External Parasites in Small Animals PDF

External parasites in small animals Dr. Roger Ramirez Why are these pets scratching? Parasites Fleas Lice Biting flies Mites Ticks Helminths Disease in animals influenced by parasite and individual immunologic (hypersensitivity) reactions Skin lesions caused by parasites can serve as gateway for oth...

External parasites in small animals Dr. Roger Ramirez Why are these pets scratching? Parasites Fleas Lice Biting flies Mites Ticks Helminths Disease in animals influenced by parasite and individual immunologic (hypersensitivity) reactions Skin lesions caused by parasites can serve as gateway for other infectious agents Review information from last semester on these parasites Common to see secondary infections produced by the parasites, especially in mites Fleas Remember from DWT: Where does each stage occur? environment· eggs laid on host then fall off What is the minimum length the life cycle? It days 1 month is the average amount of time Which stage(s) can survive winter weather? pupa Covered by a cocoon Important facts about flea life stages Eggs Oval, shiny, ivory colored, about 5 mm in length Favorable conditions: humidity >50%, temp around 25°C Larva Start white, turn brown Turn brown from hemoglobin in feces Requirement for adult flea feces in diet 83% can develop at base of carpet Pupa About 5 mm, hard to see Adult emerges 10 days - 6 months Stimuli for emergence: pressure, heat ↑ s Best survival at >50% humidity Can survive winter and stop development to wait for the right conditions Adult If you want to stop the lifecycle, you need to stop the adults (in the first Begins as soon as on the host 24 hours). It’s easier than trying to stop the other life stages because Mating occurs, eggs about 24-36 hours after first blood meal they could be anywhere. Once blood feeding occurs, permanent parasites They usually live for about 100 days; up to 1 year - up to 2 months without feeding Knowing this is a KEY to flea control in dogs The common flea in our homes are provided with ideal conditions, so they develop faster than if in the outside environment Fleas Survey of fleas on dogs in southern Italy 1276 dogs tested 17.9% infested 960 fleas Higher risk: Housed with other dogs/cats Pets to guard, hunting, and stray dogs Rinaldi et al., 2007 Fleas are usually in the back (hind) of the dog. Clinical effects of fleas Continuum of reaction to fleas Little response Flea bite dermatitis Flea allergy dermatitis (flea bite hypersensitivity). In cats - 8% When fleas bite Flea makes several insertions of mouthparts to find a capillary In all animals: presence of flea and initial bites cause some irritation, pruritus, minor cellular response Flea saliva contains histamine-like compounds and proteolytic, cytolytic, and > Physiologically-active systems anticoagulant enzymes Animals become sensitized to varying degrees (Type 1, Type 4, and basophil hypersensitivity) red ↑ nives Erythematous wheal classic primary lesion in hypersensitive dog or cat Evidence that dogs with continuous exposure develop lower antibody levels and reduced lesions - - Flea bite dermatitis is the most common veterinary dermatological entity In dogs and cats hi The cutaneous reaction in basophil hypersensitivity is characterized clinically by less indurated erythema than in classic delayed hypersensitivity, and microscopically by numerous basophils in the papillary dermis. It is a distinct form of hypersensitivity reaction with a delayed-time course Allergy = hypersensitivity > - Flea allergy dermatitis (FAD) Dogs - erythema, alopecia, papules and crusts with scratching leading to self-trauma especially on the rump and tailhead but may manifest over the entire body Cats - miliary dermatitis with alopecia, pruritus, licking, scratching and self trauma ↳ a term used to describe a skin condition in cats that most commonly results from an allergic reaction. The term 'miliary' is derived from the word milium, which is Latin for 'millet', as the