Ticks are carriers of a large number of diseases. Doctors know 15 diseases that transmit ticks, and 7 of them can cause pathology in humans. Among them are borreles (Lyme disease) and tick-borne encephalitis. Over the past 30 years in many countries, the number of cases of infection of dogs with tick-borne encephalitis has increased by 30 times. The tick distribution area and their physiology has changed. Now they become active in February-March. Some species can cause infection even in the winter.
Content
- Способ заражения и характеристика возбудителя 1. Method of infection and characterization of the pathogen
- Симптомы и признаки патологии 2. Symptoms and signs of pathology
- Методы диагностики патологического состояния 3. Methods for diagnosing a pathological condition
- Методы лечения патологии 4. Methods of treating pathology
- Профилактика сезонного заражения 5. Prevention of seasonal infection
Method of infection and characterization of the pathogen
Tick-borne encephalitis is a disease caused by the introduction of a virus that affects the tissues of the brain and spinal cord of an animal. It is caused by a flavirus (Flavivirus), a lipid-coated microorganism containing a helix of RNA whose dimensions are 40-50 nm. The carrier and main “vessel” supporting the life of the virus are ixodid mites. Infection of a dog occurs in a transmissible way - when a tick sucks. Tick-borne encephalitis virus is divided into three genotypes:
- Far Eastern;
- European (Western);
- Siberian.
Each type of virus causes characteristic symptoms and damage. With the secretion of the salivary glands, the virus enters the dog’s bloodstream. There he is captured by macrophages. In them, the first phase of the reproduction of the virus. A vacuole forms around the absorbed virus, within which the virus replicates the RNA and forms the virus coat proteins (capsid). 
Formed adult virions form groups surrounded by vacuoles and are transported to the inner surface of the cell membrane. Tearing it, they go into the extracellular space. With lymph flow, viruses enter the lymph nodes, invade the vascular endothelium, are transported to the liver and spleen - this is where its second reproduction occurs.
Lymphatic flow carries the virus to the motor neurons of the spinal cord, localized in the cervical region, and through them the pathogen enters the cerebellum and the soft sheath of the brain. The incubation period for adult dogs is 1-2 weeks. When puppies become infected, this period is shortened.
Symptoms and signs of pathology
Symptoms depend on the form of tick-borne encephalitis. The following forms of lesions are distinguished:
- febrile;
- meningoencephalomyelitis;
- meningeal;
- meningoencephalitic.
Symptoms do not appear immediately. The initial stage is hidden, then the following signs of the disease appear in dogs:
- increase in body temperature to febrile values;
- behavior change - apathy or aggressiveness;
- refusal of food;
- gait disturbance;
- loss of coordination;
- disturbance of accommodation of the eyes, the occurrence of strabismus;
- laryngeal spasm, change in barking timbre;
- cramps, muscle paresis;
- reduced sensitivity of the dog's face;
- tremor of the muscles of the body, especially in dogs of small breeds and puppies.
European tick-borne encephalitis virus causes severe fever, which has a two-phase course. The first phase can last from 2 to 4 days. At this time, the virus is introduced and spreads through the dog's body. The first phase of fever is accompanied by non-specific signs:
- febrile phenomena;
- complete refusal of food;
- muscle aches and cramps;
- vomiting.
Then comes a temporary remission, which lasts 7-8 days. In 25-32% of dogs, the second phase causes the symptoms of meningitis, encephalitis. The forecast for the introduction of the Far Eastern strain of the virus is unfavorable. Far Eastern virus causes brain damage in the form of meningitis, meningoencephalitis and focal lesions with a high probability of death.
It mainly causes paralysis of the front paws and respiratory muscles. This strain is the most dangerous, as it causes severe consequences. The appearance of a new species of the Far Eastern strain, which caused hemorrhagic tick-borne encephalitis, was recorded.
When meningoencephalic form of the disease is observed diffuse or focal damage to the nervous tissue. Diffuse form is accompanied by:
- epileptic seizures;
- respiratory failure;
- problems with swallowing, head muscle paresis;
- muscle weakness.
