Equine Health Update February 2017 Issue - Page 26

EQUINE | Equine Disease Update ciated with evidence of respiratory disease. Equine infectious anemia was recorded in Canada and the USA. Nine cases were diagnosed on three premises in Saskatchewan Province, Canada. Two cases were confirmed on each of two premises in New York and Oklahoma, USA. France recorded that equine piroplasmosis was endemic in the country. In the USA, Theileria equi infection was confirmed in Quarter horse racehorses engaged in non-sanctioned racing in Tennessee (seventeen cases) and Wyoming/Utah (21 cases). Germany reported nine cases of CEM on eight premises, the majority in stallions and horses of the Icelandic breed. The USA reported cases/outbreaks of salmonellosis during the third quarter. Two cases involved serogroup B Salmonella spp., 10 with serogroup C1 spp. and two with serogroup D1 spp. Outbreaks of clostridial enteritis due to Clostridium perfringens Type A, genotyped as β-2 toxin positive, were recorded by the USA, two in Kentucky and two in Minnesota. France and Germany confirmed limited outbreaks of rotavirus infection in foals. One case of infection with Lawsonia intracellularis was diagnosed in a foal in Kentucky, USA. Single cases of rabies were recorded in Oklahoma and Florida, USA. The USA reported 49 cases of Eastern equine encephalomyelitis during the period under review. The greatest numbers of cases were confirmed in Florida, Wisconsin, and South Carolina. The USA confirmed a total of 88 cases of West Nile encephalitis involving seventeen states. The vast majority were in non-vaccinated horses or those with incomplete vaccination histories. Rhodococcus related disease was considered endemic in the USA. Notwithstanding the fact that it is very difficult to estimate the prevalence of this infection, some 40 cases were confirmed during the third quarter. Japan confirmed eight cases of Getah virus infection on one premises, the majority having incomplete vaccination histories. Infected horses displayed typical clinical signs of the disease. The USA reported three cases of Equine Monocytic Ehrlichiosis in Maryland and West Virginia. Isolated cases of Ehrlichiosis were also confirmed in Germany and Switzerland. Observation, Science, and Equine Lameness Diagnosis A significant number of pain-related gait abnormalities in horses are evident only when the horse is ridden, and are not apparent when the horse is handwalked or lunged. Even when these horses are ridden, the lameness may not be overt. While there have been many recent technical advancements in the objective assessment of gait, these are generally of limited value for detection of bilaterally symmetrical alterations in gait that result in reduced performance such as generalized stiffness, lack of willingness to work, alteration in quality of movements such as lack of hindlimb engagement and impulsion, and alteration in the rider’s feel of the contact via the reins and bit to the horse’s mouth. A rider often assumes that these problems are attributable to thoracolumbar region pain, because the problems are only manifest when the horse is ridden. When observed on the lunge, such horses may lean into the circle—often more on one rein than the other—and show exaggerated contractions of the epaxial muscles. However, studies have shown that experimentally induced forelimb or hindlimb lameness may reduce range of motion of the thoracolumbosacral vertebral column. Radiographic examination may reveal impinging spinous processes, and this finding often results in an erroneous conclusion implicating thoracolumbar pain as the primary problem. We have demonstrated that by using diagnostic analgesia to abolish overt or subclinical lameness, the rider often appreciates an increased range of motion of the horse’s back. To investigate these clinical ob- 26 • Equine Health Update •