Canine Cancer:  New Weapons for the Fight

Canine Cancer: New Weapons for the Fight

by Diana Bocco

While the word “cancer” is one that no pet parent wants to hear, many things have changed in the past decade.

“New anti-cancer therapies are constantly being developed and tested, and some cancers that were previously incurable can be effectively managed for months or even years,” says Annette M. Sysel, DVM, president of the Bauer Research Foundation and winner of the 2015 American Hero Veterinarian award.

In fact, Sysel –who works tirelessly to improve diagnostics and treatments for cancer — points out that some cancers can now be managed fairly well.

“Pet owners now have a wide range of resources, including veterinary oncologists, clinical trials, and holistic veterinary practitioners, at their disposal to help them make informed decisions about their pet’s cancer, positively impact their pet’s survival, and improve their pet’s quality of life,” Sysel adds.

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Annette M. Sysel, DVM

Identifying and Understanding Cancer

Cancer doesn’t differentiate among species, although there are differences when it comes to types and how cancer behaves in dogs vs. humans.

“Dogs develop the same cancers that humans do, albeit at a different frequency,” explains Dr. John Chretin, head of oncology at VCA West Los Angeles Animal Hospital  “The example would be mast cell tumors, which happen to be one of the three most common that dogs develop but are considered to be quite rare in humans.”

Another thing that impacts how cancer behaves in dogs? Dogs cannot complain about their ailments, says Chretin.

“Dogs can’t tell us they have tenderness somewhere that is not going away, fatigue, or that they noticed a new bump somewhere on their body,” Chretin explains. “They have to rely on us to be able to notice those changes.”

And it’s easy for those signs to go unnoticed or simply assumed to be a normal part of growing older.

Chemo Beads and Cisplatin

One of the newest forms of treatment for canine cancer is chemo beads, a type of dissolvable bead that contains the chemical Cisplatin.

“Cisplatin is a chemotherapy agent that is used to treat various types of solid tumors, such as some skin tumors, some bladder tumors, and bone cancer,” explains Darren Wright, DVM, owner of Kaibab Animal Hospital in Scottsdale, Arizona, who specializes in cancer treatment. “Cisplatin was originally developed as an injectable chemotherapy agent that was given intravenously, but is now also used by directly injecting it into certain types of tumors.” 

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Darren Wright, DVM

Eventually, scientists figured out that Cistaplin could be infused into implantable beads that can be surgically placed at the location of the tumor to deliver a high concentration of drug right in that area. 

“The local levels are higher than could ever be reached by giving the medication intravenously,” Wright explains. “The use of beads allows for the high-dose, long-term application of the medication, as the beads are designed for sustained release over time.”

The use of beads is becoming a more popular way to deliver medications directly to the area where they’re needed. This is important because chemo drugs are essentially poison.

“When we use medications intravenously, the medication not only affects the tumor but also affects healthy tissue, such as the heart, liver, and kidneys,” Wright says. “When we use beads, we are able to get a high dose of medication right where we want it but limit the dose at the other healthy organs; this targeted therapy can allow for much better response in these tumors.”

While the use of beads offers some great benefits, they can’t be used for every type of cancer.

“Cisplatin beads are more suited for some ‘solid state tumors’ where there is a discrete cancerous mass in the body,” Wright explains. “After surgery to remove the tumor, these beads can be implanted into that location to deliver a high-dose of chemotherapy right where the tumor was or, in cases where we can not surgically remove the tumor, we can implant the beads directly into the tumor to try and control the cancer.”

What’s Happening in the Lab

New discoveries in cancer treatment for dogs are happening all the time. One area that is advancing rapidly is immunotherapy. 

“Immunotherapy is a means of either restoring normal immune function or somehow enhancing it to do what it was intended,” Chretin explains.

While immunotherapy is still in its infancy and in many ways still limited to research, vaccines (a form of immunotherapy) are advancing rapidly.

“We now have Oncept, a USDA approved vaccine for use in the treatment of melanoma in dogs,” Wright says. “We also now have monoclonal antibody therapy for animals with lymphoma.”

Another significant change has been the establishment of the field of comparative oncology, says Sysel.

“Comparative oncology is the study of cancers that occur naturally in animals, and the findings are used to develop treatments that can benefit both humans and pets,” Sysel explains. “Comparative oncology results in a win-win situation for all — humans benefit because new treatments can be discovered more quickly and cost-effectively, and dogs benefit because they receive access to cutting-edge investigational cancer treatments.”

Detecting Cancer Early

And there is more good news: in addition to treatment, there have also been numerous advancements on the diagnostic side. According to Chretin, one of the biggest ones is flow cytometry.

“It’s a way of taking a large sample of cells (normal and abnormal), isolating the ones of interest, and identifying exactly what they are and what unique aberrancies they might have,” says Chretin.

In the past, obtaining similar information required large biopsies, weeks of waiting, and was very expensive.

“With flow cytometry only very small samples of fluid or tissue are required and within a matter of days we have the results,” he adds.

One thing is certain: the earlier you can catch cancer, the better the prognosis.

“I always recommend every six-month exams in pets by your veterinarian as this is the best time to catch any physical abnormalities,” Wright says.  “However, if your pet is ever starting to lose weight, slow down in activity level, has any strange lumps, especially lumps that are growing in size, it is always recommended to have these issues checked out.” 

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