2. Solar dermatosis
• Solar - Something that is related to sun.
• Dermatosis – Any disease of the skin.
• Solar dermatitis occurs from an actinic reaction on white skin, light
skin or damaged skin that is not sufficiently covered by hair.
3. • Canine solar dermatitis, or chronic sun damage to the skin, is a
common dermatologic disorder in hot, sunny climates. It can also
affect animals that live in high altitudes or that spend a great deal of
time outside, even in temperate zones.
4. • Rapidity of onset and severity of the reaction depends on sun
exposure and intensity of sunlight
• Solar dermatitis is purely a phototoxic reaction (sunburn) and has no
apparent relationship to a hypersensitivity state .
• The pathogenesis of photo toxicity is incompletely understood but it
involves the epidermis and blood vessels of superficial and deeper
vascular plexus
5. • Unfortunately, solar dermatitis can sometimes mimic other skin
diseases such as allergies or pyoderma and, thus, go unrecognized
and untreated until irreversible damage or sun-induced skin cancers
have developed.
7. Epidemiology
• Solar dermatitis most commonly affects the white-haired and non
pigmented skin of short-coated breeds such as pit bull terriers,
Staffordshire bull terriers, bull terriers, boxers, Dalmatians, American
bulldogs, and whippets, but any dog with white or lightly pigmented
hair and skin is at risk
• Any age group can be affected
• Sex – Both males and females are affected
8. Pathogenesis
• The solar spectrum is composed of about 40% visible light rays (400
to 700 nm), 50% infrared light rays (700 to 20,000 nm), and 9%
ultraviolet (UV) light rays (100 to 400 nm). UVA rays (320 to 400 nm)
penetrate more deeply into the skin than UVB rays do, and UVA rays
are associated with photosensitivity reactions
• Prolonged exposure to shorter wavelength UVB solar rays (290 to 320
nm) causes phototoxicity (sunburn), directly damaging keratinocytes
and causing superficial skin blood vessel dilatation and leakage
9. • . Sun damage of epithelial structures subsequently leads to increases
in inflammatory cytokines, prostaglandins, and leukotrienes as well as
toxic oxygen intermediates that perpetuate and amplify tissue injury.
• Prolonged and repeated sun damage leads to keratinocyte
proliferation, mutagenesis and premalignant actinic keratoses, which
can progress to invasive squamous cell carcinoma.
10. • Melanin present in pigmented skin absorbs UV rays, which in most
cases helps prevent deeper UV light penetration and actinic damage.
• Black skin absorbs about 45% more solar radiation than white skin
does. UV light contributes little in terms of thermal or heat burden,
where as visible radiation can penetrate into the skin and create
thermal injury and necrosis
11. Clinical signs
• Sun damage usually occurs on non pigmented thinly haired areas
such as the flank, inguinal and axillary areas, and the dorsal nose, but
it can occur on the dorsal and lateral trunk and lateral limbs as well as
other areas.
• In dogs that prefer to lie on one side of their body, lesions may be
worse on the more chronically sun-exposed side.
• The duration and intensity of sun exposure influence the degree of
skin damage.
12.
13.
14. • . The initial signs of actinic damage are erythematous, scaly lesions,
which may be tender. With repeated sun exposure, actinic folliculitis,
follicular cyst formation, and dermal fibrosis occur.
• In dogs with pigmented areas on their skin, there is often sharp
demarcation between areas of normal skin with protective pigment
and damaged non pigmented skin
17. Solar-induced lesions of
patchy erythema,
alopecia, and fibrosis
with comedones and
scattered small bullae on
the dorsolateral trunk of
an American bulldog.
18. Solar dermatitis on
the inguinal area of
an American bulldog.
After years of sun
damage, a large
squamous cell
carcinoma has
formed.
19. • With chronic sun exposure, damaged areas become thickened and
scarred with comedones, erosions, ulcers, crusts, and draining tracts.
• Secondary bacterial pyoderma is common. Sun-induced skin tumors
such as squamous cell carcinoma , hemangioma, and cutaneous
hemangiosarcoma may occur.
• The pruritus associated with solar dermatitis is usually otherwise
minimal.
20. Diagnosis
• Diagnosing solar dermatitis involves considering a patient's
signalment and clinical signs and ruling out other causes of scaly,
erythematous dermatitis or folliculitis .
• Ultimately, skin biopsy and histology are used to diagnose solar
dermatitis and solar-induced neoplasia.
• Depending on the degree of secondary bacterial infection, systemic
antibiotics may be indicated for two to three weeks before biopsy to
ensure that infection does not alter histologic interpretation.
21. • Additionally, clearing secondary skin infection also increases the
likelihood of correctly selecting solar-induced rather than infection-
induced skin lesions for biopsy.
