Healthy Pastures, Healthy Horses

08/09/2025

The new issue of our E2E info-letter is now ready! Thanks to our subscribers for their patience this week. :)

Info-letter subscriptions are how we're able to continue to donate a thousand plus hours a year to keeping your equines safe and your pastures healthy.

This week we explore: What precisely causes a toxic event? ~ An emerging threat: purple mint ~ Pasture species selection tool ~ The benefits of feral horse grazing on grassland diversity of flowering plants ~ The 24 behaviors of the ridden horse pain ethogram ~ Does limiting grazing time severely restrict intake? ~ Are donkeys and mules more or less susceptible to plant toxins? ~ More findings of the restricted intake grazing studies ~ The relationship of vitamins and minerals to the severity of plant toxicity ~ When do plant toxic events in feral/wild populations begin to rise? ~ Fall pasture tips ~ Options for weight estimation ~

Subscriptions are available monthly ($5.00, 4-5 issues) or yearly ($50.00, 52 issues). You can also order a sample issue for $1.00. The topics we include aren't covered in our FB posts, so you won't see the material repeated here. See the pinned post above for info on how to subscribe (Buy Me a Coffee, PayPal, Zelle, Venmo). We work hard and long to ensure that you get your money's worth. :)

The info-letters contain three pages of informative, original, easy-to read content for all equine stewards. An entire month of issues costs less than a stop at a coffee stand, so treat yourself or someone you care about, support the work we do, and keep your equines safe and your pastures healthy!

We'd like to thank our loyal subscribers for their support and also for their very kind words of appreciation. Those mean a lot and we're always gratified that folks are enjoying our efforts and knowledge!

08/09/2025

Welcome back to Mythinformation Monday!

This is the sixth in our series about myths and misinformation on equines and plant toxicity.

Myth #6: That's been in my horse's pasture for years and he's never gotten sick from it so it's not a danger.

There are some toxins that don't immediately cause clinical signs, but over time, ingested amounts add up. There is a toxic threshold before which there are no signs, but when that threshold is reached, toxicity occurs. Toxins that affect the liver also have a cumulative effect. Clinical signs may not be present until the liver is 75% compromised, after which there is no recovery.

There are also numerous plants that aren't significantly toxic until the right set of circumstances arises. That may be a drought, a freeze, heavy rains after drought, poor forage growth one year, or a weather event that causes plant damage. Our animals may eat them once or twice with no effect, but the next time they do, toxicity may occur.

It also has *everything* to do with pasture condition. We can't repeat or stress that enough. If forage is depleted and good grasses are hard to find, they *will* eat plants that aren't good for them. Yes, they've left it alone for years, but this year has had little rainfall and there's little forage left (and we've left the horses on the pasture well past the 3" minimum grass height). Equines do not like having empty bellies, and that hunger drive takes the place of what we would consider common sense.

We as equine stewards know that training methods that work well with one horse may not with another, and every diet is not right for every horse. Each is different mentally as well as physically. In the same way, all equines don't respond identically to toxins. Toxicity can be influenced by body condition, age, preexisting conditions, water intake, fitness level and past ingestion of toxins...even stress levels.

We've heard this time and time again: 'My horse eats that, and he's fine.' Awhile back we were involved in a case with Kleingrass (Panicum coloratum) toxicity and one comment from an equine steward was that her horse eats it regularly and isn't sick, so it can't be toxic. The recommendation was to advise her strongly to ask her vet for a liver panel, and to do it sooner rather than later.

It really isn't a bad idea to get a blood panel done every few years if financially feasible, even if there are no outward signs of toxicity. It's always easier (and far less expensive) to treat disorders early and make dietary changes rather than wait until the damage is severe.

Remember that animals are always ok...until they're not. Sometimes they - and we - get darn lucky, but the outcome may not be as good the next time around.

