Ocular tuberculosis in a horse.

This research article presents the first documented case of a horse contracting systemic tuberculosis that affected its eyes. The horse’s health gradually declined leading to complete blindness before it was put down. The post-mortem examination revealed extensive damage caused by the tuberculosis bacteria.

Disease progression and euthanasia

• The article begins by outlining the condition of the horse. It reports the diminishing health of the animal which was marked by blindness in both eyes over time, and progressive deterioration of its physical condition. Given the debilitating state and the lack of improvement, the decision was made to euthanise the horse.
• This euthanasia and subsequent examination allowed for a deeper understanding of the invasive nature of the disease and the extent to which it had affected the horse’s body.

Pathological findings

• Upon examination, the researchers found pathological signs of tuberculosis throughout the horse’s body. These conditions were mainly found as granulomatous lesions, which are inflammatory growths that were formed as a response to the infection.
• These lesions were not confined to a single area but spread throughout various parts of the body including the myocardium (heart muscle), lungs, bronchial lymph nodes, kidneys, liver, pancreas, colon and the visceral serosal surfaces (membranes that line body cavities).
• The severity of the infection was most apparent in the myocardium, indicating that the disease had significantly affected the horse’s heart.
• Furthermore, the infection in the eyes came in the form of granulomatous uveitis, a kind of inflammation in the middle layer of the eye, and unilateral retinal detachment. This eye condition likely explained the horse’s progressive blindness.

Identification of the causative agent

• Upon studying the bacteria responsible for the infection, it was identified as Mycobacterium avium, a species of mycobacteria known to cause severe lung disease and other systemic infections in various hosts including humans.
• This identification of the causative agent is crucial in understanding how the horse might have contracted the disease and how such infections can be prevented and treated in the future.