Here are some possible reasons for a horizontal crack in a horse's hoof wall:
* Concussion: Repeated impact from hard surfaces or improper hoof trimming can cause the hoof wall to crack horizontally.
* Poor hoof care: Neglecting regular trimming, shoeing, and hoof care can weaken the hoof wall and make it more prone to cracking.
* Nutritional deficiencies: A lack of essential nutrients, like biotin, can impact the hoof's strength and make it more susceptible to cracks.
* Underlying medical conditions: Certain medical conditions like laminitis, abscesses, or even ringworm can cause hoof wall cracks.
* Environmental factors: Extreme weather conditions like prolonged dryness or humidity can also affect hoof health.
Important Note: A horizontal crack in a horse's hoof can be painful and can lead to further complications if left untreated. It's crucial to consult a veterinarian immediately to diagnose the cause and determine the best course of treatment.