Description

Hydroxyzine hydrochloride is an antihistamine used to treat allergic skin reactions in horses.  The drug works by competing with histamine for uptake at the histamine receptors on sensitive cells in the respiratory tract, intestines, blood vessels, and the skin, thereby counteracting the inflammation and itching of allergic reactions.

Usage

Hydroxyzine is given to treat hives, itchy or bumpy allergic skin reactions, and inflammation.  Antihistamines given orally take 20 to 45 minutes to begin counteracting the release of histamine from damaged cells and the resulting effect it has on the horse's body.  

Dosage and Administration

Hydroxyzine
Method	Dosage (click row for calculator)	Concentration	Period	Duration
Oral	0.5-1 mg/kg	50 mg/tablet	2 to 4 times daily	NA
Intramuscular injection	0.5-1 mg/kg	50 mg/ml	2 to 4 times daily	NA
Notes: Federal law restricts this drug to use by or on the order of a licensed veterinarian. Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian). Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Sedation is the most common side effect.  Fine tremors, whole body tremors, excitement, and seizures are less common.

Precautions

High doses of antihistamines can cause birth defects in laboratory animals.  Hydroxyzine should only be used in pregnant and lactating animals if the benefits outweigh the risks.  Animals may react differently to antihistamines and the dose of hydroxyzine should be tailored to the individual horse.

Hydroxyzine is not FDA approved for use in horses, although its use is considered accepted practice.  It is a prescription drug and U.S. federal law restricts this drug to use by or on the lawful written or oral order of a licensed veterinarian.

Hydroxyzine is prohibited or regulated in most sanctioned competitions.  It is important to consult the individual regulatory group.

Interactions

Hydroxyzine has an additive effect when combined with other central nervous system depressant drugs, such as tranquilizers.

Overdose

Overdose may cause increased sedation and increased risk of other side effects.