Dermatology - Demodicosis Flashcards
What mites cause demodicosis in dogs and which is the most common?
Demodex canis (common) and Demodex injai
What mites cause demodicosis in cats and which is the most common?
Demodex cati and Demodex gatoi (common)
Where does the life cycle of D. canis, injai, and cati occur?
the entire life cycle is completed in the hair follicle of the host
Where does the life cycle of D. gatoi occur?
in the outer layers of the stratum corneum
What are the stages of the Demodex lifecycle?
egg, larva, nymph, adult
How is Demodex canis acquired?
They are considered natural inhabitants of the skin, but they proliferate during pregnancy and thus are transmitted at birth
Which species of Demodex is thought to proliferate due to a genetic predisposition?
Demodex canis
How do Demodex affect the immune system?
they suppress it leading to secondary bacterial and fungal infections - the patients becaume an immunologic cripple
What may predispose an animal to infection with Demodex?
any immunodeficiency syndrome
What Demodex species is spread by direct contact?
Demodex gatoi
What are the two types of demodicosis caused by Demodex canis?
Localized and generalized
What age dogs is generalized demodicosis more common in?
dogs less than a year of age
Where is localized demodicosis commonly seen?
on the forelimbs, face, and on periocular skin
What does localized demodicosis typically look like?
Well circumscribed areas of alopecia with mild scaling and erythema confined to one body area
What form of demodicosis does not typically have secondary problems associated with it?
localized
True or False: 90% of lesions due to generalized demodicosis will spontaneously resolve, 10% will not
False - 90% of the lesions in localized cases will resolve and 10% will become generalized
What areas of the body are typically involved in cases of generalized demodicosis?
the face, forelimbs, and feet
What lesions are typically associated with generalized demodicosis?
Lesions include generalized erythema, crusting, scaling, and patchy to diffuse alopecia, sometimes with bluish or bruised appearance
What secondary infections (lesions) are commonly associated with generalized demodicosis?
Folliculitis and furunculosis, leading to the development of papules, pustules, and fistulous tracts. Staphylococci are the most common agents isolated
Other than skin lesions, what other secondary complications are associated with generalized demodicosis?
Anorexia, pyrexia, and depression; generalized lymphadenopathy is present
Is pruritis associated with generalized demodicosis?
It is absent or mild unless there is secondary infection - then it is moderately intense
What is adult-onset demodicosis defined as?
onset of generalized demodicosis after 1-2 years of age
What conditions is adult-onset demodicosis associated with?
Immunosuppressive disorders, such as hyperadrenocorticism, hypothyroidism, organ failure, etc, and systemic administration of glucocorticoids
Where, on the body, are Demodex injai typically found?
over the dorsal midline, often in animals under stress
What type of lesions does Demodex injai cause?
erythema, excessive oiliness to skin and hair, and pruritus
What may be the only clinical sign of demodicosis caused by Demodex gatoi?
Pruritus - it is usually (but not always) present
What is the most common finding with cats that have a Demodex gatoi infestation?
symmetrical alopecia caused by licking
What is the treatment of choice for demodicosis caused by Demodex gatoi?
lime sulfur rinses (weekly for 3-8 treatments)
What diagnostic tools are prefered to diagnose demodicosis?
skin scrapings or a trichogram
In adult-onset and severe cases of demodicosis what diagnostic tests are indicated?
Culture, fecal flotation (in case they ate it), cytology, bacterial culture and susceptibility, general health, and evaluation of thyroid hormones
What will reveal the presence of mites in hair follicles but is not the preferred procedure to make a diagnosis?
skin biopsies
Describe the recommended therapy for localized demodicosis.
No therapy is required in a vast majority of cases, topical therapy with benzoyl peroxide or rotenone may provide some benefit, client education is important, and the prognosis is excellent
What therapy is recommended to provide symptomatic and supportive care in generalized demodicosis cases?
Treat pyoderma with proper antibiotic therapy (most important), shampoos to remove crusts, debris, and help control pyoderma, and hydrotherapy to alleviate pain
What topical acaricidal agents can be used to treat generalized demodicosis (even if they are no longer in production)?
Mitaban, Lime sulfur, Metaflumizone + amitraz (Promeris), and Imidocloprid + Moxidectin (Advantage-multi)
How should you use Mitiban to treat generalized demodicosis?
Rinses are recommended at 1 week intervals for 8-12 weeks and then are continued until two consecutive scrapings are negative - they may be necessary on an intermittent basis on a long-term basis for chronically affected dogs
What side-effects are associated with Mitiban use?
lethargy, bradycardia, and vomiting
What can reverse the side-effects associated with Mitiban?
yohimbine
What demodex species is lime-sulfur ineffective in treating?
Demodex canis and Demodex cati infestations
What is Lime sulfur effective in treating and how is it applied?
Demodex gatoi - weekly for 6-8 treatments
What is Promeris effective in treating?
doesn’t matter it is no longer in production
Advantage-Multi (Imidocloprid + Moxidectin) is approved for dogs and cats to treat demodicosis, but cannot be used where (not labeled)?
in the United States
If Advantage-Multi were to be used in treating demodicosis, what is the recommended dose?
Weekly application
What can be used as systemic therapy for generalized demodicosis?
Ivermectin, Milbemycin oxime (Interceptor), Moxidectin, Doramectin, Isoxazoline class insecticides
What is the recommended dose of Ivermectin to treat demodicosis?
0.5-0.6 mg/kg daily for extended time periods
What is the recommended treatment plan with Ivermectin in demodicosis cases?
Doses should be initiated at lower doses and then slowly increased to the final dosage. Treat for one month past two negative (weekly) scrapings
What is a sign of Ivermectin toxicity?
dilated pupils, ataxia, muscle tremors, seizures, vomiting, or diarrhea
In amitraz-resistant cases of demodicosis, Ivermectin has shown a 60-70% cure in how many days?
90-120 days
What patients should you not use Ivermectin in and why?
In collie dogs or related breeds because they MDR1 gene mutation that does not allow them to flush drugs out of the blood brain barrier which causes a build up and thus toxicity
Interceptor (Milbemycine oxime) may be effective in what percentage of chronic cases and how long is treatment contined?
It may be effective in up to 60% of chronic cases and is continued for 30 days past negative scrapings
In what cases is Interceptor not recommended in and why may some people not choose it?
It is not recommended in avermectin-sensitive dogs. It is also very expensive
What drugs do Moxidectin and Doramectin act like?
Ivermectin because they are all avermectins
What Isoxazoline class insecticides can be used to treat demodicosis?
Nexgard (Afloxalaner), Bravecto (Fluralaner), and Simparica (Sarolaner)
What therapies are ineffective in treating demodicosis?
topical selamectin (Revolution), oral lufenuron (Sentinel), topical ivermectin, and regular application of amitraz-containing flea collars
What appears to be affective in treating Demodex injai demodicosis?
Oral ivermectin, isoxazolines, and amitraz rinses
Aside from lime sulfur, what can be used to treat Demodex gatoi demodicosis?
Bravecto and extra-label Advantige-Multi
What treatment is entirely contraindicated in treatment of demodicosis?
corticosteroids
A
Follicular
B
Folliculbr
C
Follicular
D
Surface
E
Dog
F
Dog
G
Cat
H
Cat
I
Trichogram, skin scraping
J
Trichogram, skin scraping
K
Trichogram, skin scraping
L
skin scraping
M
No
N
No
O
No
P
Yes
Q
Isoxazolines, Ivermectin
R
Isoxazolines, Ivermectin
S
Ivermectin
T
Lime Sulfur
