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Ticks: more harmful to animals and people than you think

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Ticks are not only annoying parasites that feed on your pet's blood, they also transmit dangerous diseases to both animals and humans. Let's take a look at their modus operandi.

When we're talking about blood-sucking vermin, it's almost impossible to decide which ones are the most disgusting. However, among mosquitoes, fleas, leeches and horseflies, there's no doubt that the tick occupies a very special place, as does its relative the spider; since, despite the generally held belief, it's not an insect, but a mite.

Ticks can transmit a wide variety of diseases, from bacterial and viral to protozoal and parasitic diseases. In other words, this mite is such a versatile disease incubator that, first and foremost, it fascinates biologists, secondly, it competes with mosquitoes and, third and most importantly, it drives pet owner's mad.

The life cycle of ticks in a nutshell

Ticks go through four stages of life: egg, larva, nymph and adult. Except as an egg, they need to feed on blood during all these stages. To make this easier, once they attach themselves to their victim, they secrete an anaesthetic with their saliva, so their bite is painless. By doing this, they can stay unnoticed for days and days while they feed. Once their appetite is sated, they detach from their victim and moult to the next stage. In the case of adults, both males and females reproduce after feeding; in many species, this occurs on the host. After mating, the ticks leave their victim and return to the environment. The males die soon after and the females die after laying their eggs.

This is where a little arithmetic helps us understand why tick infestations can be so severe: a single female can lay 1,500 to 5,000 eggs in her lifetime; in some species, this figure can be much higher.

Unlike other ectoparasites, such as fleas (which die within a few weeks or a few months if they're not able to feed) ticks can last up to a year and a half if they can't find a victim. That's why once a place is infested, it'll remain packed with these villains for a long time.

The way ticks transmit diseases is a bit repulsive. When feeding on its host, it regurgitates its intestinal contents and so injects the pathogens it has living inside it into the victim. Bacteria, viruses, protozoa and even nematode larvae pass into the victim's bloodstream. For a tick bite to transmit disease, it must remain attached for at least 20 hours. We explain some of the main tick-borne diseases in Spain below.

An adult common tick (Ixodes ricinus). Unlike fleas, these parasites cannot jump, so they wait in vegetation with their front legs extended and latch onto their victim's fur as they pass.

Tick-borne diseases that affect dogs

Both the nymphs and adults are responsible for the transmission of diseases, but there is increasing evidence that larvae may transmit diseases too.

The victims can be both animals and humans. It is important to be clear that your pet cannot infect you directly, as the vast majority of tick-borne diseases are transmitted solely via a tick bite. However, if your best friend contracts any of these conditions, it means there are nymphs or adults nearby that could infect you.


This severe condition is caused by protozoa of the genus Babesia, which invade the red blood cells. Upon noticing the presence of an intruder, the body activates an immune response that unfortunately causes the destruction of the red blood cells. This process is known as a haemolytic crisis ("destruction of the blood") and the typical signs and symptoms are weakness, anaemia, brown urine and pale mucous membranes. It is potentially fatal if not treated in time.

Quite a few tick species transmit this disease and, from a geographical point of view, it's very common in central Europe. In Spain, it's more common in the north.

Lyme disease

Also known as borreliosis, the causes of this animal disease transmissible to humans are bacteria of the genus Borrelia. In the case of dogs, this dangerous disease usually presents as intermittent lameness and the joints appear swollen. Other common symptoms are weakness, anorexia and loss of appetite. In some severe cases, it can lead to kidney failure or heart conditions, which can be fatal.

The species Ixodes ricinus(common tick) is the main one responsible for spreading it.

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A full I. ricinus female. Ticks are insatiable parasites and are not satisfied until they are almost bursting with blood. A full female tick can expand to 10 times its size.

Canine ehrlichiosis

Ehrlichia canis, a tiny intracellular bacteria, is responsible for this disease which mainly affects the white blood cells. Therefore, if your dog had this, they would show signs of weakness, fever, weight loss and bleeding, especially from the nose.

The vector for the bacteria is the brown dog tick (Rhipicephalus sanguineus), one of the most common in Spain. Unlike other species, this one can infest interior spaces. Inside our house, it develops faster and its life cycle can be completed in as little as two months.

Apart from the diseases described, ticks can also transmit others to our furry friends, such as hepatozoonosis, anaplasmosis and tularaemia. Tularaemia, emerging in Spain, is very dangerous for public health.

Tick-borne diseases that affect cats

In general, cats are less susceptible to tick attacks, but that doesn't mean they're not exposed to dangerous pathogens. In fact, although not very common, Lyme disease, ehrlichiosis and babesiosis can also affect cats (tularaemia is very rare). In contrast, feline haemotrophic mycoplasmosis is a serious condition specific to cats.

Feline haemotrophic mycoplasmosis

This unusual infection is potentially fatal. Although usually transmitted by fleas, it can also be tick-borne. The causative microorganism is a bacterium called Mycoplasma haemofelis, which adheres to the surface of red blood cells, causing an immune reaction that leads to their destruction, resulting in severe anaemia.

How can I protect my pet?

Having seen the serious threat ticks pose to the health of both animals and people, let's find out what you can do to defend your pets from them. Assuming that they have to adhere to their host for at least 20 hours to transmit diseases, when you're in an infested area, you need to perform daily inspections. That way, if you find one, you can detach it from your faithful friend before it can cause any further damage. To detach the tick, proceed very carefully and, whatever you do, try not to squash it, as this will only make it regurgitate and potentially release its load of pathogens.


Ticks lurk in areas of dense vegetation, scrub, woods and grasslands. If you go for a walk in these areas, don't forget to check your pet to make sure they've no ticks attached.

To find ticks, it helps to know that their favourite places are safe, comfortable spots. The most common places in cats and dogs are under the ears, in the armpits, on the paws (especially between the toes), on the neck (especially under the collar), between the hind legs and under the tail; some ticks even reach the eyelids and snout. That's why it's so important to check your pet whenever you walk through the woods or through dense vegetation. By the way, don't forget to inspect yourself too!

We're sure you already know, but one way to keep your faithful friend protected is by using repellents and flea and tick collars. Pipette treatments, like Dynacan, are very effective for repelling and getting rid of adult ticks and the larvae and nymphs. Remember: prevention is the key!