Dermatological and morphological findings in quarter horses with hereditary equine regional dermal asthenia

Abstract

Despite the regional pattern of the cutaneous signs, skin with decreased thickness was not regionally distributed in the HERDA-affected horses. Histopathological evaluation is informative but not conclusive for establishing the diagnosis. Samples of skin from the neck, croup or back are useful for diagnosis of HERDA. However, the final diagnosis must be confirmed using molecular testing.

Hereditary equine regional dermal asthenia (HERDA) in Quarter Horses: A review of clinical signs, genetics and research

“…; Badial et al . b) demonstrated that pathologists differ in their ability to identify characteristic changes, confirming that biopsy interpretation should be performed by experienced equine dermatopathologists and that DNA testing is preferred to histology for HERDA diagnosis.…”

“…Care and experience are required to differentiate artifactual from pathological separation of the dermis in punch biopsies. Two separate studies (White et al 2004;Badial et al 2014b) demonstrated that pathologists differ in their ability to identify characteristic changes, confirming that biopsy interpretation should be performed by experienced equine dermatopathologists and that DNA testing is preferred to histology for HERDA diagnosis.…”

“…Despite having the HERDA mutation and clinical manifestations of the disease, many HERDA horses have undergone routine surgical procedures such as castrations (Badial et al . b; Rashmir‐Raven et al . ) and surgical repair of traumatic wounds ( Fig a,b ) with good results; this sometimes confuses horse owners into believing the horse is unaffected.…”

“…; Badial et al . b), affected horse's skin may be more susceptible to the effects of collagenase degradation (Rashmir‐Raven et al . ).…”

“…In humans UV light exposure causes disruption of the dermal extracellular matrix by inducing matrix metalloproteinases (MMPs) including collagenases (Rittie and Fisher 2002). Because HERDA horse collagen is more soluble, loosely bound and disorganised than normal horses (White et al 2004(White et al , 2007Grady et al 2009;Badial et al 2014b), affected horse's skin may be more susceptible to the effects of collagenase degradation (Rashmir-Raven et al 2015).…”