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Parasites Flashcards

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Dermatology Board Prep flashcards
1
Q

Causative agent of Psoroptic mange in cattle?

A

Psoroptes bovis

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2
Q

Treatment options for Cheyletiella

A

Lime sulfur dips, Fipronil, Macrocyclic Lactones, Probably Isoxazolines??

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3
Q

How is Pelodera dermatitis diagnosed?

A

nematode larvae may be found in skin scrapings from affected skin or in associated bedding

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4
Q

Calliphorine myiasis (blowfly strike) is caused by what blowflies in North America?

A

Phormia regina and Phormia terrae-novae

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5
Q

T/F: Finding onchocerca spp. in a skin biopsy is definitive as the cause of the skin disease.

A

False - skin of normal horses and other dermatoses may contain Onchocerca without it being the cause of the pathology

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6
Q

Management/Treatment recommendations for cutaneous habronemiasis

A

combination of local and systemic therapy - ivermectin/moxidectin (larvicides), systemic glucocorticoids, topical glucocorticoids (tresaderm, Synotic); Fly control - disposal of manure and soiled bedding

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7
Q

Distribution of lesions of Notoedres cati

A

Medial pinna –> face –> eyelids –> neck –> generalized

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8
Q

Where do screw-worms lay their eggs?

A

edge of wounds, near body openings, do not breed in carcasses***

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9
Q

Management recommendations to control Haematobia spp. (horn flies)

A

removal of cow manure; daily application of fly spray

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10
Q

Define perionyxis

A

inflammation of the epidermis around a nail

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11
Q

Moxidectin is a macrocyclic lactone derived from what?

A

fermentation of Streptomyces spp.

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12
Q

What are the species of Habronema that produce cutaneous habronemiasis in horses?

A

Habronema muscae, Habronema majus, Draschia megastoma

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13
Q

Class of Ectoparasiticide: Permethrin

A

Voltage-gated sodium channel blockade (Adulticide)

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14
Q

How long do Psoroptes mites survive off the host in a typical barn?

A

14-21 days

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15
Q

In what species is Dermatophilosis a notifiable disease in the US?

A

cattle

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16
Q

What breed is specifically exluded in the label for Amitraz?

A

Chihuahuas

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17
Q

Management recommendations to control Stomoxys calcitrans (stable fly)

A

regular (at least 2x/week) removal of moist bedding, hay, and mure; use of residual environmental sprays

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18
Q

Side effects of DEET in horses

A

sweating, irritation, local skin exfoliation

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19
Q

Why are two baths needed to treat a lice infestation?

A

The first bath removes the adults, but the eggs are cemented to the hair and need a second bath to remove

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20
Q

Method of elimination of afoxolaner

A

biliary excretion of free afoxolaner and via hepatic metabolism and biliary and renal clearance of afoxolaner metabolites

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21
Q

Screw-worm species found in North, Central, and South America?

A

Cochliomyia hominivorax and Cochliomyia macellaria

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22
Q

Where do blow flies lay their eggs?

A

wounds or carcasses

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23
Q

What is the vector of Habronema muscae and Draschia megastoma?

A

Musca domestica

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24
Q

Side effects of Amitraz in horses

A

somnolence, depression, ataxia, weakness, colonic impaction

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25
Q

How is Dermanyssus Gallinae diagnosed?

A

Mites can be demonstrated in skin scrapings; history of exposure to chicken houses or poultry quarters

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26
Q

Where does Stomoxys calcitrans (stable fly) lay their eggs?

A

wet straw, bedding, or manure (especially aging manure)

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27
Q

T/F: Absorption of afoxolaner is increased when given with food.

A

False - can be given with or without food

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28
Q

T/F: Afoxolaner is registered for treatment of canine demodicosis in Europe.

A

TRUE

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29
Q

What do Thaumetopoea spp. (pine/oak caterpillars) contain that can cause mast cell degranulation and histamine release?

A

thaumetopoein

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30
Q

Class of Ectoparasiticide: Nitenpyram

A

Neonicotinoid: blocks Ach receptor (Adulticide)

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31
Q

Compared with animals who have localized demodicosis or those that are healthy, dogs with generalized demodicosis have lower mRNA for what cytokines?

