Flea allergy Flashcards
What are fleas?
- Small, brown, wingless bloodsucking insects
Flea order
- Siphonaptera
What is the major flea of cats and dogs?
- Ctenocephalides felis felis
What are the two main fleas that affect dogs and cats?
- Ctenocephalides felis felis (#1)
- Echidnophaga gallinacean (Poultry sticktight flea)
C. canis
- Probably extinct in the US
What is the flea of humans and medium sized mammals (fox, possum, raccoon, etc.)?
- Pulex irritans
Where is the sticktight flea (Echidnophaga gallinacean) found?
SE US and Florida
What is the life cycle of C. felis fleas (basic)?
- Eggs –> 3 larval stages –> pupa –> adult
How long does the entire life cycle take for C. felis?
- 3-4 weeks
- Can be completed in as little as 12-14 days
- Can take up to 50 weeks
Where do fleas come from?
- Fleas outdoors come from eggs deposited from flea infested feral dogs and cats and urban wildlife**
- Eggs deposited can develop into adults (eggs - larvae - pupae - adults)
- As pets are let outside, newly emerging fleas jump on pets
- Or fleas jump on people and are transported back into homes
What does C. felis development require?
- Warm temperature and humidity >50%
- Times vary depending on temp and humidity
Where are eggs laid?
- Laid on the host and FLL OF ONTO THE ENVIRONMENT
How do flea eggs handle freezing or low humidity?
- They don’t (they die)
Flea eggs - how long to hatch
Usually around 2-10 days
- May go dormant and fall and not hatch for 3-4 months
What do larva feed on?
- Feed on organic debris and flea feces
- Blood (adult flea feces) is an important component
- Larvae feed on a variety of organic debris incluign flea egg shells and other flea larvae
Where do flea larvae hang out?
- Migrate away from light
- Migrate into carpet and soil
- Base of carpet
- Cracks and crevices of hardwood flores
- Negative phototaxis and positive geotaxis
- <15% of larvae placed in carpet move more than 8 inches before they pupate
How long do flea larva last?
- 5-11 days
- If they find appropriate habitat and survive, the will pupate within 8-34 days
What environments can kill flea larva?
- Freezing
- Direct sunlight
- High temperature >95°F
- Relative humidity >50%
How long can pupal stage last?
- Usually lasts 8-9 days
- can survive up to 50 weeks
- Basically they spin a silk-like cocoon
- Silk fibers are sticky and coated from debris from the environment
- Inside, the larva undergoes metamorphosis
Can pupal stage resist desiccation and temperature?
- Yes
When does the pupal stage emerge?
- As adult fleas from the cocoon when stimulated by exhaled CO2, vibrations, and heat
- Delayed emergence if no emergence stimuli
Once an animal gets fleas, what happens?
- male and female fleas required for patent infestation
- Female flea initiates feeding immediately
- Female secretes pheromones
- Mating occurs
- Within 24 hours female fleas begin laying eggs and can produce 40-50 eggs each day
Source points outdoors for flea larva
- Under decks and crawl spaces
- Dark spaces
- Shrubs and bushes
Source points for fleas indoors
- Couches
- Cracks in the wood floors
How long can flea outbreaks take to fully control?
- Up to 2-3 months
Under what deadline must adult fleas find a host? and what will happen if they don’t find them?
- 1-2 weeks or they die
What attracts emerged adult fleas, and what is a stimulus for the jump response?
- Attracted to light (phototaxis)
- Stimulus for jump response is a decrease in light intensity (shadow)
- May bite humans before finding their preferred hosts
Will adult fleas die in the winter if they’re on a host?
- Nope, they can survive
- Important because they can survive on untreated dogs and cats, or other wildlife
What will happen to eggs, larva, and pupae in freezing temperatures?
- No
What does it mean that C. felis are permanent ectoparasites?
- They prefer a permanent host, even though they can transfer from host to host
- Therefore,treatment should be directed at all animals in the household
How quickly does C. felis feed?
- seconds to minutes
- 90-95% feed within 5 minutes to 1 hour
- Females can consume 10x body weight within 24 hours and 15x body weight thereafter
Do we have products that can stop fleas from feeding?
- No
Pathophysiology of flea allergy? What type of hypersensitivity?
