Parasites Flashcards
Causative agent of Psoroptic mange in cattle?
Psoroptes bovis
Treatment options for Cheyletiella
Lime sulfur dips, Fipronil, Macrocyclic Lactones, Probably Isoxazolines??
How is Pelodera dermatitis diagnosed?
nematode larvae may be found in skin scrapings from affected skin or in associated bedding
Calliphorine myiasis (blowfly strike) is caused by what blowflies in North America?
Phormia regina and Phormia terrae-novae
T/F: Finding onchocerca spp. in a skin biopsy is definitive as the cause of the skin disease.
False - skin of normal horses and other dermatoses may contain Onchocerca without it being the cause of the pathology
Management/Treatment recommendations for cutaneous habronemiasis
combination of local and systemic therapy - ivermectin/moxidectin (larvicides), systemic glucocorticoids, topical glucocorticoids (tresaderm, Synotic); Fly control - disposal of manure and soiled bedding
Distribution of lesions of Notoedres cati
Medial pinna –> face –> eyelids –> neck –> generalized
Where do screw-worms lay their eggs?
edge of wounds, near body openings, do not breed in carcasses***
Management recommendations to control Haematobia spp. (horn flies)
removal of cow manure; daily application of fly spray
Define perionyxis
inflammation of the epidermis around a nail
Moxidectin is a macrocyclic lactone derived from what?
fermentation of Streptomyces spp.
What are the species of Habronema that produce cutaneous habronemiasis in horses?
Habronema muscae, Habronema majus, Draschia megastoma
Class of Ectoparasiticide: Permethrin
Voltage-gated sodium channel blockade (Adulticide)
How long do Psoroptes mites survive off the host in a typical barn?
14-21 days
In what species is Dermatophilosis a notifiable disease in the US?
cattle
What breed is specifically exluded in the label for Amitraz?
Chihuahuas
Management recommendations to control Stomoxys calcitrans (stable fly)
regular (at least 2x/week) removal of moist bedding, hay, and mure; use of residual environmental sprays
Side effects of DEET in horses
sweating, irritation, local skin exfoliation
Why are two baths needed to treat a lice infestation?
The first bath removes the adults, but the eggs are cemented to the hair and need a second bath to remove
Method of elimination of afoxolaner
biliary excretion of free afoxolaner and via hepatic metabolism and biliary and renal clearance of afoxolaner metabolites
Screw-worm species found in North, Central, and South America?
Cochliomyia hominivorax and Cochliomyia macellaria
Where do blow flies lay their eggs?
wounds or carcasses
What is the vector of Habronema muscae and Draschia megastoma?
Musca domestica
Side effects of Amitraz in horses
somnolence, depression, ataxia, weakness, colonic impaction
How is Dermanyssus Gallinae diagnosed?
Mites can be demonstrated in skin scrapings; history of exposure to chicken houses or poultry quarters
Where does Stomoxys calcitrans (stable fly) lay their eggs?
wet straw, bedding, or manure (especially aging manure)
T/F: Absorption of afoxolaner is increased when given with food.
False - can be given with or without food
T/F: Afoxolaner is registered for treatment of canine demodicosis in Europe.
TRUE
What do Thaumetopoea spp. (pine/oak caterpillars) contain that can cause mast cell degranulation and histamine release?
thaumetopoein
Class of Ectoparasiticide: Nitenpyram
Neonicotinoid: blocks Ach receptor (Adulticide)
Compared with animals who have localized demodicosis or those that are healthy, dogs with generalized demodicosis have lower mRNA for what cytokines?
IFN-gamma and TNF-alpha
Why doesn’t ivermectin kill trematodes and cestodes?
they lack GABA system (and ivermectin is a GABA receptor agonist in its mechanism of kill)
Milbemycin is the fermentation product of what?
Streptomyces hygroscopus aureolacrimosus
Where in the environment is Dermanyssus Gallinae found?
primary host is poultry - lives in nests and cracks in cages or houses
Technique for demonstrating Onchocerca spp. microfilariae in affected tissues
macerate a punch biopsy specimen with saline, allow to sit for 30 minutes and then observe under microscope
Species of Cheyletiella that affects rabbits?
Cheyletiella parasitovorax
Rhipicephalus sanguineous can be a vector for what diseases?
