Poisoning in Horses: Common Toxic Substances
by: Equine Disease Quarterly
October 01 2008, Article # 12815
Poisoning in horses is not a common occurrence, but when poisoning occurs, effects can be disastrous and far-reaching. Listing all toxic substances is impossible, as virtually everything on the planet can be toxic at sufficiently high dosages. What dose is safe and what dose is toxic varies with each toxin, each animal, and each situation. Factors that influence risk from a toxic substance include animal age, concurrent diseases, exposure to concurrent toxins or drugs, reproductive status, and route of exposure. This article will briefly summarize some of the more common toxic substances that can pose risks to horses in North America.
Herbal Supplements: The use of herbal supplements for horses has become common in recent years. Many people believe that if something is "natural," it must be safe and non-toxic. However, some of the most toxic substances on earth are completely natural (such as botulinum toxin, taxine in yew plants, and nicotine). Many herbal and natural supplements are inherently toxic, and many herbal products contain impurities and unknown amounts of "natural" ingredients. Herbal supplements are not well regulated, and studies investigating risks associated with use of these products in horses are lacking.
Plants, Feeds, and Feed Additives: Pastures can contain toxic plants and grasses that can pose risks at certain times during the year or under certain circumstances. Too many toxic plants exist to list here, and importance varies greatly with geographic location. However, all weeds should be viewed with suspicion and identified if possible. Additionally, grains can be contaminated with seeds from poisonous plants. Many shrubs, trees, and ornamental plants can be toxic to horses.
Hay and feed pellets can pose a toxic risk when unintended substances are incorporated into the feed. These substances include toxic weeds, toxic insects such as blister beetles, and dead animals that can serve as the origin of botulinum toxin production. Rotting, decomposing feeds or improperly stored haylage can also contain botulinum toxin. Pelleted or supplemental feeds can contain contaminants such as ionophores (such as momensin) or antibiotics due to mixing errors or contamination from transport vehicles. By-products from grain distillation can be present in supplemental feeds and can contain mycotoxins and antibiotic residues.
Mycotoxins: Grains can contain fungal toxins. Grain screenings or broken grain pieces carry a higher risk of containing significant concentrations of aflatoxins and fumonisins, both important mycotoxins. Some grass forages can contain mycotoxins such as slaframine and lolitrems. Endophyte-infected tall fescue grass can contain egovaline and other mycotoxins that can cause reproductive problems in horses.
Metals and Minerals: Mineral and salt supplements potentially can contain incorrect concentrations of minerals due to mixing errors or accidental mislabeling. Direct exposure to toxic metals such as arsenic and lead can occur through contaminated soils; dump sites; ashes of burned, treated lumber; some pesticides; and paint from older buildings or bridges.
Pesticides: Pesticides include products designed to kill rodents, fungi, insects, snails and slugs, weeds, birds, and coyotes or other predators. Many horse owners have rodenticide products in their barns, not realizing that anything that will kill a rodent will also kill a horse if the dosage is high enough. Many pesticides contain flavorings or grain bases that are very attractive to horses. Risks from insecticides, fungicides, and herbicides are generally highest with concentrated products or treated seeds.
Industrial Toxins: Contamination of pasture, water, and air can occur from industrial chemicals and petroleum products that are emitted upwind or upstream. Industrial toxins are not a common cause of poisoning in horses, but veterinarians and owners should be aware of nearby industrial and mining activities.
Venomous Animals: Bites from venomous snakes--most importantly rattlesnakes, copperheads, and water moccasins--are common occurrences in horses in the southern and western parts of North America. Bees, wasps, black widow spiders, fire ants, and brown recluse spiders can also pose risks to horses.
Horse owners, farm managers, and veterinarians should be aware of the myriad of potentially toxic substances that can pose risks to horses and take steps to minimize the chance that poisoning will occur.
