Localized or Generalized Alopecia Flashcards
definition of alopecia
loss of hair from areas of the body where it is normally present
basic causes of alopecia
decrease in hair numbers, hair miniaturization, or hair breakage
diagnosis of cause of alopecia
skin scraping, cytology, fungal culture, trichography, skin biopsy
what is trichography useful for
determining if hair loss is due to self-trauma and detecting follicular dysplasia
what further tests should be done with generalized alopecia
minimum data base (bloodwor and U/A) and endocrine testing
differentials for alopecia
folliculitis vaccine-associated ischemic dermatopathy familial canine dermatomyositis hyperadrenocorticism hypothyroidism alopecia X cyclic flank alopecia pattern baldness color dilution alopecia sertoli cell tumor anagen defluxion telogen defluxion feline symmetrical alopecia
3 most common causes of localized alopecia
bacterial folliculitis (dog) demodicosis (dog) dermatophytosis (cat)
what is vaccine associated ischemic dermatopathy
alopecia over a vaccine site
cause of vaccine associated ischemic dermatopathy
caused by focal cutaneous vasculitis which leads to ischemic injury of skin
when and in what breeds does vaccine associated ischemic dermatopathy occur in
few months after vaccine
fluffy white breeds – mini poodles and bichon frises
diagnosis of vaccine associated ischemic dermatopathy
clinical signs, history of vaccine and FNA +/- skin biopsy
rule out demodicosis
treatment of vaccine associated ischemic dermatopathy
pentoxifylline – anti-inflammatory methylxanthine to improve blood flow through damaged vessels
what is familial canine dermatomyositis
hereditary, idiopathic inflammatory condition of the skin and sometimes muscles
what breed does familial canine dermatomyositis occur commonly in
shetland sheep dogs and collies – autosomal dominant with variable gene expressivity
when do alopecic lesions of familial canine dermatomyositis occur
most commonly before 6 months and can progress up to a year
lesions of familial canine dermatomyositis
alopecia, erythema, scaling and mild crusting;
+/- mild pruritus
can have marked atrophy (thin skin with no visible hair follicles)
diagnosis of familial canine dermatomyositis
clinical signs and skin biopsy;
also do a skin scraping to rule out demodicosis
treatment of familial canine dermatomyositis
pentoxifylline, vitamin E
possibly cyclosporine or topical tacrolimus
how does hyperadrenocorticism cause alopecia
hypercortisolism suppresses hair growth leading to telogenization of hairs
characteristics seen in the skin with hyperadrenocorticism
thin, hypotonic skin symmetrical alopecia easy bruising poor wound healing seborrhea sicca increased susceptibility to bacterial infection and demodicosis calcinosis cutis comedones coat color lightening
3 characteristic findings with hyperadrenocorticism
thin skin, comedones and calcinosis cutis
systemic signs of hyperadrenocorticism
PU/PD/PP, panting, muscle wasting, pot-belly appearance
confirmation of hyperadrenocorticism can be made with what test
ACTH stimulation test
what does hypothyroidism cause regarding the skin
epidermal atrophy and abnormal keratinization
lesions of hypothyroidism
scaly, dry and hyperpigmented skin
skin can be thicker than normal
failure of hair to grow because thyroid hormone is necessary to initiate anagen
when does pruritus occur with hypothyroidism
when a secondary bacterial infection is present
common location for alopecia with hypothyroidism
tail and bridge of nose
diagnosis of hypothyroidism
low free T4 levels + clinical signs
classic hypothyroid dogs show what levels of T4, free T4 and TSH
low T4 and free T4
high TSH
which breeds are predisposed to alopecia X
pomeranians, siberian huskies, samoyeds, malamutes, mini poodles
when do clinical signs of alopecia X start to occur
before 3 years of age
clinical signs of alopecia X
dull, dry hair coat with loss of primary hairs;
alopecia affecting the trunk, caudal thighs, neck and tail
treatment of alopecia X
S/N intact dogs; oral melatonin;
other treatments are controversial because of adverse effects to treat a cosmetic disease
clinical signs of cyclic flank alopecia (dog)
bilaterally symmetrical hair loss and hyperpigmentation in the flanks that resolves without treatment but may recur in the future
which breeds are affected by cyclic flank alopecia
bull dogs, boxers, airedale terriers
diagnosis of cyclic flank alopecia
skin biopsy showing dysplastic, keratin filled follicles
treatment of cyclic flank alopecia
no treatment required;
can use oral melatonin to speed hair regrowth and prevent in future
which colors does color dilution alopecia occur in
blue or fawn coat colors
which breed is the poster child for color dilution alopecia
doberman
what is a characteristic finding regarding the hairs in color dilution alopecia
brittleness and breakage of affected hairs by 6 months of age
cause of color dilution alopecia
abnormal melanin deposition in hair shafts and skin –> large irregular macromelanosomes disrupt the integrity of the hair shaft
true or false: dogs with color dilution alopecia are prone to secondary bacterial infections
true
diagnosis of color dilution alopecia
rule out other causes of alopecia by skin scraping and biopsy
trichogram should show characteristic clumping of melanin
treatment of color dilution alopecia
avoid mechanical trauma and treat secondary infections;
can try melatonin but prognosis for hair recovery is poor
what is feline symmetrical alopecia
a cutaneous reaction pattern
cause of feline symmetrical alopecia
commonly overgrooming –> may be due to pruritus or psychogenic
other possible underlying cause: hyperthyroidism of FLUTD
diagnosis of feline symmetrical alopecia
trichograms show ends of hair are broken;
biopsy will show growing anagen hairs
differentials for feline symmetrical alopecia
flea bite hypersensitivity, atopic dermatitis, adverse food reaction, dermatophytosis, cheyletiella;
less commonly could be truly psychogenic
what is anagen defluxion
when an insult, such as severe disease or antimitotic drug, causes hair shafts to break off suddenly
when does hair loss occur with anagen defluxion
within days of insult
what is telogen defluxion
seen 1-3 months after insult and results from hair follicles entering the telogen phase in synchrony due to stressful incident or drugs
