Final answer:
Iron supplementation can cause toxic liver injury in neonatal foals if over-administered at birth. This underscores the importance of careful supplementation under veterinary guidance, as the foal's livers are particularly sensitive during the neonatal period.
Step-by-step explanation:
The supplement that can cause toxic liver injury in neonatal foals if given at birth is Iron (A). It is essential to be cautious when administering supplements to neonatal foals since their liver and metabolic systems are still developing. Excessive iron can accumulate quickly and lead to toxicity, potentially causing severe liver damage or even death.
While elements such as calcium (B), magnesium (C), and zinc (D) are also important for the health of foals, they typically do not cause liver toxicity when administered in appropriate amounts. Supervision by a veterinarian is crucial to ensure the correct dosage and to avoid any harmful effects. It is also important to note that liver damage can occur due to various factors, including consumption of dietary supplements, and is not confined to neonatal foals. In humans, dietary supplements, particularly bodybuilding supplements, have been linked to cases of liver damage, some of which have required liver transplants or have been fatal.