Your dog may be the first member of your household to contract a tick-borne disease — and its diagnosis may be the first warning that your family is at risk. Canine seroprevalence of Borrelia burgdorferi (Lyme disease bacterium) closely mirrors human Lyme disease geography, with 5.1% of nearly one million US dogs testing positive nationally and rates reaching 50-85% in hyperendemic counties of Massachusetts and Connecticut Trends in Parasitology / PMC, 2021. The tick that infected your dog is feeding in the same yard where your children play.

This article covers what tick-borne diseases look like in dogs, cats, horses, and livestock; what prevention products are available and how they work; the critical danger of permethrin to cats; and the wildlife species that sustain the tick-disease cycle in your environment.

Tick-borne diseases in dogs

Infections transmitted by ticks are increasingly recognized as important causes of disease in dogs Today's Veterinary Practice / NCVP, 2015. The major canine tick-borne diseases include Lyme borreliosis, anaplasmosis, ehrlichiosis, Rocky Mountain Spotted Fever, babesiosis, and hepatozoonosis — and a single point-of-care test (SNAP 4Dx Plus) can screen for four of them simultaneously Today's Veterinary Practice / NCVP, 2015.

Canine Lyme disease

The most serious canine Lyme manifestation is Lyme nephropathy — a protein-losing nephropathy with glomerulonephritis that is often fatal and may have a breed predisposition in Labrador Retrievers, Golden Retrievers, and Bernese Mountain Dogs American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018. More commonly, dogs develop polyarthritis with shifting-leg lameness.

Most seropositive dogs never develop clinical signs — the debate over whether to treat clinically normal seropositive dogs is ongoing American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018. When treatment is indicated, the consensus first-line protocol is doxycycline at 10 mg/kg by mouth twice daily for 30 days — a longer course than the 10-14 day treatment used in humans American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018.

The C6 peptide test, which detects antibodies to a VlsE protein region specific to natural infection, differentiates infection from vaccine response in dogs — a distinction not available in human diagnostics American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018.

Vaccination controversy mirrors human medicine

The canine Lyme vaccination debate mirrors the human one: the ACVIM consensus panel notes that vaccination may be appropriate in endemic areas but is not recommended as a universal practice American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018. The geographic expansion of Ixodes scapularis (black-legged tick / deer tick) and B. burgdorferi into the Great Lakes, Mid-Atlantic, southern Appalachia, and southern Canada is increasing canine disease reports in previously low-risk areas Today's Veterinary Practice / NCVP, 2015.

Other canine tick-borne diseases

The burden extends well beyond Lyme. The most burdensome canine tick-borne infections are ehrlichiosis (Ehrlichia canis) and babesiosis Trends in Parasitology / PMC, 2021. Canine ehrlichiosis seroprevalence reaches 3.9% in Arkansas and 3.8% in Oklahoma Trends in Parasitology / PMC, 2021.

Canine babesiosis presents in two forms: Babesia canis (more severe, acute disease) and Babesia gibsoni (chronic, often in pit bull-type breeds) Today's Veterinary Practice / NCVP, 2015. Hepatozoonosis, caused by Hepatozoon americanum and H. canis, is uniquely transmitted when dogs ingest infected ticks rather than through tick bites — a transmission route found in no other major tick-borne disease Today's Veterinary Practice / NCVP, 2015.

Dogs as family risk indicators

"Overall, large-scale serosurvey results closely reflect the geographic distribution of reported human Lyme disease cases with hyperendemic foci found in counties in central and northern California and the New England states." Trends in Parasitology / PMC, 2021

A dog's positive tick-borne disease test is not just a veterinary finding — it is a sentinel indicator that the family's tick exposure is real and ongoing. The market for pet antiectoparasite products reflects the scale of concern: Fipronil (Frontline) alone has sold over one billion units since 1996 Trends in Parasitology / PMC, 2021.

Tick prevention products for dogs

Isoxazolines: the modern oral preventatives

The isoxazoline class — NexGard (afoxolaner), Bravecto (fluralaner), Simparica (sarolaner), and Credelio (lotilaner) — dominates modern canine tick prevention. All four are FDA-approved for control of Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), Rhipicephalus sanguineus (brown dog tick), and Amblyomma americanum (lone star tick) Journal of Veterinary Pharmacology and Therapeutics, 2022.

These drugs work by inhibiting GABA- and glutamate-gated chloride channels in invertebrate nervous systems, with significant selectivity for invertebrate over vertebrate receptors — explaining their high safety margin in mammals Journal of Veterinary Pharmacology and Therapeutics, 2022.