Contact: Dr. Cynthia Gaskill, 859/253-0571 ext. 148; Livestock Disease Diagnostic Center; University of Kentucky, Lexington, Ky.
Are you saying all of those mares died??? How terribly sad! Any idea what may have caused this?
_________________ Marleen
Posted: Wed Oct 08, 2008 8:44 pm
caliber
Site Admin
Joined: 15 Jul 2007
Posts: 2857
Location: Paso World
Marleen, and many others are still sick.
They are claiming bad hay from their Private supplier, but the "Feed Store" company is saying otherwise.
I rather wait till I hear more from the local authorities, to assure all horses in the Ocala area are HAY SAFE......... Ocala is the Horse Capital of the USA! (no sure on that statement, but that is what they say).
Wow, I sure hope someone gets to the bottom of this quickly. I'm very sad for the horses that are suffering because of this. Feel bad for the owners too, I can't imagine having to go through something like that!
Best of luck to all involved.
Please keep us posted!
_________________ Marleen
Posted: Fri Oct 10, 2008 8:55 am
BigJ
Joined: 28 Jan 2008
Posts: 1040
Equitransfer made the NPR radio news this morning. The report said over 100 horses dead; reason unknown. It said bad hay is suspected. Several neocropsies have been performed with no definitive result. Toxicology samples have been taken and waiting on results.
The report didn't identify the hay source or confirm the hay was the cause of death.
In the case of botulism, the bacteria Clostridium botulinum produces spores which sticks to the hay when it is cut and baled. The spores become bacteria, which produce a deadly toxin.
The bacteria thrive in environments absent of oxygen.
In some cases, grass that is cut and wrapped and allowed to ferment, which is conducive to the deadly bacteria's growth if not handled correctly, Clark said.
The processed hay is called haylage and is typically given to cattle because cattle are less susceptible to botulism, Clark said.
Horses are highly susceptible to the disease and many veterinarians, including Clark, due not recommend haylage be given to horses.
Davila said the hay he gave his sick horses was haylage, but that it was inoculated to make it safe for horses.
You don't feed haylage to horses. I wonder who innoculated it? Davila was playing with fire and knew it. Animal nutrition is a prerequisite for vet students.
_________________ Be the change you want to see in the world. Gandhi
You’ll find that even though this is highly precautionary against, it also extols the benefits in some remarks.
What I gather out of the whole search, is that it is my opinion, that I'm just not sure that a normal form of botulism could be responsible. Maybe it is, but it's hard for me to believe that every bale would be contaminated in the amounts it would take to kill this many. I just don't believe that these people opened foul smelling bales of hay and knowingly fed it to horses.
And he wasn't cutting costs either, as haylage is more expensive.
There are numerous remarks above that suggest haylage as counteractive to dust and some suggestions that it might be better for horses that have problems with IR etc.
I live in an area where the majority of people who have horses wouldn't hesitate to feed even black moldy hay to horses, they buy their horses at a sale where they swap owners for less than 300 each, they'll feed spoiled grain if they can get it cheaper. I'm sure plenty colic all the time. I wish they'd lose horses at this same rate, but they don't. It's just hard for me to believe that this situation comes from a negligent activity, since I'm familiar with true negligence.
As far as vet's being the persons I would go to for nutrition advise, well, I learned a long time ago how little most local vet's know about nutrition studies. This couple specialised in something completely different and knowing how truly hard it is to become a vet and the information you must retain to practice etc., it's really hard for me to be critical.
Honestly, I'm shocked that people have acted so quickly to virtually stone people whom I know do not neglect horses, didn't shortcut veterinary training, and overall, didn't knowingly cut corners, and really, likely are people who are probably still suffering through absolute shock.
Well, I'll throw no virtual stone, and anyone reading my comments here if they have any way to report to the Davila's that I am very sorry for this tragedy and I send instead a supportive embrace.
