What does larkspur do to cows?

Larkspur causes heavy cattle losses in western range states. Larkspur is highly palatable to cattle, and losses can be expected when cattle are allowed to graze larkspur-infested ranges, especially where the plant is abundant or grows in large, dense patches. Tall larkspurs increase in palatability as plants mature.

Are larkspur flowers poisonous to animals?

Larkspur. Larkspur is toxic to dogs, cats, and horses. If ingested, it can cause both neuromuscular and respiratory paralysis, and symptoms ranging from muscle weakness to muscle stiffness and tremors. In the worst case, it can cause cardiac failure and even death.