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
How is Demodex injai infection diagnosed? What is characteristic?
trichogram, skin scraping
long mite seen in LOW numbers –> recommend taking 7-10 samples of multiple techniques and careful examination of slides
What are 3 options for treating Demodex injai infection?
- Isoxazolines - treatment of choice
- Ivermectin
- Advantage multi - weekly application
What are the 2 most common Demodex species that infect cats?
- D. cati - follicular, rare, often found in ear
- D. gatoi - surface-dwelling, common
Demodex cati:
comedones
What is seen in this trichogram?
Demodex mites
Where is Demodex cati infection commonly found?
ears - oily d/c
How do Demodex gatoi infections typically present? How is it diagnosed?
ventral alopecia and pruritis +/- symmetrical
skin scraping, fecal flotation, histopathology
Demodex gatoi:
ventral alopecia
- surface swellers, deep scraping not necessary
Demodex gatoi, skin scrape:
- superficial mites seen in variable numbers
- small, require conscious searching
- cats manifest with pruritus and licking –> fecal floats recommended
Why are fecal floatations able to be used to diagnose Demodex infestations? In what species does it work best for?
patients may be pruritic so they will lick the affected area + mites will float in all fecal solutions –> focus on air bubbles where mites will float
D. gatoi
What are the 2 treatments of choice for demodicosis in cats? What is another options?
- Fluralaner - Bravecto for cats, treat every 8 weeks for 2-3 doses
- lime sulfur - treat weekly for 4-8 treatments, 2 treatments past negative skin scrapings
Advantage Multi - topical spot-on applied every 1-2 weeks
Treatments of choice for demodicosis:
What is the most common cause of sarcoptic mange? What is characteristic?
Sarcoptes scabiei var canis –> highly contagious, zoonotic potential (wild canids act as reservoirs)
severe pruritus from irritation and hypersensitivity reactions
What is the life cycle of sarcoptic mange like?
females burrow into skin to lay eggs –> develop into larva, nymph, and adults within 3 weeks
What are 3 important historical features associated with sarcoptic mange? What may these signs respond to?
- multiple animals in household involved
- pruritus following exposure from kenneling, boarding, or holidays
- humans in household may have lesions
glucocorticoids –> progressively less effective
What are 3 clinical signs associated with sarcoptic mange?
- intense pruritis
- generalized lymphadenomegaly (hypersensitivity)
- crusts, scaling, erythema, alopecia, excoriations
What are the 4 classical distributions of sarcopic mange lesions?
- periocular areas
- ear margins
- elbows
- lateral extremities
Sarcoptic mange:
characteristic elbows
Sarcoptic mange:
What are 3 options for diagnosing sarcoptic mange?
- identify mite - multiple superficial skin scrapes (ear margins, elbows), fecal flotation
- serology - ELISA (IDEXX)
- histopath - not sensitive!
What are scybala?
fecal pellets from sarcoptic mange that can be seen on skin scrapes
How is sarcoptic mange treated?
treat all suspected animals, all animals in the household, AND the environment
- control pruritus with glucocorticoids
- suggest humans with lesions consult with physician
What 2 topical treatments are recommended for sarcoptic mange?
- baths and rinses - keratolytic baths to remove crust and scales, benzoyl peroxide, ketoconazole, or miconazole to treat secondary infections
- ascaricides - 2% lime sulfur applied every 6-8 weeks, monitor with skin scrapings
total body clips recommended for medium and long coats
What 6 ascaricides are recommended for sarcoptic mange?
- Selamectin (Revolution) - 2 doses in 2-3 week intervals, no adverse effects noted
- Moxidectin (Advantage Multi) - labeled for monthly treatment, but clearance is slow and can be done 2-3 months, treatments q 14 days for mange
- Ivermectin (Ivomec) - ataxia, vomiting, not recommended in herding breeds
- Fipronil (Frontline) - total body spray once weekly for 2 weeks, topical irritation
- Milbemycin oxime (Interceptor) - neurologic signs in herding breeds, lethargy, vomiting
- Isoxalines - mites typically clear in 30-60 days, if lesions persist consider other factors
What are 5 parts to practical management of sarcoptic mange?
- glucocorticoids
- treat all affected dogs and cats with lime sulfur rinse for immediate relief
- treat all household animals with selamectin, ivermectin moxidectin, afoxolaner, fluralaner, or sarolaner
- clean and disinfect environment
- recommend consultation of humans with their physician if lesions are present
What are some things that cause treatment failure in cases of sarcoptic mange?
- incorrect diagnosis
- secondary problem - Malassezia dermatitis
- incorrect dosage of insecticide
- insufficient treatment
- incomplete application of rinses and pour-ons
- re-infestation (farm dogs)
How is sarcoptic mange prevented?
monthly preventatives
- Advantage Multi
- Isoxazolines
- Revolution - efficacy includes mites!
What are lesions of sarcoptic mange like in humans?
mosquito bite-like lesions that are intensely pruritic
- persist for weeks to months
What species of Cheyletiella infect animals? Where does the life cycle take place?
- C. yasguri - dogs
- C. blakeii - cats
- C. parasitovorax - rabbits
- C. firmani - exotics
entirely on the animal —> attaches eggs to hairs
What does Cheyletiella look like on a skin scrape?
- large
- no suction cups on extremities
- more spider like
walking dandruff
What clinical signs are seen with Cheyletiella infection? In puppies?
- variable levels of pruritis
- scaling and erythema progress to crusts
- excoriations
scales over the base of the tail
Cheytiella:
walking dandruff –> scales!
Cheytiella:
- hard, erythematous scale
- pruritic
How can Cheytiella infestation be diagnosed?
- direct observation with magnifying lens
- tape preparations
- skin scrapings
- fecal flotation
- flea comb to remove scale and KOH digestion
What information can be given about Cheytiella infection with a trichogram?
can locate eggs laid on hair
What are 5 options for treating Cheytiella?
- Ivermectin/Selamectin/Moxidectin
- Isoxazolines
- topical ascaricides - lime sulfur, Amitraz, Carbamates
- disinfect environment
- intermittent use of flea control products to reduce infestation
