Prognosis

The veterinarians will base their assessment on the information gathered during the four stages of the diagnostic process. To establish a provisional prognosis, they may consider certain factors such as:

• Age: In a study comparing a group of survivors and deceased individuals who received similar treatments, it was calculated that horses under 5.25 years old had an 87.1% risk of dying [1].
• Standing:  This factor is described in several studies as a positive parameter for survival prognosis [3, 4].
• Signs of pain: If severe and uncontrollable, they can be a reason for ethical euthanasia.
• Affected muscle groups: Damage to the heart or respiratory muscles has a more significant impact on the prognosis than alterations to postural muscles.
• Lactate level: A British study on hospitalized cases indicates that the lactate level could contribute to assessing the prognosis [2].
• Total calcium level: Another study shows that the total calcium level significantly contributes to the prognosis [1].
• Case progression: It was calculated that when a horse is still alive on the third day after the appearance of the first signs, it has a 50% chance of survival.

However, some parameters do not factor into the prognosis establishment:

• CK level: This level is not correlated with the survival/death of the animal. In fact, a surviving horse presented one of the highest values of CK activity (7,000,000 IU/L) ever measured.
• Blood level of hypoglycin A or MCPA-carnitine [1].

The final prognosis can only be determined with the analysis of acylcarnitine profiles, which reflects the significance of energy disturbances. In particular, acetylcarnitine (C2), decadienoylcarnitine (C10:2), and stearoylcarnitine (C18) allow for the calculation of a fairly robust survival prognosis [1, 5]. Recently, a study highlighted that isovalerylcarnitine (C5 carnitine) is the most discriminating parameter for confirming a diagnosis of atypical myopathy and establishing a survival prognosis [5].Unfortunately, this form of analysis is not currently a standard practice in veterinary medicine, and the process of obtaining such an analysis can be time-consuming.