small, crusted lesions of miliary dermatitis resemble millet Diagnosis seeds Observation of fleas, flea feces Fleas may be virtually absent on FAD animals Intradermal skin testing ↳ Immune-problem Flea allergy dermatitis (FAD) Intradermal skin testing 122 dogs with skin disorders were selected for the intradermal skin test 8.2% of the dogs were allergic to the flea saliva (FAD) can be allergic to fleasaliva Flea allergy dermatitis (FAD) Merck veterinary manual Typically confined to the dorsal lumbosacral area (rump) and tailhead Then, caudomedial tights, ventral abdomen and flank Other areas involved: neck, forearms and base or ears - - Kramer and Mencke, 2001 Main area to find lesions of flea allergy dermatitis Flea allergy dermatitis (FAD) http://www.skinvetclinic.com/fleaallergydermatitis.html Miliary dermatitis starts around the neck and lower back - sometimes generalized along the dorsum Other areas involved: periauricular area, ventral abdomen and caudal and medial hind limbs Kramer and Mencke, 2001 Other effects of fleas Anemia, primarily young animals Especially if they have a lot of fleas Disease transmission Tapeworm Dipylidium caninum - zoonotic & Haemosipholitus Felis is an intermediate host for this Acanthocheilonema reconditum Rickettsia spp. - zoonotic R. felis R. typhi S Bartonella Cat scratch fever- transmitted by fleas henselae - zoonotic Mycoplasma haemofelis The treatment for heartworm is very toxic. Don’t want to give it to a dog that doesn’t need it. Don’t want to confuse microfilaria from a different species with heart worm Fleas - Control Objectives Break flea cycle indoors Minimize reinfestation Remove fleas and control allergic reactions flea allergy dermatitis Adequate control of low/moderate infestation of non-FAD pet may require only treatment of pet with effective pesticide Complete flea control requires Treatment of the pet Treatment of contact animals Control in environment (indoor and perhaps outdoor) PHARMACOLOGY ecopazarespurpose of eslow down metabolism of active synergists modeactivity permeability Pyrethrins neuronal membranes - > - hyperexcitability. activity efficacy - - pretty safe often used w/ OTC cat + short - ↳ common formulations - generic product name - Topical synergists for cons Na plant products any a acaricidal of Piperonylbutoxide) (e g. residual insecticidal Repellent Activity · ↑ pesticide spectrum of · 11 in ↳ products acting rapidly Sprays , shampoos dusts, , environmental metabolized by light death ↳ rapid effect yrethroids & insecticidal same as inhibits persistent + carbamates -depolarization animals. 4 DO NOT USE insecticidal of acaricidal membrane use both an op Never Safety carbamate issues ↳ more potent Last Longer + ON CATS organophosphates acetylcholinesterase ↳ Sm pretysate acaricidal pyrethrins repellent ↳ Toxicity ↳ lethal for cats In Sm + enr. - synaluses. ↳ small animal product + tog. · Topical Dichlororos , i Tetrachlororiphos Carbary - animal fled · - products Theuthin 0 potential carbamate used To XIS Topical propoxur op- food animal Pesticide Macrocyclic ndtotoglutamaannelsof Rhyperpolarization actories ↓ multiple oral spot-ons - nerves effects in muscles · endectosdes insecticidal muscles Reparalysis internal a dep , on , + external persistence Selamectin pour-ons of weeks Eprinomectin injections parasites acaricidal : formulation parasite ↳ affects safe additive feed ↳ topical : best for drug parasite ectoparasites Ivermectin Moxidectin ↳ systemic reproduction synap Ses -neonicotinoids acetylcholine receptors > low to verts - ↳ + persistence depends on fleds high for honeybees in insects. inverts. compound to acetylcholine , receptor ↳ dif. In insects Location than caricidal low sm receptors r rabbits Spinosad oral S> ineforam weeks protection Lipophilic e + fish - susceptible persistence caricidal a environmental use against pests synapses Bind TO GABA + glutamate gated insecticidal a caricidal sa fe of Sm. topical weeks oral Highly effective ! prevent Babesia + Borrelia