A

IFN-gamma and TNF-alpha

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32
Q

Why doesn’t ivermectin kill trematodes and cestodes?

A

they lack GABA system (and ivermectin is a GABA receptor agonist in its mechanism of kill)

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33
Q

Milbemycin is the fermentation product of what?

A

Streptomyces hygroscopus aureolacrimosus

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34
Q

Where in the environment is Dermanyssus Gallinae found?

A

primary host is poultry - lives in nests and cracks in cages or houses

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35
Q

Technique for demonstrating Onchocerca spp. microfilariae in affected tissues

A

macerate a punch biopsy specimen with saline, allow to sit for 30 minutes and then observe under microscope

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36
Q

Species of Cheyletiella that affects rabbits?

A

Cheyletiella parasitovorax

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37
Q

Rhipicephalus sanguineous can be a vector for what diseases?

A

Tularemia (Francisella tularensis), Ehrlichia canis, Babesia canis, Anaplasmosis, Tick Paralysis, Rocky Mountain Spotted Fever

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38
Q

T/F: Lice are host specfici and spend their entire life on the host.

A

TRUE

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39
Q

How is Straelensia Cynotis diagnosed?

A

Skin biopsy - larval mite seen within follicle on biopsy; pseudoepitheliomatous follicular hyperplasia and perifollicular dermal mucinosis; Skin scrapings fail to demonstrate the parasite

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40
Q

Where is Otobius megnini located in the US?

A

southern and western US

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41
Q

Rhipicephalus sanguineous AKA? Soft or hard tick?

A

Brown dog tick - hard tick

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42
Q

How does the mutation in the ABCB1 gene predispose animals to ivermectin toxicity?

A

the deletion mutation causes P-glycoprotein synthesis to terminate prematurely, resulting in severely truncated, nonfunctional P-glycoprotein molecules; transport of certain drugs out of the CNS is impaired –> leading to accumulation of drug within the CNS to toxic levels

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43
Q

In what species is Screwworm miasis a notifiable disease in the united states?

A

horses, cattle, goats, sheep, swine

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44
Q

Which animal would take longer to develop a hypersensitivity to fleas: one that is continously exposed or one that is intermittently exposed?

A

Continuous exposure results in a delayed onset of clinical signs and less severe lesions

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45
Q

What attracts Culicoides gnats to their host?

A

sight, body temperature, heart sound, smell – CO2, lactic acid, octenol

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46
Q

Class of Ectoparasiticide: Dinotefuran

A

Neonicotinoid: blocks Ach receptor (Adulticide)

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47
Q

Screw-worm species found in Africa, Asia, India, Arabian peninsula, Levant?

A

Chrysomya bezziana

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48
Q

In what species is Chorioptic mange a notifiable disease in the US?

A

sheep

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49
Q

Weekly application of topical moxidectin/imidacloprid could be considered for what disease?

A

demodicosis – esp mild-moderate cases (daily oral ivermectin is more effective but has more side effects)

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50
Q

Why is it recommended to clip the hair coat in medium and long-haired dogs when using amitraz rinses for treatment of demodicosis?

A

amitraz requires adequate skin contact for optimal efficacy

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51
Q

What are the clinical signs of Demodicosis in cats?

A

alopecia, comedones, follicular casts, papules, pustules, +/- pruritus (D. gatoi –> truncal pruritus)

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52
Q

Where do black flies (Simuliidae spp.) reproduce?

A

shaded areas with RUNNING WATER

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53
Q

Geographic distribution of Chorioptic mange in horses

A

worldwide

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54
Q

Histopathologic findings with mosquito bite hypersensitivity

A

eosinophilic interstitial to diffuse dermatitis with or without intraepidermal eosinophilic microabscesses or nodular eosinophilic granulomas with collagen flame figures; infiltrative and necrotizing eosinophilic mural folliculitis

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55
Q

Mechanism of action of chitin synthesis inhibitors

A

inhibition of chitin formation results in nonviable eggs and larvae (chitin found in exoskeleton of insects)

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56
Q

Where does selamectin accumulate externally?

A

sebaceous glands, hair follicles, basal epithelium

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57
Q

Geographic distribution of Trombiculiasis

A

worldwide

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58
Q

Causative agent for warbles in goats?

A

Przhevalskiana silenus 3rd stage larva

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59
Q

What type of parasite is Pelodera?

