Generality
Lyme disease (or borreliosis) is a bacterial infection transmitted by tick bites.
In dogs, the pathogen responsible for the disease ( Borrelia burgdorferi ) causes very variable symptoms in the skin, joints, nervous system and internal organs (heart and, to a lesser extent, the kidneys and liver).
Causes and transmission methods
Pathogen
- Lyme disease is caused by a spirochete, called Borrelia burgdorferi . This bacterium is pathogenic for dogs and other animals, including humans.
- In Europe, the infection can also be transmitted by other species and genotypes of Borrelia, such as B. afzeli and B. garinii, whose pathogenicity to the dog is still a matter of discussion.
- The natural hosts of Borrelia are small wild rodents, which constitute the main reservoirs of the infection; the dog represents, like the man, an occasional guest.
Vector
In Italy, Lyme disease is mainly carried by Ixodes ricinus ticks, which find their natural habitat mainly in the woods and in rural environments.
These arthropods transmit the pathogen responsible for the disease ( Borrelia burgdorferi ) to the dog during the bite necessary to make their blood meal. Subsequently, the bacteria penetrated into the skin of the host are conveyed to the regional lymph nodes and disseminated throughout the body.
Distribution
Lyme disease in dogs has been described in some areas of the United States and Central Europe, but is also present in different regions of our country. In Italy, the habitat at greatest risk corresponds to that of the Ixodes ricinus mints, that is wood edges, glades and bushes with high humidity.
Symptoms
Borreliosis is a multi-systemic disease that occurs in dogs with great variability.
Usually, the first manifestation is a transient skin rash, which develops around the site of the infecting bite. Also reported in humans, this sign is unfortunately difficult to detect in dogs.
After a rather long incubation period (within two to five months), the following may appear:
- High fever (sometimes, intermittent);
- Muscle pains;
- Lameness (one or more limbs involved);
- Appetite decrease;
- Enlargement of peripheral lymph nodes;
- Lethargy :;
- Fatigue;
- General malaise.
Over time, the dog manifests joint pain and, often, bilateral swelling in the carpus, elbow, tarsus and knee can be observed. Characteristically, lameness resolves spontaneously after 3-4 days, then reappears every 2-4 weeks, at least 2-3 times.
In dogs, muscle problems and joint inflammation can become complicated in polyarthritis, a rather typical sign of Lyme disease.
If left untreated, borreliosis can also involve the liver and kidneys, as well as causing neurological and cardiac disorders, even with serious chronic sequelae.
It should be noted that dogs can be infected, but they do not always develop obvious signs or show completely unspecific symptoms, that is not indicative of a particular disease.
Diagnosis
The diagnosis of Lyme disease is based on the combination of medical history (evaluation of possible exposure of the dog to ticks in the months preceding the onset of symptoms), finding of typical manifestations and execution of serological tests (ELISA method and Western Immunoblot), from which it can emerge the animal's positivity with respect to the infection.
Anti- Borrelia burgdorferi antibodies appear 4-6 weeks after the infectious bite and can persist for years, both in spontaneously cured animals and in those treated with antibiotic therapy.
Haematologic or haematochemical changes indicative of Lyme disease in the dog are not reported, but the joint fluid and urine may show signs of inflammation. Following glomerular damage, proteinuria may occur.
Treatment
If identified and treated early, Lyme disease generally has a good prognosis.
During the acute phase, the treatment of borreliosis involves the administration of antibiotics (such as doxycycline, amoxicillin and azithromycin) for at least three weeks.
The veterinarian can also indicate specific treatments (eg non-steroidal anti-inflammatory drugs) to favor the complete disappearance of the symptoms.
Vaccination and other forms of prevention
- As regards the prevention of Lyme disease, it is possible to subject the dog to vaccination. However, it is necessary to remember that this form of protection is not absolute on European territory, by virtue of the presence of different species and genotypes of Borrelia, whose role is still to be defined.
- In any case, different preventive interventions are possible with respect to the carriers. First of all, dogs should be treated against ticks before the start of the season at risk (February-March) with topical products with repellent and other activities prescribed by the veterinarian. This approach should be repeated throughout the period at risk, approximately until September-November.
- After attending the rural and wooded areas, you must inspect your dog and possibly remove the ticks as soon as possible, taking care not to leave the buccal apparatus in the pet's skin. The areas of the body preferred by this parasite to make a blood meal are groin, armpits, head and chest.
