Antihistamines are medications used to treat allergies and to counteract the effect of histamine. Histamine is a molecule that acts in the body as both hormones and neurotransmitters, to regulate biological functions.
Histamine is present in significant amounts in animals and plants. Also, it is a normal part of the inflammatory cascade, which is a vital part of the body’s defense.
These antihistamines are fighting with histamine for absorption in histamine receptors in sensitive cells such as intestines, respiratory tracts, blood vessels, and skin. Veterinarians can use these antihistamines to treat allergic disorders and hypersensitivity.
The veterinarian selects the antihistamine depending on his preference, the symptoms to be treated, and the horse. This type of medication is given by injection or orally.
In some over-the-counter commercial antihistamines is oral pyrilamine malate and tripelenamine. They usually come in powder or are granular to be mixed with food. Usually, these medications are used for preventive maintenance for horses with allergies.
Are Antihistamines Safe In Horses?
Human antihistamines are administered to horses. Usually, they are considered safe, but they can have questionable value.
Some examples of this type of medication are Allacan, Antihistamine, Beaconease, Benadryl, Bell ‘s Healthcare, Cetirizine hydrochloride, Chlorphenamine, Clarityn, Galpharm, Haylief, Loratadine, Murine, Nasaleze, Numark, Opticrom, Optrex, Otrivine, Pirinase, Piriteze, pollenase and Sterimar.
Although Cetirizine is considered not effective for the treatment of Sweet Itch in horses, many people who have already used it do not recommend it, check with your veterinarian about these medications.
There are occasions that customers use 25 mg of diphenhydramine (Benadryl) and have commented that hives decreased. Although you should know that the FDA has not approved the use of diphenhydramine in horses. Therefore, if you wish to use it, it is better to talk to the veterinarian first before continuing this treatment.
These oral medications usually take longer to take effect than injectable antihistamines. That is why orals are used to prevent mild itching, swelling, hives caused by allergic skin problems. It is also used for respiratory allergies and low-grade ophthalmic allergies.
You can find injectable commercial antihistamines that are labeled for use on horses. These medications contain pyrilamine malate or tripelenamine that act faster by injection. These antihistamines are used for more severe allergies, such as hives or facial swelling caused by insect bites.
An advantage that antihistamines have is that it has fewer side effects than corticosteroids. That is why the use of antihistamines is very important to reduce the dose of corticosteroids when used at the same time.
Possible Side Effects
You should keep in mind that some horses may react differently to antihistamines, so you must provide the correct dose. The dosage should be based on the conditions of the horse and age and always with the advice of a veterinarian.
The most common side effects of these medications are mild sedation and fine muscle tremors. Although side effects are more common in injectable antihistamines, your horse may also have an anxiety reaction and lack of coordination.
You should know that some antihistamines are prohibited in sanctioned competitions. Use with caution in horses with sweating disorders (anhydrosis) and horses with warfarin and other anticoagulant drugs.