease in older patients, like Cushing’s, DM, autoimmune disease, chemotherapy
What are 3 clinical features seen in Demodex injai infestation?
- adult dogs
- most common over dorsal lumbar region
- pruritus, alopecia, and grassy skin/hair coat
Demodex injai:
otitis cleared up with treatment