What is Melanoma in Dogs?
Melanoma is a type of tumor that develops when the melanocytes (pigmented cells) start reproducing abnormally forming masses, lesions, or nodules. Melanocytes are specialized cells that produce the pigment melanin.
The tumors can be malignant (malignant melanoma) or benign (melanocytomas). Malignant melanomas are metastatic and quickly spread to other areas of the body such as the lungs, liver, and regional lymph nodes.
Based on location, there are several types of melanoma in dogs:
- Oral Melanoma. Canine oral melanoma is the most common melanoma type (accounts for up to 80% of all melanoma cases. Melanoma tumors in the oral cavity are malignant tumors – invasive and with high metastatic rates.
- Nailbed Melanoma. The nailbed (subungual crest) is another common melanoma site. This melanoma type presents in 15-20% of the cases. Nailbed melanoma is metastatic and usually spreads to regional lymph nodes.
- Dermal Melanoma. Cutaneous melanoma affects the dog’s skin and manifests with dark lesions. The lesions can be solitary or irregularly distributed in different locations. Most dermal melanomas are benign.
- Ocular Melanoma. Ocular melanoma may develop on various eye tissues such as the eyelid, conjunctiva, and uvea. Most eye melanomas are benign. However, due to their location, they are problematic and impair vision unless removed.
How Serious is Melanoma in Dogs?
Melanoma in dogs can be very serious. Malignant melanomas grow uncontrollably, causing pain and becoming unmanageable in size. Plus, they tend to spread to other organs quickly.
Considering the aggressive nature of melanoma, diagnosed dogs usually die within a year of the time of diagnosis, even if adequate and prompt treatment is provided.
What do Melanomas Look Like on Dogs?
Melanomas usually appear as dark pigmented patches. The lesion may be flat or raised like a bump. Some melanomas are amelanotic – non-pigmented (reddish or pink).
In the advanced stages, the tumor lesion may increase in size and become ulcerated. If this happens, then they start bleeding.
What Causes Melanoma Cancer in Dogs?
The exact cause of melanoma in dogs is unknown. Usually, canine melanoma is caused by a combination of genetic and environmental factors such as:
- Age. Older dogs are at a higher risk of developing canine melanoma. The average age of melanoma diagnosis in dogs is ten years or older. However, oral tumors can also occur in younger dogs.
- Excessive Skin Licking. First Vet states that excessive licking of one spot may stimulate the melanocytes to start multiplying uncontrollably. Over time, this may lead to mutation and tumor formation.
- Sun Exposure. The exact role of sun exposure in melanoma development is unclear. This is confirmed by ASPCA Pet Insurance. However, the site mentions that melanoma is more common in light-colored dogs and in non-hairy body areas.
Sun exposure, unlike in humans doesn’t appear to play a role in determining risk for melanoma in dogs.
What are the Symptoms of Melanoma in Dogs?
The clinical signs and symptoms of melanoma in dogs depend on the type of cancer. Here is a general overview of the possible manifestation:
- Bad breath (halitosis)
- Unusual chewing behavior
- Refusal to eat
- Excessive drooling
- Weight loss
- Limping or lameness
- Dark skin patches
- Difficulty breathing.
If your dog is exhibiting any of these signs and symptoms, see your vet as soon as possible for a proper diagnosis.
Diagnosing Melanoma in Dogs
Diagnosing melanoma in dogs starts with a physical examination. Since the primary tumor is visible, the vet will inspect its physical characteristics (swelling, ulceration, or bleeding).
To confirm the diagnosis, the vet must perform fine-needle aspiration (FNI) and biopsy. The analysis of the specimen taken with FNI is called cytology, and with biopsy – histopathology.
FNI and biopsy will confirm the diagnosis and then help with tumor staging. The procedure is called mitotic index – the percentage of melanoma cells undergoing mitosis (cell division) at a time. It is used as a measure of how fast the tumor is expected to grow.
To evaluate the dog’s overall health and check for metastasis, the veterinarian will perform blood tests, urinalysis, chest x-rays, abdominal ultrasounds, MRI, and CT scans.
How do You Treat Melanoma in Dogs?
There are several mainstream treatment options for melanoma in dogs – surgery, radiation therapy, chemotherapy, and immunotherapy.