A

free-living nematode that lives in damp soil or decaying organic material such as rice hulls, straw, and marsh hay

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60
Q

Mechanism of action of nicotinic acetylcholine receptor antagonists

A

bind to Ach receptor on postsynaptic portion of nerve cells => results in accumulation of Ach => leads to hyperexcitation, convulsions, paralysis death

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61
Q

What are the natural hosts of Cuterebra spp.?

A

rabbits and other rodents

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62
Q

Properties of lime sulfur

A

Anti-parasite, fungicidal, keratolytic, anti-pruritic, bactericidal

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63
Q

Class of Ectoparasiticide: Pyriproxyfen

A

Insect Growth Regulator - Juvenile Hormone Analog

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64
Q

Clincal presentation of cutaneous habronemiasis

A

papules, granulomatous inflammation with small yellowish granules (necrotic, caseous to calcified foci surrounding nematode larvae)– located on legs, ventrum, prepuce, urethral process of penis, medial canthus, eyes, conjunctiva, commissures of the lips, wounds

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65
Q

Most common Mallophaga (chewing lice) found on dogs?

A

Trichodectes canis

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66
Q

How is Cutaneous habronemiasis diagnosed?

A

deep scrapings or smears from lesions (especially if the yellowish granules are retrieved) may reveal nematode larvae; Biopsy - nodular to diffuse dermatitis characterized by eosinophils and mast cells, multifocal areas of discrete coagulation necrosis – nematode larvae may be found in the necrotic foci with palisading granulomas around it

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67
Q

Anatomical differences between arachnids and insects

A

Arachnids lack wings, Arachnids have 4 pairs of legs, Arachnids have fused head and thorax

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68
Q

Examples of ectoparasiticides that inhibit acetylcholinesterase

A

organophosphates and carbamates

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69
Q

Administration of inactivated Parapox virus suis has been shown to aid in treatment of what disease?

A

generalized demodicosis - in combination with amitraz

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70
Q

Treatment with Ivermectin or Moxidectin PO is very effective in treatment of psoroptic mange in horses. However, horses are still considered infectious for the first few weeks of treatment. Why?

A

ivermectin does not kill eggs

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71
Q

Class of Ectoparasiticide: Deltamethrin

A

Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)

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72
Q

Class of Ectoparasiticide: Indoxacarb

A

Voltage-gated sodium channel blockade (Adulticide)

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73
Q

What is the onset of action of Spinosad?

A

begins to kill fleas within 30 minutes, maximum effectiveness in 4 hours (dogs), 24 hours in cats

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74
Q

Clinical lesions due to Onchocerca cervicalis are caused by what stage of the parasite?

A

microfilariae

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75
Q

Describe the life cycle of Psoroptes mite?

A

adult mites pierce the skin, causing fluids to leak and form crusts to cover the mites –> mites mate and lay eggs under the crusts –> larvae hatches and moves through the crust, molting through two nymph life stages to become an adult again –> life cycle is completed on the single host

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76
Q

What is the vector of Habronema majus?

A

Stomoxys calcitrans (stable fly)

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77
Q

Ctenophalides felis felis can be the vector for what pathogens?

A

Bartonella henselae, Rickettsia felis, Yersinia pestis (inefficient vector)

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78
Q

T/F: The entire life cycle of Sarcoptes scabiei is on the host.

A

TRUE

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79
Q

Which type of louse moves rapidly and is difficult to find and capture (sucking or chewing louse)?

A

chewing lice

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80
Q

Otobius megnini AKA? Soft or hard tick?

A

Spinous ear tick - soft tick

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81
Q

How long can Dermanyssus gallinae mites survive without food? Which phase doesn’t feed at all?

A

9 months; nymphs don’t feed at all

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82
Q

Mechanism of action of Indoxacarb

A

Within the insect, indoxacarb is bioactivated to its active metabolite => blocks voltage-gated sodium channels in the nervous system => reulst in rapid cessation of feeding, paralysis, and death within 4-48 hr

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83
Q

Which is larger: Sarcoptes scabiei var canis or Notoedres cati?

A

Sarcoptes

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84
Q

T/F: Fecal flotation has a high yield of demodex mites in affected animals due to ingestion of mites.