Tularemia (Francisella tularensis), Ehrlichia canis, Babesia canis, Anaplasmosis, Tick Paralysis, Rocky Mountain Spotted Fever
T/F: Lice are host specfici and spend their entire life on the host.
TRUE
How is Straelensia Cynotis diagnosed?
Skin biopsy - larval mite seen within follicle on biopsy; pseudoepitheliomatous follicular hyperplasia and perifollicular dermal mucinosis; Skin scrapings fail to demonstrate the parasite
Where is Otobius megnini located in the US?
southern and western US
Rhipicephalus sanguineous AKA? Soft or hard tick?
Brown dog tick - hard tick
How does the mutation in the ABCB1 gene predispose animals to ivermectin toxicity?
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
In what species is Screwworm miasis a notifiable disease in the united states?
horses, cattle, goats, sheep, swine
Which animal would take longer to develop a hypersensitivity to fleas: one that is continously exposed or one that is intermittently exposed?
Continuous exposure results in a delayed onset of clinical signs and less severe lesions
What attracts Culicoides gnats to their host?
sight, body temperature, heart sound, smell – CO2, lactic acid, octenol
Class of Ectoparasiticide: Dinotefuran
Neonicotinoid: blocks Ach receptor (Adulticide)
Screw-worm species found in Africa, Asia, India, Arabian peninsula, Levant?
Chrysomya bezziana
In what species is Chorioptic mange a notifiable disease in the US?
sheep
Weekly application of topical moxidectin/imidacloprid could be considered for what disease?
demodicosis – esp mild-moderate cases (daily oral ivermectin is more effective but has more side effects)
Why is it recommended to clip the hair coat in medium and long-haired dogs when using amitraz rinses for treatment of demodicosis?
amitraz requires adequate skin contact for optimal efficacy
What are the clinical signs of Demodicosis in cats?
alopecia, comedones, follicular casts, papules, pustules, +/- pruritus (D. gatoi –> truncal pruritus)
Where do black flies (Simuliidae spp.) reproduce?
shaded areas with RUNNING WATER
Geographic distribution of Chorioptic mange in horses
worldwide
Histopathologic findings with mosquito bite hypersensitivity
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
Mechanism of action of chitin synthesis inhibitors
inhibition of chitin formation results in nonviable eggs and larvae (chitin found in exoskeleton of insects)
Where does selamectin accumulate externally?
sebaceous glands, hair follicles, basal epithelium
Geographic distribution of Trombiculiasis
worldwide
Causative agent for warbles in goats?
Przhevalskiana silenus 3rd stage larva
What type of parasite is Pelodera?
free-living nematode that lives in damp soil or decaying organic material such as rice hulls, straw, and marsh hay
Mechanism of action of nicotinic acetylcholine receptor antagonists
bind to Ach receptor on postsynaptic portion of nerve cells => results in accumulation of Ach => leads to hyperexcitation, convulsions, paralysis death
What are the natural hosts of Cuterebra spp.?
rabbits and other rodents
Properties of lime sulfur
Anti-parasite, fungicidal, keratolytic, anti-pruritic, bactericidal
Class of Ectoparasiticide: Pyriproxyfen
Insect Growth Regulator - Juvenile Hormone Analog
Clincal presentation of cutaneous habronemiasis
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
Most common Mallophaga (chewing lice) found on dogs?
Trichodectes canis
How is Cutaneous habronemiasis diagnosed?
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
Anatomical differences between arachnids and insects
Arachnids lack wings, Arachnids have 4 pairs of legs, Arachnids have fused head and thorax
Examples of ectoparasiticides that inhibit acetylcholinesterase
organophosphates and carbamates
Administration of inactivated Parapox virus suis has been shown to aid in treatment of what disease?
generalized demodicosis - in combination with amitraz
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?
ivermectin does not kill eggs
Class of Ectoparasiticide: Deltamethrin
Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)
Class of Ectoparasiticide: Indoxacarb
Voltage-gated sodium channel blockade (Adulticide)
What is the onset of action of Spinosad?
begins to kill fleas within 30 minutes, maximum effectiveness in 4 hours (dogs), 24 hours in cats
Clinical lesions due to Onchocerca cervicalis are caused by what stage of the parasite?
microfilariae
Describe the life cycle of Psoroptes mite?
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
What is the vector of Habronema majus?
Stomoxys calcitrans (stable fly)
Ctenophalides felis felis can be the vector for what pathogens?
