Lecture 7 2/10/25 Flashcards
What can cause loss of hair?
-traumatic removal/scratching out
-spontaneous falling out
-lack of new hair growth
Which inflammatory conditions can cause hair to fall out?
-pyoderma
-demodicosis
-dermatophytosis
What is the distribution of non-inflammatory alopecias?
-more diffuse
-often symmetrical
-spares the extremities
What are the two broad categories of non-inflammatory alopecia causes?
-diseases associated with abnormal hair growth
-hair cycle abnormalities
What are the characteristics of telogen hairs?
-not a pathologic state
-do not have to shed
-can be difficult to pull out
Which breed has an anagen-dominant hair cycle?
poodles and poodle mixes
What are the characteristics of follicular dystrophies/dysplasias?
-abnormality of the development of the hair
-becomes apparent during anagen
-hairs are abnormal, fragile, and malformed
-trule follicular dysplasias are rare
Which breed has a true follicular dysplasia/ectodermal defect?
chinese crested
What are the characteristics of congenital hypotrichosis?
-not well characterized
-can be born without normal pelage
-can be born with normal pelage and have hair loss within first 6 months of life
-non-inflammatory
What is the mechanism behind color dilution alopecia/black hair follicular dysplasia?
defective melanization due to defects in melanosome migration/transfer
What are the clinical signs of color dilution alopecia/black hair follicular dysplasia
-alopecia that is color-restricted
-seborrhea
-pyoderma
How is color dilution alopecia diagnosed?
-trichogram; can see the melanosomes clumped and bulging
-histopath; can see melanin clumping within shaft and periadnexally
What is the treatment for color dilution alopecia?
symptomatic treatment of the seborrhea and pyoderma
What are the clinical signs of hair cycle issues?
-bilateral symmetrical diffuse alopecia
-dull, dry, brittle hair
-hair fails to grow back after clipping
-pigmentary changes/bleached hairs
-seborrhea/comedones
-secondary infections
-nonpruritic
What are the endocrine causes of alopecia/hair loss?
-hypothyroidism
-cushing’s
-hyperestrogenism
What are the dermatologic signs of hypothyroidism?
-alopecia, especially in areas of wear
-failure to shed
-failure to grow past clipping
-bleaching of hairs
-myxedema
-recurrent infections
What are the dermatologic signs of cushing’s?
-symmetrical alopecia
-thinned hair coat/hypotrichosis
-atrophy of the skin
-comedones
-milia
-recurrent pyoderma
-hyperpigmentation
-poor wound healing
-bruising
-demodicosis
-calcinosis cutis
What are the possible sex hormone dermatoses?
-hyperestrogenism
-hyperandrogenism
What are the possible causes of hyperestrogenism?
-cystic ovaries
-testicular tumors
-iatrogenic
Why does elevated estrogen lead to hair loss?
estrogen inhibits anagen initiation
What are the clinical features of hyperestrogenism?
-bilaterally symmetric alopecia
-comedones
-secondary seborrhea
-hyperpigmentation
-enlarged nipples and vulva (females)
-irregular heat cycles (females)
-linear preputial dermatosis (males)
-macular melanosis (males)
-abnormal testicles (males)
When is hyperandrogenism an issue?
animals that have androgen-responsive hair follicles; example is lions
What is the pathogenesis behind hyperandrogenism?
-testicular tumors
-adrenal tumors
What are the clinical features of hyperandrogenism?
-intact males
-hyperplasia of circumanal glands
-tail gland hyperplasia
-seborrhea oleosa
-rarely alopecia
What are the characteristics of alopecia X?
-adrenal hyperplasia-like syndrome
-response to growth hormones
-castration responsive
-biopsy responsive
-pseudo-cushing’s
Which breeds develop alopecia X?
plush-coated breeds
What is the typical presentation of alopecia X?
-adult dogs 1 to 10 years of age
-males equal to females
-loss of truncal hair
-hyperpigmentation
-not systemically ill
-not cushingoid or hypthyroid
What is the pathomechanism of alopecia X?
not known, but thought that patient has a failure to initiate or maintain anagen
How is alopecia X diagnosed?
-rule out cushing’s and hypothyroidism
-biopsy to confirm non-inflammatory alopecia and rule out sebaceous adenitis
What are the treatment options for alopecia X?
-castration
-growth hormones
-testosterone
-mitotane
-melatonin
-trilostane
-medroxyprogesterone
What is the long term prognosis for alopecia X?
-poor prognosis for maintaining hair growth; often lose hair against on subsequent hair cycle
-treatment should be stopped once hair grows back to give treatment best chance of working again if hair is lost again
Which conditions are considered patterned alopecia?
-tardive hypotrichosis
-pinnal alopecia of dachshunds
-ventral and caudal alopecia of dachshunds and bostons
-pattern alopecia of portuguese water dogs, irish water spaniels, and american water spaniels
-caudal thigh alopecia of greyhounds
What are the characteristics of cyclic flank alopecia?
-seasonal truncal alopecia
-hair loss usually occurs in winter
-more common in dogs in northern regions
-may not happen every year
Which breeds are predisposed to cyclic flank alopecia?
-airedale
-boxer
-english bulldog
-french bulldog
-other short-coated breeds
What is the clinical presentation of cyclic flank alopecia?
-age of onset between 1.5 and 4.5 years old
-usually symmetrical
-often hyperpigmented
How is cyclic flank alopecia diagnosed and treated?
-diagnosed by ruling out endocrinopathies and doing a biopsy
-treatment via melatonin and potentially low-level laser
What are the characteristics of post-clipping alopecia?
-failure to regrow hair following close clipping
-seen following surgical procedures or epidurals
-hair usually grows back within 1 year
-can be seen in plush-coated breeds when clipped at wrong time in hair cycle
How is post-clipping alopecia diagnosed?
-rule out endocrinopathies
-biopsy possible but not indicated
What are the treatments for post-clipping alopecia?
-time
-melatonin
What is telogen defluxion?
hair loss 1 to 3 months after a stressful incident or illness
What are the characteristics of excessive shedding?
-normal shed cycles occur in spring and fall
-if shedding is normal, cannot epilate until bald
-hyper dogs may shed more
-should check for endocrinopathies
What are the treatments for excessive shedding?
-regular grooming with antiseborrheic shampoo
-diet changes/adding fatty acids
-adjusting light and/or temperature exposure
