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What is Nettles Allergy?

Allergic reactions to nettles can occur when your horse brushes against the plant, eats the plant or inhales the spores from the plant. Young horses are especially at risk of having a nettles allergy. Symptoms include severe constipation and inflammation of the intestinal mucosa. 

Oozing, soft nodules or doughnut shaped, raised areas will appear on parts of your horse’s body. These nodules can cause itching; however, they rarely cause pain. Generally, nettles allergies will present in the late spring and summer months.

Nettles, also called common nettle, stinging nettle, nettle leaf and urtica dioica, are a part of the Urticaceae family and are a herbaceous perennial, flowering plant. Nettles are native to Western North America, Northern Africa, Europe and Asia. Some horses do have a nettles allergy that causes problems within the gastrointestinal tract.

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Symptoms of Nettles Allergy in Horses

When you notice that your horse is acting oddly and/or there are physical symptoms that need immediate attention by a veterinarian, you should remove your horse from their pasture and put them in a well bedded stall. Contact your veterinarian for an assessment and do not feed your horse anything until your veterinarian has arrived. Symptoms of a nettles allergy include:

  • Sudden onset of soft nodules over part of your horse’s skin
  • Oozing nodules, usually a clear liquid
  • Itching
  • Constipation 
  • Rubbing affected areas

Causes of Nettles Allergy in Horses

Nettles allergy will occur when your horse is exposed to the allergen that is found on the nettles plant. The symptoms are typically cosmetic and do not cause severe pain to your horse. The nodules that occur are not pretty to look at and many horse owners are worried about the cosmetic look of their horse. 

Many times nettles allergy will clear up by itself when there is a change in the environment and/or diet. Your veterinarian may need to put your horse on steroid injections if the nodules do not clear within a few weeks. 

In many instances, it will be difficult for your veterinarian to identify the exact allergen that is causing your horse’s allergic reaction without running a full allergy panel.

Diagnosis of Nettles Allergy in Horses

Your veterinarian will take a full medical history and ask you about your horse’s environment and diet. They will conduct a full physical examination of your horse, paying close attention to the nodules that have presented. 

Your veterinarian will run basic tests such as a complete blood count, fecal examination, and urinalysis. A biochemistry panel may also be ordered. These tests will rule out potential causes of the allergic reaction. A biopsy of one of the nodules will help your veterinarian confirm that your horse is having an allergic reaction but it will not necessarily identify the allergen. 

It may be difficult for your veterinarian to identify the allergen that is causing your horse’s problems without conducting a full allergy panel and eliminating common allergens. This can be time consuming and expensive. Your veterinarian may walk through your horse’s pasture looking for plants that could potentially cause an allergic reaction. They may take samples and test those to plants to find which one is the problem.

Treatment of Nettles Allergy in Horses

In many cases of nettles allergy in horses, treatment is not necessary. The condition resolves itself within just a few weeks after being removed from the environment or changing the diet. 

In some instances where the allergy is severe, your veterinarian may recommend steroid injections to stop the allergic reaction, steroids can also be added to your horse’s feed if you do not want the injections. Antihistamines can also be useful to stop the allergic reaction. 

For the actual nodules that are on your horse’s skin, your veterinarian will prescribe a mild antiseptic solution to be used along with antibiotic creams and corticosteroid creams.

Recovery of Nettles Allergy in Horses

Your horse’s prognosis is good and many times may not require additional medications. Your horse will need to be kept away from the nettles plants to keep them from having another allergic reaction. Although not painful for your horse, cosmetically your horse looks terrible when their skin is covered in soft, oozing nodes.

Be sure to follow all dosing instructions carefully on the medications prescribed by your veterinarian. If you have any questions regarding the medications, contact your veterinarian. Reducing your horse’s stress can also help keep them from having a relapse. An allergic reaction occurs when the immune system is not working properly and stress will hinder your horse’s immune system. 

Pasture management should be practiced and any nettles plants should be removed to avoid any more reactions. If necessary, use a pasture safe herbicide on your horse’s pasture to eliminate any possible allergens.