Bartonella henselae, Rickettsia felis, Yersinia pestis (inefficient vector)
T/F: The entire life cycle of Sarcoptes scabiei is on the host.
TRUE
Which type of louse moves rapidly and is difficult to find and capture (sucking or chewing louse)?
chewing lice
Otobius megnini AKA? Soft or hard tick?
Spinous ear tick - soft tick
How long can Dermanyssus gallinae mites survive without food? Which phase doesn’t feed at all?
9 months; nymphs don’t feed at all
Mechanism of action of Indoxacarb
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
Which is larger: Sarcoptes scabiei var canis or Notoedres cati?
Sarcoptes
T/F: Fecal flotation has a high yield of demodex mites in affected animals due to ingestion of mites.
False - yields fewer mites than skin scrapings and has frequent false-negatives
What are the two targets for axonic excitotoxins?
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)
Examples of ectoparasiticides that inhibit acetylcholine receptors
spinosad, nicotine, neonicotinoids
Examples of juvenile hormone analogs?
Methoprene, pyriproxyfen
Difference between Cheyletiella eggs and Louse eggs?
Cheyletiella eggs are attached to hairs by fine strands, Louse eggs are cemented to hair shafts
When are Trombiculid larvae most active (season)?
summer and fall
List four ways that ticks are different from mites (anatomy and hosts)
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
Where are flea larvae found?
in the environment - postively geotactic and negatively phototactic (live in carpets, cracks, and crevices)
Name four parasites that can live in the stratum corneum of large and small domestic animals and be visible on biopsy
Psoroptes, Chorioptes, Sarcoptes, Cheyletiella
What can Haemotopinus suis be a vector for? Public health significance?
Swinepox - can pass from humans to pigs
Where does Oxyuris equi infest?
cecum and colon of horses
Examples of chitin synthesis inhibitors?
lufenuron
Treatment options for Sarcoptes
Lime sulfur dips, Fipronil, Imidacloprid/Flumethrin, Macrocyclic Lactones, Isoxazolines
In what season are Chorioptes mites more prevalent in horses?
Winter – horses are more frequently stabled closer together, so they have more contact which favors parasite transmission
Parasites commonly seen on rabbits
Cheyletiella parasitovorax, Psoroptes cuniculi, Leporacarus gibbus (fur mite), Ctenophelaides felis, Cuterebra spp., Sarcoptes spp.
What are the species of Demodex found in the cat?
Demodex cati, Demodex gatoi, and possibly a third unnamed mite
T/F: Environmental treatment is recommended in cases of Cheyletiellosis.
False - not usually recommended as survives off the host for very little time
Dermacentor variabilis AKA? Soft or hard tick?
American dog tick - hard tick
What stage of the Trombiculid mite typically infests horses?
larvae
Species of Cheyletiella that affects dogs?
Cheyletiella yasguri
Clinical signs of caprine pediculosis
Dermatologic= alopecia, irritation, papulo-crustous dermatitis, self-excoriation; System = anemia, weakness, decreased productivity
Ivermectin is derived from the fermentation of molecularly synthesized what?
Streptomyces avermitilis
Sarcoptic mange is reportable in what species in the united States?
horses, cattle, swine, sheep
What parasites can sulfur be used to treat?
Non-follicular mites (Sarcoptes, Notoedres, Cheyletiella, Lice, Demodex gatoi)
Adverse effects of amitraz in dogs
depression, sleepiness, ataxia, pruritus, urticaria, edema, skin irritations, polyphagia, polydipsia, hypotension, bradycardia, hyperglycemia, vomiting, diarrhea
T/F: Absorption of fluralaner is increased when given with food.
TRUE
Species of fleas that can infest animals
Ctenocephalides felis felis»_space;» Ctenocephalides canis > Pulex irritans, Echidnophaga gallinacean, Xenopsylla cheopis, Nosopsyllus fasciatus
Describe life cycle stages of Sarcoptes scabiei var canis
4 stages: egg–> larva –> nymph –> adult
Ixodes scapularis AKA? Soft or hard tick?
Black legged tick - hard tick
Species of Anoplura (sucking lice) found on dogs?