chloride channels Fipronil released to surface overtime insecticidal don't use in these species growth crop persistence of synapses Bind To GABA more insect animal ↳ fleas > - ↳. toxicity synapses - Dinotefuran oral topical Insecticidal - some a neonicotinoids isoxazolines topical some (weeks) · Bind henylpyrazoles + formulation synapses einosyns Imidacloprid Nitenpyram Toxicity Insecticide Binds to persistence of weeks some ↳ tosical absorbed animal Juvenile normone early stages Life - Topical pupa ↳ larva insect development Inhibitors Chitin formation early stages Life ↳ larva - Metholc rene Pyriproxyfen of : Begg Bravecto of : Begg > - Lotilaner specific to arthropods regulators Afoxolaner Fluralaner Sarolaner - simparica pupa Topical oral , Lufenuron cyromazine Flea products requiring a prescription or commonly sold in veterinary practices Missing: lotilaner - isoxazoline (Credelio) and sarolaner - now cat approved (Revolution plus - with selamectin) main ones seen in practice Here are links to two good, brief descriptions from Todays Veterinary Practice of drug groups used for flea and tick control and some of the factors to consider in selecting products: > fleas only https://todaysveterinarypractice.com/practicalparasitologythe-flea-infested-pethow-managepet-environment/ https://todaysveterinarypractice.com/practicalparasitologythe-flea-infested-pet-overviewcurrent-products/ Know drug use for ticks, fleas, etc. Fleas - Treatment Products used for pet treatment discussed later Initial treatment to remove heavy flea burden, use fast acting product If severe skin lesions present, don’t want to use topical pesticide, better to use oral product with rapid action Mechanical removal with flea comb Treat symptomatically as needed Pruritis, etc… Fleas - Environmental control Most of the fleas in the household are the eggs, larvae, pupa. Only 5% are adults Repeated vacuuming - use a beater bar rotating brush unit > - win I over head Remove materials from floor, move furniture Removes flea stages and flea dirt Stimulates fleas in pupae to emerge Dispose of bag after each use - freeze, burn, put in sealed plastic bag and discard VACUUMING IS IMPORTANT Deeper the carpet pile, fewer fleas removed Steam cleaning of carpets very effective Mop floors - especially cracks and crevices Do through cleaning before any pesticide use Continue to vacuum daily Fleas - Environmental control Wash bedding, etc. at 60°C for 10 minutes and dry at maximal setting Use premise sprays with pyrethroids, IGRs, IDIs - very important to include IGR/IDI Foggers generally not effective, don’t reach many fleas - IGR insect = ID1 = growth regulators inhibitors insect development Fleas - Environmental control Desiccant type products: diatomaceous earth (wear mask to avoid NEED TO KILL THE ADULT WITHIN THE FIRST 24 HOURS inhaling) and boric acid - they lay eggs 24 hours after the first blood meal. Light traps to detect and help to remove fleas Professional exterminator in extreme cases Fleas - Outdoor control Concentrate in areas good for flea survival Clear brush and debris Cedar chips/oil and other products with essential oils have some activity Flea-eating nematodes Targeted insecticide treatment of sleeping areas Other fleas found on dogs and cats Live with the mouth part inserted in the skin. Poultry stick tight flea - Echidnophaga gallinacea Primarily a bird pest Can also parasitize dogs, cats Adult female attaches semi-permanently Human flea - Pulex irritans - Rodent flea - Xenopsylla cheopis Important because of plague transmission in endemic 6 Yersinia Pestis areas Small animal ectoparasites Lice (collectively) stressed animals> couse burdens Transmission? direct contact/formites close contact Most likely encountered in what circumstances? winter animals kept outside more Effective treatments include imidacloprid, fipronil, selamectin, permethrin - probably isoxazolines but not labelled for that—not common in pets receiving routine veterinary care Wash bedding, dryer