"The isoxazolines are a novel class of ectoparasiticides with potent inhibitory activity on glutamate- and gamma-aminobutyric acid-gated chloride channel located in nervous system of invertebrates." Journal of Veterinary Pharmacology and Therapeutics, 2022

The key differentiator among products is duration and formulation. Bravecto (fluralaner) is the only isoxazoline with a 12-week duration — three times longer than the others — and the only one available as both oral and topical formulation for dogs and cats Journal of Veterinary Pharmacology and Therapeutics, 2022. NexGard, Simparica, and Credelio are monthly treatments.

All isoxazolines are highly lipid-soluble with greater than 99.9% plasma protein binding. One practical concern: lotilaner (Credelio) bioavailability drops dramatically without food — 82% fed versus 24% fasted in dogs — making administration with a meal critical for efficacy Journal of Veterinary Pharmacology and Therapeutics, 2022.

Speed of kill matters for pathogen transmission

Because isoxazolines are systemic drugs, they require tick attachment for drug delivery — the tick must begin feeding to ingest the drug. This makes speed of kill clinically significant: the shorter the tick feeds, the lower the pathogen transmission risk Parasites & Vectors / Springer, 2023.

A head-to-head comparison of Bravecto and Simparica TRIO for I. scapularis kill found significant differences in residual speed. At Day 28 post-treatment (near the end of Simparica TRIO's labeled duration), Bravecto maintained 92.2% kill at 8 hours versus 0.0% for Simparica TRIO, and 99.6% versus 27.7% at 12 hours Parasites & Vectors / Springer, 2023. The minimum sarolaner dose in Simparica TRIO (1.2 mg/kg) was reduced by 40% compared to standalone Simparica (2.0 mg/kg), which may explain the slower kill Parasites & Vectors / Springer, 2023.

Other product categories

The CAPC product reference database lists all FDA- and EPA-approved parasite control products for dogs and cats, covering oral, topical, and collar formulations CAPC (capcvet.org), 2016. Products are categorized by regulatory authority — EPA-registered products (including many spot-on treatments) face different regulatory requirements than FDA-approved drugs CAPC (capcvet.org), 2016.

Tick checks during outdoor activities

Shared outdoor activity creates shared risk. The Appalachian Trail Conservancy notes that leashes are required on almost half of the Appalachian Trail — relevant for tick exposure because off-leash dogs explore tick habitat more extensively Appalachian Trail Conservancy, 2025. Checking your dog for ticks after outdoor activity is as important as checking yourself.

Cats and tick-borne disease

Cats get exposed but rarely get sick from Lyme

Cats are exposed to B. burgdorferi with seroprevalence rates of 47-71% in endemic northeastern US areas — but clinical Lyme disease has not been convincingly demonstrated in cats Trends in Parasitology / PMC, 2021, American College of Veterinary Internal Medicine / Journal of Veterinary Internal Medicine, 2018. Cats face a different tick-borne threat: cytauxzoonosis, caused by Cytauxzoon felis, carries a case fatality rate exceeding 90% Trends in Parasitology / PMC, 2021.

Permethrin will kill your cat

The single most important tick prevention fact for cat owners is that permethrin — the active ingredient in many dog flea and tick products — is potentially fatal to cats. This is not a theoretical risk. In the largest published case series of feline permethrin poisonings, 286 cats exposed to permethrin spot-on products:

Convulsions lasted an average of 38.9 hours. Recovery typically took 2-3 days but in some cases 5-7 days Journal of Feline Medicine and Surgery / VPIS, 2024.

Cats are uniquely vulnerable because they lack sufficient glucuronidase transferase to metabolize permethrin, resulting in high circulating levels that concentrate in nervous tissue AAFP (catvets.com), 2014. Canine permethrin spot-on products contain 45-74% permethrin, compared to less than 0.1% in safe feline products — a 450-to-740-fold concentration difference Journal of Feline Medicine and Surgery / VPIS, 2024.

"The topical application of flea control products marketed for dogs containing permethrins to cats constitutes a major portion of feline toxicities reported to the ASPCA Animal Poison Control Center." AAFP (catvets.com), 2014

Cats can be poisoned not only by direct application of dog products but also by secondary contact with recently treated dogs Journal of Feline Medicine and Surgery / VPIS, 2024, AAFP (catvets.com), 2014. If permethrin seizures occur in a cat, standard diazepam is NOT effective — methocarbamol, barbiturates, propofol, or inhalant anesthetics should be used instead AAFP (catvets.com), 2014.

Safe tick prevention for cats exists. Bravecto (fluralaner) is available in topical formulation specifically approved for cats Journal of Veterinary Pharmacology and Therapeutics, 2022. The critical rule for multi-pet households: never apply a dog tick product to a cat, and separate recently treated dogs from cats until the product has dried completely.

