Marquis Paste

Ponazuril, the active ingredient in Marquis, crosses the blood/brain barrier to reach the central nervous system where it kills Sarcocystis neurona,^1,2 and stops parasite from inflicting further damage to the central nervous system. Concentrations achieved in the CSF at steady state were shown to kill 94% of merozoites in cell culture.2

• • Marquis (ponazuril) Paste (ponazuril) Paste is easy to administer and safe when used as directed.Dosage

5 mg/kg (2.27 mg/lb) body weight once daily for a period of 28 days

Each gram of paste contains 150 mg of ponazuril (15% w/w)

The life cycle of EPM requires both a definitive host and an intermediate host.

• • An intermediate host is one in which the parasite lives, but does not reproduce or shed an infective form of the parasite.
  • In the case of EPM, the intermediate host ingests the sporocyst – the sporocyst hatches in the gut of the intermediate host and releases sporozoites.
  • These sporozoites then invade the vasculature of the host and are carried to muscle tissue where they form muscle cysts, called Sarcocysts.
  • Intermediate hosts for EPM include the nine banded armadillo, the striped skunk, raccoons and domestic cats.  A study has shown that 59% of raccoons have tested positive to S. neurona.  Oppossums become infected by eating the road-killed carcass of naturally infected raccoons.⁴
  • The definitive host of EPM is the opossum. A definitive host is one in which the parasite reproduces in the intestine and releases an infective form of the organism (in the case of EPM, the infective form of the organism is the egg, called a sporocyst).¹

Risk Factors Associated with EPM

• • The competency of the immune system of the horse can certainly play a role in the disease – the immune system can be compromised during times of stress and the horse could begin to exhibit signs of the disease. Therefore younger horses with developing immune systems or older horses with compromised immune systems can be at risk.
  • Also horses who are in heavy training or whose immune systems are stressed from being shipped long distances for competitive events can be at risk.
  • Of course those horses who have a higher exposure to the sporocysts due to the presence of opossums are at risk.
  • Horses residing on premises where EPM was previously diagnosed have an increased risk for developing EPM.