Piroplasmosis is a common tick-borne disease of horses. In some cases, the horse may remain asymptomatic, but in the most severe forms, piroplasmosis can cause the death of the horse within forty-eight hours.
What is piroplasmosis?
Piroplasmosis is transmitted by ticks that carry the 2 protozoa (single-celled microorganisms) responsible for the disease: Babesia caballi or Theileria equi. This parasitic disease of the horse is transmitted by a tick bite, through their saliva. It is only transmitted through the saliva of the ticks, so affected horses cannot infect each other. It can also affect other animals, as well as humans. Most often, horses are healthy carriers of the disease and may not develop symptoms for a long time. However, piroplasmosis can be triggered when the protozoa begin to multiply in the horse’s bloodstream and thus cause symptoms of fatigue.
Ticks are particularly prevalent in spring and autumn, in the undergrowth or at the edge of the forest, so you should be particularly vigilant and inspect your horse regularly if it lives in the meadow or goes for a walk in the forest.
What are the symptoms of piroplasmosis?
Piroplasmosis is sometimes difficult to diagnose because in its mildest form there are simply symptoms of fatigue in the horse, weight loss or loss of appetite, which can be symptoms of many other horse diseases.
In its most acute forms, piroplasmosis can affect the foal in particular (this is called neonatal piroplasmosis), which will present anemia, fever and a yellow coloring of the mucous membranes (which will also be dotted with small red spots). In the case of adult horses, the symptoms of piroplasmosis are numerous: a fever of more than 40° (causing the horse to sweat heavily), a sharp drop in energy, anorexia (due to a loss of appetite), yellow discoloration or congestion of the mucous membranes, edema (on the limbs or above the eyes), the presence of blood in the urine, an increase in the heart rate and/or respiratory rate, dehydration, or even a recumbent position of the horse (which is too weak to stand up).
What treatment?
In order to diagnose piroplasmosis, a blood smear will be observed under a microscope in the clinic to show the piroplasms in the red blood cells. The treatment most often used is imidocarb. In the case of infection by the protozoan Babesia caballi, your veterinarian will give 2 injections of imidocarb 24 hours apart. In case of infection by Theileria equi, the treatment will consist of 4 injections at 72 hours interval, because this form is more resistant. However, the eradication of piroplasmosis is not guaranteed at the end of the treatment, even if the clinical signs may disappear. It is therefore necessary to be attentive to potential relapses. Also beware of the side effects of imidocarb, which can cause colic. As the treatment is quite heavy for the horse, it is important not to hesitate to supplement it with vitamins, minerals and amino acids in order to stimulate the production of red blood cells.
In severe cases, the horse may be placed on a drip to rehydrate it or be transfused if the anemia is too severe. Following treatment, the horse should be rested for at least one month.
