What are nail bed tumors?
The nail bed is part of the nail matrix that contains blood vessels, nerves, and melanocytes (melanin-producing cells). As
the nail is produced by the root, it streams down along the nail bed, which adds material to the undersurface of the nail
making it thicker.

How common are nail bed tumors in cats and dogs?
While no specific breed appears to be at higher risk, one study showed that approximately 25% of dogs with malignant nail
bed tumors had black coat. While primary nail bed tumors are rare in cats, other types of cat cancers often metastasize
(spread) to the nail bed location, particularly bronchiolar adenocarcinoma, lung and skin squamous carcinoma, and
apocrine sweat gland carcinosarcoma.

What are the symptoms of nail bed tumors in cats and dogs?
The typical symptoms are the presence of a mass at the nail bed, lameness (limping), and ulceration. Nail bed squamous
cell carcinoma (SCC) occurs in older dogs (average age of 9 years) and approximately 75% of cases involve large breeds
and over two thirds have black coats. These SCC tumors are often ulcerative and bleeding, and the associated nail may
be broken or missing. The bone is almost always destroyed at the site of the tumor. Nail bed melanomas are potentially
malignant tumors with a high risk of metastasizing (spreading) to distant organs.

How is the diagnosis made?
X-rays of the affected paw are done to assess the presence of a mass and to detect any bone destruction. Approximately
75% of primary nail bed tumors will result in local bone destruction. Nail bed tumors become often infected and can be
initially misdiagnosed as osteomyelitis (bone inflammation) or nail infection. In order to determine the exact nature of the
mass, either
cytologic or histopathologic analysis of the mass should be done in order to design an appropriate treatment
strategy and predict the pet's prognosis. The commonly used diagnostic procedures for skin tumors are fine-needle
aspiration cytology and
tissue biopsy. Cytology is an important tool that can help the veterinarian distinguish a tumor from
inflammatory lesions and to evaluate whether the present mass spread to the lymph nodes but only histopathologic
examination of the tumor can definitively establish the tumor's type, grade (level of aggressiveness), what treatment is most
appropriate and prognosis about future behavior. Depending on the tumor type and its known level of aggressiveness,
additional diagnostic tests can include blood tests to assess the overall health of the pet, chest X-rays to check for lung
metastasis, and abdominal ultrasound to check for metastasis to other internal organs (eg liver, spleen).

Does cancer cause pain in pets?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.

To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

What are the treatment options for cats and dogs with nail bed tumors?
The recommended treatment for nail bed tumors is amputation of the affected digit (finger/toe) in order to prevent the
tumor from growing back. Additional treatment for SCC does not appear to be required in most cases. In contrast,
malignant nail bed melanomas typically require additional treatment but radiation therapy and chemotherapy have shown
only a modest benefit. In March 2007, the U.S Department of Agriculture granted a conditional approval of a DNA vaccine
against dog oral melanoma. The vaccine was developed through a partnership between Merial, Memorial Sloan-Kettering
Cancer Center (MSKCC) and The Animal Medical Center (AMC) of New York. Clinical studies of the vaccine in dogs
showed significantly longer life spans even in dogs with advanced stages of oral melanoma. The vaccine is administered
via a new Canine Transdermal Device, which delivers the vaccine without the use of a needle. The approved protocol for
oral mealnoma involves administration of a dose of the vaccine every two weeks for four treatments, followed by a booster
dose every six months. Although not approved specifically for nail bed melanoma, some veterinary oncologists offer this
option.

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

Are there any clinical trials investigating new treatments for nail bed tumors?
There are available clinical trials investigating new treatments for melanoma in dogs (although some only recruit patients
with oral melanomas), which are either partially or fully funded. To learn more about trials, please visit the
Melanoma
Clinical Trials section.

Additionally, there are several clinical trials available for cats and dogs with any tumor type for which your pet may qualify.
To learn more these trials (which are partially or fully funded by the institutions), please visit the
Dog Clinical Trials (any
tumor type) or Cat Clinical Trials (any tumor type) section.  

To learn more about clinical trials open to enrollment in the United States, please visit the
Clinical Trials for Melanoma
section.

What is the prognosis for cats and dogs with nailbed tumors?
Approximately one third to one half of malignant melanomas will develop distant metastasis, namely to the regional lymph
nodes and the lungs. Amputation of the affected digit controls the local tumor but recurrence (coming back) occurs in
about 30% of dogs. Approximately half of the dogs diagnosed with malignant nail bed melanoma die as a result of distant
metastasis. Nail bed soft tissue sarcomas are typically aggressive within their local region but rarely metastasize to distant
organs, providing the dogs with good prognosis following surgical treatment. Mast cell tumors of the nail bed in the dog are
usually aggressive and these dogs face poorer prognosis. The prognosis for cats with metastatic nail bed tumors is very
poor, with a median survival time of approximately 1.5 months. Amputation of the affected area rarely helps because the
tumor typically spreads to other areas very quickly. Nail bed SCC in cats has somewhat better prognosis, although the
reported median survival is only about 3 months.

Sources:
  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998.
Nail Bed Tumors in Cats and Dogs
PET CANCER CENTER
Comprehensive guide to cancer diagnosis and treatment in cats and dogs
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 4/10/13
NAIL BED TUMORS IN CATS AND DOGS
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