Feeling feverish
An underlying fever (pyrexia) — a temperature greater than 38.5°C — is one of the most common reasons for a horse presenting with lethargy. Horses may also present with a history of reduced appetite and increased respiratory rate, and may shift their weight from one leg to another. Further diagnostic testing is often required to ascertain the cause. Or some people opt for symptomatic treatment in the form of anti-inflammatory drug therapy, and if no improvement is noted then opt for further tests.
Causes of fever include…
■ Viral infections: horses present with lethargy and the above clinical signs as well as diffuse swelling of their distal limbs. If the patient has a respiratory tract virus they may also present with a cough, nasal discharge and enlarged lymph nodes. Diagnosis can be made based on the history and physical examination findings, as well as blood tests. Swabs/ bloods may be taken to ascertain what virus is causing these clinical signs. Otherwise, treatment is symptomatic and predominantly based on antiinflammatory drug therapy.
■ Bacterial infections: horses present with lethargy. Physical examination and bloodwork findings will often indicate a bacterial infection. Further diagnostic tests including ultrasound and endoscopy may be required to determine the location of infection. Sampling and investigation of the infectious material will provide further diagnostic and treatment information. Treatment is based on broad-spectrum antimicrobials, antiinflammatories and intravenous fluid therapy should the patient be dehydrated or showing signs of blood poisoning.
■ Lymphangitis: horses present with a history of lethargy due to the accompanying fever and pain associated with the condition, alongside being unwilling to move and having swelling of the affected limb. Swelling is often very focal in the initial stages, but subsequently spreads to affect the entire limb. Treatment is based on anti-inflammatory and antimicrobial drug therapy alongside controlled exercise and limb massage.