Linognathus setosus
Clinical signs of Simulium spp. (black flies) bites
painful papules and wheals –> often become vesicular, hemorrhagic, and necrotic; Saliva contains allergens and a toxin that causes increased capillary permeability
What is different about where the eggs of the Echidnophaga gallinacea flea are found compared to C. felis?
female of E. gallinacea burrows into the skin and eggs are laid there. Eggs hatch on the host but larvae fall into environment.
Clincal features of amitraz poisoning in people
altered sensorium, miosis, hyperglycemia, bradycardia, vomiting, respiratory failure, hypotension, hypothermia
How does Norwegian or Crusted scabies differ from ordinary scabies in dogs?
high number of mites found in skin scrapings, absence or low intensity of pruritus, formation of thick parakeratotic crusts all over the body
Mechanism of action of fipronil
blocks GABA and glutamate-gated chloride channels
Why is it recommended to treat with systemic glucocorticoids for the first five days of treatment of equine cutaneous onchocerciasis?
massive destruction of microfilariae may exacerbate both cutnaeous and ocular inflammation for first 3-4 days of therapy (thought to be a hypersensitivity reaction)
What is the (2) etiologies of clinical signs of caprine pediculosis?
a. Irritation from biting and sucking
b. Hypersensitivity reaction to antigens in lice saliva
What are the vectors for Onchocerca spp.?
Onchocerca gutturosa: Simulium spp. and Culicoides spp.; Onchocerca reticulata: Culicoides spp.; Onchocerca cervicalis: Culicoides spp. and mosquitoes
Where do Haematobia spp. (horn flies) lay their eggs?
fresh cow manure
Class of Ectoparasiticide: Methoprene
Insect Growth Regulator - Juvenile Hormone Analog
Describe life cycle stages of Otodectes
Egg –> Larva –> Protonymph –> Deutonymph –> Adult
How many hosts does Rhipicephalus sanguineus need to complete its life cycle? What is its principal host?
can complete its life cycle with only ONE animal as the host; dog is the primary host
How long is the screw worm life cycle?
21 days in warm weather
Species of Demodex seen in the horse
Demodex caballi – eyelids and muzzle (larger mite); Demodex equi – body (smaller mite)
Class of Ectoparasiticide: Spinosad
Activated nicotonic acetylcholine receptors (Adulticide)
Most common Anoplura (sucking lice) found on horeses? What area of the body does it prefer?
Haematopinus asinis - favors head, neck, back, thighs, fetlock
What one tick can Selamectin be used to prevent or treat?
Dermacentor variabilis (American dog tick)
Fleas can be the intermediate host for what parasites?
Dipilidium caninum, Acanthocheilonema reconditum, Rodentolepis nana, Hymenolepis diminuta, rarely Leishmania spp.
T/F: Dogs exposed to fleas early in their life are less likely to develop flea allergy.
TRUE
Describe life cycle stages of Cheyletiella
egg –> Larva –> Nymph 1 –> Nymph 2 –> Adult (5 stages)
Most common Mallophaga (chewing lice) found on horses? What area of the body does it prefer?
Werneckiella equi - prefers head, mane, and base of the tail
Class of Ectoparasiticide: Lufenuron
Insect Growth Regulator - Chitin Synthesis Inhibitor
T/F: All pyrethrins and pyrethroids are toxic to cats.
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)
Treatment recommendations for macrocyclic lactones for demodicosis
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
Chigger found in Europe that causes a papular to nodular dermatitis. Skin scrapings usually fail to demonstrate the parasite.
Straelensia Cynotis
Solutions used in fecal floatations
Zinc sulfate, Sheather’s solution; Need >5 g of feces
Where is imidacloprid stored in the body?
sebaceous glands
T/F: Cheyletiella spp. can be zoonotic.
True - have poor host specificity and are highly contagious
Amblyoma americanum AKA? Soft or hard tick?
Lone star tick - hard tick
Class of Ectoparasiticide: Flumethrin
Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)
Clinical lesions due to Onchocerca gutturosa and reticulata are caused by what stage of the parasite?
adult worms - curaneous nodules are produced by a granulomatous reaction
What stage of larvae enter the dog’s skin in an Ancylostoma infection?
3rd stage larvae
Mechanism of action of isoxazolines
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
What is the recommended frequency of amitraz dips?
weekly amitraz rinses at 0.025 - 0.05%
What is the intermediate host for Dracunculus medinsis and insignis
aquatic crustaceans (Cyclops spp.)