on high heat, clean environment , , Animal species Anoplura (sucking) Mallophaga (biting or chewing) Dog Linognatus setosus Trichodectes canis Heterodoxus spiniger Cat None Felicola subrostratus Small animal ectoparasites Animal species Anoplura (sucking) Mallophaga (biting or chewing) Dog Linognatus setosus Trichodectes canis Heterodoxus spiniger Cat None Felicola subrostratus & biting & sucking I Felicola subrostratus Flies - review DWT notes Fly bite hypersensitivity Small papules and wheals on with central crusts that can progress to ulceration Pinnae and face most often ears Associated with mosquitoes, stable flies (Stomoxys), black flies (Simuliidae) Treatment Insecticide with repellent activity Vaseline or other barriers Cuterebra - rodent bot fly Fly strike - myiasis Myiasis is infection with a fly larva Bed bugs - Cimex spp. Bed bugs and pets Not so much on pets because don’t like hairy skin Prefer human blood although will bite what is available Pets may translocate bedbugs in the same way a suitcase does Pet treatment Do not need specific pet treatment in the same way that don’t need specific human treatment Small animal pesticides not labeled for bedbugs - may not be effective When cleaning, launder pet bedding in hot water, dry on high setting Small animal dermatitis - mites Mite Dog or Cat Transmission Predilection Site Diagnosis Short hair areas initially - pinnae, face, forelegs Skin scraping Face Skin scraping Direct contact, fomites Ears Ear swab, otoscope Dog, cat Shortly after birth from dam – not contagious Face, ears Skin scraping Cheyletiella spp. Dog, cat - zoonosis Direct contact, fomites Trunk Hair coat brushings, Adhesive tape Trombiculid mites - harvest mites Dog, cat From environment Ears, face Lesions Pneumonyssoides caninum Dog-rarely seen Direct contact Nasal passages, on nose Observing mites or rhinoscopy Dermanyssus, Ornithonyssus Uncommon in pets From environment None May be hard to find organisms Lynxacarus radovskyi Cat-rare in US Direct contact Trunk, hind legs As for Cheyletiella Sarcoptes scabiei Dog - zoonosis Feline sarcoptic mite (Notoedres) Cat (rare) - Zoonosis? Otodectes cynotis Dog, cat Demodex Direct contact, fomites Direct contact, fomites Sarcoptes scabiei Common cause of dermatitis in dogs not receiving effective routine miticidal treatment ↳ killing mites Dog specific mite strain Lesions typically start on pinnae, lateral hocks and elbows but can spread Mites burrow, hypersensitivity reactions may be extreme Itchy Pruritus, often severe, leading to excoriations, self-inflicted Y trauma and pyoderma scratching Some dogs with mild signs may act as “carriers” Sarcoptes scabiei deep enough to ger Diagnosis by skin scrapping capillary bleeding - Sometimes skin biopsy needed Reaction of animals out of proportion to number of mites present making recovery of mites on skin scraping difficult Also of value to check feces for presence of mites/eggs If clinical judgement says scabies, treat in absence of mites treat if you think its scabies Sarcoptes scabiei Treatment Selamectin, moxidectin/imidacloprid approved for treatment Fipronil, flumethrin/imidacloprid “aid in control/treatment” Became common practice to use large animal dose of ivermectin for treatment, but this is no longer necessary - should use approved product Small animal dermatitis Otodectes cynotis - canine and feline ear mite Life cycle 18-28 days Pathogenesis Hyperplasia and hyperkeratosis of ear canal epithelium Hyperplasia of ceruminous and sebaceous glands with accumulation of dark ↳ ear wax ceruminous exudate (like coffee grounds) Animals may show head shaking, scratching at ears In heavy infestations mites move out of ears onto adjacent skin Cross transmission can occur Ear mites Diagnosis Otoscope Ear swab https://www.capcvet.org/guidelines/otodectic-mite/ Wide variation in reaction to mites, can have high burden with few signs and vice versa Approved treatments Cats: selamectin, moxidectin/imidacloprid, ML ear products Dogs: