Disease Outbreaks; Horse Diseases/epidemiology; Horse Diseases/virology; Orthopoxvirus/isolation & purification; Orthopoxvirus/pathogenicity; Poxviridae Infections/veterinary; Skin Diseases, Viral/veterinary; Animals; Brazil/epidemiology; DNA, Viral/isolation & purification; Disease Models, Animal; Feces/virology; Horses; Lung Diseases, Interstitial/complications; Lung Diseases, Interstitial/pathology; Lung Diseases, Interstitial/virology; Poxviridae Infections/epidemiology; Poxviridae Infections/pathology; Poxviridae Infections/virology; Rabbits; Respiratory Distress Syndrome/mortality; Respiratory Distress Syndrome/pathology; Respiratory Distress Syndrome/virology; Rhinitis/complications; Rhinitis/pathology; Rhinitis/virology; Skin Diseases, Viral/epidemiology; Skin Diseases, Viral/pathology; Skin Diseases, Viral/virology; Survival Analysis; Viremia/mortality; Viremia/pathology; Viremia/virology