How can we help?

You can also find more resources in our Help Center.

117 terms

Parasites of Dogs and Cats: Arthropods

Exam II
STUDY
PLAY
Cuterebra spp:
Taxonomy
-Class: Insecta
-Order: Diptera
-Family: Oestridae
-Genus species: Cuterebra spp.
-Common Name: Rodent bot fly, rabbit bot fly, New World skin bot flies
Cuterebra spp:
Hosts
-Principal Hosts: Rabbits and rodents
-Other Hosts: Dogs, cats, squirrels and chipmunks
-Zoonosis
Cuterebra spp:
Identification
-Adults: large, stout bodies, bee-like, do not feed, mouthparts are vestigial
-Third Stage: 2-4cm long, dark brown, covered with black spines
Cuterebra spp:
Life Cycle
-Female lay eggs along rabbit runs and near rodent burrows
-Host brushes past and first stage larva (infective) hatch instantaneously and crawl immediately into the host's fur
-larvae enter host through the skin or natural body openings and migrate to a subcutaneous site where it develop to a third stage larva in a month
-Larvae emerge through a hole in the skin, drop into the soil and pupate
-Adults emerge in spring, copulate and lay eggs
Cuterebra spp:
Sites of Infection
-Subcutaenous connective tissue of cats and dogs (Aug-Oct)
-Though not common, can also locate in nasal and oral regions and migrate to the brain with fatal results
Cuterebra spp:
Pathogenesis and Lesions
-Fibrotic cysts forms from the larva in subcutaneous tissue
-Migration of larvae in cat brain leads to infarction and feline ischemic encephalopathy
Cuterebra spp:
Clinical Signs
Seasonally, dog or cat presents with a lump in neck or legs or fur is constantly wet and a hole drips clear fluid
Cuterebra spp:
Diagnosis
-Color and spines of thirs stage larvae together with season
-Larvae can be removed by enlarging its breathing hole and carefully removing with forceps (without crushing)
-Crushing lead to Type 1 hypersensitivity reaction
-Wound heals slowly, because of secondary bacterial growth or leakage of Cuterebrae antigens
Cuterebra spp:
Treatment and Prevention
-MCL heartworm prevention
-Imidacloprid
-Fipronil
Culicidae:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Diptera
-Family: Culicidae
-Common Name: Mosquitoes
Culicidae:
Identification
-One pair of wings and 1 pair of halteres
-Legs are thin and long
-Complex mouth parts form a long proboscis which projects forward into a thin tube
-Antennae as long as proboscis
-Palps may be short or long
Culicidae:
Pathogenesis and Lesions
-Transmits diseases and many other pathogens, particularly viruses to humans and domestic animals
-Domestic animals: Rift valley fever, EEE, heartworm of dogs and other filarial nematodes and biting stress
-Humans: malaria, filariasis, yellow fever, dengue, encephalitis, Rift valley fever and biting stress
General Characteristics of Suborder Ischnocera (Mallophaga)
-Biting, chewing lice
-Wide mandible mouthparts
-Feed on skin, hair, feathers, other organic material
-3mm, yellow
-Rapid movement to move over skin and covering
-Often bird lice
General Characteristics of Suborder Anoplura
-Bloodsucking lice, more pathogenic
-Pointed nose
-Large, 3-5mm
-Dark blue, depending on amount of blood ingested
-Slow moving
-Clasping hair shaft
-Lice of mammals
Trichodectes canis:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Phthiraptera
-Suborder: Ischnocera
-Genus species: Trichodectes canis
-Common Name: Dog Biting Louse or Canine Chewing Louse
Trichodectes canis:
Hosts
Dogs
Trichodectes canis:
Adult Identification
-Wingless
-1.9mm long
-Head as broad or broader than thorax with biting mouthparts
-Yellowish
Trichodectes canis:
Nymph Identification
-Similar to adult, but smaller
Trichodectes canis:
Egg (or Nits) Identification
-Elongated
-Operculated
-Whitish
-Easily noticed
Trichodectes canis:
Life Cycle
-Females lay whitish eggs ("nits"), which develop to adults in a month
-Eggs hatch to nymphs and after 3 molts fully grown adults are present
-Requires the host to complete life complete
-Lice are active on host
Trichodectes canis:
Sites of Infection
-Hair
-Skin
Trichodectes canis:
Pathogenesis and Lesions
-Vector of Dipylidium caninum
-Heavy infections of lice found in animals neglected and underfed
-Young are most affected
Trichodectes canis:
Clinical Signs