We can't assume simply because we don't see outward clinical signs that there are no toxic agents at work, nor can we assume that because they ate a plant previously and seemed fine that this will always be true. We also can't know exactly what they're eating unless we sit beside them every moment they're on pasture.

Let's remember too that picas exist, which are akin to addictions. Animals will seek out odd or unpalatable plants even when there are healthy grasses available, and sometimes those plants are toxic.

This doesn't mean that we should live in a constant state of anxiety, but it does mean that we need to remain vigilant and proactive, and act responsibly in protecting our equines. There's no benefit to denial or ignorance.

Remember: a hungry horse is a horse at risk.

07/09/2025

Just checking in with you guys. We had extended wifi and phone outages at the same (what are the chances?) so haven’t been able to post for a couple days. Couldn’t access the info-letter either so it’ll be a bit late too.

Hope you’re enjoying the weekend, hopefully with your fuzzbuckets!

(Benji and Jupiter, two of our faves 😍)

04/09/2025

~ Late-season grazing dangers ~

We're getting to the end of the grazing season in much of the US and similar latitudes. This is when grazing management gets a little challenging. Not only have many of the grasses stopped producing well, but some of the unwanted plants are still vigorous.

It's a good time to be vigilant, because some previously innocuous plants that equines passed over for grasses are green and still look attractive to a hungry horse.

We'll look at two here:

The first is creeping buttercup, Ranunculus repens. It is listed as a invasive or noxious w**d in some counties/states. Many Ranunculus spp. are toxic; the active compound is protoanemonin. It loses toxicity when dry and/or when dried in hay, fortunately.

It is not only a mouth and GI tract irritant, but it can cause colic, which can be deadly. It's possible for equines to develop a pica (craving) for it and seek it out. It may also cause loss of milk production, so should be considered if a mare's production drops. The bad news is that it's very difficult to eradicate.

The second is oxalis, shamrock, or wood sorrel (Oxalis spp.). It's on many states' invasive and noxious lists as well as Canada's. Oxalates are the toxic element in these, and they cause kidney damage, diarrhea and GI upset, colic, tremors, and sometimes death.

A fairly large quantity must be ingested over a relatively short period of time, so toxicity from oxalis isn't very common. Still, because it can be dangerous in quantity, and it does tend to be aggressively invasive, it's good to keep populations in pasture well under control. It's apparently not too unpalatable so horses may see it as fair game.

If equines have a nutritious, tasty, plentiful diet, it's uncommon for them to graze on toxic plants. However, in depleted pastures they'll eat many plants they wouldn't consider last spring. Boredom can also play a large factor, and some equines simply chase green. Any green.

It's always better to address small populations than to ignore them, so for control and eradication measures, our county w**d board, conservation district, or extension office can give guidance on control for our area.

Let's be vigilant and keep 'em safe!

03/09/2025

~ It's WeedsDay! ~

Let's look at our FrIDay toxic plant and ID quiz from last week. We didn't have a correct ID, surprisingly.

They are locow**ds (Astragalus and Oxytropis spp.) and they have a strong potential for toxicity in equines.

Locow**d is a general term that also includes the milkvetches. There are over twenty known toxic locow**d and closely related milkvetch species (though thankfully the majority of these species are not known to be toxic), and they vary from region to region. The Astragalus spp. are considered to be higher in toxicity than the Oxytropis spp.

They can cause toxic events in all grazing animals, though there is great variability, depending upon each animal's age/size/condition, the amount eaten, and the length of time it was consumed. The main toxic compound in locow**ds is swainsonine, an alkaloid, though a few also contain a neurotoxin. We see most toxicity from these plants in the Plains and Rocky Mountain states of the US.

The toxic threshold is often substantial, meaning that the quantity that must be ingested to induce toxicity is fairly large. An exact amount has not yet been established. In pastures with only a small population of locow**d, ingestion of enough to reach the threshold is unlikely.

