What action should be taken first when an animal presents with difficulty breathing?

When an animal presents with difficulty breathing, the immediate priority is to ensure that it receives supplemental oxygen. This action directly addresses the hypoxia (low oxygen levels) that might be present due to respiratory distress. Administering supplemental oxygen can stabilize the animal's condition by improving its oxygen saturation and alleviating the immediate threat to its life.

Time is critical in cases of respiratory distress, and providing oxygen can buy crucial moments while further diagnostics and treatments are being organized. Depending on the situation, oxygen can often be administered quickly and with relatively few complications, making it a vital first step in management.

While other options may have their place in the overall treatment protocol, they do not directly address the life-threatening nature of respiratory distress as effectively or immediately as providing oxygen does. For example, waiting for a doctor or taking radiographs does not offer any immediate relief to the animal's breathing difficulties, and starting IV fluids would be more appropriate if there were concerns about shock or dehydration rather than immediate respiratory issues.