-Causes pruritus
-Dog scratches causing self inflicted injury, loss of hair
-In heavy combined infestations (w/ Linognathus) anemia can occur
-Dogs are restless and scratch continuously
Trichodectes canis:
Diagnosis
Identification of louse
Trichodectes canis:
Treatment and Prevention
-Transmission by direct contact with brushes, combs and blankets
-Appropriate insecticides are carbaryl-containing shampoo, spray or dip
Linognathus setosus:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Phthiraptera
-Suborder: Anoplura
-Family: Linognathidae
-Genus species: Linognathus setosus
-Common Name: Dog Sucking Louse
Linognathus setosus:
Hosts
Dogs
Linognathus setosus:
Adult Identification
-Wingless
-3-5mm long
-Dorsoventrally flattened
-Slate grey
-Head narrower than the thorax
-Sucking mouthparts
Linognathus setosus:
Nymph Identification
-Similar to adult, but smaller
Linognathus setosus:
Louse Identification
-Long nosed
-Bluish black
Linognathus setosus:
Eggs (or Nits) Identification
-Elongated
-Operculated
-Whitish (but are often dark blue if fully fed)
-Less easy to see on hair
-Piercing mouthparts (feed on blood)
Linognathus setosus:
Life Cycle
-Similar to Trichodectes canis
-Female attach eggs to hair, which develop to adults in a mouth
-Egg hatches to nymphs, and after 3 molts fully grown adults are present
-Requires a host to complete life cycle
-Nymphs and adults can live off their hosts for only a few hours
-Whole cycle is 2-4 weeks
Linognathus setosus:
Sites of Infection
Skin
Linognathus setosus:
Pathogenesis and Lesions
Heavy infestation can cause severe anemia
Linognathus setosus:
Clinical Signs
Loss of body condition and damage to skin
Linognathus setosus:
Diagnosis
Louse identification
Linognathus setosus:
Treatment and Prevention
-Transmission is by direct contact with brushes, combs and blankets
-Appropriate insecticides are carbaryl-containing shampoo, spray or dip
Ctenocephalides felis and Ctenocephalides canis:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Siphonaptera
-Family: Pulicidae
-Genus species: Ctenocephalides felis and canis
-Common Name: Cat flea and Dog flea
Ctenocephalides felis and Ctenocephalides canis:
Hosts
-Dogs and cats
-Wide range of other hosts if dogs or cats are not available
Ctenocephalides felis and Ctenocephalides canis:
Adult Identification
-Dark brown
-Wingless insects
-3mm long
-Laterally compressed bodies which have a glossy surface allowing easy movement through hairs, long legs, pronotal ctenidia or combs
-Piercing sucking mouthparts
Ctenocephalides felis and Ctenocephalides canis:
Larva Identification
-Worm-like
-5mm long
-Body segmented
-Chewing mouthparts feeding on organic debris, including the blood in the feces of adult fleas
Ctenocephalides felis and Ctenocephalides canis:
Pupa Identification
-White
-5mm
-Color dependent on the adherent debris in the environment
Ctenocephalides felis and Ctenocephalides canis:
Egg Identification
-Oval
-Pearly white
-0.5mm
Ctenocephalides felis and Ctenocephalides canis:
Life Cycles
-Both sexes are bloodsuckers and adults are parasitic
-Eggs are laid on the host and fall to the surrounding environment
-Three larval stages are maggot-like with chewing mouthparts
-Larvae prefer secluded dark areas, such as the base of the pile of thick carpets and carpeted or dirt floor basements
-The 3rd larva spins a cocoon and becomes a pupa, and an adult emerges
-Pre-emerged adults are stimulated to emerge from the cocoon when there are vibrations in the area
-They are stimulated by cues, which include, visual, thermal, carbon dioxide and air currents
-Once on a host, adult fleas are permanent residents
-Direct transfer of fleas from host to hos is limited and animals acquire fleas primarily from infested environs
-Fleas feed on blood within 5 minutes of arriving on a host
-Mating occurs after feeding and egg production is within 24-48 hours after first blood meal
Ctenocephalides felis and Ctenocephalides canis:
Optimum Conditions
-18-27 degrees Celsius and >70% relative humidity
-None of the flea stages can survive freezing, temperatures above 35 degrees C or relative humidity <50%
Ctenocephalides felis and Ctenocephalides canis:
How Long Do They Survive?