- Hypersensitivity
- Type I and Type IV hypersensitivity (most have both)
- IgE mediated reactions
- Cutaneous basophil hypersensitivity
How do animals become sensitized to fleas?
- Repeated exposure
Why don’t all dogs react to flea bites?
- Some dogs may have immunologic tolerance rather than hyposensitization
Where is the flea antigen found?
- Present in saliva
- Multiple antigens
Is it technically accurate that a single flea bite will produce a clinical reaction in a hypersensitive animal and the animal will react for up to two weeks?
- Not really accurate
- Depends more on degree of hypersensitivity and number of fleas and antigen injected
Where are the largest # of eggs found?
- WHere pet spends most of its time
What is more successful: preventative flea control or waiting until the flea population is established?
- Preventative is more helpful
What is the primary cause of flea infestations?
- Acquisition of newly emerged fleas from an infested environment
- Direct transfer of fleas from 1 host to another is possible though
Can dogs or cats achieve natural desensitization therapy?
- No
How long is flea bite hypersensitivity maintained?
- Years
What are factors that favor development of FAD?
- Intermittent exposure
- First exposure to fleas later in life
- Animals with environmental allergies (atopy)
Are dogs with FAD pruritic?
- YES
Where are dogs with FAD pruritic?
- Caudal dorsal back
- Flank
- Ventral abdomen
- Can be generalized!
- Basically where the dog would wear pants
What lesions do we see with flea allergy dermatitis?
- Primary papular eruptions
- Self-trauma/secondary lesions (crusting, scaling, alopecia, lichenification, acute moist pyotraumatic dermatitis, secondary pyoderma)
What is the name of “hot spot” associated with FAD?
- Acute moist pyotraumatic dermatitis
Are cats with FAD pruritic?
YES
Where are cats with FAD pruritic?
- Neck
- Tail base
- Can be generalized
What lesions do we see with feline FAD?
- Crusted papules = miliary dermatitis**
- Pruritus with no lesions
- Alopecia (excessive grooming)
- Esoinophilic granuloma complex (indolent ulcers, esoinophilic plaques, esoinophilic granulomas)
What are parts of the eosinophilic granuloma complex?
- Indolent ulcers
- Eosinophilic plaques
- Eosinophilic granulomas
Diagnosis of Flea allergy dermatitis?
- Clinical diagnosis and response to treatment
- Clinical signs
- Presence of fleas and/or flea feces (dirt)
What are flea-nial owners?
- WHere are the fleas?
- Cats are very efficient groomers
- Other animals in the home may be carriers!
- Infestations at home!
- Threshold phenomenon
- Outdoor exposure is huge!***
If you don’t find fleas or flea dirt, does that rule out a diagnosis?
- No
What might you find in the fecal of an animal that supports a diagnosis of FAD?
- Tapeworms!
- Dipylidium caninum
What tests are supportive of FAD?
- Allergy testing
- bloodwork
- Biopsy
Bloodwork that suggests FAD
- Eosinophilia
SKin biopsy of FAD
- Perivascular dermatitis with eosinophila
By the time an owner notices fleas, how long have immature flea stages been developing in the home?
- 1-2 months
What is the name for the group of immature flea stages that provide an ongoing source of new adult fleas?
- Biomass
Treatment principles for FAD
- Treat secondary infections (Pyoderma, Malassezia dermatitis)
- Treat pruritus accordingly
- Client education is important
- Treat all animals in the environment
Differential diagnoses for FAD?
- Food allergies
- Environmental allergies
- Ectoparasites (scabies, cheyletiellosis)
What are some questions to ask when choosing flea control?
- Is the animal hypersensitive (if so, be more aggressive)?
- Where do you live/work? (does it freeze over)
- What products does your practice carry?
- Is the pet bathed frequently?
- Is the environment already infested?
Causes of treatment failure for FAD
- Poor client compliance (often result of poor client education and failure to convince the owner of the problem)
- Suboptimal treatment regiment
- Insecticide resistance (not as frequent; more likely failure to treat flea infested source or newly hatched fleas from pupal stage)
- Incorrect or incomplete diagnosis (e.g. other allergy or concurrent allergy)
Are adulticide flea collars with organophosphates and pyrethroids effective?
- No
- OTC
- There is resistance
Is Brewer’s yeast effective for flea repellent?
