equis - Articles
Hair: leukotrichia
Synonym(s): Hair whitening, White hairs
Introduction
- Cause: leukotrichia occurs commonly as post-inflammatory change, eg from branding in saddle areas or the legs due to ill-fitting equipment and bandaging. Other infectious or immunologic causes are also reported.
- In horses carrying the G allele color is present at birth but increasing number of white hairs develop with age, eg Arabians, Andalusians, Lipizzaners.
- Signs: white hairs.
- Diagnosis: history and clinical signs.
- Treatment: no effective treatment known.
- Prognosis: depends on condition.
Presenting signs
- White hairs with or without pre-existing skin lesions (either localized or generalized depending on the underlying cause).
Geographic incidence
- Hyperesthetic leukotrichia reported only in the USA.
Age predisposition
- In gray horses, leukotrichia is progressive and it starts around 2-3 years of age.
Breed/Species predisposition
- Leukotrichia with the G allele:
- Arab Arab.
- Andalusian Andalusian (Purebred Spanish horse).
- Lipizzaner Lipizzaner.
- Camargue Camargue.
- Percheron Percheron.
- Reticulated leukotrichia:
- Quarterhorse Quarterhorse.
- Thoroughbred Thoroughbred.
- Standardbred Standardbred.
- Other breeds.
- Spotted leukotrichia:
- Thoroughbred Thoroughbred.
- Arab Arab.
- Shire Shire.
- Andalusian Andalusian (Purebred Spanish horse)
Pathogenesis
Etiology
- Variable from genetic to inflammatory Skin: vitiligo.
- Skin trauma.
- Special forms of leukotrichia include reticulated leukotrichia, spotted leukotrichia and hyperesthetic leukotrichia.
Reticulated leukotrichia
- This is uncommon.
- Pathogenesis is unknown and it is hypothesized to be a variation of erythema multiforme Erythema multiforme.
- It develops at young age and starts with crusty lesions that once shed, leads to permanent leukotrichia with cross-hatched, net-like or herringbone symmetric distribution over the back between the withers and the base of the tail.
- It may be secondary to herpesvirus infection Equine herpesvirus or vaccinations Vaccination in some animals.
Spotted leukotrichia
- Spots of white hair (1-3 cm), in the absence of skin lesions, on the rump area or on the sides
.
- The cause is unknown and in most cases it is a permanent change.
- The skin is usually pigmented, but when leukoderma is present, the prognosis for repigmentation of the hair is worse.
Hyperesthetic leukotrichia
- Affects older horses (may be a variant of reticulated leukotrichia).
- Horses develop single or multiple extremely painful crusts (1-4 mm) over the dorsum from the withers to the base of the tail that persist for 1-3 months and then result in patchy leukotrichia.
- The disease appears to have a cyclic behavior, but the cause is unknown.
Predisposing factors
General
- Autoimmune.
- Genetic.
- Trauma.
- Inflammation.
- Viral.
- Vaccination.
- Drug eruptions.
- Local anesthetics
Anesthesia: local - overview.
Timecourse
- Depends on underlying disease.
Diagnosis
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Treatment
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Prevention
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Outcomes
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Stannard A A (2000) Pigmentary disorders. Vet Derm 11 (3), 205-210 PubMed.
- Fadok V A (1995) Update on four unusual equine dermatoses. Vet Clin North Am Equine Pract 11 (1), 105-110 PubMed.
Other sources of information
- Scott D W & Miller W H (2011) Pigmentary Abnormalities. In: Equine Derm. Saunders, USA. pp 389-397.
- Knottenbelt D C (2009) Pascoe’s Principles and Practice of Equine Dermatology. 2nd edn. Ed: Knottenbelt D C. Saunders, USA.