In dachshunds, "Isabella" is another name for a fawn coloration. It results when a dog carries a recessive gene for chocolate coloration from both parents and a gene for color dilution. Isabella dachshunds may be solid-colored or may have tan or cream points.
Both Isabella and blue dachshunds carry a gene for color dilution, which is related to color dilution alopecia. Abnormal distribution of melanin in the hair shaft causes the dilute color but can also cause structural abnormalities in the hair shaft, allowing the shaft to break easily. Affected dogs usually start exhibiting broken hairs when they are 1 to 3 years old and may develop skin infections from blocked hair follicles or excessive scratching of the affected areas.