Posted: Fri Oct 10, 2008 1:49 pm
caliber
Site Admin
Joined: 15 Jul 2007
Posts: 2857
Location: Paso World
Thanks for sharing Britz, very interesting reports..
Yes, it is very, very sad. It's a hard lesson learned.
No Britz, I do not confer with my vet to feed my horses. However, I do know that animal nutrition is part of veterinary course work. I also know that any one who owns horses, is responsible, studies horse nutrition.
To be safe for horses it takes such a specific set of conditions and even then you aren't sure. Europe feeds sheep brains to cows, so don't get me started while we feed chicken manure to cows. Speaking of which, I see the haylage is tested to the nth degree to be sure it CAN be fed to horses.
The USA is not a haylage producer for horses, I'm guessing or the haylage farmer/seller would have an analysis saying it was safe for horses.
Now a whole bunch are freaking out not knowing what the difference is between rolled hay and haylage or how to examine grass that is hay not haylage. Botulism occurs naturally in the ground and surroundings.
_________________ Be the change you want to see in the world. Gandhi
I'm just saying, there's a wildfire of stuff over this, and I'm sure no matter what, some people might be a bit more careful examining their hay.
I just can't stay quiet when good people are being cyber-tarred, feathered and crucified, when I am sure, really sure, that there wasn't criminal intent or conscious negligence.
I agree, studying nutrition should be a high priority, but like for instance, think of how many people overload senior horses on alfalfa because they think it's better for them, when it can actually tax the kidneys? I'm not out there telling the world those people are horrible.
Of course you know, as always, I'm not just talking about here, it didn't turn into the Salem WItch Trials here, but elsewhere. I just wanted to be sure that I came out strong in protesting bad neighbor behavior.
Posted: Sat Oct 11, 2008 9:01 am
BigJ
Joined: 28 Jan 2008
Posts: 1040
I understand...here's the thing
If the people you described who bought sale auction horses and were feeding haylage for cows, what would you think and say about that?
How many feed haylage to horses in Ocala, in Florida, in the USA? Why do most horse owners chose not to feed haylage? Why was it during the drought last year we were all wanting hay and not haylage to feed our horses?
If I said I knew a dairy farmer who had 20-25% of his herd die on him in a week would you think something exotic or suggest there is a common thread such as water or food? That is the first thing that comes to any livestock owner--check the food source.
If I said a vet had fed haylage to horse what would be the first thought in your head? Without saying a word wouldn't you think twice about doing business with a horse vet who demonstrates a willingness to put horses at risk?
Now none of that is cyber-death, it's the plain common sense thinking any livestock owner SHOULD have and any animal deserves.
Trying to protect someone because what? A "name", a reputation, because he is an horse vet, because he is a Paso Fino horse vet??? Please! Protect the industry, the breed, YOUR horse! Again, empowering others, protecting others by suggesting they are ignorant when they are in a place where they should know is destroying the very thing you care about-the horses.
I'm angry about the entire episode. It's tragic, but what caused the tragedy? Those trying to protect the person are grasping at some alien exotic disease, those protecting animals realize it is probably a traceable, known toxicity. There are very few competent vets that would suggest otherwise. A livestock farmer that has more then one animal at the same time with the same symptoms would be told to look for a toxic source: food, water, common feed buckets, pesticide contamination, etc.
It is salt in the wound to read how a panic has now started...not to protect animals by vaccinating against botulism...but to vaccinate suggesting that what has happened is a "freak of nature" skewing it to protect a horse vet who fed haylage, a dangerous food source to horses. To run around screaming botulism, botulism, is everywhere is inane. Of course it is! Been around all the time! Suddenly there's some weird association between dried hay and haylage, therefore ALL grass is dangerous? Breathing is dangerous! Buy some 24/7 inhalant to keep our horses safe!
I feel pity for the man. He made a mistake, and he was in a position where those type of mistakes can't be made.
_________________ Be the change you want to see in the world. Gandhi
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