-Pre-emerged fleas can survive 30 weeks
-Newly emerged unfed adult fleas can survive for 2 weeks before finding their first blood meal
-Adult fleas on the cat or dog can survive for 100 days but once they leave their host will die in 2-4 days
-Egg-adult 20-30 day
-The complete life cycle can extend up to 1-2 years
Ctenocephalides felis and Ctenocephalides canis:
Sites of Infection
-Skin
-Back
-Ventral abdomen
-Inner thighs
Ctenocephalides felis and Ctenocephalides canis:
Pathogenesis and Lesions/Clinical Signs
-Flea bite allergy dermatitis refers to a condition in which animals may be asymptomatic, experience occasional scratching or be highly allergic with an intense pruritus and dermatitis
-Large numbers of fleas can produce severe pruritus, alopecia and anemia
-Irritation to fleas is most likely due to frequent bites and the injection of proteolytic enzymes and histamine-like substances into their hosts
-Hypersensitivity with varying degrees of pruritis and chewing, licking and scratching
-All dogs are susceptible to these conditions
Ctenocephalides felis and Ctenocephalides canis:
Vectors
-Viruses
-Bacteria (Bartonella henselae)
-Tapeworms
Ctenocephalides felis and Ctenocephalides canis:
Diagnosis
Presence of fleas, flea feces and blood on host and in bedding
Ctenocephalides felis and Ctenocephalides canis:
Treatment and Prevention
-Requires breaking the life cycle strategically in several places
-Numerous insecticides are available for application on the animal and to the environment
-Not all insecticides treat all life cycle stages
-Environment control
Reduviidae:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Hemiptera
-Family: Reduviidae
-Common Name: Assassin bugs or kissing bugs
Reduviidae:
Hosts
-Many animals
-Humans (painful bites)
Reduviidae:
Identification
-18mm in length
-2 pairs of wings
-Mouthparts have 3 segmented beaks designed for piercing and blood sucking
-Triangular shield between the wing bases
-Able to feed painlessly on their hosts, but often inflict painful bites
Cimicidae:
Taxonomy
-Phylum: Arthropoda
-Class: Insecta
-Order: Hemiptera
-Family: Cimicidae
-Common Name: Bed Bugs
Cimicidae:
Hosts
-Many animals
-Humans
Cimicidae:
Identification
-5-7mm in length
-Wingless
-Mouthparts have 3 segmented beaks designed for piercing and blood sucking
-Triangular shield between the wing bases
-Able to feed painlessly on their hosts
Comparison of Reduviids and Cimicids
Reduviids
-Painful bites
-Have mouthparts designed to pierce and suck blood
-Transmit Trypanosoma cruzi
-Allergic reactions at site of bite (skin)
Cimicids
-Painless bites, until later after feeding
-Have mouthparts designed to pierce and suck blood
-Does not transmit disease
-Allergic reactions at site of bite (skin)
Ixodes spp:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Family: Ixodidae
-Genus spp: Ixodes spp.