- No
- Neither is diatomaceous earth or garlic
What treatments were used to treat the premises and eliminate immature stages?
- Insecticides
- Insect growth regulators (IGRs)
- Flea dips
- Flea collars
- Flea powders
- e.g. RAID
- No residual activity
What are current recommendations for controlling infestations?
- preventing reproduction!
Describe the two mainstays of breaking the cycle of FAD?
- Effective residual adulticides to kill fleas within 24 hours (or before they can begin to lay eggs)
- Use of IGRs or insecticides to kill any eggs that are produced (methoprene/pyriproxyfen or lufenuron)
What are the two ways that you can look at speed of kill, and which is most important for control?
- Initial speed of kill
2. Residual speed of kill
Initial speed of kill - how do most products rank?
- Most products do a good job and kill within 24 hours
Residual speed of skill - definition?
- How long they kill newly acquired fleas
Importance of residual speed of kill
- Killing newly acquired fleas fast enough
- Prevent flea reproduction
- Reduce injection of antigens and minimize FAD
- Provide client satisfaction
How long until most monthly products decrease their residual efficacy and speed of kill?
- most in 2 weeks
- Then it won’t be able to kill within the 24 hour window, which is necessary
Further factors that can decrease the residual speed of kill of most adulticides?
- under-dosing by client
- bathing/swimming
- Not all flea strains are equally susceptible
How effective are isoxazolines?
- Very effect
MOA of isoxazolines
- Inhibit GABA and glutamate gated chloride channels
Where do isoxazolines circulate?
- in plasma proteins
Route of elimination of isoxazoline?
- Hepatic
Examples of isoxazolines
- Fluralaner (Bravecto)
- Afoxolaner (Nexgard)
- Sarolaner (Simparica)
- Lotilaner (Credelio)
Initial speed of kill and residual speed of kill for Bravecto (fluralaner)?
- Initial: 80% by 4 hours and 100% by 12 hours
- Residual speed of kill is 100% up to 12 weeks out
Initial and residual speed of kill of Bravecto, Nexgard, Simparica, Credelio
- Initial is 100% for Bravecto, Nexgard, Simparica, and Credelio (Nexgard and Simparica work the fastest)
- Residual is 97% 4 weeks out and 100% for everything else
- Bravecto is still strong at 8 weeks
How long does Fluralaner work vs Afoxolaner, Sarolaner, Lotilaner?
- Fluralaner is 3 months
- Afoxolaner is 28 days
- Sarolaner and Lotilaner are 30 days
Which isoxazolines are safe for animals with food allergies?
- Fluralaner or Bravecto (hydrolyzed pork)
- Sarolaner or Simparica (hydrolyzed soy)
What other ectoparasites do isoxazolines treat/prevent?
- Ticks
- Demodex mites
- Scabies
- Otodectes
Nitenpyram - speed of kill?
- Kills fleas in 30 minutes
- 100% gone by 24 hours, but residual activity doesn’t last for even 48 hours
- Helps create a “flea bubble” with use of other adulticides
- Every other day for 1 month
- Also treats maggots
Speed of kill and residual kill for spinosad (comfortis) and spinosad + milbemycin oxime (Trifexis)
- Speed of kill is 100% in 4 hours
- Labeled for use for 30 days
- They lose efficacy much more quickly
What does Trifexis (spinosad + milbemycin oxime) work against
- Heartworm and GI parasites
Allergies with Trifexis and Comfortis?
- Both are beef flavored
Mechanism of capstar?
- neonicotinide
- Binds nicotinyl ACh receptors on postsynaptic neurons, causing paralysis and death
- Paralyzes flea mouthparts prior to injecting saliva
Mechanism of spinosad (comfortis/trifexis)?
- Binds nicotinyl ACh receptor on postsynaptic neurons, causing paralysis and death
Mechanism of imidocloprid (Advantage)/
- Binds to insect’s nicotinyl acetylcholine receptor sites on postsynaptic neurons
- Mammalian muscarinic acetylcholine receptors do not bind imidocloprid effectively
- Adheres to hair and skin and not absorbed systemically
- Kills by contact
- hair is larvicidal in environment
Imidocloprid route?
- Topical spot on
Is Imidocloprid (advantage) absorbed?
- No
What can reduce efficacy of imidocloprid?
- Bathing/swimming
Labeled length of imidocloprid?
