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Terms in this set (96)
Infestation with lice
Parasitism of living animals by fly larvae (maggots)
Skin disease caused by parasitic mites
Excoriation, erosion, crust, alopecia, papules, etc.
Common lesions resulting from pruritus
Top three differential diagnoses for pruritus
Insecta - 6 legs
Arachnida - 8 legs
What are the two classes of arthopod groups? How do you tell them apart?
Flies, fleas and lice
What ectoparasites are in the insecta class?
Ticks and mites
What ectoparasites are in the arachnida class?
True (fleas laterally compressed)
T/F fleas are laterally compressed and wingless
What is the most common flea found on dogs and cats?
(a) newly emerged adult flea jumps onto host
(b) egg drops to the ground
(c) larva hatches, hides and develops
(d) larva spins cocoon and pupates
(e) following metamorphosis, adult flea emerges
Life cycle of Ctenocephalides felis
~3 weeks (Ctenocephalides felis)
How long does it take for the complete life cycle of Ctenocephalides felis
What is the lifespan for Ctenocephalides felis
Type I and IV
What hypersensitivity reactions are commonly seen with FAD?
What are fleas an intermediate host for?
T/F Fleas, ticks, lice, mites and flies can all be vectors for other diseases
False, they only move through hair in one direction (forward)
T/F fleas can move any direction through hair
Usually can be seen with the naked eye; but a flea comb can be used
What diagnostic tools can you use to diagnose fleas?
What color will the "flea dirt" turn if it is truly a flea infestation?
All animals will develop what pruritic skin lesion when bitten by fleas?
False, lice (are dorsoventrally flattened wingless insects with claws designed for holding onto the hair)
T/F fleas are dorsoventrally flattened wingless insects with claws designed for holding onto the hair
Chewing and sucking
What are the two types of lice?
(chewing lice can be found on mammals and birds)
What type of lice is only found on mammals?
Chewing: broad head, wider than thorax; designed for eating scale and hair/feathers
Sucking: head narrower than thorax; designed for piercing the skin and sucking blood and tissue fluid
How do you tell the difference between chewing and sucking lice?
Chewing: claws are smaller; found in singles on mammalian species and doubles on avian species
Sucking: powerful legs with big claws
Is there a difference between the legs/claws of a chewing vs. sucking louse?
Yes (entire life on host)
Do lice spend their entire lives on the host?
1. Cement eggs on host hairs
2. Nymph hatches from egg (no larval stage)
3. Molts 3 times before becoming adult
Life cycle of lice
How long does the life cycle of louse take?
What season will you usually see pediculosis?
Cats only have a chewing louse
Dogs have both
Do cats have chewing and sucking louse? Dogs?
Usually can be seen with naked eye; a flea comb can be used to look at hairs under microscope
How do you diagnose lice?
Surface (non-burrowing) vs. subsurface (burrowing)
How are mange mites grouped?
Surface: long legs, lesions they create are shallow, pathogenicity is mainly inflammatory and hypersensitivity reactions
Subsurface: short legs
How do you tell the difference between surface and subsurface mites?
Examples of surface (non-burrowing) mites
Sarcoptic mites: Sarcoptes scabiei, Notoedres cati, Trixacarus caviae
Knemidocoptes (Nem-ido-cop-teez) sp.
Examples of subsurface (burrowing) mites
Skin scrapings or trichogram
How do you diagnose mange mites?
1. Fertilized female mite creates tunnel in upper layer of epidermis; lays eggs while feeding
2. Eggs hatch in less than 1 week releasing 6-legged larva that crawl to skin surface; then burrow into epidermis forming 'molting pockets' where they become 8-legged nymphs
3. Males then look for unfertilized females on the surface or in a molting pocket
Life cycle of Sarcoptes scabiei
How long does the life cycle take for Sarcoptes scabiei?
Similar to Sarcoptes, but they do not burrow into the skin
Life cycle of surface (non-burrowing) mites
Erythema with papule formation; secondary scale, crust and alopecia
If a patient presents with pruritus and you suspect Sarcoptes scabiei what clinical signs should you see?
Ventral distribution; elbows, hocks and pinna
What areas do you normally see Sarcoptes scabiei in?
Useful when you are worried about scabies.
Rub pinnal margin between thumb and forefinger.
Positive result = elicits scratching by rear limb
When would you use the pinnal-pedal reflex to aid in diagnosis? Describe how to perform this and what a positive result looks like
Dogs and pigs
What species do you usually seen scabies in?
T/F if you see a case of scabies, you should be concerned about animal neglect
Birds (only species of burrowing mite for them)
What species do you normally see Knemidocoptes in?
Poultry: 'scaly leg' and/or 'depluming itch'
Caged birds: 'scaly beak'
Different species of Knemidocoptes cause diseases such as what in poultry? What about caged birds?