However, in infested pastures with low populations of good grasses, given that equines are especially susceptible and may develop picas that induce them to seek out the plant, the chance of toxic events is much higher. Studies show that toxicity normally occurs after several days to weeks of grazing on the plants, though it may infrequently occur rapidly.

(As a FYI: it is an endophytic fungus that produces swainsonine in locow**ds, not the plant itself. Therefore, the amount of toxin depends upon the fungal level, growing conditions, growth stage, and species of locow**d. It appears that the most palatable stage occurs during and after flowering, before seed pods mature.)

Some symptoms of toxicity include tremors, reduced water intake, decreased appetite and weight loss, anxiety, odd mouth movements, rough/dull coat, unpredictable behavior, lack of coordination reluctance to move, spontaneous abortion, depression, cardiac events, and death.

Locoism tends to be permanent in equines with severe toxicity. Even in more mild cases, odd behaviors take months to abate. Animals that recover often exhibit a preference for locow**ds and will seek them out when returned to pasture.

There is also a concern about locow**ds causing selenium toxicity (chronic selenosis). Some species of Astragalus are accumulators (mostly milkvetches), but the amount of selenium in these plants would render them highly unpalatable, and thus very unlikely to be eaten. It takes selenium-rich soils for plants to bind toxic amounts of selenium; these are normally in areas of low rainfall. Plants will also accumulate more selenium during drought periods.

We cover clinical signs of Se toxicity in the 8/24 info-letter.

The first step after identifying locow**d or milkvetch as the source of toxicity is immediate removal of equines from the pasture or removal of suspected hay. Animals should be kept in a quiet and stress-free environment with good feed and clean water. Our vets will decide on treatment based on clinical signs, tests, and severity of toxicity.

Though hand-pulling is an option for removing just a few of these plants from pastures, control of locow**ds and vetches may be most successful with the use of herbicides. Specific recommendations may vary based on our location. Application is most effective from early bloom stage on, through fall. These are best used with the advice of our local w**d board, extension agent, or conservation district.

The seed bank is large for these plants, and the seeds remain viable for decades, so continued monitoring is a necessity, with the possible need for re-treatment. There are natural insect predators of locow**ds, so overuse of insecticides is not recommended in those areas.

Those species that have been most often associated with locoism include:

Astragalus emoryanus, emory milkvetch
A. lentigenosus, spotted loco, freckled milkvetch
A. mollissimus, woolly loco
A. missouriensis, Missouri milkvetch
A. nothoxys, sheep milkvetch
A. pubentissimus, Green River milkvetch
A. wootonii, Wooton loco
Oxytropis besseyi, Bessey's loco
O. campestris, field loco
O. lambertii, Lambert's loco
O. sericea, white loco

Our first step is to identify the species we have and whether it may be a problem plant. Identification of locow**ds and milkvetches can be difficult; we may have to enlist the help of someone who is knowledgeable in plant ID.

While it is necessary to remain vigilant about what is in our pastures, particularly with plants that induce picas, the foremost and best thing we can do to prevent toxic events is to ensure healthy populations of forage grasses through good pasture management practices and provide plentiful clean water.

02/09/2025

~ It's Toxo Tuesday! ~

We're hearing from folks that they've had some record-breaking heatwaves this summer, including recently. This kind of weather is a challenge for stewards and a danger for our equines. It's a good time for a post on the effects of heat and drought on a group of grasses.

During heat waves and droughts, equine stewards need to be aware of grasses that produce toxic Prussic acid when stressed. These species include Johnsongrass (Sorghum halepense), Sudangrass (Sorghum bicolor et al.) and some hybrids (Sorghum spp), among others. They're not ordinarily preferred forage, but in the depleted pastures of late summer they are more likely to be eaten.

Sorghum spp. are members of the cyanogenetic (cyanide producing) plant group. They produce glucosides which aid in breaking down the cyanide to prussic acid.

