What is the primary treatment for a downer cow that is ketotic with low calcium levels?

The primary treatment for a downer cow exhibiting signs of ketosis along with low calcium levels is calcium-dextrose intravenous (IV) fluids. In this situation, the cow is in a state of metabolic distress, as indicated by ketosis and hypocalcemia (low calcium levels).

Calcium is crucial for muscle function, and low levels can lead to a condition known as parturient paresis or milk fever, where the cow becomes weak and unable to rise. Administering calcium through IV fluids provides immediate correction of hypocalcemia, allowing muscle function to resume.

The addition of dextrose is particularly beneficial in cases of ketosis, as it provides an immediate energy source. Decreased glucose availability can exacerbate the cow's inability to mobilize fat stores effectively, leading to ketosis. Therefore, using a calcium-dextrose combination addresses both energy needs and calcium deficiency, facilitating recovery.

Other options might provide some benefit, such as oral electrolytes for rehydration or supplements for calcium; however, in acute cases of severe hypocalcemia in downer cows, these methods would not be as effective or timely as IV administration, which acts quickly to stabilize the cow's condition.