- 30 days
Imidocloprid with permethrin (K9 advantix) - can it be used on cats?
- NO it can kill them
- Useful against ticks though
Advantage multi (imedicloprid with moxidectin) - what is it effective against?
- Heartworm
- Also miticidal properties if used every 2 weeks for 3 consecutive treatments
What is the drug in seresto?
- Imidocloprid with flumethrin
- Slow release collar
How long is imidocloprid plus flumethrin useful for (seresto)?
- 8 months, but reduced efficacy if you bathe your dog regularly
What is seresto useful against?
- Fleas and lice (fleas and lice)
- Ticks and scabies (flumethrin)
Selamectin - drug type?
- Avermectin
How is selamectin absorbed?
- Systemically
WHere does selamectin form reservoirs?
- SEbaceous glands
What life stages does selamectin kill?
- adulticide and ovicide
Is selamectin more useful for dogs or cats?
- More useful for cats
How long is selamectin useful?
- 30 days
- Efficacy lost in 2-3 weeks
What is selamectin active against and in which species?
- Heartworm prevention (dogs and cats)
- Scabies (dogs)
- Otodectes (dogs and cats)
- Hookworms (cats)
- ROundworms (cats)
- Ticks (dogs)
Mechanism of selamectin?
- Induced neuromuscular paralysis by increasing chloride permeability of glutamate-gated chloride channels
Vectra 3D active ingredients and mechanism
- Dinotefuran/pyriproxifen/permethrin
- Neonicotinoid
- Bind flea postsynaptic nicotinic acetylcholine receptors
Spectrum of action for dinotefuran/pyriproxifen/permethrin?
- Labeled for fleas, ticks mosquitoes
Fipronil (Frontline)mechanism
- Inhibits GABA mediated chloride
- Collects in sebaceous glands and hair follicles, then redistributes to skin surface
- Not systemically absorbed
- Kills by contact
What is fipronil toxic to?
- Rabbits
Spectrum of fipronil?
- Kills adult fleas and ticks
List the residual adulticides?
- Isoxazolines
- Capstar (nitenpyram)
- Spinosad (comfortis)
Imidocloprid (Advantage) - Selamectin (Revolution)
- Dinotefuran/pyriproxifen/permethrin (Vectra 3D)
- Fipronil
WHere can you use insect growth regulators?
- On pets or applied to the environment
How do insect growth regulators work (which life stage of the flea to they impact)?
- prevent flea eggs from hatching
- Larvae cannot pupate
- Often combined with Bravecto to break the cycle
Examples of insect growth regulators
- Methoprene (Frontline plus)
- Pyriproxifen (Vectra 3D)
Mechanism of insect growth regulators
- Juvenile hormone mimic - disrupts embryonic and post embryonic development
- Prevents flea eggs from hatching; existing larvae cannot pupate
- In general, doesn’t affect adult flea
Insect development inhibitor examples
- Lufenuron
Methoprene more info
- Available in sprays, collars
- Eggs exposed within 24 hours after being laid failed to hatch
- UV sensitive
Pyriproxyfen more info
- Sprays, collars, Vectra 3D
- Affects egg formation as well
- UV stable
- Doesn’t wash off
Mechanism of insect development inhibitors
- Environmental control administered to pet
- Interferes with chitin synthesis (eggs and larvae)
- Eggs non-viable because larval exoskeleton formation inhibited
Is it okay to use lufenuron (Program, sentinel) as a primary flea control?
- NO
- No adulticide, so the fleas will still jump on and cause problems
Flavor of lufenuron
- Beef
What additional drug is in sentinel besides lufenuron?
- Milbemycin oxime
How to manage the itch with FAD?
- Look for and treat all secondary infections
- Put out the fire (the itch) for 2-3 weeks
How to put out the itch for FAD?
- Corticosteroids: short, tapered anti-inflammatory dose/course (avoid injectables)
- Apoqel (oclacitinib)
- Cytopoint (lokivetmab)
What secondary infections are most likely with FAD?
- Yeast and pyoderma
Antihistamines for managing the itch?
- Not useful!
- Mediocre at best
How long can cytopoint provide relief?
- Approximately 30 days
Which drugs are recommended for cats?
- Selamectin
- Fluralaner
Which drugs are recommended for dogs
- Fluralaner
- Advantage K9