Surgery. Surgical removal of the lesion is the treatment of choice for small melanomas that have not spread. In some cases, a veterinary oncologist might suggest surgery for palliative reasons. For toenail melanomas, the surgeon will perform an amputation of the entire toe.
Radiation Therapy. Radiation is often used for tumors that have spread in conjunction with surgery to improve the treatment outcome. Radiation is started two weeks after the tumor is removed and may prevent or delay tumor regrowth.
Chemotherapy. Chemo is sometimes suggested as part of the treatment plan. The usually used drug is carboplatin. Chemotherapy for melanoma in dogs is given in four to six doses, every three weeks.
Immunotherapy. There is a melanoma vaccine developed for the treatment of melanoma in dogs and is used in conjunction with surgery or radiation. A dog with melanoma will need a few initial doses and then booster doses.
In addition to medical treatment, ask your vet about some of the holistic cancer treatments you can offer your dog. Popular available options are diet and CBD.
Diet. Special diets are particularly important for dogs with oral melanoma. This is because the lesion’s presence in the mouth is uncomfortable or even painful. Your vet or a veterinary nutritionist should be able to tell you what foods are best for your dog.
Cannabidiol (CBD) Products. CBD has many health benefits but the most relevant for a dog living with cancer would be anxiety and inflammation relief. When choosing pet CBD for your dog, opt for pet-safe vet-approved brands such as Honest Paws.
What is the Melanoma Vaccine for Dogs?
The melanoma vaccine, also known as OnceptⓇ, is a specific type of melanoma treatment. It consists of an injection that triggers the dog’s immune system to destroy cancer cells.
Initially, the canine melanoma vaccine is administered in four doses, one every two weeks. Then, the dog needs a booster dose, every six months. The vaccine has minimal side effects and is well-tolerated.
The melanoma vaccine can be used alone or combined with other treatments. In general, it works for dogs with stage II and stage III tumors.
However, do not be confused by the name. Despite the name and unlike vaccines, OnceptⓇ is not used for melanoma prevention. Instead, it is used as a treatment.
How Effective is the Melanoma Vaccine for Dogs?
So far, the melanoma vaccine for dogs is very effective. The vaccine has shown great results in prolonging life expectancy in dogs with melanoma.
In a study from 2015, the median survival time for dogs treated with the melanoma vaccine was 29 months. Considering, the average survival time with other treatment options is less than one year, this is a positive result.
According to Edwin Brodsky, DVM, Diplomate ACVIM (Oncology), the melanoma vaccine is not a substitute for other treatments. In fact, the vaccine is most effective if local control is achieved via surgery and/or radiation therapy.
How Much Does the Canine Melanoma Vaccine Cost?
The canine melanoma vaccine costs between $1000 and $1500 per dose. This can vary significantly depending on your location and pet health insurance policy.
What can I do to Prevent Melanoma in Dogs?
There isn’t one thing you can do to prevent melanoma in dogs. However, there are several pet owners can do to decrease the risk of this skin cancer. Here are some tips:
- Provide a Healthy Diet. A good canine diet consists of meat-based foods and occasional additions of health-boosting fruits (apples, blueberries) and vegetables (carrots, celery, kale, broccoli, spinach), rich in vitamins, minerals, and antioxidants.
- Regular Physical Exercise. Encourage your dog to participate in some form of physical activity such as walking, hiking, and playing outdoors. This not only helps to maintain a healthy weight but also improves general wellbeing.
- Limited Sun Exposure. According to VCA Hospitals, the role of UV lights in melanoma in dogs development is not established. However, it is better to be cautious and keep your dog protected from sunlight, especially if light-colored and with short hair.
- Regular Vet Checkups. See your vet as often as needed to confirm that your dog is in good health and if not, that it gets treatment in time. Regular veterinary care is critical for monitoring your dog’s health and wellbeing.
In case your dog gets melanoma, you need to provide the best treatment possible. However, this is often expensive, with vaccination alone costing up to $10.000.
How Long Does a Dog Live With Melanoma?
According to Blue Pearl Vet, the median survival time for dogs with melanoma depends on the cancer’s stage (time of diagnosis) and type of treatment.
Surgically treated dogs with stage I melanoma usually live around 17-18 months, dogs with stage II between 5 and 6 months, and dogs with stage III melanoma live for 3 months. Dogs with stage IV melanoma (and lung metastasis) usually live only a couple of weeks.