Ticks are vectors of many serious diseases, and a single tick can carry several pathogens. Tick-borne diseases remain a growing threat to both animals and humans. They can cause severe and chronic clinical signs and, in some cases, may even be fatal.
Tick activity is increasingly observed in early spring, autumn and even winter, which is why protection against these ectoparasites should be maintained throughout the year. When temperatures fall below freezing, inactive ticks shelter in leaf litter to survive. Ixodes ricinus can survive for 24 hours at temperatures of approximately −20°C and for up to 30 days at −10°C. However, once the temperature rises to around +5°C, tick activity increases and they begin searching for hosts. Adult ticks become more active at temperatures above 5°C, while nymphs become active above 8°C.
The most common tick species in Poland is Ixodes ricinus (the castor bean tick). However, other species are also present, including Dermacentor reticulatus and Ixodes trianguliceps, which can also transmit diseases that pose a serious risk to animals.
The best-known and most commonly diagnosed tick-borne disease in dogs in Poland is babesiosis. Other important tick-borne diseases include granulocytic anaplasmosis, monocytic ehrlichiosis, tick-borne encephalitis and Lyme disease.
Cats, like dogs, are also exposed to ticks. In recent years, an increasing number of tick-borne diseases have also been reported in cats. In Poland, the most commonly reported tick-associated disease in cats is haemotropic mycoplasmosis. Other diseases that may occur include babesiosis, hepatozoonosis and cytauxzoonosis.
Tick-borne diseases in dogs
Granulocytic anaplasmosis
Granulocytic anaplasmosis is caused by the bacterium Anaplasma phagocytophilum, transmitted by Ixodes ricinus, a tick species commonly found in Poland.
Clinical signs vary considerably and usually develop within one to two weeks after a tick bite. Affected animals may develop fever, lethargy, sudden drowsiness, loss of appetite and lameness caused by inflammation of the joints.
Some dogs may also experience diarrhoea, vomiting, neurological signs, coughing, skin lesions, mild nosebleeds and petechiae on the mucous membranes. In acute cases, weight loss and enlargement of the lymph nodes, liver and spleen may also occur.
Canine babesiosis
Babesiosis is a serious and commonly diagnosed tick-borne disease in dogs. It is caused by protozoan parasites, most notably Babesia canis. Until relatively recently, this was the only species reported in Poland. In 2018, the presence of another species, Babesia gibsoni, was reported for the first time.
The parasite multiplies within red blood cells and damages them, resulting in anaemia. Clinical signs may include high fever (39.5–41°C), yellowing of the mucous membranes, lethargy, loss of appetite and dark brown urine. Vomiting and diarrhoea may also occur.
Acute kidney injury is a common complication of babesiosis. In recent years, cases of cerebral babesiosis have also been reported. The main underlying mechanisms are thought to include inflammation and impaired blood flow within cerebral vessels. Clinical signs may include paralysis, ataxia, aggression, vocalisation, seizures and unequal pupil dilation.
Lyme disease
Lyme disease is caused by spirochaetes belonging to the genus Borrelia. Although the disease is particularly well known in humans, it can also affect dogs.
Clinical signs may include high fever, lethargy, enlarged lymph nodes and pain during movement. The most commonly recognised clinical manifestation is joint involvement, accompanied by lameness and joint swelling. The lameness may shift from one limb to another over several days.
Some dogs may develop acute glomerulonephritis. However, many infections in dogs remain asymptomatic.
Monocytic ehrlichiosis
Monocytic ehrlichiosis is caused by Ehrlichia canis and is transmitted by the brown dog tick and Ixodes ricinus. Clinical signs may appear approximately one to four months after a tick bite.
Signs include fever, loss of appetite, weight loss and weakness. Lameness, blindness, nosebleeds, swelling of the hind limbs, pale mucous membranes, haematuria and mucopurulent inflammation of the eyes and nasal passages may also occur.
Haemorrhages and petechiae are characteristic findings. Neurological signs may include seizures, hyperaesthesia and ataxia, while ophthalmic abnormalities may include corneal opacity and haemorrhage into the anterior chamber of the eye.
When treatment is initiated promptly, there is a chance of complete recovery. Interestingly, German Shepherds appear to be particularly predisposed to severe disease.
Two to four weeks after the onset of acute signs, some dogs may recover spontaneously. Alternatively, the infection may progress to a subclinical phase lasting for months or, in some cases, even years.
Tick-borne encephalitis
Tick-borne encephalitis is being reported increasingly often in humans in Poland, but it is less widely recognised that the disease can also affect dogs.
It is caused by a virus belonging to the genus Flavivirus within the family Flaviviridae. In dogs, the clinical course is generally severe and is almost always fatal.
Typical signs include fever, severe lethargy, aggression, reluctance to eat or drink and impaired coordination. Ataxia, loss of sensation around the head, strabismus, hyperaesthesia of the neck and unequal pupil dilation may also occur.