A

False - yields fewer mites than skin scrapings and has frequent false-negatives

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85
Q

What are the two targets for axonic excitotoxins?

A

voltage-gated sodium channel blockade => permanent depolarization of axonal membrane => paralysis; chloride-channel receptor antagonists => prevent repolarization (GABA receptor antagonists and Glutamate-gated chloride channel antagonists)

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86
Q

Examples of ectoparasiticides that inhibit acetylcholine receptors

A

spinosad, nicotine, neonicotinoids

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87
Q

Examples of juvenile hormone analogs?

A

Methoprene, pyriproxyfen

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88
Q

Difference between Cheyletiella eggs and Louse eggs?

A

Cheyletiella eggs are attached to hairs by fine strands, Louse eggs are cemented to hair shafts

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89
Q

When are Trombiculid larvae most active (season)?

A

summer and fall

90
Q

List four ways that ticks are different from mites (anatomy and hosts)

A

ticks are larger with hairless or short-haired leathery body; exposed armed hypostome (organ below mouth); pair of spiracles near cosae and fourth pair of legs; not host-specific

91
Q

Where are flea larvae found?

A

in the environment - postively geotactic and negatively phototactic (live in carpets, cracks, and crevices)

92
Q

Name four parasites that can live in the stratum corneum of large and small domestic animals and be visible on biopsy

A

Psoroptes, Chorioptes, Sarcoptes, Cheyletiella

93
Q

What can Haemotopinus suis be a vector for? Public health significance?

A

Swinepox - can pass from humans to pigs

94
Q

Where does Oxyuris equi infest?

A

cecum and colon of horses

95
Q

Examples of chitin synthesis inhibitors?

A

lufenuron

96
Q

Treatment options for Sarcoptes

A

Lime sulfur dips, Fipronil, Imidacloprid/Flumethrin, Macrocyclic Lactones, Isoxazolines

97
Q

In what season are Chorioptes mites more prevalent in horses?

A

Winter – horses are more frequently stabled closer together, so they have more contact which favors parasite transmission

98
Q

Parasites commonly seen on rabbits

A

Cheyletiella parasitovorax, Psoroptes cuniculi, Leporacarus gibbus (fur mite), Ctenophelaides felis, Cuterebra spp., Sarcoptes spp.

99
Q

What are the species of Demodex found in the cat?

A

Demodex cati, Demodex gatoi, and possibly a third unnamed mite

100
Q

T/F: Environmental treatment is recommended in cases of Cheyletiellosis.

A

False - not usually recommended as survives off the host for very little time

101
Q

Dermacentor variabilis AKA? Soft or hard tick?

A

American dog tick - hard tick

102
Q

What stage of the Trombiculid mite typically infests horses?

A

larvae

103
Q

Species of Cheyletiella that affects dogs?

A

Cheyletiella yasguri

104
Q

Clinical signs of caprine pediculosis

A

Dermatologic= alopecia, irritation, papulo-crustous dermatitis, self-excoriation; System = anemia, weakness, decreased productivity

105
Q

Ivermectin is derived from the fermentation of molecularly synthesized what?

A

Streptomyces avermitilis

106
Q

Sarcoptic mange is reportable in what species in the united States?

A

horses, cattle, swine, sheep

107
Q

What parasites can sulfur be used to treat?

A

Non-follicular mites (Sarcoptes, Notoedres, Cheyletiella, Lice, Demodex gatoi)

108
Q

Adverse effects of amitraz in dogs

A

depression, sleepiness, ataxia, pruritus, urticaria, edema, skin irritations, polyphagia, polydipsia, hypotension, bradycardia, hyperglycemia, vomiting, diarrhea

109
Q

T/F: Absorption of fluralaner is increased when given with food.

A

TRUE

110
Q

Species of fleas that can infest animals

A

Ctenocephalides felis felis&raquo_space;» Ctenocephalides canis > Pulex irritans, Echidnophaga gallinacean, Xenopsylla cheopis, Nosopsyllus fasciatus

111
Q

Describe life cycle stages of Sarcoptes scabiei var canis

A

4 stages: egg–> larva –> nymph –> adult

112
Q

Ixodes scapularis AKA? Soft or hard tick?

A

Black legged tick - hard tick

113
Q

Species of Anoplura (sucking lice) found on dogs?

