I received terrible news from a friend in California today. It seems, his beloved Rowan, a beautiful young Gypsy Vanner, lost his life over the weekend.

Rowan was boarded in Santa Barbara, California, at a lovely private home with horse facilities.

The owner of the property put two of her own horses, along with Rowan, in a pasture with avocado trees. Evidently, she has done this before, without the horses coming to harm.

All three of the horses ingested avocados or the leaves or bark from the trees. Avocado trees contain a substance called Persin, which is a cardiac toxin. Every part of the tree contains this toxin, which is potentially deadly to livestock.

In this particular instance, the first thought, as it usually is, was colic. The horses were transported to the renowned Alamo Pintado Equine Hospital where they received the best of care.

Sadly, Rowan didn't respond to treatment and passed away Saturday night. One of the property owners horses succumbed to the poison Sunday morning and at last word, the third horse is unlikely to survive.

My friend is heartbroken. The property owner is heartbroken. It's hard to imagine the grief they must be dealing with today as they try to comprehend the sudden loss of their beloved horses.

Looking at pictures of the beautiful young Rowan this morning brought me to tears. All I can think of to do on his behalf is post a warning to others.

I requested permission from my friend first. The photo accompanying this essay is Rowan in happier times.

When you look up avocado poisoning in horses on the internet, there are warnings about the toxicity, but little about the potential for death.

In addition to horses; cattle, goats, sheep, cats, dogs, rats, rabbits, mice and even birds (particularly caged birds) are all susceptible to avocado poisoning.

Avocados are grown all over the world. Here in the states, they are a common crop in California, Texas, New Mexico, Arizona, Hawaii and Florida.

Persin is a cardiac toxin, meaning it affects the heart. The poison is present in the leaves, bark, skin and pit. Symptoms include gastrointestinal irritation, vomiting in non-livestock species, fluid accumulation around the heart, respiratory distress, and swelling, respiratory distress and death.

In horses, when symptoms first begin, it would be easy to mistake the condition for colic. If you suspect that your pet was exposed to avocado poisoning, get them to a vet immediately.

I used to live on a ranch in California. We were surrounded by avocado orchards and while I knew they weren't good for the horses, I had no idea how dangerous they could be. While riding on the trails surrounding our house, no one thought much of the horses idly grabbing leaves from the trees as they walked by.

Now we know better. If you live in an area where avocados are grown, please make sure, first and foremost, that you can identify those trees when you see them. They are dangerous without the tell tale presence of the fruit.

Do not let any of your animals graze near or eat any part of the avocado tree or plant.

If you suspect your animal has been exposed to avocado, call a vet immediately.

Be vigilant. Don't let the tragic deaths of these beloved horses pass without learning the lesson they can teach. And say a prayer for my friend, Kevin and his horse Rowan. He is dealing with a terrible loss and the collective thoughts of others who understand the love of a horse may bring him some comfort.