Photosensitivity in horses.
Photosensitivity in horses refers to heightened skin sensitivity to ultraviolet (UV) light, often caused by certain chemicals present in the skin that react to UV exposure. This condition falls under the Equine Pastern Dermatitis umbrella and can be more severe than sunburn or mud fever, necessitating prompt identification of the cause.
Primary Photosensitivity
Primary photosensitivity happens when horses come into contact with or ingest plants containing Polycyclic compounds. In New Zealand, these can include:
- St. John's Wort
- Ragwort
- Rye
- Buckwheat
- Ground Elder, and more.
Keeping pastures free of toxic plants is crucial for equine well-being. Certain medications can also trigger photosensitivity, so consulting with your vet about potential side effects is important.
Secondary Photosensitivity
Similar to primary photosensitivity, secondary photosensitivity results from ingesting compounds that are typically harmless unless the horse's liver is compromised. Plants containing these compounds in New Zealand may include:
- St. John's Wort (again)
- Buttercup
- Lantana
- Bermuda Grasses
- Heliotrope
- Paterson’s curse
- Blue-Green Algae
- Multiple liver-damaging fungi
Liver biopsies and evaluations of liver enzymes, blood, urine, and feces can help pinpoint the offending toxins in cases of liver disease.
Symptoms
Symptoms vary depending on the stage but can include redness, swelling, discomfort, itching, hair loss, open sores, crustiness, and lameness. It primarily affects lighter parts of a horse's body but can affect any coat color in severe cases. Early recognition is crucial to prevent extensive tissue damage and secondary infections.
Treatment
Limiting sun exposure early by keeping horses indoors or using protective covers can aid in the healing process. Removing offending plants from the property, addressing liver issues, and limiting fly exposure are essential steps. Veterinary treatments such as corticosteroids, anti-inflammatories, or antibiotics may be recommended.
EquineCare Probiotic
EquineCare Probiotic offers a holistic option for healing by smothering out offensive bacterial and fungal compounds using beneficial microbes. Keeping wounds clean and protected is paramount.