A

Linognathus setosus

114
Q

Clinical signs of Simulium spp. (black flies) bites

A

painful papules and wheals –> often become vesicular, hemorrhagic, and necrotic; Saliva contains allergens and a toxin that causes increased capillary permeability

115
Q

What is different about where the eggs of the Echidnophaga gallinacea flea are found compared to C. felis?

A

female of E. gallinacea burrows into the skin and eggs are laid there. Eggs hatch on the host but larvae fall into environment.

116
Q

Clincal features of amitraz poisoning in people

A

altered sensorium, miosis, hyperglycemia, bradycardia, vomiting, respiratory failure, hypotension, hypothermia

117
Q

How does Norwegian or Crusted scabies differ from ordinary scabies in dogs?

A

high number of mites found in skin scrapings, absence or low intensity of pruritus, formation of thick parakeratotic crusts all over the body

118
Q

Mechanism of action of fipronil

A

blocks GABA and glutamate-gated chloride channels

119
Q

Why is it recommended to treat with systemic glucocorticoids for the first five days of treatment of equine cutaneous onchocerciasis?

A

massive destruction of microfilariae may exacerbate both cutnaeous and ocular inflammation for first 3-4 days of therapy (thought to be a hypersensitivity reaction)

120
Q

What is the (2) etiologies of clinical signs of caprine pediculosis?

A

a. Irritation from biting and sucking

b. Hypersensitivity reaction to antigens in lice saliva

121
Q

What are the vectors for Onchocerca spp.?

A

Onchocerca gutturosa: Simulium spp. and Culicoides spp.; Onchocerca reticulata: Culicoides spp.; Onchocerca cervicalis: Culicoides spp. and mosquitoes

122
Q

Where do Haematobia spp. (horn flies) lay their eggs?

A

fresh cow manure

123
Q

Class of Ectoparasiticide: Methoprene

A

Insect Growth Regulator - Juvenile Hormone Analog

124
Q

Describe life cycle stages of Otodectes

A

Egg –> Larva –> Protonymph –> Deutonymph –> Adult

125
Q

How many hosts does Rhipicephalus sanguineus need to complete its life cycle? What is its principal host?

A

can complete its life cycle with only ONE animal as the host; dog is the primary host

126
Q

How long is the screw worm life cycle?

A

21 days in warm weather

127
Q

Species of Demodex seen in the horse

A

Demodex caballi – eyelids and muzzle (larger mite); Demodex equi – body (smaller mite)

128
Q

Class of Ectoparasiticide: Spinosad

A

Activated nicotonic acetylcholine receptors (Adulticide)

129
Q

Most common Anoplura (sucking lice) found on horeses? What area of the body does it prefer?

A

Haematopinus asinis - favors head, neck, back, thighs, fetlock

130
Q

What one tick can Selamectin be used to prevent or treat?

A

Dermacentor variabilis (American dog tick)

131
Q

Fleas can be the intermediate host for what parasites?

A

Dipilidium caninum, Acanthocheilonema reconditum, Rodentolepis nana, Hymenolepis diminuta, rarely Leishmania spp.

132
Q

T/F: Dogs exposed to fleas early in their life are less likely to develop flea allergy.

A

TRUE

133
Q

Describe life cycle stages of Cheyletiella

A

egg –> Larva –> Nymph 1 –> Nymph 2 –> Adult (5 stages)

134
Q

Most common Mallophaga (chewing lice) found on horses? What area of the body does it prefer?

A

Werneckiella equi - prefers head, mane, and base of the tail

135
Q

Class of Ectoparasiticide: Lufenuron

A

Insect Growth Regulator - Chitin Synthesis Inhibitor

136
Q

T/F: All pyrethrins and pyrethroids are toxic to cats.

A

False - cats are more sensitive to synthetic pyrethroids than pyrethrins, but can tolerate them at LOWER concentrations (e.g. flumethrin in the Seresto collar is a synethetic pyrethroid but can be used on a cat)

137
Q

Treatment recommendations for macrocyclic lactones for demodicosis

A

Oral ivermectin 0.3-0.6 mg/kg daily, Moxidectin 0.3-0.5 mg/kg daily, Milbemycin oxime at 1.0-2.0 mg/kg daily or Doramectin 0.6 mg/kg SQ once weekly

138
Q

Chigger found in Europe that causes a papular to nodular dermatitis. Skin scrapings usually fail to demonstrate the parasite.