In what species is Sarcoptes scabiei infestation a notifiable disease?
horses
What is an advantage of Nitenpyram over other adulticides?
quick onset of action (<30 min)
Diagnostic methods for demodicosis where identification of more than one mite is indicative of clinically relevant demodicosis
Deep skin scraping, trichograms, tape strips, examination of exudate
Mechanism of action of acetylcholinesterase inhibitors
blocks breakdown of Ach => leads to accumulation of Ach => leads to hyperexcitaiton, convulsions, paralysis, death
T/F: There is no specific antidote for ivermectin toxicosis.
TRUE
Argasid ticks (soft) that can affect horses?
Otobius megnini, Ornithodorus spp.
T/F: Mild, localized demodicosis will resolve spontaneously in most cases.
TRUE
Examples of ectoparasiticides that utilize voltage-gated sodium channel blockade
Indoxacarb, DDT, pyrethroids
What is the first clinical sign of ivermectin toxicity?
mydriasis
T/F: The entire life cycle of Otodectes is on the host
TRUE
What treatments are recommended for feline demodicosis?
Weekly 2% lime sulfur dip; Weekly 0.0125% amitraz dip; Weekly administration of moxidectin/imidacloprid
Where is fipronil stored in the body?
sebaceous glands
What is the primary host of Dermacentor variabilis adult tick? Immature tick?
adult tick: dog; immature tick: field mouse
Size of Psoroptes mites? What do they feed on?
Large (0.4-0.8 mm long), nonburrowing - feed on tissue fluids
Hypoderma larvae infestations are most commonly seen in horses in what environments?
close proximity to cattle
Examples of ectoparasiticides that utilize chloride channel receptor antagonists
cyclodienes, avermectins, fipronil, isoxazolines
Class of Ectoparasiticide: Imidacloprid
Neonicotinoid: blocks Ach receptor (Adulticide)
Mechanism of action of macrocylic lactones
binds to invertebrate-specific glutamate-gated chloride channels => prevents repolarization => paralysis of somatic and pharyngeal pump muscles
Which T-lymphocyte subpopulation is consistent with generalized demodicosis infection?
Decreased overall lymphocytes with lower absolute numbers of CD4+ lymphocytes
T/F: Lufenuron has activity against both fleas and ticks.
False - fleas only
Fipronil is effective against what ectoparasites?
fleas, ticks, cheyletiella, chewing lice, sarcoptes, otodectes (spot-on application in ears)
How long do Chorioptes mites survive off of the host?
70 days - cleaning the environment is an important part of management
Adverse events associated with organophosphates
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
Clinical signs of Lynxacarus Radovsky infestation
mites attach to hair and give a salt-and-pepper appearance to dull and dirty coat; patchy alopecia; severe cases - maculopapular to exfoliative dermatitis
Why can moxidectin be used in dogs with ABCB1 gene mutations?
Moxidectin is a poor P-glycoprotein receptor substrate, so it is safer compared to ivermectin
Ixodid ticks (hard) that can affect horses?
Dermacentor albipictus, Amblyomma americanum
Why is a thorough ocular examination necessary before beginning treatment for equine cutaneous onchocerciasis?
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)
T/F: Isoxazolines have a similar mechanism of action to macrocyclic lactones.
True - block chloride channels, but act at a separate site from macrocyclic lactones, cyclodienes, and fipronil
Mechanism of action of amitraz
antagonized octopamine receptor of insect CNS; adrenergic agonist, inhibits monoamine oxidases
Amitraz is contraindicated in what species?
rabbits!
T/F: Lynxacarus Radovsky is highly contagious.
False - infection typically occurs by direct contact
Describe life cycle stages of Ctenocephalides felis felis
Egg –> L1 –> L2 –> L3 –> Pupae –> Adult
T/F: Macrocyclic lactones can bind to GABA-gated chloride channels in the brain
True - mammals are resistant to neurotoxic effects because of the p-glycoprotein efflux pump in the blood-brain barrier (exception: ABCB1 mutants)
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?
