Last week I wrote about poisonous plants. It was brought to my attention that I forgot a plant. I informed my people they were wrong. I’m a cat, I didn’t forget. I wanted to give Creeping Indigo its own special blog. That’s my story, and I’m sticking to it! So, without further ado, Creeping Indigo.

It’s a Creeper For Sure

This tiny, unassuming little spawn of Satan grows very close to the ground in areas of short grass. It gets a cute pink, sort of peachy-colored flower. Watch for this, since it’s the easiest way to spot it. When it doesn’t have flowers, you’re going to have to look very close to identify it. The super-scientific description is prostrate with alternate compound leaves, with alternate leaflets. What that means, is it grows really close to the ground, and its leaves are really a bunch of tiny leaves that come off opposite sides of the stalk, but not in the same place. I put a picture of it below so you can see the pretty flowers, and the leaves. 

There’s more fun in store from this demon. While most of the roots are close to the surface, the taproot can be two feet long, and it puts out an ungodly amount of seed pods. Both of these are capable of spawning more spawns of Satan. I promise I’m going to talk about the poisonous part, but that taproot and those seed pods are what will really have you swearing at this plant. They combine to make it nearly impossible to get rid of without a lot of effort. More on that later.

What Makes it Poisonous?

To be honest, that’s a great question. I have found that to be human code for “I have no idea.” However, I’m a cat. I know the answer. Creeping Indigo has two toxins: 3-nitropropionate (3-NPA) and indospicine. 3-NPA is a toxin aimed, ironically, at defending the plant against destruction by plant eaters. Seems to me if horses still eat the plant, it’s not a very good defense mechanism, but cats are carnivores so I’m probably not the best judge on that topic. For even more fun, 3-NPA is metabolized very quickly, making it nearly impossible to find. Indospicine is easier to find in blood tests, making it the choice for an attempt at a diagnosis if ingestion is suspected. 

What Do The Toxins Do?

3-NPA is a very, very not nice toxin. Like, Teannie-Cat-in-a-really-bad-mood bad toxin. Like me when it’s raining and cold out, and my humans won’t make it stop. Seriously, it’s bad. This toxin works by stopping mitochondria, the power plant of cells, from making energy. Nerve cells are often the hardest hit in this scenario, which works as a nice lead in for most common symptoms. 

Symptoms for Creeping Indigo can be tough! Early signs are often really subtle, and only noticeable to people who know their horses well. It starts with quieter than normal behavior, maybe some low head carriage. Nothing very specific or obvious. Over the next few days, these horses will lay down more and more, and may even lose the ability to stand. Sometimes they head-press into the corner of a stall, or fall asleep while standing. They may do the opposite, and develop what appear to be neurotic walking behaviors. It all depends on which nerve cells are most affected by the havoc 3-NPA is wreaking. 

Indospicine is the nicer of the two toxins, but nicer like cod liver oil is better than castor oil. Indospicine acts by inhibiting a potent natural anti-oxidant called nitric oxide synthase. It causes the mucous membranes to ulcerate, the eyes to run, and the cornea to lose its ability to remain clear. This toxin makes horses feel bad, but these symptoms can all be recovered from. 

But Can You Fix It, Doc?

The answer is No, and this is why: Creeping Indigo is such a bad, bad dude. In fact, it can be nearly impossible to identify it as the cause of all the symptoms we just talked about, because nothing it does can be identified on bloodwork or even necropsy (the fancy name for an animal autopsy). Tell me that isn’t crazy! Horses found with mild symptoms and Creeping Indigo available for them to graze on should be removed immediately. However, what they have for symptoms almost always remain. This stuff is for real scary.

How Much Is Too Much?

There isn’t a hard and fast answer for that. We do know that one bite isn’t going to make them sick. They probably need to eat upwards of ten pounds to start showing symptoms, which is similar to a flake of hay, but like all things, it’s going to be different for everyone. Abstinence is the only truly safe way to go. 

I Am Appropriately Scared. Now What?

Oh how I wish I had an easy answer for you, my humans, but I don’t. Start with a soil test to make sure you have happy grass soil. Creeping Indigo doesn’t like to grow in areas of tall-ish grass. Making your pastures happy and lush will let Mother Nature help you wage this war. Next, check areas of high traffic, edges of driveways, anywhere grass is naturally short to evaluate your level of Creeping Indigo problem. These plants can be sprayed with GrazonNext HL to kill the plants. BUT, and it’s a huge but, dead plants are still poisonous so you still need to remove them, and the seed pods are resistant to all manner of death as near as I can tell. This means you should plan on evaluating your Creeping Indigo status on a regular basis. For this plant, you never get to call it quits. 

Until next week,

~Tony

P.S. Wondering if you have Creeping Indigo? Still not sure after looking at my pictures, and using the heck out of The Google? Call your nearest County Extension Office. They are a wealth of information of all kinds of things, weeds and pasture care being two of them.