A

Straelensia Cynotis

139
Q

Solutions used in fecal floatations

A

Zinc sulfate, Sheather’s solution; Need >5 g of feces

140
Q

Where is imidacloprid stored in the body?

A

sebaceous glands

141
Q

T/F: Cheyletiella spp. can be zoonotic.

A

True - have poor host specificity and are highly contagious

142
Q

Amblyoma americanum AKA? Soft or hard tick?

A

Lone star tick - hard tick

143
Q

Class of Ectoparasiticide: Flumethrin

A

Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)

144
Q

Clinical lesions due to Onchocerca gutturosa and reticulata are caused by what stage of the parasite?

A

adult worms - curaneous nodules are produced by a granulomatous reaction

145
Q

What stage of larvae enter the dog’s skin in an Ancylostoma infection?

A

3rd stage larvae

146
Q

Mechanism of action of isoxazolines

A

target a binding site that inhibits insect and acarine ligand-gated chloride channels (particularly GABA-gated), thereby blocking pre- and postynaptic transfer of chloride ions across cell membranes –> prolonged hyperexcitation results in uncontrolled activity of the CNS and death of insects and acarines

147
Q

What is the recommended frequency of amitraz dips?

A

weekly amitraz rinses at 0.025 - 0.05%

148
Q

What is the intermediate host for Dracunculus medinsis and insignis

A

aquatic crustaceans (Cyclops spp.)

149
Q

In what species is Sarcoptes scabiei infestation a notifiable disease?

A

horses

150
Q

What is an advantage of Nitenpyram over other adulticides?

A

quick onset of action (<30 min)

151
Q

Diagnostic methods for demodicosis where identification of more than one mite is indicative of clinically relevant demodicosis

A

Deep skin scraping, trichograms, tape strips, examination of exudate

152
Q

Mechanism of action of acetylcholinesterase inhibitors

A

blocks breakdown of Ach => leads to accumulation of Ach => leads to hyperexcitaiton, convulsions, paralysis, death

153
Q

T/F: There is no specific antidote for ivermectin toxicosis.

A

TRUE

154
Q

Argasid ticks (soft) that can affect horses?

A

Otobius megnini, Ornithodorus spp.

155
Q

T/F: Mild, localized demodicosis will resolve spontaneously in most cases.

A

TRUE

156
Q

Examples of ectoparasiticides that utilize voltage-gated sodium channel blockade

A

Indoxacarb, DDT, pyrethroids

157
Q

What is the first clinical sign of ivermectin toxicity?

A

mydriasis

158
Q

T/F: The entire life cycle of Otodectes is on the host

A

TRUE

159
Q

What treatments are recommended for feline demodicosis?

A

Weekly 2% lime sulfur dip; Weekly 0.0125% amitraz dip; Weekly administration of moxidectin/imidacloprid

160
Q

Where is fipronil stored in the body?

A

sebaceous glands

161
Q

What is the primary host of Dermacentor variabilis adult tick? Immature tick?

A

adult tick: dog; immature tick: field mouse

162
Q

Size of Psoroptes mites? What do they feed on?

A

Large (0.4-0.8 mm long), nonburrowing - feed on tissue fluids

163
Q

Hypoderma larvae infestations are most commonly seen in horses in what environments?

A

close proximity to cattle

164
Q

Examples of ectoparasiticides that utilize chloride channel receptor antagonists

A

cyclodienes, avermectins, fipronil, isoxazolines

165
Q

Class of Ectoparasiticide: Imidacloprid

A

Neonicotinoid: blocks Ach receptor (Adulticide)

166
Q

Mechanism of action of macrocylic lactones

A

binds to invertebrate-specific glutamate-gated chloride channels => prevents repolarization => paralysis of somatic and pharyngeal pump muscles

167
Q

Which T-lymphocyte subpopulation is consistent with generalized demodicosis infection?

A

Decreased overall lymphocytes with lower absolute numbers of CD4+ lymphocytes

168
Q

T/F: Lufenuron has activity against both fleas and ticks.

