Fainting or near Fainting. Rapid Heartbeat â Tachycardia. When the heart beats too quickly (usually above 100 beats per minute), the lower chambers, or ventricles, do not have enough time to fill with blood, so they cannot effectively pump blood to the rest of the body.
If a horse has two copies of Gray, all offspring of this horse will be gray. Research indicates that horses with one copy of Gray often retain some of the original pigment while homozygotes tend to progress to almost completely white. Gray is found in many breeds and is the predominant color of the Lippizaner breed. Gray horses have a high incidence of dermal melanomas that are commonly seen around the tail and head. Over 70% of Gray horses older than 15 years will develop melanoma.
Genetically, a bay dun is a bay horse with the dun gene that causes the lighter coat color and the primitive markings. A buckskin is bay horse with the addition of the cream gene, causing the coat color to be diluted from red to gold, often without primitive markings. Dun, also called bay dun, classic dun or zebra dun, the most common type of dun, has a tan or gold body with black mane, tail, and primitive markings. 2  Genetically, the horse has an underlying bay coat color, acted upon by the dun gene.