-Common Names: Black-legged tick or deer tick, Western black-legged tick, European sheep tick, hedgehog tick, British dog tick, Australian and South African paralysis ticks
Ixodes spp:
Hosts
-All mammals
-Birds
-Humans
-Larvae and nymphs of some species feed on mice and the adults on deer
-All stages may occur on other animals
-Each species may have preferred hosts
Ixodes spp:
Adult Identification
-Dark brown, small ticks
-4mm when unfed, 10mm females when fed
-Scutum is inornate
-No eyes or festoons
-Palps are long
-Anal groove forms an arch anterior to the anus
-Ventral surface of male almost entirely covered with a series of plates
-4 pairs of legs
Ixodes spp:
Life Cycle
-3 Host tick
-Eggs hatch to larvae
-Larvae attach to host 1, feed, drop off and molt
-Nymphs attach to 2nd host, feed, drop off and molt
-Adult attach to 3rd host, feed, drop off
-Females lay eggs in secluded places and die
-2 hosts can be same animal or species or other species
-2-4 year life cycle
-Adult females engorge in fall, overwinter and lay eggs in spring
-Development takes longer if any stage can't find a host
Ixodes spp:
Sites of Infection
-Skin
-All over body esp. axilla, inguinal region, face and ears
Ixodes spp:
Pathogenesis and Lesions
-Causes paralysis in many hosts
-Local skin reactions to bites
-Transmit viral, protozoal and other infectious diseases including Lime disease
-Ehrlichia
-Tick worry
-Entry point for bacterial disease
Ixodes spp:
Diagnosis
Engorged females seen easily
Ixodes spp:
Treatment and Prevention
-Topical products: synthetic pyrethroids (not on cats)
-Insecticide collars
-Spraying environment
Dermacentor spp:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Family: Ixodidae
-Genus spp: Dermacentor spp
-Common Names: American dog tick, Rocky Mountain wood tick, Winter tick or elk tick, Tropical horse tick
Dermacentor spp:
Hosts
-Larvae and nymphs feed on small rodents and other small mammals
-Adults feed on dogs, humans, horses, cattle, wildlife
-Will infest cats and humans
Dermacentor spp:
Adult Identification
-Pale brown to gray
-Medium size ticks
-6mm when unfed and fed females are 15mm
-Scutum is ornate with festoons
-Palps are short
-Basis capituli is rectangular
Dermacentor spp:
Life Cycle
-3 host ticks
-Eggs hatch to larvae
-Larvae attach to host 1, feed, drop off and molt
-Nymphs attach to 2nd host, feed, drop off and molt
-Adult attach to 3rd host, feed, drop off
-Larvae and nymphs feed on rodents and adults feed on dogs and larger mammals
-Egg to adult may take several months to years
-Females lay eggs in secluded places and die
Dermacentor spp:
Sites of Infection
Skin around head and neck
Dermacentor spp:
Pathogenesis and Lesions
-Most common tick on dogs in most of N. America
-Transmits RMSF in dogs and humans caused by Rickettsia rickettsi, Q fever and tularemia
-Transmits Babesia species to dogs and horses
-Tick paralysis in dogs, cats and cattle
Dermacentor spp:
Diagnosis
Identification of tick
Dermacentor spp:
Treatment and Prevention
-Fipronil
-Topical products: synthetic pyrethroids (not on cats)
-Insecticide collars
-Spraying environment
Rhipicephalus sanguineus:
Taxonomy
-Class: Arachnida
-Order: Acari
-Family: Ixodidae
-Genus spp: DRhipicephalus sanguineus
-Common Names: Brown dog tick or kennel tick, Brown ear tick, Red-legged tick
Rhipicephalus sanguineus:
Hosts
-Dogs and humans
-Will feed on cats, if in same househol
Rhipicephalus sanguineus:
Adult Identification
-Yellow, sometimes reddish or blackish brown
-Medium size ticks
-5mm when unfed and 12mm when fed females
-Scutum is inornate with festoons
-Short palps
-Basis capituli is hexagonal
Rhipicephalus sanguineus:
Life Cycle
-3 host ticks
-Eggs hatch to larvae
-Larvae attach to host 1, feed, drop off and molt
-Nymphs attach to 2nd host, feed, drop off and molt
-Adult attach to 3rd host, feed, drop off