• Biopsy can be performed by administering lidocaine locally and
obtaining multiple skin punch or excisional biopsy samples of
different lesions
22.
23. • In early cases of solar dermatitis, histologic examination shows
variable degrees of perivascular dermatitis, folliculitis, and dermal
fibrosis or increased collagen accumulation or collagen damage.
• Solar elastosis (linear bands of degenerated basophilic elastin
accumulation arranged parallel to the skin surface) may be seen.
• In chronic cases, histologic examination may show follicular cysts,
pyogranulomatous inflammation, and precancerous actinic keratosis
or neoplastic cells.
24.
25. Treatment
• The best treatment for canine solar dermatitis is prevention. Educate
owners of at-risk dogs about the need for sun avoidance .
• Also tell owners of affected and at-risk dogs that oral and topical
medications cannot replace sun avoidance in treating and preventing
solar dermatitis.
26. • The main treatment recommendation for solar dermatitis is
restricting sun exposure by keeping the dog indoors during the day,
especially between 9 a.m. and 3 p.m., which is considered the most
intense UV radiation time.
• If some sun exposure is unavoidable, then frequent (twice a day11)
topical application of a waterproof, high-SPF sunscreen (a product
with an SPF > 15 absorbs more than 92% of UVB rays12 ) that is
labeled as safe for puppies and that protects against UVA and UVB
rays is indicated.
27. Beta-carotene or acetretin
• To decrease sun damage, beta-carotene (30 mg orally b.i.d. for 30
days then 30 mg/day for life) in combination with anti-inflammatory
doses of oral glucocorticoids may be effective in early cases.
• Skin damage may also be reduced by administering oral retinoids
(synthetic vitamin A analogues, which are more potent and less toxic
than vitamin A ) such as acitretin at a dosage of 0.5 to 1 mg/kg orally
every 24 hours.
28. Vitamin A
• The dosage of oral vitamin A in dogs should not exceed 400
IU/kg/day, and patients should be monitored for the same potential
side effects as listed for retinoids.
Pentoxiphylline
• This medication can improve circulation to the skin, thus assisting
with perfusion and healing.
29. Imiquimod
• Actinic keratosis in people may be helped by using a topical
immunomodulator such as imiquimod
• Imiquimod's mechanism of action involves inducing local antitumor and
antiviral immune responses by stimulating lymphocytes, dendritic cells,
and macrophages
• The cream is left on the skin for eight hours before being washed off with
mild soap and water. Side effects include localized redness, crusting,
burning, and pruritus at the site of application. In dogs with more extensive
lesions of solar dermatitis
30. Monitor for disease progression
• Even with future sun avoidance, prior skin damage can still progress
to skin neoplasia months or years after exposure .
• Once skin neoplasia has occurred, aggressive surgical resection or
laser therapy should be performed. In addition, if large or invasive
masses are present, screening for metastasis to draining lymph nodes
and internal structures is necessary.
31.
32. Feline solar dermatitis
• It is a chronic actinic dermatitis of white ear and occasionally the
eyelids , the nose and lips of cats .
• Caused by repeated sun exposure
• The etiology and pathogenesis remains as same as the canine solar
dermatitis
• Affects more in 3 months of age and those with white and blue eyes
33.
34.
35. Clinical findings
• Earliest sign is erythema and fine scaling of margin of pinna .
• Hair is lost making it more access to sunlight
• In advance cases consist of severe erythema of pinna , peeling of skin
and mild pruritus seen
• Margins may be curled
36.
37.
38. • Actinic keratosis or invasive squamous cell carcinoma can develop in
some cases
• Cancerous changes can take in cats more then 6 years of age and
sometimes also observed in 3years
• Squamous cell carcinoma is local and ulcerated and hemorraghic
39. Diagnosis
• Diagnosing solar dermatitis involves considering a patient's
signalment and clinical signs and ruling out other causes of scaly,
erythematous dermatitis or folliculitis.
• Ultimately, skin biopsy and histology are used to diagnose solar
dermatitis and solar-induced neoplasia.
40. • Histopathology study shows that in early stages , superficial
perivascular dermatitis (spongitic, hyperplastic changes) is present
• Vacuolated (sun burn cells) may be seen
• Solar elastosis is noted
• With formation of squamous cell carcinoma , the epidermal surface is
ulcerated and dermis is invaded by nests of polyhedral epithelial
tumors cells
• In advance cases the masses of tumor tissue gets extended to level of
cartilage
41. Treatment
• Keep ear protected with water proof sunscreen cream or spray
• Beta Carotene – 25 mg TD P/O
• Carotiniods quench the triplet state of singlet oxygen and free radicals
from complex which is damaging the skin
• If retinoid treatment is ineffective superficial radiation with hand held
strontium probe is beneficial
• If all this above therapy don’t work then radial amputation of pinna
is done