A

False - fleas only

169
Q

Fipronil is effective against what ectoparasites?

A

fleas, ticks, cheyletiella, chewing lice, sarcoptes, otodectes (spot-on application in ears)

170
Q

How long do Chorioptes mites survive off of the host?

A

70 days - cleaning the environment is an important part of management

171
Q

Adverse events associated with organophosphates

A

Muscarinic, nicotinic, central; muscarinic: hypersalivation, miosis, frequent urination, diarrhea, vomiting, colic, and dyspnea due to increased bronchial secretions and bronchoconstriction. Nicotinic effects include muscle fasciculations and weakness. The central effects include nervousness, ataxia, apprehension, and seizures

172
Q

Clinical signs of Lynxacarus Radovsky infestation

A

mites attach to hair and give a salt-and-pepper appearance to dull and dirty coat; patchy alopecia; severe cases - maculopapular to exfoliative dermatitis

173
Q

Why can moxidectin be used in dogs with ABCB1 gene mutations?

A

Moxidectin is a poor P-glycoprotein receptor substrate, so it is safer compared to ivermectin

174
Q

Ixodid ticks (hard) that can affect horses?

A

Dermacentor albipictus, Amblyomma americanum

175
Q

Why is a thorough ocular examination necessary before beginning treatment for equine cutaneous onchocerciasis?

A

Ocular signs may be seen in conjunction with cutaneous onchocerciasis (keratitis, vitiligo of bulbar conjunctiva, white papules in pigmented conjunctiva, depigmentation around optic disc, uveitis)

176
Q

T/F: Isoxazolines have a similar mechanism of action to macrocyclic lactones.

A

True - block chloride channels, but act at a separate site from macrocyclic lactones, cyclodienes, and fipronil

177
Q

Mechanism of action of amitraz

A

antagonized octopamine receptor of insect CNS; adrenergic agonist, inhibits monoamine oxidases

178
Q

Amitraz is contraindicated in what species?

A

rabbits!

179
Q

T/F: Lynxacarus Radovsky is highly contagious.

A

False - infection typically occurs by direct contact

180
Q

Describe life cycle stages of Ctenocephalides felis felis

A

Egg –> L1 –> L2 –> L3 –> Pupae –> Adult

181
Q

T/F: Macrocyclic lactones can bind to GABA-gated chloride channels in the brain

A

True - mammals are resistant to neurotoxic effects because of the p-glycoprotein efflux pump in the blood-brain barrier (exception: ABCB1 mutants)

182
Q

A dog is found to have hyperkeratotic paw pads and hookworm eggs on fecal examination and paw scrapings. What do you expect to find on biopsy?

A

Rare larvae (if present surrounded by neutrophils, eosinophils, and mononuclear cells) with larval migration tracts through the epidermis and neutrophilic/eosinophilic perivascular dermatitis

183
Q

Clincal signs of ivermectin toxicosis

A

mydriasis, lethargy, vomiting, ataxia, tremors and temporary blindness, stupor, coma, respiratory failure, death

184
Q

Mechanism of action of imidacloprid

A

competitive inhibition at post-synpatic acetylcholine receptor (neonicotinoid)

185
Q

Method of elimination of fluralaner

A

excreted unchanged in feces by hepatic elimination

186
Q

What are five diseases that Dermacentor variabilis can be a vector for?

A

a. Rocky Mountain Spotted Fever
b. St. Louis encephalitis
c. Tularemia (Francisella tularensis)
d. Anaplasmosis
e. Tick paralysis

187
Q

T/F: Damalina ovis is host-specific.

A

False - can pass between goats and sheep

188
Q

Why can concurrent treatment with spinosad lead to ivermectin toxicosis?

A

spinosad is a potent inhibitor of canine p-glycoprotein

189
Q

What is the difference in morphology between Demodex injai and Demodex canis?

A

Demodex injai is longer-bodied

190
Q

Describe the life cycle of Ixodes ticks

A

a. Eggs hatch in 2 – 7 weeks
b. Larvae feed for 3 – 12 weeks, then drop off before molting to nymphs
c. Nymphs feed for 3 – 10 days then rest for 17 – 100 days before molting to adults
d. Adults live 19 months and lay eggs

191
Q

In what species is Psoroptic mange a notifiable disease in the US?