Horses, livestock, and the global economic burden

The global economic impact of ticks and tick-borne diseases is estimated at USD 22-30 billion per year, with the largest share from livestock mortality and morbidity, especially in cattle and small ruminants MDPI (Veterinary Sciences), 2025:

"The economic impact of ticks and TBDs globally is estimated to reach as much as USD 22–30 billion/annum with the largest share attributed to livestock mortality and morbidity, especially in cattle and small ruminants." MDPI (Veterinary Sciences), 2025

Chemical acaricides remain the primary control method for livestock ticks but are increasingly challenged by resistance. In Ecuador's dairy farms, Rhipicephalus microplus (cattle tick) shows resistance to amitraz (42% of farms), ivermectin (39%), and alpha-cypermethrin (24%) MDPI (Veterinary Sciences), 2025. The One Health approach — recognizing the interconnectedness of human, animal, and environmental health — is essential for addressing the wildlife-livestock interface where ticks cycle between domesticated and wild animals MDPI (Veterinary Sciences), 2025.

The wildlife that sustains the tick-disease cycle

Understanding which animals sustain tick populations and which infect ticks with pathogens is essential for any prevention strategy that goes beyond individual protection.

The white-footed mouse: the disease reservoir

The white-footed mouse (Peromyscus leucopus) is the principal reservoir for B. burgdorferi, Babesia microti (Babesia parasite), and the agent of human granulocytic anaplasmosis, making it the single most important wildlife host in the Lyme disease transmission cycle Connecticut Agricultural Experiment Station / CDC, 2007. Larval ticks feed on mice in late summer, acquire pathogens, and emerge the following spring as infected nymphs — the stage most responsible for human infections Connecticut Agricultural Experiment Station / CDC, 2007.

White-footed mice have a home range of 0.1-1.0 hectares Journal of Medical Entomology / PMC, 2021, making rodent-targeted approaches (permethrin-treated cotton in tick tubes, acaricide-containing bait boxes) feasible at the residential scale. However, these approaches work for I. scapularis but not for A. americanum (lone star tick), whose larvae feed on a broader range of hosts Journal of Medical Entomology / PMC, 2021.

White-tailed deer: the reproductive host

White-tailed deer are the primary reproductive hosts for adult I. scapularis — a single female tick can lay 2,000-3,000 eggs after feeding on a deer Connecticut Agricultural Experiment Station / CDC, 2007. Deer do not infect ticks with B. burgdorferi (they are not competent reservoirs for the bacterium), but they sustain tick populations at the landscape level Connecticut Agricultural Experiment Station / CDC, 2007. Deer home ranges of 8-42 hectares for does and 28-130 hectares for bucks in urban areas mean that deer management must operate at community scale, not individual property scale Journal of Medical Entomology / PMC, 2021.

Computer simulations have shown that complete elimination of deer could reduce nymphal A. americanum below tolerance threshold by the second year and eliminate the population by year eight — but this is impractical in real-world settings Oxford University Press (Journal of Integrated Pest Management), 2017.

The brown dog tick: an indoor threat

Rhipicephalus sanguineus (brown dog tick) is the only hard tick species that can complete its entire life cycle indoors, and was recently identified as the vector of RMSF in Arizona tribal community outbreaks — where incidence rates reached 150 times the national average Trends in Parasitology / PMC, 2021, Open Forum Infectious Diseases (OUP), 2022. The hyperendemic RMSF cycle in northern Mexico involves free-roaming and stray dogs supporting enormous populations of this tick in peri-domestic settings PLOS Neglected Tropical Diseases, 2024.

Sources

Compiler Notes

  • The Seresto collar is listed in the CAPC product reference but the vault contains no dedicated safety, efficacy, or counterfeit analysis source. The seresto-collar-efficacy-safety-counterfeit node remains a gap.
  • Opossum tick consumption data (frequently cited in popular media as a major tick predator) is not directly documented in any vault source. This commonly repeated claim is not included per the no-training-data rule.
  • The horse/livestock section is thin — the vault's primary livestock source is the 2025 MDPI tick control review, which covers livestock from a global agricultural perspective rather than US horse/companion livestock management. A dedicated equine tick-borne disease source would strengthen this section.
  • The cat tick prevention section recommends Bravecto topical as an available option; the CAPC database would list additional cat-safe products but the index entry for that source does not enumerate specific cat products.
  • Wildlife ecology coverage draws primarily on the 2007 Stafford handbook. More recent data on deer population dynamics and tick abundance correlations would strengthen the deer management discussion.