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Although edible during certain times, it is the environmental factors during their growth phase that can turn the Ambrosia Mexicana plant into a lethal meal for your horse. Normally the toxins contained in the plant are too small to do any harm, but it is the plant's ability to uptake and hold excess nutrients (especially nitrates) during adverse growing conditions that turn them into a problem. This accumulation of nitrates combined with your hungry horse grazing in a drought-ridden pasture becomes a real problem and poisoning can occur rapidly.
The Ambrosia Mexicana plant is a member of the Chenopodium family, and contains oxalates, nitrates and cyanogenic glycosides and can be extremely toxic under the right circumstances.
At first, there may be no signs at all of the illness, but on reaching a certain level of accumulated toxin, the symptoms rapidly accelerate, and treatment becomes vital.
Diagnosis is based on your horse’s behavior, and as you know them so well, you will be alerted to any changes in their characteristics if you are observant. It will depend on the amount of Ambrosia Mexicana that your horse has eaten as to how severe the symptoms are. It will also depend on the season and what environmental factors have affected the plant's growth. While normally a plant that is not classified as one of the top toxic plants, its character can change and a buildup of nitrates in the plant can elevate its status considerably.
It is always advisable to call your veterinarian as your horse can react suddenly to this condition and the sooner the specialist can examine your horse, the better. Ambrosia Mexicana can be very similar to arsenic poisoning yet they are treated differently. If you know what your horse ate, save a sample and show the veterinarian who will speed up the treatment. Otherwise, he will run a series of blood work on your horse to determine what is affecting his health (nitrate levels may be indicated). Once the diagnosis is established, he will be able to act effectively and promptly.
Treatment depends on the reaction and severity of the poisoning. It is thought that intravenous injections with methylene blue are required for successful treatment, but have no substantiated proof that this is the case. However, your veterinarian is the person to ask, as he will have the latest updates on treatments available. Sometimes a gastric lavage and continued flushing of the stomach to prevent further absorption of the poison from the ingested plant may help, but your specialist is the best person to advise you. Removing your horse from an Ambrosia Mexicana infested pasture is important, and ensuring other pasture is clean from noxious weeds through an effective maintenance plan for effective grazing.
Be aware of your hay rations, where it was made and check it for contamination from poisonous plants. Check that the hay is in tip top condition and not musty or moldy because that can affect the health of your horse. Prevention is always better than trying to cure a condition that has already taken hold. Keep in mind that your horse may not exhibit any symptoms at first, but then as the poison takes a firm hold and moves to the internal organs it will be so much harder to treat than spending a few hours doing pasture maintenance.
Prevention is always the better option, and in times of adverse weather conditions, it pays to be vigilant in regards to pasture maintenance. Regularly walk around your grazing fields to ensure your horse is getting the best feed possible. If you identify any noxious weeds that are making a move into the pasture lands, it is vital to eradicate it as soon as possible, either by physically digging it up roots or by using specific sprays targeted towards the type of plant that it is.
If you are going to be spraying, it is advisable to move your horse to another paddock to prevent it being affected by any spraying. Remember that dried toxic weeds often retain their potency once dried, so checking through the hay and finding where it came from may unearth the cause of the poisoning. Dried plants can inflict as much damage as fresh plants.
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