Ticks: small, persistent… but far from harmless

Understanding their biology to better prevent their effects on health

The biology of ticks and why they pose a real health problem

Ticks are blood-feeding arthropods of the arachnid class, whose life cycle—larva, nymph and adult—is strictly linked to the need to feed on blood at each stage. This dependence explains their role as biological vectors, capable of acquiring pathogens during feeding and subsequently transmitting them to another host.

From an ecological point of view, many European species, such as Ixodes ricinus, are active even at relatively low temperatures. Field studies have shown that host-seeking activity can be maintained above 5–7 °C, which explains why, in temperate climates, the risk extends over much of the year and not just in summer. In everyday practice, this means that limiting prevention to a few months leaves real windows of risk.

In this context, it is worth remembering that not all tick-borne infections necessarily require a classic bite. In dogs, it has been shown that Hepatozoon canis can be transmitted when the animal ingests an infected tick, for example by biting it or during grooming, which helps to explain infections in animals whose owners do not remember seeing any attached parasites.

Many domestic infestations begin when a tick “hitchhikes” into the home after a trip, an outing or a stay at a kennel. This supports simple but very effective measures: checking the animal when it arrives home, washing travel textiles and not being complacent because “there have never been any here”. Therefore, after walks in areas with tall grass, along roadsides or in wooded areas, it is particularly effective to carry out a systematic tactile check of the animal, paying particular attention to the ears, neck, armpits, groin and interdigital spaces, areas where ticks most frequently attach themselves.

Your vet advises: A 90-second method that works

When checking by eye, half of them are missed. However, if you always follow the same order (ears → neck → armpits → groin → between the toes → base of the tail) and feel against the grain, detection is greatly improved, especially in long-haired dogs and cats that groom themselves and ‘cover their tracks’. This is practical advice that is a logical consequence of the biology of the parasite.

The main health problem is not the mechanical bite, but the transmission of pathogens. In a European study of Ixodes ricinus ticks collected in the wild, 358 of 1078 ticks (33.2%) carried at least one pathogen, and 5.9% were co-infected with two or more microorganisms. This data is particularly relevant from a clinical point of view, as co-infections can lead to more complex clinical pictures, with less specific signs and more variable responses to treatment.

In dogs and cats, many of these infections begin subclinically and manifest weeks or months later with intermittent fever, anaemia, lameness, apathy or kidney problems. This delayed progression explains why basing protection on the appearance of symptoms is ineffective: by the time signs appear, the infection is already established.

Modern antiparasitics: the basis of effective tick prevention

Current prevention relies on antiparasitics with highly specific active ingredients, designed to interfere with the parasite’s vital functions. However, their actual effectiveness depends both on the product and on its correct integration into the animal’s daily routine.

Oral antiparasitics: systemic protection and reduced risk of transmission

Oral antiparasitics act systemically, distributing themselves through the bloodstream after being absorbed by the digestive system. When the tick attaches itself and begins to feed, it comes into contact with the active ingredient and dies within a relatively short period of time. This detail is clinically relevant, as the probability of pathogen transmission increases with the duration of attachment.

Experimental studies have shown that certain molecules can prevent the transmission of Babesia canis for prolonged periods. In a study published in Parasites & Vectors, transmission was prevented for up to 84 days after administration of the product.

In clinical practice, associating tablet administration with a fixed habit—for example, a specific date of the month—significantly reduces forgetfulness, which remains one of the main causes of preventive failure.

Topical pipettes (spot-on): efficacy dependent on skin management

Topical pipettes (spot-on) are distributed through the skin’s lipid film, the natural oily layer of the skin. This mechanism explains why frequent bathing or the use of lipid-removing shampoos can reduce their efficacy. Applying the pipette directly to the skin and spacing baths several days before and after application significantly improves actual protection, a simple but clinically relevant detail.

Antiparasitic collars: continuous protection and reduced forgetfulness

The latest generation of anti-parasite collars release the active ingredient slowly and steadily, maintaining effective concentrations for six to eight months. Their main advantage is continuity, as they reduce the risk of forgetfulness. For this protection to be effective, the collar must remain in contact with the skin; checking it periodically and adjusting it if the animal grows or loses weight prevents silent losses of effectiveness.

At this point, it is important to remember that not all ticks depend exclusively on the outdoors. Some species, such as Rhipicephalus sanguineus, can complete much of their life cycle indoors, which explains persistent infestations in homes, kennels or dog facilities, and reinforces the need to combine animal protection with environmental control measures when the problem recurs.

Complementary measures: sprays, powders and shampoos as occasional support

In addition to these main tools, there are complementary measures such as anti-parasite sprays, powders and shampoos. Their action is usually short-lived and localised, so they should not be considered a structural prevention measure, but they can provide occasional benefits after exceptional exposure or as initial support in mild infestations.

Vaccination against tick-borne diseases: complementary protection

Vaccines do not act on the tick, but on the infectious agent, so their use is always complementary to antiparasitic treatments.

Vaccination against piroplasmosis or babesiosis

In the case of piroplasmosis or babesiosis, vaccination against Babesia canis does not prevent infection, but it does significantly reduce the severity of the disease. The aim of vaccination is to modulate the clinical response, decrease parasitaemia and reduce the risk of severe anaemia and systemic complications.

