Quantity
The toxic dose in horses isn't precisely established, but cases of fatal cardiac damage have occurred from horses browsing avocado leaves over just a few days. Even a few leaves can cause illness. There is no safe amount of any part of the avocado plant for horses.
Notes
This is primarily a concern in warmer climates where avocado trees grow — California, Florida, Australia, Mediterranean regions, Central and South America. Leaves and bark are the most common exposure when trees overhang paddock fences. The fruit itself is less likely to be encountered unless dropped by birds or wind. Avocado meal or oil used in some mixed feeds can also be a hidden source.
Negative Signs
* Colic — pawing, rolling, looking at flanks
* Edema — swelling of the head, neck, chest, and lower legs
* Difficulty breathing (fluid in the lungs)
* Irregular heartbeat
* Swollen, hard udder in mares (non-infectious mastitis)
* Lethargy and weakness
* Death from heart failure in severe cases
FAQ
Q: My horse lives in a region with avocado orchards. How worried should I be?
A: Very worried if there's any chance of access. Avocado leaves, bark, and fruit are all toxic to horses, and horses will browse on trees if they can reach them. Solid fencing between your horse and any avocado trees is non-negotiable. Check for fallen fruit and windblown leaves regularly.
Alternatives
If avocado trees are anywhere near your horse's paddock or turnout, fence them off completely — including fallen fruit and leaf litter. There is no safe way to let a horse near an avocado tree.
Risks & Disclaimer
If your horse ate any part of an avocado tree or fruit, call your vet immediately. Heart damage from persin can be irreversible. Horses pastured near avocado orchards are at chronic risk and should be relocated if possible.