Grain sorghum has higher levels of prussic acid at all times, so equines should not ever be permitted to graze it. The other sorghum-type varieties are not always highly toxic, and have been consumed without known ill effect under certain conditions (though due to the danger of potential toxicity they are not recommended forage for equines). Under most conditions with limited consumption, these compounds don't usually cause toxic events, since they are eliminated as they are ingested.

However, during (and following) drought and heat conditions, this group of plants presents a much higher danger to grazing animals. This is even more likely in soils with high nitrogen levels or after treatments of fertilizers or pesticides.

Toxicity can also be created by mowing and trampling, which result in the same stress reaction in plant cells. We must note too that the new, sudden growth resulting from rains that follow dry spells will very possibly have high levels of these toxins. (Something to remember for later in the fall: frost and wilting also cause release of prussic acid in these species.)

Prussic acid works by causing hypersaturation of the blood with oxygen, which in turn deprives tissues of it. It's very unpleasant for affected animals, to say the least. If they have ingested forage containing significant levels of prussic acid, clinical signs can include changes in respiration, labored breathing, spasms/tremors, low blood pressure, colic, foaming at the mouth, diarrhea, inability to stand, convulsions, urinary incontinence, coma, and in severe cases, death. Blood and mucous membranes will be a bright cherry red. There are IV injections that are successful at treating prussic acid toxicity, but they must be administered quickly, before symptoms escalate in severity. If any of these signs are observed, an immediate vet call is in order and the vet should be advised that prussic acid toxicity is suspected.

As we can see, these are not grass species we want to encourage in any areas where equines may graze. They are vigorous and sturdy, and their presence can discourage the growth of good, healthy forage. As equine stewards we are cautious about grazing any pastures that are heat-stressed because of sugar levels, but that caution is even more appropriate when sorghum species are present.

01/09/2025

Welcome back to another installment of Mythinformation Mondays!

This is the fifth in our series on myths and misinformation about equines and plant toxicity.

Myth #5: Horses are big animals so they must have tough guts.

This is a dangerous mindset for our equines' sakes. While it's true that horses are big animals, that doesn't translate into hardy digestive systems.

As we mentioned a few weeks ago, the monogastric (equine) and the ruminant (other grazing animals) digestive systems vary greatly. The multi-chambered stomachs of ruminants allow for much better detoxification of plant materials, while the single stomachs of equines means that toxins are much more likely to enter the gut and from there, the bloodstream.

Equines actually have a much more delicate system than one would think by looking at them. They're highly sensitive to many toxins that don't affect ruminants much. They are also reactive to sudden changes in diet, sugars in forage, fiber content of forage, and molds. Anyone who has dealt with colic knows how quickly it can happen, and how insignificant the cause can seem.

Of course, we as equine stewards have created many of these problems. By feeding a monoculture of just one type of hay, we build guts that aren't able to tolerate a variety of feeds. There are reasons that the numbers of IR, EMS, Cushing's, and related disorders have risen and continue to rise. A diet that consists of varied grasses and forbs creates a much stronger gut than a diet of solely one type of grass. Animals that have steadily eaten just one forage species like timothy or orchard are more likely to feel the effects of even small amounts of toxic plants. As we mentioned, this is one reason wild horses don't experience toxic events like our domesticated ones do.

While in many ways our equines are hardy and tough animals, when it comes to their digestive systems, not so much. It's our job as their stewards to give them the best forage possible, including a variety of grasses and forbs, and the absence of toxic and injurious plants and w**ds.

31/08/2025

The new issue of our E2E info-letter is now ready for subscribers to enjoy. :)

Info-letter subscriptions are how we're able to continue to donate a thousand plus hours a year to keeping your equines safe and your pastures healthy.

