Fleas, Ticks, and Prevention

Fleas, Ticks, and Prevention

Tyler Fields, DVM

Flea Life Cycle

Eggs

  • Size: Approximately 0.5 mm in length; color: white.

  • Deposited on the host animal and typically fall into the surrounding environment within a few hours after deposition.

Larvae

  • Feed off organic debris found in the environment.

  • Prefer development in comfortable areas where pets frequent.

  • Speed of development influenced by temperature and humidity levels.

Pupae

  • Often found in environments such as carpets, soil, and bedding.

  • The cat flea's (C. felis) pupae can hatch in as quickly as 8 days, with the majority hatching between 13 to 14 days.

  • C. felis can remain quiescent (inactive) for up to 30 weeks, demonstrating substantial resilience.

  • Conditions that stimulate emergency hatching include mechanical pressure, carbon dioxide levels, and temperature.

  • Pupae exhibit resistance to freezing, drying, and insecticides.

Common Flea Species

  • Ctenocephalides felis: Commonly known as the cat flea, it is the most prevalent flea species.

  • Ctenocephalides canis: Known as the dog flea.

Adult Flea Characteristics

  • 90 to 95% of fleas emerge within 21 to 35 days in temperate climates.

  • 96 to 99% of fleas emerge within 14 to 28 days in subtropical climates.

  • Fleas begin feeding immediately upon emergence.

  • Flea excrement is referred to as flea dirt, characterized by a red-black color.

  • Egg production initiates within 20 to 24 hours after the female flea takes its first blood meal.

  • A single female flea can produce between 40 to 50 eggs per day.

  • Under typical conditions, adult fleas usually survive for 2 to 3 months.

Goals with Flea Prevention

  • Alleviate discomfort and itchiness (pruritus) caused by fleas, particularly focusing on preventing flea allergy dermatitis.

  • Control the spread of diseases transmitted by fleas, including:

    • Bartonella henselae: Causative agent of cat scratch fever.

    • Dipylidium caninum: Causative agent of tapeworm infections.

    • Acanthocheilonema reconditum: A tropical, non-pathogenic filarial worm, distinct from heartworm.

    • Mycoplasma haemofelis: A red blood cell parasite.

    • Yersinia pestis: Agent of plague.

    • Francisella tularensis: Agent of tularemia.

Flea Allergy Dermatitis

  • It is a hypersensitivity response triggered by antigenic material in flea saliva.

  • Patients with flea allergy dermatitis present with specific dermatological patterns indicative of the condition.

  • Fleas might not be visibly present on the affected patient, particularly in cats, giving rise to the saying, "These cases are fleas until proven otherwise."

Flea Anemia

  • Defined as anemia caused by heavy flea infestations, typically affecting young or small kittens and puppies.

  • Flea anemia can be life-threatening.

  • Treatment often involves the off-label use of medications to counteract anemia and flea burdens.

Formula for Flea Control

  • Flea control can be summarized with the formula:
    extFleaControl=extEnvironmentalTreatment+extFleaPreventionext{Flea Control} = ext{Environmental Treatment} + ext{Flea Prevention}

Environmental Control

  • Environmental treatment addresses the largest populations of flea infestations.

  • Control products vary, including sprays, bombs, and powders.

  • It is crucial to adhere to the label instructions for application.

  • Regular vacuuming can help physically remove fleas, eggs, and larvae from the environment.

  • After vacuuming, ensure that the vacuum canister is emptied outside to prevent re-infestation.

Ticks: Overview

  • Classification: Ticks are arachnids.

  • Types:

    • Hard Ticks (Family: Ixodidae): Characterized by a sclerotized shield (scutum) and anterior mouthparts including the basis capitulum.

    • Soft Ticks (Family: Argasidae): Lacking a sclerotized scutum with ventral mouthparts.

  • Adult hard ticks feed on a host, while soft ticks do not have a feeding habit as adults.

