Vasculitis is a term that describes inflammation of blood vessel walls. A variety of different conditions can cause it. Still, it is usually precipitated by a reaction of the horse’s immune system against bacteria, viruses, rickettsial organisms (such as the one that causes Potomac horse fever), drugs and medicines, or unknown reasons.
How does Vasculitis spread?
Transmission occurs directly between horses incubating the disease, who have symptoms but are recovering and indirectly (fomites). This bacterium has an incubation period of 3 to 14 days.
How It Spreads Like Wild-Fire?
The garrotillo agent, also known as a strangulating agent, causes the disease by attaching itself to the nasal and oral mucosa’s epithelial cells, invading the nasopharyngeal mucosa, leading to acute pharyngitis and rhinitis. When the host organism cannot prevent the inflammatory process, the agent invades the mucosa and pharyngeal lymphatic tissue.
As the disease progresses, abscesses are formed, especially in the retropharyngeal and submandibular lymph nodes, causing local obstruction due to compression. They fistulate seven to 14 days later, being drained, releasing the pus full of bacteria, contaminating the environment.
Signs and Symptoms of Vasculitis
The clinical signs manifested by the animals are typical of a generalized infectious process; it also presents a serious nasal secretion, which then becomes mucopurulent and, within a few days it becomes purulent, productive cough, pain on palpation of the mandibular region, lymphadenopathy, especially of the submandibular lymph nodes, neck extension due to pain in the region of the larynx and pharynx.
Although older animals may not develop abscesses due to a previous infection by the bacterium S. equi subsp. equi . The lethality of this disease is low, but it can lead to death from complications such as:
Hemorrhagic purpura: it is characterized by an acute immuno-mediated vasculitis that occurs, most of the time, in convalescent animals of the garrotilho, due to the precipitation of immunocomplexes in the capillaries, which are formed by antibodies and fractions of the bacterium, resulting in severe edema in the limbs, head and other parts of the body.
Empyema of the guttural pouches may occur during the disease’s clinical course or the period of recovery of equine adenitis. The persistent infection of these bags can lead to aspiration of pus and, sometimes, even the formation of chondroid.
Diagnosis of Vasculitis
The diagnosis is made through the clinical picture, and its confirmation can be made through the isolation of the bacterium S. equi subsp. equi, through the investigation of purulent nasal secretion or abscess content, collected with the aid of a nasal swab and kept under refrigeration until the moment of analysis. The Polymerase Chain Reaction (PCR) technique can also be performed, detecting the live or dead agent. The ELISA technique can also be used to search for antibodies against the bacteria in question.
How to treat Vasculitis?
The treatment is based on the disease stage. Horses that do not have abscesses in the lymph nodes should be treated with penicillin G, at a dosage of 18,000-20,000 IU / kg, or trimethoprim in combination with sulfametaxol at a dose of 20 mg/kg, administered intramuscularly for 5-10 days. When the animal has abscesses, there is the application of revulsive substances to facilitate its maturation and be pronounced, such as iodine.
After that, a dressing should be applied on the spot. At-risk animals should be previously treated with penicillin during the period of exposure to the microorganism, in cases of complications, supportive treatment, such as fluid therapy, medications, expectorants, and antimicrobials in dosages higher than those normally recommended.
