Sarcomas in Dogs and Cats

Pets are important members of many families, and like any family member, a pet’s cancer diagnosis is an emotional and difficult time. Sarcomas are more common in dogs and cats than in people, particularly in certain dog breeds and at feline injection sites. 

In keeping with our mission to help those affected by sarcoma, the Sarcoma Alliance has compiled helpful information on finding support and treatment for dogs and cats with sarcomas.

Dog and cat cancer facts:

  • Approximately 1 of every 4 dogs will die of cancer.
  • About 15 percent of skin lumps and 7 percent of subcutaneous lumps in dogs are soft-tissue sarcomas.
  • About 1 in every 10,000 cats will develop an injection-site soft-tissue sarcoma.
  • In contrast to many breeds of dogs, osteosarcomas are rare in cats.
  • Certain dog breeds appear to be at higher risk for developing sarcomas, including:
    • Hystiocytic sarcoma – Rottweiler, Flat-Coated Retriever, Bernese Mountain Dog
    • Soft-tissue sarcoma – Labrador Retriever, Golden Retriever
    • Osteosarcoma (more often in large breeds) — Golden Retriever, Rottweiler, Greyhound, Flat-Coated Retriever, Afghan Hound, Irish Wolfhound,  Great Dane
    • Hemangiosarcoma – German Shepherd Dog
    • Liposarcoma – Shetland Sheepdog



By treating dogs with cancer, veterinarians gain important insights into improving treatments for humans.


Dr. Stephen Withrow

This has special significance for people with sarcoma because “sarcoma is five times more common in dogs than humans,” said Stephen Withrow, DVM, DACVS (surgery), DACVIM (oncology), professor of surgical oncology at Colorado State University in Fort Collins and the founding director of its Flint Animal Cancer Center, the largest such center in the world.

The many sarcoma subtypes diagnosed in people are well represented in dogs, said Christina Mazcko, a biologist who manages the National Cancer Institute‘s Comparative Oncology Program. The subtypes include osteosarcoma, chondrosarcoma, synovial sarcoma, leiomyosarcoma, gastrointestinal stromal tumor (GIST), hemangiosarcoma (angiosarcoma) and other soft-tissue sarcomas.

Dr. Withrow is the only veterinarian admitted as a member of the Musculoskeletal Tumor Society. The surgeon also belongs to the Children’s Oncology Group. He’s proud that he has served as a resource for surgeons who operate on humans.

“Physicians are not always aware of what’s happening in animal studies, but some have realized we see more sarcoma cases than they do.”

Colorado State’s veterinary school is one of 20 across the United States and Canada that work with the NCI in the Comparative Oncology Trial Consortium, said Dr. Withrow, past president of the Veterinary Cancer Society.

“We can do so much more together than we can as single institutions.”

Nine clinical trials have been completed, and two are underway. More than 150 pet owners have participated, and board-certified veterinary oncologists supervise the dogs’ care. What veterinarians learn is then integrated into studies of cancer biology and therapy in humans, Mazcko said.

“Along the way, the dog has helped with imaging; the safety and efficacy of chemo delivery; radiation dose responses; and giving chemo in arteries,” Dr. Withrow said. Treating dogs with cancer also has been useful in discovering what doesn’t work or doesn’t work as well as hoped, he said. “We proved hyperthermia had only mild improvement in local control.

“Fighting sarcoma is like slogging through mud. It’s not a sprint. There are no home-runs but we’ve made progress.

“A major breakthrough in osteosarcoma was MTP-PE [mifamurtide], an immunotherapy popularized by a vet.” Half of the dogs who received it benefited, but when it was tested in humans, only 15 percent got a response. “The drug was sold to a company in Europe, and it’s no longer available in the U.S.” He calls the stalemate between pharmaceutical companies and the FDA “sick.”

“For pharmaceutical companies, the target is humans, where they can charge these inordinate prices.” In general, people won’t pay as much to treat their dogs. Plus, companies fear that, if they test their drugs in dogs first and side effects occur, the companies will have a harder time getting approval for clinical trials for humans.

Clinical trials for dogs cost less money and give quicker results than those in humans, Dr. Withrow said. “It’s money well spent.”

“Of the estimated 72 million dogs in the United States, up to 1 million are diagnosed with cancer each year,” Mazcko said. Mice are commonly used to study cancer, and they are inbred to develop tumors. They are injected with cancer cells grown in the lab. In contrast, veterinarians are studying cancers that occur naturally in dogs and that “are very similar to those seen in human patients.”

The strong genetic similarity has been demonstrated by the recent completion of the canine genome (the entire set of genetic material in dogs) and the increasing availability of biological and genomic reagents (substances used in a chemical reaction to analyze other substances), she said.

Like people, dogs experience recurrence, resistance and metastasis, she said. Dogs and humans are exposed to similar environmental risks. Dogs are large enough that their imaging studies can be compared to those of humans, and dogs can often tolerate multiple forms of treatment, such as chemotherapy and radiation.

When their cancers have not grown much or spread far, dogs can get experimental treatments not yet approved for humans — even though the new drugs may be less harsh than conventional chemotherapy, she said.

