Valerian Allergy in Horses

Valerian Allergy in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

Most common symptoms

Collapse / Diarrhea / Hair Loss / Hairloss / Itching / Noisy Breathing


0 Veterinary Answers

Most common symptoms

Collapse / Diarrhea / Hair Loss / Hairloss / Itching / Noisy Breathing

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Valerian Allergy in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

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What is Valerian Allergy?

Valerian root is a herb that is frequently used to help people with anxiety and insomnia, and it has a similar sedative effect on equines. It is sometimes recommended for horses that experience fear from traveling or during storms and is relatively safe when used as directed by a veterinary professional.

Adverse reactions to this medication do occur, however, and allergic responses, although uncommon, are possible. If your horse experiences an allergic reaction, a veterinarian should be consulted to determine the cause of the reaction so that the allergen can be removed from the horse’s environment or alternate allergy treatments can be sought.

Valerian root is a natural remedy sometimes used to calm horses that are anxious or aggressive. On occasion, horses that are exposed to valerian root can develop an allergy to the compounds in this plant.

Symptoms of Valerian Allergy in Horses

The symptoms of an allergy to valerian root may vary, depending on the type of reactions that the horse experiences. Allergic reactions can trigger any combination of the following symptoms for horses:

  • Crusting on the skin
  • Diarrhea
  • Difficulty breathing
  • Hair loss
  • Hives        
  • Itching
  • Persistent cough
  • Runny nose
  • Swelling of the skin
  • Watery eyes
  • Weeping sores
  • Wheezing

Anaphylaxis is a rare and severe reaction to an allergen. If you see the following responses, immediate medical treatment is required:

  • Collapse
  • Drastic drop in blood pressure
  • Severe difficulty breathing


Although allergies to this herb are rare, they can happen, and there are multiple ways that an allergic reaction could be triggered by a herb such as Valerian root. 

Anaphylactic Shock

Anaphylactic reactions are very rare and should be addressed immediately. This type of response usually occurs quite rapidly after the horse is exposed to the allergen and may include severe breathing distress, a rapid drop in blood pressure, or even collapse. This type of reaction often leads to death if untreated. 

Respiratory Reaction

Valerian root, either through ingestion or through the inhalation of pollen, may result in a respiratory response. This occurs when the histamine activated by the allergen causes swelling in the tissues of the nasal passages, throat, or the airways.

Skin Reaction

Reactions like itching, hives, and swollen skin are common reactions to histamines that are released on the skin due to an allergic response.

Causes of Valerian Allergy in Horses

Valerian root is often recommended as a natural medication for horses that are anxious and need calming, but dosages and treatment length should always be evaluated by an equine veterinarian. Some of the reasons that valerian root may be used can include:

  • Anxiousness or aggressiveness due to breeding season
  • Easing a fear of travel
  • Reducing startle responses during storms
  • Temporary measures for training nervous horses
  • Unmanageable behavior

Diagnosis of Valerian Allergy in Horses

If your horse is experiencing an anaphylactic reaction shortly after being exposed to valerian root, then the timing will provide a starting point for making a preliminary assumption of an allergy to the herb. Signs of milder reactions may be delayed by several hours, and valerian is often mixed with other herbs or mixed into the food for administration which makes it more challenging to determine the source of the symptoms. Standard blood tests such as biochemical profiles and complete blood counts may expose increased levels of eosinophils, a specialized type of white blood cell that can be an indication of an allergic reaction, although eosinophils are also frequently elevated in horses that are hosting parasites in their gastrointestinal system. Intradermal testing and serum testing are both options that are utilized to help define an individual horse’s sensitivities. A sample of blood extracted from the animal is tested against suspected or common allergens for serum testing, however, it has a high ratio of false positives.

Intradermal testing is a slightly more reliable procedure, but it is also somewhat more invasive and involves sedating the patient and shaving a patch on their necks in order to introduce a minuscule amount of common or suspected allergens under their skin. The intradermal injections are then evaluated at several intervals typically starting at fifteen minutes from injection until twenty-four hours after being injected.


Treatment of Valerian Allergy in Horses

Horses that are exhibiting signs of distress will generally be started on supportive treatments without delay. Although unlikely, an anaphylactic response is possible, and when this occurs breathing may become severely impaired due to the swelling of the membranes in the lungs and blood pressure can drop dangerously. Anaphylactic reactions require immediate treatment which employs epinephrine injected directly into the animal’s jugular, needed to protect the health of the horse. Horses who have moderate to severe allergic reactions are frequently provided with an IV line set up as well to provide the large volumes of water that are needed to adequately support the horse’s extensive circulatory system. 

Once valerian root is identified as the allergen, it should no longer be offered to the horse. Standard treatment plans beyond avoidance generally include medications such as corticosteroids and antihistamines to help reduce the general symptoms of allergy, and anti-inflammatory medication may help to reduce any fever, swelling, and pain that have resulted.

Recovery of Valerian Allergy in Horses

It is important to note that valerian root, although natural, is a sedative. It functions by slowing the central nervous system and although most studies indicate that it is a fairly safe medication to employ in certain circumstances, no studies have been done on either humans or animals regarding the safety of taking valerian root regularly over an extended period of time. It is also extremely important to consult your veterinarian before adding any supplements or medications to your animal’s regimen to help determine the proper dosage and duration for treatment. This herb is also capable of combining negatively with other drugs that affect the central nervous system, such as prescribed sedatives or anesthesia.

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Valerian Allergy Questions and Advice from Veterinary Professionals