What is the "sheep scab mite"?
yes, highly contagious (P. ovis)
Is Psoroptes ovis contagious?
Psoroptes ovis: pointed mouth, end of leg is a funnel-shaped sucker mounted on a segmented stalk
Chorioptes bovis: rounded mouth, end of leg is a cup-shaped sucker mounted on a shorter unsegmented stalk
How do you tell Psoroptes ovis and Chorioptes bovis apart?
Rubbing, scratching and self-inflicted damage
Pruritus associated with Psoroptes ovis shows clinical signs such as...
Otodectes cynotis (ear mite)
What is the common ear mange mite of cats and dogs?
False, cats with Otodectes cynotis usually have few clinical signs, but in dogs it is a common cause of otitis externa
T/F dogs with Otodectes cynotis usually have few clinical signs, but in cats it is a common cause of otitis externa
False, they are usually mild and often overflooked
T/F clinical signs of dogs and cats with a Cheyletiella infestation are severe
Excessive amount of scurf (dandruff) and slight pruritus; scurf is "highly motile"
What clinical signs do you see with Cheyletiella?
What is the common name for Cheyletiella?
Yes, highly contagious (Cheyletiella)
Is Cheyletiella contagious?
How long is the life cycle for Cheyletiella?
1. Kill ectoparasite by damaging it's nervous system via selective toxicity
2. Insect Growth Regulators (IGRs) disrupt development of juvenile stages
What are the two common mechanisms of action for ectoparasiticides?
Ability of a parasiticide to kill the target organism without harming the host
No, it only prevents new infestations from occurring
Do IGRs kill the ectoparasite?
Pyriproxyfen & Methoprene
Examples of IGRs
Are macrocyclic lactones narrow or broad spectrum antiparasitics?
Avermectins and Milbemycins
What are the two classes off macrocyclic lactones?
Ivermectin, Eprinomectin, Doramectin and Selamectin
Examples of Avermectins
Milbemycin oxime and Moxidectin
Examples of Milbemycins
No (Avermectins in horses)
Are there any approved Avermectins for use against lice or mites in horse?
What do we normally use ivermectin for in dogs and cats?
Cattle and swine
What species are labeled for use of Ivermectin for ectoparasite control?
What species can use Eprinomectin and Doramectin for ectoparasite control?
Heartworm & flea prevention; ear mite treatment
What do we use Selamectin for in dogs and cats?
What drug in the Avermectin class can we use on dogs and cats, off-label, to treat scabies and ticks?
No; even though it is absorbed systemically, it does not kill them
Does Selamectin kill Demodex mites when used off-label?
Cats; it is toxic
What species should we avoid when using synthetic pyrethroids?
Do synthetic pyrethroids work systemically or topically?
Fleas, lice, ticks and superficial mites;
also has repellent activity against flies and mosquitoes
What do synthetic pyrethroids kill?
Broad-spectrum against fleas, mites and many ticks
Are Isoxazoline ectoparasiticides narrow or broad spectrum?
Although it has revolutionized how veterinarians treat mange
T/F Isoxazoline is not labeled for use against mites in the US
Examples of drugs in the Isoxazoline class
T/F Isoxazolines have a wide margin of safety, but they can cause neurological adverse effects
Treatment: short-term measure aimed at producing an immediate impact on parasite population
Control: long-term perspective aimed at preventing future infection and minimizing disease risk
Difference between treatment and control
Name the ectoparasite in the photo; found in the external ear canal of a cat
Name the ectoparasite in the photo; found on the surface of a dog with excessive scurf and slight pruritus
Name the ectoparasite in the photo; found on the surface of a cow
Name the ectoparasite in the photo; found on the surface of a sheep with pruritus resulting in the animal rubbing, scratching and causing self-inflicted wounds
Name the ectoparasite in the photo; found on a dog that presented for intense pruritus.
Clinical signs include erythema, crust and alopecia. Lesions are local to the elbows, hocks and pinna
Name the ectoparasite in the photo; found on a guinea pig
Name the ectoparasite in the photo; found on a caged bird presenting with 'scaly beak'
Notoedres cati (macroparasite on slide)
Name the ectoparasite in the photo; found on a cat with intense pruritus
Notoedres cati (lesions)
What ectoparasite could be causing the lesions shown in the photo? The cat has intense pruritus and is causing excoriations
What ectoparasite could be causing the lesions shown in the photo? The dog presented for chronic pruritus.
Fleas (most likely Ctenocephalides felis)
What ectoparasite could be causing the lesions shown in the photo? Dog presented for a sudden onset of pruritus causing alopecia and papules.
What is shown in the photo?
Flea larva among hatched eggs and flea feces
What is shown in the photo?
What kind of louse is shown in the photo?
Louse egg attached to a hair
What is shown in the photo? Found on trichogram from a dog with a sucking louse infestation
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