Rare larvae (if present surrounded by neutrophils, eosinophils, and mononuclear cells) with larval migration tracts through the epidermis and neutrophilic/eosinophilic perivascular dermatitis
Clincal signs of ivermectin toxicosis
mydriasis, lethargy, vomiting, ataxia, tremors and temporary blindness, stupor, coma, respiratory failure, death
Mechanism of action of imidacloprid
competitive inhibition at post-synpatic acetylcholine receptor (neonicotinoid)
Method of elimination of fluralaner
excreted unchanged in feces by hepatic elimination
What are five diseases that Dermacentor variabilis can be a vector for?
a. Rocky Mountain Spotted Fever
b. St. Louis encephalitis
c. Tularemia (Francisella tularensis)
d. Anaplasmosis
e. Tick paralysis
T/F: Damalina ovis is host-specific.
False - can pass between goats and sheep
Why can concurrent treatment with spinosad lead to ivermectin toxicosis?
spinosad is a potent inhibitor of canine p-glycoprotein
What is the difference in morphology between Demodex injai and Demodex canis?
Demodex injai is longer-bodied
Describe the life cycle of Ixodes ticks
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
In what species is Psoroptic mange a notifiable disease in the US?
cattle, goats, sheep
T/F: Spinosad is active against both fleas and ticks.
False - fleas only
3 Reportable parasites in goats
Psoroptes cuniculi and Psoroptes bovis; Screw worms; Sarcoptes scabiei var ovis
Most common Mallophaga (chewing lice) found on cats?
Felicola subrostratus
Management recommendations to control Simulium spp.
stabling during the day and frequent applications of repellants
Xenopsylla cheopis can be the vector for what pathogens?
Rickettsia typhi, Yersinia pestis
What is muramyl dipeptide? For what disease has it been studied?
mycobacterial cell wall component, has been shown to increase lymphocyte response to mitogens in dogs with demodicosis
Where are Culicoides eggs laid?
damp, marshy areas, on decaying vegetation, or in manure
What are the ways that ticks can harm animals? (4)
- 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
What pathways does Amitraz have an effect on?
monoamine oxidase inhibitor, alpha 2-adrenergic agonist, and inhibits prostaglandin synthesis
T/F: Psoroptes mites are host-specific.
False - show little-to-no host specificity
Most common causative agent of pediculosis in pigs
Haematopinus suis (Anoplura)
How is Lynxacarus Radovsky diagnosed?
Mites can be found on skin scrapings or acetate tape impression
Pyrethrins are derived from what?
oil extract from chrysanthemum flower
Species of Cheyletiella that affects cats?
Cheyletiella blakei
How often should treatment for generalized demodicosis be monitored? How long should miticidal therapy be continued?
monitor clinically and microscopically monthly until 2 negative skin scraping; continue miticidal therapy 4 weeks beyond second negative skin scrape
What are the clinical signs of Demodicosis in dogs?
alopecia, comedones, follicular casts, papules, pustules, +/- pruritus, greasiness (D. injai)
Class of Ectoparasiticide: Cyphenothrin
Synthetic pyrethroid - Voltage-gated sodium channel blockade (Adulticide)
What species of flies lay their eggs in cow manure?
Haematobia spp., Musca autumnalis
Clinical signs of Chorioptic mange in horses
draft horses and other horses with feathered fetlocks – alopecia and crusting secondary to self-trauma, ulcerations may also be seen
Causative agents of Psoroptic mange in horses?
Psoroptes ovis, Psoroptes equi, Psoroptes natalensis, Psoroptes cuniculi
Fipronil is toxic to what species?
rabbits - is FATAL to them
Where do Lynxacarus radovsky mites occur in the world
a. Australia
b. Hawaii, Florida, Texas
c. Brazil
What is the difference between Pyrethrins and Pyrethroids?
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
How is therapy altered when treatment with daily ivermectin is initiated in potential ABCB1 affected animals?
slow titration up to the therapeutic dose over several days – allows close monitoring for adverse reactions and early identification of ivermectin-sensitive individuals
Trichodectes canis (canine chewing lice, Mallophaga) can act as intermediate host of what parasite(s)?
Dipilidium caninum
Where do Tabanids (horse flies) lay their eggs?
leaves or stems of vegetation overhanging water –> larvae move to damp areas to complete their life cycle
Clinical signs of Psoroptic mange in horses
may be asymptomatic or may show signs of ear disease, truncal dermatitis, mane and tail disease
What life stage of the flea is known as the “Achilles heel”?
larvae - most susceptible to dying, less than25% survive
What is the diagnostic tool of choice for demodicosis?
deep skin scraping