-Adults copulate
-Fertilized females lay eggs in secluded places outdoors and indoors and die
-Eggs develop to larvae
-Has adpated to clinics, kennels and homes
-Feed primarily on dogs
-Egg to adult takes 2 months
-Unfed adults can survive for well over a year
-Tick can't tolerate freezing but has adapted to modern indoor living extremely successfully
Rhipicephalus sanguineus:
Sites of Infection
-Skin
-Adults prefer skin between toes and ears
-Larvae and nymphs often at the back of neck
Rhipicephalus sanguineus:
Pathogenesis and Lesions
-Most common in Southern US
-Transmits Babesia canis and Ehrlichia canis, an agent of canine monocytic ehrlichiosis and RMSF
-Transmits many other protozoal, viral and rickettsial organisms of animals and humans
-Transmits Hepatozoon canis which occurs outside the US
Rhipicephalus sanguineus:
Diagnosis
Identification of tick
Rhipicephalus sanguineus:
Treatment and Prevention
-Amitraz tick collar
-Topical products: synthetic pyrethroids (not on cats)
-Insecticide collars
-Spraying environment
Sarcoptes scabiei:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Suborder: Astigmata
-Family: Sarcoptidae
-Genus species: Sarcoptes scabiei
-Common Name: Sarcoptic mange mite, itch mite, scabies mite
Sarcoptes scabiei:
Hosts
-All domestic animals
-Humans
-Rare in cats
-Each host has its own strain
-HIghly contagious in dogs
-Zoonotic: animal to human infestation
Sarcoptes scabiei:
Adult Identification
-Round, 500um in diameter
-Short legs with 2 anterior pairs extending beyond the margin of the body
-Female has suckers on long unsegmented stalks on pairs 1 and 2
-Male has suckers on long unsegmented stalks on pairs 1, 2 and 4
Sarcoptes scabiei:
Life Cycle
-Fertilized female creates a winding burrow or tunnel in upper layers of epidermis, feeding on liquid oozing from damaged tissues
-Eggs laid in tunnels, hatch in 3-5 days to larvae that crawl on the skin surface
-Larvae burrow and form "molting pockets" where nymphs and adults develop
-All stages tunnel in epidermis, resurface and burrow again
-Adult male emerges and seeks female
-After fertilization females produce new tunnels
Sarcoptes scabiei:
PPP
17-21 days
Sarcoptes scabiei:
Sites of Infection
Skin
Sarcoptes scabiei:
Pathogenesis and Lesion
-Erthema
-Scale
-Crust formation
Sarcoptes scabiei:
Clinical Signs
-Begins on relatively hairless areas of body
-Lateral aspect of the elbow and pinna of the ear are common starting places
-Lesions consist of follicular papules, areas of erythema, crusts of dried serum and blood and excoriations (scratch or abrasion of skin) from scratching to relieve the intense itching and pruritus
Sarcoptes scabiei:
Diagnosis
-Skin scraping
-Despite the extensive lesions related to the presence of this mite, frequently it is very difficult to find the mites on dogs, even those dogs exhibiting advance lesions
Sarcoptes scabiei:
Treatment and Prevention
-Selamectin is number one choice
-Subcutaneous ivermectin is used to treat this mange
-These mites can temporarily infest humans and therefore the treatment of the pet will usually cure the humans
Demodex canis:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Suborder: Prostigmata
-Family: Demodicidae
-Genus species: Demodex canis
-Common Name: Demodectic mange mite, follicle mite
Demodex canis:
Hosts
-Dogs
-Cats have their own species (Demodex cati), but is rare
Demodex canis:
Adult Identification
-Elongate tapering body
-400 um
-4 pairs of stumpy legs on anterior (cigar with legs)
Demodex canis:
Life Cycle
-Entirely in hair follicles and sebaceous glands
-Mites are normal fauna of skin
-Adults in follicles
-Females lay eggs
-Larvae and nymphs at mouth of follicle
-Egg to adult in 2-4 weeks
-Transmission to the newborn pups is from bitch to pup by direct contact during nursing in first 2-3 days postpartum
