Skin Cancer
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Our guide has been authored by qualified veterinarians, but should not be taken as substitute for medical advice or professional veterinary consultation. If your pet displays any unusual symptoms, we strongly advise seeking guidance from a veterinarian
Understanding Skin Cancer in dogs
Skin growths are among the most frequently diagnosed and treated conditions in veterinary practice, particularly in dogs. These growths encompass a variety of types, including mast cell tumors, tumors originating from skin nodules and hair follicles, squamous cell carcinoma, melanoma, histiocytoma, and cutaneous lymphoma. While many of these growths are benign and pose no significant threat, it’s important to note that some may exhibit local invasiveness and possess the potential to metastasize to other organs of the body, warranting closer attention and intervention.
Sharon's story
Just as Sharon, the 5-year-old boxer, was wrapping up another routine check-up at the clinic, her owners recalled noticing a small lump on her cheek a few days prior - a tiny, swollen, reddish bump. With a quick 3-second prick, a sample was collected. Within 10 minutes, results indicated suspicion of mast cell tumor growth. The vet conducted blood tests and an abdominal ultrasound to rule out any metastasis in the internal organs. Two days later, Sharon underwent surgery for its removal. When the biopsy results returned, they confirmed it was a mast cell tumor. Sharon was then referred to a veterinary oncologist who devised a chemotherapy regimen for her over several months, which she endured. Almost 8 years have passed since, and Sharon still graces us with her presence.
Skin Cancer's Causes: Uncovering Triggers
Like in most cancer cases, it’s not precisely known why some dogs will develop tumors and some won’t. However, several risk factors have been identified:
- Genetics – certain breeds are more prone to develop different types of skin tumors.
- Prolonged exposure to chemical substances like pesticides
- Previous exposure to certain viruses
- Increased exposure to sunlight – some tumors appear mainly in areas exposed to sunlight without fur.
Recognizing Skin Cancer: Signs and Symptoms
- Skin lesion/subcutaneous lumps: it may appear completely benign, like a spot or a bump on the skin's surface, or as an exuding, itchy, or bleeding sore. In many cases, the lesion won't bother the dog, while in others, they may lick or scratch it persistently.
- Mast cell tumors: these usually appear as raised, reddish lesions on various skin areas.
- Melanomas: these appear as dark-colored lesions.
- Histiocytomas: these usually appear as raised, red lesions.
- Tumors of hair follicles and sebaceous glands: these typically appear as small, cauliflower-like growths.
Skin Cancer Diagnosis: How it's Identified
Your veterinarian will commence with an assessment at the clinic, evaluating the size, appearance, and location of the lesion or lump. Typically, a straightforward examination procedure called cytology will be conducted without the need for anesthesia, involving needle aspiration and microscopic examination of cells. Based on this evaluation, a decision will be made whether to proceed with a complete removal procedure under anesthesia or to opt for a partial biopsy of the growth, especially in cases where complete surgical removal is challenging due to size or location. The biopsy will confirm the tumor type, its benign or malignant nature, and assess its severity. If there’s suspicion of an aggressive or invasive tumor, further staging tests will be carried out depending on the suspected tumor and its location – including X-rays or ultrasound – to ascertain the depth of the skin tumor, involvement of lymphatic vessels, and potential spread to organs such as the spleen, liver, lungs, or brain.
Treating Skin Cancer: Options and Approaches
Since there are many types of skin tumors in dogs, each treatment plan will be tailored to the type of tumor, its location, and its stage. In cases of early diagnosis, many of these tumors can be fully treated and cured. The treatment will typically involve one or more of the following elements:
- Surgery – for tumors not diagnosed conclusively by cytology, or with suspicion of invasiveness or malignancy, surgical removal under full anesthesia is recommended. Sometimes surgical removal alone will suffice and constitute the entire treatment plan, while other times it will be part of a broader treatment plan.
- In clear cases of benign tumors that don’t bother the animal, periodic follow-up may be recommended.
- Chemotherapy – this treatment will be given orally or through injection. Chemotherapy is effective for certain types of skin tumors or as a complementary treatment after surgical removal.
- Non-chemotherapy drug treatments may be given in some cases to evaluate the impact or reduction of the tumor – antibiotics, for example, in tumors with secondary bacterial infection, or antihistamines and steroids that can significantly reduce mast cell tumors before surgery.
- Radiation therapy – suitable for certain types of skin tumors, especially those located in anatomical areas where surgical removal is not possible. It’s a very effective method for some tumors, but only available at specialty hospitals.
Skin Cancer: Surprising Facts
Between 60-70% of skin tumors in dogs are benign, and most of them appear on the limbs.
Mast cell tumors have a "strange" tendency to react dramatically - they may swell and become inflamed after diagnostic puncture and then shrink, sometimes disappearing completely after treatment with antihistamines and steroids.
Melanoma is more common in dogs with dark fur, and its aggressiveness depends on its location. Melanomas that appear on the digits and oral cavity of dogs are usually more aggressive and likely to have already metastasized.
Vet's Tip: Dealing with Skin Cancer
When your veterinarian recommends surgically removing a skin tumor, especially if there’s suspicion that it’s an invasive and/or metastatic tumor, they’ll try to do so with the widest and deepest “margins” possible to ensure complete removal. So don’t be alarmed if, in many cases, the incision ends up being much larger than the tumor that was removed. Additionally, it’s always advisable to send the removed tumor for histopathological examination, which can definitively tell us everything possible about the tumor – how aggressive it was and whether it was completely removed – so that we can develop an ideal treatment and follow-up plan moving forward.
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Latest in Research and Treatments
For diagnostics, an Israeli team comprising an oncologist and a specialized veterinarian has introduced a thermography-based device capable of diagnosing numerous skin tumors without requiring needle punctures or tissue biopsies. The device is simply applied over the skin tumor, akin to an ultrasound examination, and is currently undergoing initial clinical trials.
In the realm of treatment, there is a growing focus on immunobiological therapies, which stimulate the immune system to identify and combat tumors autonomously. These innovative treatments are anticipated to revolutionize cancer therapy for pets in the future.
dogs breeds Prone to Skin Cancer
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