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We love having our four-legged companions join us on our summer outings! However, in addition to heat stroke and scorched paws from hot asphalt, the sun can also damage your pet’s skin. From burns to long-term solar damage (actinic damage) to the skin, our furry friends are not immune to the negative side of UV rays.
Below, we’ll cover three major diseases caused by prolonged sun exposure: dorsal thermal necrosis, actinic skin damage, and solar-induced skin cancers.
Dorsal Thermal Necrosis
Dorsal thermal necrosis is a true thermal burn caused by prolonged direct sunlight. Although this type of burn is relatively uncommon, it may occur with high temperatures and prolonged sun exposure. Extreme exposure results in accumulation of heat, leading to a deep thermal (heat-induced) burn. As the name implies, these burns most commonly occur on the back (dorsum) of the animal. Dark-coated, particularly black-haired, dogs seem to have an increased risk. Short hair coats also appear to be an additional risk factor for development of dorsal thermal necrosis.
These injuries are most common during the summer, especially during high, peak sun hours (10 am – 4pm). Like many other types of burns, it can take several days to develop lesions from solar injury. Initial signs include tenderness, pain, or redness of the skin in affected areas. Over time, these lesions may progress to ulcerations and eschar (scab) development.
Some pets may experience signs of heat stress or heat stroke, and then subsequently develop skin lesions. Depending on the size of the area that is burned, supportive care or hospitalization may be necessary. These burns are treated like any other type of thermal burn, with antibiotics as needed, bandaging, and pain medications. In rare cases, surgery is required to help heal the wounds. Prevention is key to avoid these types of injuries. Avoiding outdoor activity during peak hours and high heat are ideal prevention measures. However, there are protective cooling vests that can be used during outdoor activity to reduce the risk.
Actinic Dermatitis (Solar Damage)
Solar damage is a progressive disease resulting from chronic exposure to the sun. It is commonly found in areas of thin or lightly-pigmented haired or thinly-haired areas, like the belly and groin. Actinic damage is most common in short-coated, light-colored dogs.
Clinical signs including redness, comedones (blackheads), and erosions or ulcerations. Progression of solar damage can lead to actinic furunculosis (rupture of the hair follicles) and, subsequently, a secondary cellulitis, which can be painful or pruritic. Actinic damage can mimic allergies, so a full history of sun exposure is important.
Solar damage is common for outside dogs and chronic sunbathers. It can have neoplastic progression, leading to development of squamous cell carcinomas or cutaneous hemangiomas/hemangiosarcomas.
Humans with sun damage are more at risk of developing melanomas, basal cell carcinomas, and other skin neoplasia. In dogs, the most common solar-induced cancers are hemangioma/hemangiosarcomas and squamous cell carcinomas.
Chronic sun damage leads to mutations in the DNA of the skin cells, which leads to neoplastic (cancerous) transformation. Squamous cell carcinomas are abnormal proliferation of the squamous cells. They present as flesh-colored firm nodules, which may be ulcerative.
Hemangiomas/hemangiosarcomas are abnormal proliferations of vessels and appear as blood blisters or blood-filled nodules. Surgical excision is generally recommended for these types of tumors. Most are locally aggressive, but can spread to other areas of the body.
Ultimately, an ounce of prevention is key in these cases. Sun avoidance during peak hours and sun protection is most important during the summer, but can be an issue year-round in areas at higher altitudes. We all want to have fun in the sun, but don’t forget to protect your pets!