How does a tick medication for dogs work? - briefly
The product delivers an active compound that penetrates the dog’s bloodstream, disrupting the tick’s nervous signaling and causing paralysis shortly after the parasite attaches. Systemic absorption provides continuous protection for the duration specified by the label.
How does a tick medication for dogs work? - in detail
Tick treatments for canines rely on chemical agents that disrupt the nervous system of the arthropod. The most common classes are isoxazolines, fipronil, amitraz, and selamectin. Each agent interferes with specific receptors or ion channels essential for tick survival.
Isoxazolines, found in products such as fluralaner and afoxolaner, bind to ligand‑gated chloride channels that are normally activated by the neurotransmitter γ‑aminobutyric acid (GABA). By blocking these channels, the compounds cause uncontrolled neuronal firing, leading to rapid paralysis and death of the parasite. The effect is systemic: after oral administration, the drug is absorbed through the gastrointestinal tract, reaches peak plasma concentration within a few hours, and distributes into skin and hair follicles where feeding ticks are exposed.
Fipronil acts as an antagonist of the γ‑aminobutyric acid‑gated chloride channel in the tick’s central nervous system. Applied topically, it spreads across the skin surface and into the lipid layer of the epidermis. When a tick attaches and begins to feed, it ingests fipronil, which then interferes with inhibitory neurotransmission, causing hyperexcitation and mortality. The drug remains active in the skin for several weeks, providing sustained protection.
Amitraz functions as an α2‑adrenergic agonist. In topical formulations, it penetrates the tick’s cuticle and activates octopamine receptors, resulting in overstimulation of the nervous system and eventual paralysis. The compound also exhibits acaricidal activity against eggs and larvae, reducing environmental infestation.
Selamectin belongs to the macrocyclic lactone family. After absorption through the skin, it binds to glutamate‑gated chloride channels in the parasite, causing an influx of chloride ions, hyperpolarization of neuronal membranes, and cessation of feeding. The drug’s lipophilic nature ensures prolonged residence in the sebaceous glands, extending efficacy for up to a month.
Key pharmacokinetic features common to most products include:
- Rapid systemic absorption (oral) or dermal diffusion (topical).
- High protein binding, limiting distribution to non‑target tissues.
- Metabolic stability that maintains therapeutic concentrations for weeks.
- Excretion primarily via bile and feces, minimizing renal load.
The protective window varies by formulation: oral isoxazolines provide 8–12 weeks of coverage; monthly spot‑on products deliver 4 weeks; collars can extend protection up to 8 months, releasing low‑dose active ingredient continuously.
Resistance management involves rotating classes of active agents, monitoring efficacy through tick counts, and integrating environmental control measures such as habitat modification and regular grooming.