Alopecia Flashcards
- Alopecia =
- Hypotrichosis =
Alopecia = hairloss
Hypotrichosis = partial alopecia
Can be congenital vs aquired. Might be secondary to pruritus or inflammation/infection.
Differentiate shedding vs alopecia. With shedding, you shouldn’t begin to see the skin through the coat.
anagen = growing, telogen = resting
Flowchart for working up alopecia.
After ruling our pruritus and infections - consider whether the alopecia is local, diffuse or multifocal.
Describe various local alopecias. (4)
traction alopecia
post clipping alopecia
injection site reaction
scare
Describe traction alopecia.
Cosmetic “defect” from over pulling e.g. with hair tyes in long haired dogs. Might be permanent.
Describe post-clipping alopecia.
More frequent in plush coated dogs.
We don’t really know why post-clipping alopecia occurs.
Spontaneous remission, might be slow.
NB don’t forget to rule out systemi diseases like hypothyroidism.
Describe injection site alopecia.
Ischemic reaction.
Even from an inj. up to 6 months prior.
Rabies vaccination may be more likely to cause this.
Remission might be slow or the local alopecia might even be permanent.
Panniculitis might be involved.
Name 5 types of diffuse (symmetrical) alopecias.
seasonal flank alopecia
black hair folliculardysplasia
color dilution alopecia
pattern baldness
alopecia x
Name 3 systemic diseases that can cause diffuse alopecia.
hypothyroidism
hyperadrenocorticism
hyperestrogenism
How does signalment affect your work up for diffuse alopecia?
If you have an old dog with diffuse alopecia and systemic signs, think endocrine diseases.
If you have a younger dog without systemic signs, think follicular dysplasias.
Derm signs of hypothyroidism?
Systemic signs of hypothyroidism?
Hypothyroidism due to thyroid inflammation or atrophy can cause diffuse alopecia.
Derm signs include alopecia on the nose bridge, haircoat loses luster and shine, becomes dry, lighter in color; bilateral alopecia, skin hyperpigmentation, thickening. Tail tip alopecia. Hypotrichosis at friction sites.
Systemic signs include as lethargy, weight gain, cold intolerance, weakness, slow heart rate, nervous system signs, aggressiveness, gastrointestinal signs, etc.
Derm signs of hyperadrenocorticism?
Systemic signs of hyperadrenocorticism?
Due to
* Adrenal neoplasia (15-20%) or hypophyseal neoplasia (80-85%)
* Iatrogenic cushings as a result of steroid use.
Can cause a diffuse alopecia.
- Skin lesions: haircoat is brittle, dry, bilateral alopecia, skin is thin, hyperpigmented. Might see comedones, skin atrophy, seborrhea, secondary skin infections, demodicosis, calcinosis cutis.
- Systemic signs: polyuria, polydipsia, polyphagia, abdominal enlargement, panting, muscle atrophy.
Feline hyperadrenocorticism can cause what 2 uncommon signs.
Often secondary curling of the eartips,
skin fragility syndrome.
Canine hyperestrogenism derm signs?
And systemic signs?
Due to an estrogen producing testicular tumor like e.g. sertolis cell tumor but there are others too, often seen in cryptorchids.
Bilateral symmetrical alopecia, pendulous prepuce,
linear dermatitis on prepuce, secondary infections and otitis.
Changes in testicles on ultrasound.
Not only skin disease! Estrogen might cause myelosupression (anemia, thrombocytopenia).
Tx with castration. Dogs might need blood transfusion before surgery. Tumors might give
metastases too, do chest rads.
Note the 1 descended testicle, the other is cryptorchid.
Diffuse alopecia
without systemic signs indicates
follicular dysplasias.
Suspicion based on clinical signs.
Diagnosis is confiremd with histopathology (skin biopsies).
Treatment is not needed/possible. It’s a cosmetic problem.
Sometimes secondary infections can develop.
Describe seasonal flank alopecia.
Also known as canine recurrent flank alopecia.
Short photoperiod (nov-march) seems to induce it.
Well circumscribed, often hyperpigmented alopecia on the flanks/sides with spontaneous remission during summer months, and usually reccurs the next year.
Describe color dilution alopecia.
Affects dilute coat colors like blue and fawn.
Is a genetic disease but does not affect every dilute coated individual.
Breeds: dobermans, whippet, weimaraner, yorkshire terrier, chihuahua.
Clinical signs develop between 3 months to 3 years old.
Melanin clumps in the hair, not diffuse melanin.
Describe black hair follicle dysplasia.
Only affects the black haired skin areas if the dog has other color present as well. Causes hairloss of the black areas.
Is rare.
Describe pattern baldness/ breed-associated follicular dysplasias.
Every breed has its own pattern.
Greyhounds can get bald thigh syndrome.
Dachshounds, french bulldogs can get affected ear pinnas, sternum, caudal thighs, ventral neck etc.
Describe alopecia X.
Exact cause is still unknown (genetic background).
More common in plushy coat breeds like pomeranians, chowchows, samojeds.
Healthy adults develop progressing alopecia on the neck, tail, trunk, thighs. Skin is thin, scaly and dry. Becomes hyperpigmented. Might develop secondary infections.
Often the head and paws are not affected while the rest of the body is.
- No systemic signs, cosmetic issue
- Diagnosed with histopathology
- Castration might produce hair growth
(temporary). - Hair regrowth at site of trauma is very suggestive of alopecia X.
- Melatonin might sometimes help (temporarily).
Name to multifocal alopecias.
sebaceous adenitis
dermatomyositis
Describe sebaceous adenitis.
Immune mediated sebaceous gland inflammation, atrophy and destruction.
Akitas and standard poodles are predisposed.
Can happen in cats too.
Clinical signs: hypotrichosis, patchy alopecia, follicular casting that owners mistake for dirt, skin is not plushy but flat.
- Might be pruritic.
- Might develop secondary infections.
Diagnose with histopathology & observation of follicular casting (pic in prompt card) on trichogram (ddx pyoderma, dermatophytosis, demodicosis).
Treatment:
* Moisturising the haircoat/skin (oil baths, omega fatty acids, conditioners, propylene glycol)
* Keratolytic shampoos to remove crusts/casting.
* Anti-inflammatory drugs like cyclosporine 5mg/kg or prednisolone 1-2 mg/kg.
* Animals usually need life long treatment.
Describe dermatomyositis.
Dermatomyositis in animals, particularly seen in breeds like Collies and Shetland Sheepdogs, is an inherited inflammatory disease affecting the skin, muscles, and sometimes blood vessels.
It typically manifests in young dogs, with clinical signs including patchy hair loss, crusting, and ulcers on the face, ears, and limbs, along with muscle atrophy and weakness, especially in the head and limbs.
The severity can vary from mild skin lesions to more systemic involvement, including difficulty swallowing or gait abnormalities.
While the exact cause isn’t fully understood, it’s believed to involve immune-mediated processes, and treatment often includes immunosuppressive drugs and supportive care to manage symptoms.
What compound can you use to treat calcinosis cutis?
topical DMSO, industrial solvent
You need to check Ca2+ from blood when treating with this because it can cause hypercalcemia.
You also need to clear all bacterial infections before treating with this as the DMSO would carry the bacteria into the body through the skin.