In case of focal encephalitis, the disease is manifested by convulsions, muscular dystrophy, and severe neurological disorders. Since the symptoms of encephalitis may resemble various pathologies of the nervous system, differential diagnosis is necessary to clarify the diagnosis.
Methods for diagnosing a pathological condition
In addition to collecting medical history and physical research, the veterinarian prescribes laboratory and instrumental studies:
- clinical blood and urine tests;
- biochemical blood tests and bakposev;
- examination of cerebrospinal fluid;
- serological examination of blood;
- radiography of the skull;
- MRI or CT scan.
The opportunity to conduct an in-depth study is not in every veterinary clinic. To simplify diagnosis, you can bring a live tick taken from a dog to a veterinary clinic. In the laboratory will conduct a study of the insect for the presence of pathogenic microorganisms, as the tick can contain not only tick-borne encephalitis virus. An insect test is carried out for the presence of a virus antigen, less commonly by PCR, fragments of the virus RNA are detected. The study can be carried out even on tick fragments.
Symptoms of the disease occur when the number of viruses has increased to a certain level, which complicates the treatment. Therefore, during the period of seasonal activity of ixodic ticks, it is necessary to apply measures to prevent infection and carefully examine the dog after each walk. If a tick stuck into the skin is detected, it should be carefully removed and immediately seek medical attention.
Pathology treatment methods
Since the disease is caused by a virus that develops inside cells, the treatment is difficult to choose adequate methods. Antiviral therapy is carried out with the help of antibiotics that can penetrate through the blood-brain barrier. Isoniazid, pefloxacin, co-trimoxazole, rifampicin are used. Chloramphenicol.
These drugs have a strong toxic effect on the dog's body, therefore, on the recommendation of a veterinarian, more benign medicines are prescribed, such as Tienam, Cefelim, Meronem, Pefloxacin, Ceftazidime. Symptomatic therapy includes:
- drugs that reduce the temperature and pain;
- corticosteroids, to reduce the severity of neurological disorders - Methylprednisalone;
- drugs to reduce intracranial pressure - Diakarb, Mannitol.
A sick dog is given vitamin preparations, as animals decrease the level of vitamins B and C. For the treatment of dogs with neurological symptoms, you can use Ribonuclease. Injection of the drug is carried out on the recommendation of a veterinarian. Injections of injections last 3-4 days. By this time, as a rule, body temperature decreases. 
For meningeal encephalitis and fever, it is necessary to apply a treatment aimed at detoxifying the body. Make the introduction of saline and buffer solutions, taking into account the state of water-salt balance and blood pH. When expressed neurological syndromes prescribe corticosteroids - Prednisone. At the same time, the dog is given potassium salts, and a special high protein diet is prescribed.
Tick-borne encephalitis can lead to bulbar disorders, which are expressed in disorders of the function of swallowing and breathing. To relieve symptoms, humidified oxygen is injected through the nasal catheter. To improve respiratory function, the drug Cytochrome is used. Also prescribed courses hyperbaric oxygenation. To eliminate the effects of hypoxia, sodium oxybutyrate and Seduxen are prescribed. In the complex treatment of tick-borne encephalitis, a special sparing diet should be observed, especially in dogs with dyspeptic disorders.
Prevention of seasonal contamination
To eliminate the possibility of infection, the dog must be protected before walking. To do this, use special acaricidal drops on withers, sprays. But it should be remembered that the effect of insecticides begins after a few hours, therefore, applying funds just before walking the dog will not protect it from tick attacks. As a barrier method, use special collars. They scare ticks. But after each walk it is recommended to conduct a thorough inspection of the animal. Examine areas with the thinnest skin - behind the ears, under the paws, on the belly.
When a tick stuck in the dog's skin is detected, it cannot be oiled, as the fat only “stuns” the insect. It is better to drop alcohol on the parasite, and then carefully “unscrew” it from the skin. The bite site is disinfected and immediately seek help, as the tick can be a carrier not only of tick-borne encephalitis, but there is no effective vaccine for dogs against diseases transported by ticks.