Tick Life Cycle

  1. Egg Stage: The life cycle begins with eggs that hatch into six-legged larvae.

  2. Larva Stage: The larvae attach to a host to feed.

  3. Molt to Nymph: Engorged larvae detach from the host and molt into nymphs.

  4. Nymph Stage: Nymphs attach to a larger host for feeding.

  5. Molt to Adult: Engorged nymphs detach from their host and molt into adults.

  6. Adult Stage: Adult female ticks feed on hosts, mate, become engorged, and subsequently drop off.

  7. Egg Laying: The engorged female lays thousands of eggs before dying.

Common Tick Species

  • American Dog Tick - Dermacentor variabilis

  • Deer Tick - Ixodes scapularis

  • Lone Star Tick - Amblyomma americanum

  • Brown Dog Tick - Rhipicephalus sanguineus

  • Identifying these species can be done by examining the shape of their mouthparts and whether the scutum exhibits ornate characteristics.

Tick Identification Practice

Questions to Consider for Tick Identification:

  • What is the actual size of the tick in question?

  • Are mouth parts short or long?

  • Does the basis capitulum have ornate features?

  • Is the tick male or female?

Reasons for Tick Prevention

  • Minimizing the risk of transmission of tick-borne diseases, including:

    • Lyme Disease

    • Ehrlichiosis

    • Anaplasmosis

    • Babesiosis

    • Rickettsioses, such as Rocky Mountain Spotted Fever.

  • Avoidance of infestations in the home, particularly with regard to Rhipicephalus sanguineus (Brown Dog Tick).

  • Prevention of zoonotic diseases that may affect humans and other animals.

Prevention: Active Ingredients in Tick and Flea Control

Isoxazolines (-laners)

  • Afoxolaner: Brand - NexGard

  • Sarolaner: Brand - Simparica

  • Lotilaner: Brand - Credelio

    • Mechanism of Action: Inhibits GABA and glutamate receptors at the neuromuscular junction in insects and acarines. This class primarily targets fleas and ticks that have bitten and fed on their host.

    • Note: Associated with neurological adverse effects.

Imidacloprid

  • Brands: Seresto Flea Collars, Advantage, K9 Advantix

    • Mechanism of Action: Acts on nicotinic acetylcholine receptors leading to CNS impairment and eventual death of insects. It has a higher affinity for imidacloprid in insects than in vertebrates.

Permethrins

  • Brand: K9 Advantix

    • Mechanism of Action: Disrupts sodium channels in nerve cell membranes, resulting in paralysis. This active ingredient also exhibits repellant properties against flies, gnats, and mosquitoes.

    • Cautions: Can be toxic to certain animal patients, particularly cats.

Fipronil

  • Brand: Frontline

    • Mechanism of Action: Accumulates in the oils of skin and hair follicles, released gradually over time. It spreads across the body in approximately 24 hours while providing coverage for both fleas and ticks.

    • Physiological Impact: Disrupts the passage of chloride ions in GABA-regulated channels affecting CNS activity. Care must be taken as it is toxic to rabbits.

Spinosad

  • Brands: Comfortis, Trifexis

    • Mechanism of Action: Functions as a nicotinic acetylcholine D-alpha receptor agonist, causing involuntary muscle contractions and tremors in insects. Effects emerge 30 minutes after dosing, with death occurring within 4 hours in dogs and 24 hours in cats.

    • Consideration: Quick-acting, which raises the concern regarding proper dosage and application timing.

Nitenpyram

  • Brand: Capstar

    • Mechanism of Action: Binds nicotinic acetylcholine receptors in postsynaptic membranes, blocking neuronal transmission, which leads to paralysis. Highly selective for insect alpha-4 beta-2 nicotinic receptors as compared to vertebrates. Effectiveness observed rapidly, often utilized in pre-operative contexts.

    • Limitation: Not practical for long-term prevention due to its very short duration of action.

Lufenuron

  • Brand: Sentinel

    • Mechanism of Action: Inhibitor of chitin synthesis, which prevents flea eggs from developing into adults.

    • Time Consideration: Control may not be evident for several weeks due to the lifecycle of fleas.

Upcoming Treatments

  • Bravecto Quantum: An extended-release injectable solution intended for one-year flea and tick prevention.

Questions and Contact Information

  • For further inquiries or clarification, please email: tyler.fields@findlay.edu