From state necropsy reports, proving (again) that abuse, suffering, and death are inherent to horseracing.
Arizona
“Proximal sesamoid fractures may carry an occurrence rate as high as 41.5% in racing Thoroughbreds. Approximately 80% of all forelimb proximal sesamoid fractures are biaxial (both the lateral and medial sesamoid bones are fractured). Racing puts excessive force on suspensory ligament attachments to the proximal aspect of these bones, and creates the condition of fetlock joint hyperextension, predisposing this location to injury.”
“The sesamoid bones are commonly fractured in racehorses, as this joint can hyperextend and the sesamoids hit the ground with a high impact force.”
“Fractures of the proximal sesamoid bones are common in racehorses from high intensity exercise and continuous activity during their careers. It is thought that continuous high intensity exercise causes microfractures in the bones that then predispose them to severe career-ending fractures.”
“Carpal bone injuries are relatively common findings in racehorses [and] are thought to be a consequence of repetitive impact trauma associated with fast exercise and training.”
“Thoroughbreds racing at high speeds typically causes catastrophic biaxial fractures.”
“Humeral fractures occur in racing animals as catastrophic failure or accumulation of stress and microfractures.”
“Exercise-induced pulmonary hemorrhage is a common finding in racehorses.”
“Chronic ulcers [are] a common finding in racehorses, mostly attributed to stress, high grain diet, and higher use of nonsteroidal anti-inflammatory drugs.”
“Racehorses are predisposed to squamous ulcerative gastritis due to their high intensity exercise, high-grain diets, and [greater than] 6 hours between meals. The high-grain diets and [greater than] 6 hours between meals causes excessive acid production and their high intensity exercise causes splashing of the acid contents onto the squamous epithelium.”
“The front fetlock joints are the most reported sites of traumatic and degenerative lesions in equine athletes, with a reported 1/3 of 2- and 3-year-old Thoroughbred horses having metacarpophalangeal cartilage lesions and osteoarthritis. Lesions in this location are at least in part due to increased weight bearing on the front limbs and the extreme flexion and stress put on the fetlock joint during racing.”
“It is hypothesized that blood pressure can increase significantly in pulmonary capillaries during exercise in horses, leading to rupture and hemorrhage. When severe, this hemorrhage can fill the lungs with blood, lead to epistaxis, resulting in death.”
“A predisposing factor for developing pleuropneumonia includes transportation over long distances, which can lead to stress-related immunosuppression, and if horse’s head is fixed in an elevated position for prolonged periods, it can inhibit clearance of the lower airways, which allows for lower airway contamination…and subsequent infections.”
“Risk factors for development of bacterial pneumonia include transportation, stressful events, and viral infections. In this case, there was history of recent transportation which likely predisposed this horse to the infection.”
California
“Mild-to-moderate injuries of the suspensory apparatus have been positively associated with mechanical fatigue associated with repetitive activities (overextension), and consequently increased risk for catastrophic injuries.”
“Young horses (2-year-olds)…are at higher risk for tibial fractures due to the potential insufficient adaption of their skeletons to the expected performance.”
“Humeral fracture frequently occurs in racing breeds due to accumulated microdamage or stress…. Repetitive high-magnitude loads during training/racing near the upper limit of physiologic loads cause microdamage or stress accumulation due to osteocyte death. This microdamage stimulates rapid bone remodeling that leads to damaged tissue removal. This reabsorption is followed by slower new tissue formation or deposition. As a result, when the tissue damage overwhelms the repair response, focal osteopenia occurs, causing weakening of the bone increasing the risk of fracture….”
“Catastrophic fractures of the MC3…occur most commonly in young animals and due to external trauma, e.g. kicks or falls, but is also associated with repetitive bone microdamage and its repair, resulting in dorsal metacarpal disease with loss of bone density and predisposing to complete fracture.”
“Up to 90% of racehorses [have] gastric ulcers; factors that increase the likelihood of ulcers: stall confinement, stress, NSAIDs.”
“Palmar Osteochondral Disease in Thoroughbred racehorses is a very prevalent disease – 67-80% – and also occurs in response to the biomechanics of high-speed exercise, cyclic load, and over-extension of the fetlock joint during training and racing.”
“Streptococcus zooepidemicus is the most common bacteria isolated from cases of pneumonia in racehorses. Some predisposing factors such as restraint during transportation, specifically when the animals are unable to lower their heads, impedes the correct clearance of oronasal secretions leading to bacterial colonization. Other environmental factors for bacterial pneumonia include high dust load and poor ventilation.”
Florida
“A condylar fracture is a disease of speed. A fracture to the left lateral forelimb is most common in racehorses as they turn the track on a weakened bone and increased loading on the lateral condyle.”
Maryland
“Pre-existing stress fractures and stress remodeling are the most common contributing factors to catastrophic failure. The fracture is a compilation of physical activity where muscles, body weight, and ground forces place excessive strain on muscles, tendons, bone, ligament, meniscus, synovial membrane, joint capsule, and cartilage.”
“Microdamage occurs because of repetitive, high-magnitude loads during training and racing.”
New Jersey
“Laminitis and coronitis are common, painful conditions of [racehorses], resulting in the separation of the epidermal laminae from the underlying basement membrane of the dermal laminae of the hoof.”
“Acute periosteal callus formation is one of the primary indicators that a horse has been subjected to repetitive mechanical overload, making it a hallmark of a pre-existing stress fracture.”
“Gastric ulceration is reported in up to 90% of racehorses and is strongly associated with the physiologic and management stresses of intense athletic training, high concentrate diets, NSAID administration, stall confinement, and intermittent feeding.”
Oklahoma
“Factors such as transport may predispose horses to respiratory disease.”
“Gastric ulcers are a common finding in athletic animals and are often related to chronic stress and diets high in concentrate.”
Pennsylvania
“Score lines and bruising in front fetlocks are suggestive of repetitive osseous stress syndrome, a common finding in fetlocks of racing Thoroughbreds.”
Washington
“Chronic gastric ulcers are common in performance horses, often associated with low-forage, high-grain diets; stress; intense exercise; NSAID usage; and/or prior gastric myiasis.”