Demodex canis:
Site of Infection
-Hair follicles
-Sebaceous glands
Demodex canis:
Pathogenesis and Lesions
-Presence of small number of mites in normal
-Pups acquire during nursing
-Most causes of mange occur between 3 and 6 months of age
-Affected dogs harbor large number of mites as a result of immunodeficiency
-Display ares of erythema and alopecia around the eyes, mouth and over bony projections on extremities
-No evidence of pruritus
-Can be localized or generalized
-Generalized: hair becomes spare over wider expanses and skin becomes course, dry and erythematous ("red mange")
-Concomitant staphylococcal pyoderma develop in generalized cases and pustules develop, break open and ooze
-Generalized is almost impossible to cure
Demodex canis:
Diagnosis
-Skin scraping can reveal the mite
-Presence doesn't necessarily indicate disease since they are normal inhabitants
Demodex canis:
Treatment and Prevention
-Localized form controlled by rotenone ointment or benzyl benzoae lotion applied daily
-Generalized form treated with Amitraz or 1% alcoholic retenone solution
-Broad bitches with a history of demodectic mange should be spayed
Cheyletiella yasguri:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Suborder: Prostigmata
-Family: Cheyletidae
-Genus species: Cheyletiella yasguri
-Common Name: "Walking dandruff")
Cheyletiella yasguri:
Hosts
-Dogs
-2 other species infest cats and rabbits
-Zoonosis
Cheyletiella yasguri:
Adult Identification
-Body has a "waist" and long legs
-500um
-"Walking dandruff" because large enough to be seen walking against a dark background, prominent palpal claws at anterior end of mite
Cheyletiella yasguri:
Life Cycle
-Mites live on skin, hair and tunnel in epidermis debris
-Mites feed on this debris
-Eggs attached to hair
-Transmission by direct contact
-Life cycle completed in 2 weeks
-They survive off their host longer than other mange mites
Cheyletiella yasguri:
Sites of Infection
Fur and hair
Cheyletiella yasguri:
Pathogenesis and Lesion
"Walking dandruff" because of mties moving on skin
Cheyletiella yasguri:
Diagnosis
-Excessive scurf or dandruff
-Can attack people, exam of an adhesive tape swab may reveal the mites
Cheyletiella yasguri:
Treatment and Prevention
Dogs respond well to topical permethrin, fipronil and amitraz
Otodectes cynotis:
Taxonomy
-Phylum: Arthropoda
-Class: Arachnida
-Order: Acari
-Suborder: Astigmata
-Family: Psoroptidae
-Genus species: Otodectes cynotis
-Common Name: Ear mite
Otodectes cynotis:
Hosts
-Dogs
-Cats
-Ferrets
-Foxes
-Rabbits and humans are reported
Otodectes cynotis:
Adult Identification
-500um in length
-Long legs extending beyond the margin of body
-Egg laying females have suckers on short, unsegmented stalks on pairs 1, 2 and 4 is rudimentary
-Males have suckers on short unsegmented stalks on pairs 1, 2, 3 and 4
Otodectes cynotis:
Life Cycle
-Feeds superficially
-Female lays 90 eggs during her lifetime
-Egg, larval and nymphal stages to mature adult takes 2-3 weeks
-Mites feed on epidermal debris and tissue fluids from the superficial epidermis
-Transmission usually by contact with infested animals
Otodectes cynotis:
Sites of Infection
Ears
Otodectes cynotis:
Pathogenesis and Lesions
In cats a dry, waxy, parchmentlike material in sheets with large number of mites in each layer is seen
Otodectes cynotis:
Clinical Signs
-Frequent shaking of head
-Dog similar to cat
Otodectes cynotis:
Diagnosis
-Behavior of animal and presence of copious production of dark cerumen (ear wax) is characteristic of otodectic otitis and exudate in ear canal
-Observing mites by auroscope or removing exudates, placing on slide and examining whitish moving specks with a hand lens
Otodectes cynotis:
Treatment and Prevention
-Ivermectin ototic suspensions are approved
-Rotenone and pyrethrin compounds are approved for treatment of this mite