“Although the treatment options and approaches are comparable in dogs and humans, there is no requirement to pursue standard treatments as a first-line option for dogs.”

This gives researchers a chance to answer questions about the drugs that could not be answered in conventional mouse studies or human clinical trials, Mazcko said.

In the 1970s, veterinarians had only crude treatments for animals with cancer, Dr Withrow said. In the next decade, vets began using imaging studies and treatments also used on humans.

In the mid-1980s, Colorado State partnered with the veterinary school at North Carolina State University and biostatisticians at Duke’s cancer center. The National Cancer Institute awarded them a prestigious program-project grant to do clinical trials, and the funding continued for about 15 years, he said.

This partnership pioneered the idea that clinical trials in veterinary medicine would provide better information for cancer treatment in humans than mouse models, he said.


Chand Khanna

“It really was Khanna’s brain child,” he said, referring to Chand Khanna, DVM, PhD, DACVIM, now director of the Comparative Oncology Program, which the NCI’s Center for Cancer Research created in 2003. He also heads the Tumor and Metastasis Biology Section of the NCI’s Pediatric Oncology Branch. “Fortunately, his boss was Lee Helman,” who supported his work.

About 10 years ago, federal grant money started drying up, and the vets doing the research had to look for money from  pharmaceutical companies, others health-care companies, foundations and nonprofits. It was a terrible blow, Dr. Withrow said.

“The Comparative Oncology Trial Consortium is limited only by funding. Great science is all around us.”



Information on COTC clinical trials is available at:

For more information on breed-specific cancers, see:


General  Cancer

Sarcoma Cancers


The Hank Kabel Sarcoma Foundation


Most veterinary schools and some veterinary practices offer advanced treatments for cancer.  A few are listed below.

Ohio State University Veterinary Medicine Center

University of Florida College of Veterinary Medicine

Washington State University

Veterinary Cancer Center

Animal Cancer and Imaging Center

Veterinary Cancer Referral Service – Oregon vets specializing in cancer



Tissue sample available for researchers

Neurotoxin effectively relieves bone cancer pain in dogs, research find

Additional Reading

Breed-Predispositions to Cancer in Pedigree Dogs; ISRN Veterinary Science; Volume 2013, Article ID 941275, 23 pages; Dobson, Jane M; Queen’s Veterinary School Hospital, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 OES, UK



Dr. Jenna Burton with Pants, a 13-year-old cat that was trapped as a feral kitten as part of a “trap, neuter and return” program. She said: “I just never got around to returning her!”

“Sarcoma is a big issue in our kitties as well,” said Jenna Burton, DVM, MS, DACVIM, an assistant professor at Colorado State.

Although rare, sarcoma worries cat owners because of the occurrence of injection-site sarcomas, formerly called vaccine-associated sarcomas. At first, they were thought to arise only when cats got vaccines, she said, but now they also have been associated with other injections, including microchips and injectable flea products. These soft-tissue sarcomas are mostly fibrosarcomas.

About 1 in 10,000 cats will get an injection-site sarcoma, she said. She still recommends cats get vaccines, especially for fatal diseases such as rabies, for their health and the health of humans and other animals.

Veterinarians also are studying needleless transdermal drug delivery, she said.

The Vaccine-Associated Feline Sarcoma Task Force has recommendations on vaccines:

In short, the task force recommends that vaccines containing rabies antigen be given as distally as possible in the right rear limb, vaccines containing feline leukemia virus antigen (unless containing rabies antigen as well) be given as distally as possible in the left rear limb, and vaccines containing any other antigens except rabies or feline leukemia virus be given on the right shoulder, being careful to avoid the midline or interscapular space.

“The current working theory is that some cats are predisposed to an exuberant fibroblastic response to injections,” said Dr. Burton, coordinator of oncology clinical trials at the Animal Cancer Center. “Part of this hypothesis is that it has been reported that cats can get sarcomas in their eyes from chronic infections or previous trauma.”

Sarcoma researchers say injury is not linked to sarcoma in humans, or, if it does occur, it’s very rare. But the link between injections in cats and sarcoma may suggest more research into injections and injuries in humans who have gotten sarcomas, she said.

Cats “rarely, rarely, rarely” get a sarcoma that starts in their bones, she said, and researchers also may want to examine why cats differ from humans in this regard.

Studying how cancer in dogs relates to cancer in humans is a well-accepted model, she said, but that’s not as true in cats, even though they may have tumors that are similar to those that occur in people.

“Cats are their own unique creatures.”

Cats are smaller than most dogs, making repeated blood and tissue sampling for research purposes more challenging, Dr. Burton said. Some people aren’t as willing to seek veterinary care for their cats with cancer, and that results in less research, too.

Some veterinary schools offer clinical trials for cats, sometimes in conjunction with other schools. But she said there is nothing for cats like the Comparative Oncology Trial Consortium.



New Vaccination Guidelines

Soft Tissue Sarcoma



Most veterinary schools and some veterinary practices offer advanced treatments for cancer.  A few are listed  below.

University of Florida College of Veterinary Medicine

North Carolina State

Ohio State University Veterinary Medical Center

Animal Cancer and Imaging Center