This week we explore: Pastures without managed grazing ~ Plants containing toxic alkaloids ~ A primer for the use of herbicides in pastures ~ Ergot alkaloids in common pasture grasses ~ How small pasture elements can affect condition ~ Wetlands: a waste of pasture space? ~ Appropriate and safe moisture levels in stored hay ~ The two forms of selenium toxicity ~ Clinical signs of illnesses and disorders that mimic plant toxicity ~ A good resource for getting started on soils testing ~ The nutrient content of forage grazed by horses in September and October ~

Subscriptions are available monthly ($5.00, 4-5 issues) or yearly ($50.00, 52 issues). You can also order a sample issue for $1.00. The topics we include aren't covered in our FB posts, so you won't see the material repeated here. See the pinned post above for info on how to subscribe (Buy Me a Coffee, PayPal, Zelle, Venmo). We work hard and long to ensure that you get your money's worth. :)

The info-letters contain three pages of informative, original, easy-to read content for all equine stewards. An entire month of issues costs less than a stop at a coffee stand, so treat yourself or someone you care about, support the work we do, and keep your equines safe and your pastures healthy!

We'd like to thank our loyal subscribers for their support and also for their very kind words of appreciation. Those mean a lot and we're always gratified that folks are enjoying our efforts and knowledge!

31/08/2025

30/08/2025

A few for the barn wall :)

29/08/2025

Time once again for our FrIDay toxic plant and w**d ID quiz!

Today's ID is actually on a group of plants that fall into two different genera. They're very widespread and some species will be found in nearly every region.

The *first person to comment with the correct ID will get a free month's subscription to our weekly info-letter. If you're a current subscriber we'll extend your subscription a month.

*Note: If you've already won a free month we kindly ask that you hold off answering until Sunday if it's not identified by then. We'll still give you another month free but this gives the new folks a chance to ID new plants for at least two days (cuz some of you guys are legit ID wizards). :)

We'd like this to be about really getting to know the plants so prefer no apps but do your thing.

So have fun with it and we hope to meet some new stewards who we haven't met before. (Not that we don't adore our regulars as well. 😘)

28/08/2025

~ Facts about toxic w**ds, Part 2 ~

The emphasis on w**ds as the only dangerous plants to equines may result in a significant potential risk: a disregard for the presence of other seemingly harmless, highly toxic plants.

For instance, some ornamental or garden plants that appear to be inoffensive can be critically toxic to equines. These include onions, Japanese yew, oleander, lily of the valley, larkspur or delphinium, persimmon, avocado, indigo, Indian paintbrush, Easter lily, daffodil, tomato, potato, English ivy, and pincherry. Many problem plants in pastures are ornamental and produce escapees from landscaping and gardens.

Each community of plants has its toxic members. Most native plant communities contain a number of toxic plants. A few of these are big sagebrush, white prairie aster, hawthorns, elderberry, goldenrods, and mahogany. Common pasture and range forbs known to be toxic include buttercups, wild mustard, wild onion, horsetails and scouring rush, wild iris or blue flag, and wild blue flax.

There are a number of common pasture grasses that can be toxic to equines, though for the most part, grasses are generally the safest forage for equines. The list of possibly toxic ones includes Sudan grass, Bermuda grass, Sorghum, German millet, and tall fescue.

There is also a potential risk by ignoring possibly toxic trees and shrubs in pastures. Included in this list are Ponderosa pine, black walnut, red maple and some maple hybrids, chokecherry, and serviceberry.

Other common toxic pasture plants include some clovers such as alsike clover, yellow sweet clover, white sweet clover, and other clovers of the Trifolium spp.

While invasive and noxious w**ds can be highly problematic in pastures and rangelands, it is not appropriate to automatically label all of them as dangerous to equines. There are a number of ‘w**ds’ that are beneficial to livestock, including equines, for forage value. Cheatgrass and common dandelion, for example, supply necessary nutrition in early spring before many other forage plants have emerged. Some w**ds are actually higher in nutrition, sugars, and proteins than some forage grasses, providing often-needed sustenance in fall when grass populations are depleted.

If equine stewards work only toward eradicating pastures of ‘w**ds’ while ignoring other toxic plants, they may find that the plants they disregarded as benign are the very ones that should have been cause for concern.