Dogs that survive the infection may recover over a period of six to twelve months. During this time, physiotherapy plays an important role in managing neurological deficits and restoring normal function.
Hepatozoonosis
Hepatozoonosis is caused by the parasite Hepatozoon canis. The disease occurs mainly in Mediterranean countries, although its geographical range has expanded considerably in recent years. The first confirmed case of canine hepatozoonosis in Poland was reported in 2021.
Unlike most other tick-borne diseases, infection occurs when a dog ingests an infected tick, which can easily happen while grooming its coat.
Wild or hunting dogs may also become infected by eating prey or carrion carrying infected ticks or containing parasitic cysts within the tissues.
Clinical signs in infected dogs may include fever, a stiff gait, lethargy and muscle weakness. Mucopurulent discharge from the conjunctival sacs may also occur, and some animals develop muscle wasting.
Tick-borne diseases in cats
Granulocytic anaplasmosis
Granulocytic anaplasmosis is an infectious multisystemic disease caused by Anaplasma phagocytophilum. Rodents act as reservoir hosts. In outdoor cats, it is still unclear whether eating an infected rodent can contribute to transmission.
Infection is diagnosed considerably less often in cats than in dogs. Clinical signs are non-specific and usually begin with fever, lethargy and depression. Some cats may develop gingivitis, conjunctivitis and deterioration in coat quality. Polyarthritis is also a common clinical sign.
Cytauxzoonosis
Cytauxzoonosis has not yet been reported in Poland. However, due to climate change, it is possible that the disease may appear in the country in the future.
It is caused by the protozoan Cytauxzoon felis. Its life cycle consists of two phases: an intraerythrocytic phase and a tissue phase. The tissue phase is associated with an acute and potentially fatal course of disease.
Vectors include Dermacentor variabilis and Amblyomma americanum ticks. Transmission through blood transfusion is also possible.
Cytauxzoonosis is another multisystemic disease. Its classical form has a peracute course and mortality approaches 100%. Death may occur within five days of the first clinical signs, which can include fever of up to 41.5°C, lethargy, loss of appetite, brown urine, dyspnoea, jaundice and circulatory abnormalities. Shortly before death, body temperature may fall below the normal physiological range and the animal may become comatose.
Haemotropic mycoplasmosis (formerly haemobartonellosis)
The disease is caused by three microorganisms: Mycoplasma haemofelis, ‘Candidatus Mycoplasma haemominutum’ and ‘Candidatus Mycoplasma turicensis’. Mycoplasma haemofelis is considered the most pathogenic.
It is the most commonly reported tick-associated disease in cats. However, the exact routes of transmission within feline populations are not yet fully understood. Both ticks and fleas may act as sources of infection.
Interestingly, the highest number of cases has been reported in regions where Rhipicephalus sanguineus ticks occur.
The incubation period can be relatively long and may exceed 30 days. Latent infections can persist for up to six months.
Affected cats may show lethargy, dehydration, loss of appetite and weight loss. As anaemia progresses, weakness, pale mucous membranes and tachycardia may also develop. Neurological signs and syncope can occur, and some cats develop pica.
Some cats infected with haemotropic mycoplasmas may remain asymptomatic carriers throughout their lives.
Lyme disease and babesiosis
Clinical Lyme disease is extremely rare in cats. Antibodies against Borrelia burgdorferi are occasionally detected in feline serum, but cats are not considered natural hosts for this pathogen.
Reports of feline babesiosis in Europe are also uncommon. In cats, babesiosis often occurs alongside other infections. Africa is the continent where feline babesiosis is most prevalent, although cases have also been reported in Italy, Portugal, Spain, Germany and Poland.
The taxonomy of these protozoan parasites has not yet been fully established because of the presence of different morphological forms, which vary in size and are classified into two groups, as well as the lack of detailed information about their vectors.
The first clinical signs in infected cats include fever, reduced appetite, lethargy and increased respiratory rate. Diarrhoea and vomiting may also occur. As the disease progresses, the mucous membranes may become pale.
References:
- Adaszek Ł., Mazurek Ł., Dębiak P., Pisarek M., Rutkowska-Szulczyk M., Deneka Ł. (2024). Kleszcze jako wektory chorób zakaźnych i inwazyjnych u kotów. Weterynaria w Praktyce; 5.
- Bown K. J., Lambin X., Telford G. R., Ogden N. H., Telfer S., Woldehiwet Z., Birtles R. J. (2008). Relative importance of Ixodes ricinus and Ixodes trianguliceps as vectors for Anaplasma phagocytophilum and Babesia microti in field vole (Microtus agrestis) populations. Applied and Environmental Microbiology; 74(23).
- Adaszek Ł., Mazurek Ł., Dzięgiel B. (2019). Erlichioza monocytarna małych zwierząt. Weterynaria w Praktyce; 4.