A

cattle, goats, sheep

192
Q

T/F: Spinosad is active against both fleas and ticks.

A

False - fleas only

193
Q

3 Reportable parasites in goats

A

Psoroptes cuniculi and Psoroptes bovis; Screw worms; Sarcoptes scabiei var ovis

194
Q

Most common Mallophaga (chewing lice) found on cats?

A

Felicola subrostratus

195
Q

Management recommendations to control Simulium spp.

A

stabling during the day and frequent applications of repellants

196
Q

Xenopsylla cheopis can be the vector for what pathogens?

A

Rickettsia typhi, Yersinia pestis

197
Q

What is muramyl dipeptide? For what disease has it been studied?

A

mycobacterial cell wall component, has been shown to increase lymphocyte response to mitogens in dogs with demodicosis

198
Q

Where are Culicoides eggs laid?

A

damp, marshy areas, on decaying vegetation, or in manure

199
Q

What are the ways that ticks can harm animals? (4)

A
  1. Cause irritation via their bites, 2. produce hypersensitivity reactions, 3. Serve as vectors for bacterial, rickettsial, viral, and protozoal diseases, 4. produce tick paralysis through their poisonous secretions
200
Q

What pathways does Amitraz have an effect on?

A

monoamine oxidase inhibitor, alpha 2-adrenergic agonist, and inhibits prostaglandin synthesis

201
Q

T/F: Psoroptes mites are host-specific.

A

False - show little-to-no host specificity

202
Q

Most common causative agent of pediculosis in pigs

A

Haematopinus suis (Anoplura)

203
Q

How is Lynxacarus Radovsky diagnosed?

A

Mites can be found on skin scrapings or acetate tape impression

204
Q

Pyrethrins are derived from what?

A

oil extract from chrysanthemum flower

205
Q

Species of Cheyletiella that affects cats?

A

Cheyletiella blakei

206
Q

How often should treatment for generalized demodicosis be monitored? How long should miticidal therapy be continued?

A

monitor clinically and microscopically monthly until 2 negative skin scraping; continue miticidal therapy 4 weeks beyond second negative skin scrape

207
Q

What are the clinical signs of Demodicosis in dogs?

A

alopecia, comedones, follicular casts, papules, pustules, +/- pruritus, greasiness (D. injai)

208
Q

Class of Ectoparasiticide: Cyphenothrin

A

Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)

209
Q

What species of flies lay their eggs in cow manure?

A

Haematobia spp., Musca autumnalis

210
Q

Clinical signs of Chorioptic mange in horses

A

draft horses and other horses with feathered fetlocks – alopecia and crusting secondary to self-trauma, ulcerations may also be seen

211
Q

Causative agents of Psoroptic mange in horses?

A

Psoroptes ovis, Psoroptes equi, Psoroptes natalensis, Psoroptes cuniculi

212
Q

Fipronil is toxic to what species?

A

rabbits - is FATAL to them

213
Q

Where do Lynxacarus radovsky mites occur in the world

A

a. Australia
b. Hawaii, Florida, Texas
c. Brazil

214
Q

What is the difference between Pyrethrins and Pyrethroids?

A

pyrethroids are synthetic chemicals that mimic the activity of pyrethrins but they are more persistent, resisting action of UV and pH –> remain effective for longer and are used for long term, residual, insect control

215
Q

How is therapy altered when treatment with daily ivermectin is initiated in potential ABCB1 affected animals?

A

slow titration up to the therapeutic dose over several days – allows close monitoring for adverse reactions and early identification of ivermectin-sensitive individuals

216
Q

Trichodectes canis (canine chewing lice, Mallophaga) can act as intermediate host of what parasite(s)?

A

Dipilidium caninum

217
Q

Where do Tabanids (horse flies) lay their eggs?

A

leaves or stems of vegetation overhanging water –> larvae move to damp areas to complete their life cycle

218
Q

Clinical signs of Psoroptic mange in horses

A

may be asymptomatic or may show signs of ear disease, truncal dermatitis, mane and tail disease

219
Q

What life stage of the flea is known as the “Achilles heel”?

A

larvae - most susceptible to dying, less than25% survive

220
Q

What is the diagnostic tool of choice for demodicosis?

A

deep skin scraping

Vet Derm Review (44 decks)

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