selamectin Isoxazolines not approved for ear mites, but reports indicate efficacy Cheyletiella spp. Species infest dogs, cats, rabbits Life cycle Surface mite Direct contact transmission - Clinical signs Exfoliative dermatitis Can show scurfy dandruff, pruritus Cats sometimes get miliary dermatitis - Cheyletiella spp. - walking dandruff Diagnosis Big mites - about 0.5 mm, can be seen claws claws Large palpal > - elongated Hair coats brushings, press scotch tape to hair coat “Walking dandruff” stuck to hair eggs Treatment/control Fipronil, moxidectin, selamectin, milbemycin reported effective Localized environmental control helpful Zoonosis Will imidacloprid work? used to treat sucking Transient human lesions in areas of contact insects + fleds Other mites Dermanyssus and Ornithonyssus Same mite group as nasal mite Infest birds (D.) and rodents (O.) but in environment when not feeding Will attach whatever is available Pneumonyssoides caninum Nasal mite Probably more common that we think & https://www.researchgate.net/figure/Pneumonyssus-caninum-Note-the-pair-of-claws-on-the-firstpairs-of-legs-x-45_fig1_1364 & Entomology and Nematology Department - University of Florida https://www.youtube.com/watch?v=m926Wyd--4w Lynxacarus radovskyi Fur mite of cats, clasps hairs Seen in Florida, Caribbean Causes pruritus, alopecia Look at hairs http://vetbook.org/wiki/cat/index.php?title=Lynxacarus_radovskyi Dermatitis due to helminths - RARE!!! Dirofilaria immitis Microfilaria dermatitis - rare Sensitization to intestinal helminths resulting in allergic skin disease - rare Test for and treat parasites Free living nematodes (Pelodera spp.) Invade inflamed skin - rare Animals confined in wet, dirty conditions Clean area, macrocyclic lactones Dermatitis due to protozoa Leishmania spp., flagellate Intracellular in the host’s monocyte-macrophage phagocytic system Number of species and subspecies very confusing Human and canine parasite Cutaneous and visceral forms of disease but both involve skin lesions Not highly endemic in US but travel of US dogs and dogs acquired in other countries can produce cases here - & - http://veterinaryrecord.bmj.com/ http://www.veterinaryimagebank.com/ Leishmania spp. Route of infection Bite of an infected sand fly Sand flies present but not important pests in most of US Other routes of infection proposed for US cases: - Possible transmission from skin lesions (blood-to-blood) Vertical transmission Signs may not develop for years after clinical exposure Zoonotic Dogs important reservoir for human infection in some countries https://ecdc.europa.eu/en/disease-vectors/facts/phlebotomine-sand-flies Leishmania spp. Clinical signs Visceral leishmaniosis - organisms generalized Non-pruritic exfoliative dermatitis and alopecia Other skin lesions Generalized lymphadenopathy : guarded poor prognosis Chronic wasting Once disease develops leads to death if untreated - - Cutaneous leishmaniosis - organisms localized to lesion Dog present with single lesion Better prognosis prg good-guarded : Dantas-Torres, 2009 Leishmania spp. Leishmania in US Species causing cutaneous leishmaniosis Southern States Probably endemic in Texas and other parts of southeast - - Dogs coming from south of the US border, Middle East - Visceral leishmaniosis Same as cutaneous species and also southern Europe Adoptions from southern Europe - this is a concern http://www.cvbd.org/ Still low endemicity in US Leishmania in US Since 2005, it turns out that infection is endemic in many foxhound kennels Many dogs are asymptomatic but clinical disease occurs in some Proposed routes of transmission: dog-todog blood contact (such as fighting), and vertical transmission Mother to baby - Petersen and Barr, 2009 Leishmania spp. Diagnosis Serology > indirect fluorescent IFA ELISA antibody PCR Treatment Treatment generally considered to only suppress infection Dogs considered chronic carriers Owners need to understand that dog is carrier of zoonotic disease Vaccine available in Europe - -