Title: Alopecia X

{{Short description|Genetic disease of dogs resulting in hair loss}}
'''Alopecia X''' is a type of adult-onset [[follicular dysplasia]] in dogs previously known by many other names. The condition was first described in 1977. The condition is believed to be caused by a genetic predisposition to a hormone defect. Often dogs will recover after [[neutering]].&lt;ref&gt;{{cite journal | last=Cerundolo | first=Rosario | title=Canine alopecia X | journal=Companion Animal | volume=14 | issue=9 | date=2009 | doi=10.1111/j.2044-3862.2009.tb00427.x | pages=47–52}}&lt;/ref&gt;&lt;ref name=&quot;sousa&quot;&gt;{{cite journal|last1=de Sousa Ferreira|first1=MA|last2=de Carvalho|first2=VM|last3=da Silva Dutra|first3=M|last4=Rodrigues|first4=FR|last5=de Araújo Viana|first5=D|last6=Ferreira|first6=TC|title=Alopecia X in dogs: report of seven cases|journal=Research, Society and Development|year=2022|volume=11|issue=10|pages=e159111032652-|doi=10.33448/rsd-v11i10.32652 |doi-access=free}}&lt;/ref&gt;

==Etymology==
The condition was previously known under multiple names including: '''adult-onset growth hormone deficiency''', '''growth hormone responsive alopecia''', '''castration responsive alopecia''', '''biopsy responsive alopecia''', '''black skin disease''', and '''congenital adrenal hyperplasia-like syndrome'''. Today it is known as '''Alopecia X''' which reflects the unknown origin of the disease.&lt;ref name=&quot;endo&quot;&gt;{{cite book | last=Feldman | first=Edward C. | last2=Nelson | first2=Richard W. | last3=Reusch | first3=Claudia | last4=Scott-Moncrieff | first4=J. Catharine | title=Canine and Feline Endocrinology | publisher=Saunders | publication-place=St. Louis, Missouri | date=2014-12-08 | isbn=978-1-4557-4456-5 | pages=55}}&lt;/ref&gt;
==Cause==
The cause is not unknown.&lt;ref name=&quot;sousa&quot;/&gt;&lt;ref name=&quot;endo&quot;/&gt; One theory of a growth hormone deficiency being the cause was abandoned when multiple studies showed normal growth hormone responses following stimulation and normal [[IGF-1]] levels in affected dogs. Why some dogs with alopecia X show a suppressed growth hormone response remains unknown.&lt;ref name=&quot;endo&quot;/&gt; Mild [[hypercortisolism]] has been suggested as a cause of alopecia X in [[miniature Poodle]]s and [[Pomeranian dog|Pomeranians]].&lt;ref name=&quot;endo&quot;/&gt;
==Risk factors==
Alopecia X primarily affects breeds with long and dense coats such as the Pomeranian, [[Keeshond]], [[Chow Chow]], [[Siberian Husky]], and [[Alaskan Malamute]].&lt;ref name=&quot;englar&quot;&gt;{{cite book | last=Englar | first=Ryane E. | title=Common Clinical Presentations in Dogs and Cats | publisher=Wiley | date=2019-07-03 | isbn=978-1-119-41458-2 | doi=10.1002/9781119414612 |chapter=Hypotrichosis and Alopecia| page=67}}&lt;/ref&gt;
==Signs and symptoms==
[[File:AlopeciaX.jpg|thumb|A Pomeranian with alopecia X]]
Initial signs of alopecia X are hair loss around the collar and rear thighs that slowly progresses to near complete alopecia of the [[trunk (anatomy)|trunk]], neck, and [[proximal]] legs. The head, [[distal]] legs, and distal tail do not experience alopecia. In some cases a sparse wooly coat will remain. [[Hyperpigmentation]] develops simultaneously; however it may not occur, especially in white-coated Poodles. Aside from this clinical affects are not notable.&lt;ref name=&quot;endo&quot;/&gt;
==Diagnosis==
Diagnosis is done via the exclusion of [[endocrinopathies]], including: [[hypercortisolism]], [[hypothyroidism]], [[hyperoestrogenism]],  and [[hyperprogesteronism]] (a rare condition in some adrenocortical or testicular tumours), as well as other conditions such as, [[cyclic flank alopecia]], [[follicular dysplasia]], and [[sebaceous adentitis]]. A skin [[biopsy]] will typically show the same changes as other endocrinopathies. There is no way to consistently and reliably differentiate alopecia X from other conditions. However 'flame follicles' — which are spikes of fused [[keratin]] that seem to protrude through the outer root sheath to the [[vitreous layer]] that creates a type of 'fiery' effect — appear to be more common in alopecia x than other [[dermatopathies]].&lt;ref name=&quot;endo&quot;/&gt;
==Treatment==
Various treatments have been used to treat alopecia X, such as: growth hormones, [[castration]], [[melatonin]], [[mitotane]], and [[trilostane]]. Treatment is not always effective, and because hair cycle arrest is a 'cosmetic' disease the risk of treatment needs to be compared to the benefit.&lt;ref name=&quot;endo&quot;/&gt; Growth hormone treatment can cause [[iatrogenic]] [[diabetes in dogs|diabetes mellitus]] so other treatments have been investigated. Anecdotal and experimental results have been promising for [[melatonin]], [[mitotane]], and parenteral [[medroxyprogesterone acetate]].&lt;ref name=&quot;englar&quot;/&gt;
==References==
{{reflist}}

[[Category:Dog diseases]]