Classic studies on vaccination against Babesia canis describe how vaccination limits key clinical parameters, especially anaemia/haematocrit, which is in line with the realistic objective of these vaccines. In addition, the regulatory documentation specifies that the objective is to reduce the severity of clinical signs and anaemia as measured by PCV, with immunity beginning approximately 3 weeks after vaccination and lasting an estimated 6 months.

Scientific result!

The babesiosis vaccine does not “block” infection, but it does modulate anaemia. A classic study on vaccination against Babesia canis described how vaccination limited the drop in haematocrit/PCV and other clinical parameters, which is in line with the realistic objective of these vaccines: not to promise “zero infection”, but less clinical severity and better progression.

Source: https://pubmed.ncbi.nlm.nih.gov/9477490/

Vaccine against borreliosis or Lyme disease

Vaccination against borreliosis or Lyme disease aims to limit the spread of Borrelia burgdorferi after infection. Studies conducted in endemic areas have shown that infection was detected in 25% of vaccinated dogs compared to 63% of unvaccinated dogs, with a preventable fraction of 60.3%. Other classic studies have described preventive efficacy of close to 78% under certain conditions, and a meta-analysis found a reduction in the probability of clinical signs with odds ratios between 0.15 and 0.23 for several signs.

The usual protocol consists of two initial doses, followed by annual revaccination, preferably before spring, when tick activity increases. The indication should be individualised based on the actual risk of exposure and the animal’s lifestyle.

To close the circle

Effective tick prevention is based on a combined strategy: knowledge of their biology, proper use of modern antiparasitics and, when the context warrants it, vaccination against certain diseases. This approach significantly reduces the incidence of infections, the severity of clinical symptoms and the long-term health impact 🐾.

References and recommended reading

Probst, J., Krücken, J., Schaper, R., et al. (2023) – Winter activity of questing ticks in Germany. – One Health – Field study demonstrating tick activity at low temperatures (≈5–7 °C), supporting the need for year-round prevention in temperate climates – https://www.sciencedirect.com/science/article/pii/S1877959X23001061

Oechslin, C. P., Heutschi, D., Lenz, N., et al. (2017) – Prevalence of tick-borne pathogens in questing Ixodes ricinus ticks collected in Switzerland. – Parasites & Vectors – Epidemiological study quantifying that 33.2% of ticks carry at least one pathogen and documenting multiple co-infections – https://pmc.ncbi.nlm.nih.gov/articles/PMC5680829/

Baneth, G., Samish, M., Alekseev, E., Aroch, I., Shkap, V. (2001) – Transmission of Hepatozoon canis to dogs by oral ingestion of ticks. – Journal of Parasitology – Experimental work demonstrating the transmission of Hepatozoon canis by ingestion of ticks and not exclusively by bite – https://journal-of-parasitology.kglmeridian.com/downloadpdf/view/journals/para/87/3/article-p606.xml

Chiummo, R., Farkas, R., Beugnet, F., et al. (2023) – Prevention of Babesia canis transmission by Dermacentor reticulatus ticks to dogs treated with fluralaner. – Parasites & Vectors – Study demonstrating the prevention of Babesia canis transmission for up to 84 days after antiparasitic treatment – https://pmc.ncbi.nlm.nih.gov/articles/PMC10373369/

Schetters, T. P. M., Kleuskens, J. A. G. M., Scholtes, N. C., Gorenflot, A. (1998) – Vaccination of dogs against Babesia canis infection. – Veterinary Parasitology – Study demonstrating that vaccination reduces clinical severity and anaemia without completely preventing infection – https://pubmed.ncbi.nlm.nih.gov/9477490/

European Medicines Agency (EMA) – Committee for Medicinal Products for Veterinary Use (2007) – Nobivac Piro: EPAR Scientific Discussion. – European Medicines Agency – Regulatory document detailing indications, mechanism of action, onset (≈3 weeks) and duration (≈6 months) of vaccine immunity against babesiosis – https://www.ema.europa.eu/en/documents/scientific-discussion/nobivac-piro-epar-scientific-discussion_en.pdf

Levy, S. A., Clark, K. K., Glickman, L. T. (2005) – Infection rates in dogs vaccinated and not vaccinated with an OspA Borrelia burgdorferi vaccine in a Lyme disease–endemic area of Connecticut. – International Journal of Applied Research in Veterinary Medicine – Field study showing a reduction in infection risk (25% vs 63%) and a preventable fraction of 60.3% in vaccinated dogs – https://jarvm.com/articles/Vol3Iss1/LEVYIJARVMVol3No1web.pdf

Levy, S. A. (1993) – Performance of a Borrelia burgdorferi bacterin in dogs. – Journal of the American Veterinary Medical Association (JAVMA) – Classic study describing a preventive efficacy of close to 78% against Lyme disease under experimental conditions – https://avmajournals.avma.org/view/journals/javma/202/11/javma.1993.202.11.1834.pdf

Vogt, N. A., Gerber, B., Goldstein, R. E., et al. (2018) – Efficacy of Borrelia burgdorferi vaccines in dogs: a systematic review and meta-analysis. – Journal of Veterinary Internal Medicine – Meta-analysis demonstrating a significant reduction in the likelihood of clinical signs (OR ~0.15–0.23) in vaccinated versus unvaccinated dogs – https://pmc.ncbi.nlm.nih.gov/articles/PMC6335541/