Cancer Care for Pets

New innovations and access to data are giving general practice veterinarians and clients something that’s been missing in treating pets with cancer – options.

If you’re looking to get a feel for cancer patient volume among the pet population, BluePearl Malvern is a good place to start. With four medical oncologists and two radiation oncologists, the hospital is the largest on the East Coast of the United States.

Craig Clifford, DVM, MS, DACVIM, and the director of BluePearl Science at the Malvern, Pennsylvania location, said the canine lymphoma cases have been on the rise over the last year and a half. And they’re not the standard garden variety of lymphoma cases either.

“An oncologist views lymphoma the way a surgeon views cruciates – you see a ton of them, and they’re pretty straightforward to treat,” Dr. Clifford said. “But we’ve been seeing a lot more complex cases.”

What’s causing the rise and severity of cases? One factor could be pet owners having difficulty getting in to see an oncologist. Even with the number of BluePearl Malvern’s medical oncologists and radiation oncologists, it still has about a 10-day waiting list.

Or, the issue may be at the initial point of veterinary care. General practitioners are often booked out, and many are unable to take on new clients. “What may be happening is that cases are not getting diagnosed as early as they used to, which means by the time they are diagnosed and set up for the referral, it’s much later, and the dog is sicker,” said Dr. Clifford.

From diagnosis to treatment

Kimberley H. Galligher, VMD, Willistown Veterinary Services, Inc., said she sees, on average, a few cases of canine lymphoma every quarter at her general practice. Those conversations with pet owners are never easy – for the pet owner or the veterinarian. After all, there’s a stigma associated with cancer. The fear of the pain and suffering seen by our human counterparts undergoing chemotherapy alone sometimes draws the line. Most people know someone in their family or life who has had it.

But veterinarians are always having tough conversations, Dr. Galligher said. “It is something, sadly, we’re used to,” she said. “It doesn’t ever make it fun, but it is something we deal with on a daily basis.”

When it comes to diagnosing and treating disease, the goal of veterinarians and veterinary professionals is to provide a quality of life, not a quantity, she said. “Just like we wish for our patients, we also want our clients and ourselves to be able to sleep at night, and we want to be able to treat them without regrets – to know we’ve done our best. So it’s challenging, but it’s something we deal with all the time.”

The first step in treating a dog with lymphoma is to make a diagnosis. A thorough medical history is collected, and a nose to tail physical examination is completed. A body map of enlarged lymph node locations and measurements is created. The diagnostic workup includes: completing fine needle aspirates of enlarged palpable lymph nodes, interpreted either in-house or via a reference lab (either digital or currier), completing serum chemistry, complete blood counts, tick serology, and imaging, if indicated.

All of this is contingent on those services not being cost-prohibitive for the clients.

If the clients are willing, Dr. Galligher will refer them to Dr. Clifford’s oncology practice. Indeed, veterinarians in private practice are often working in conjunction with an oncologist to determine what’s going to be the best-case scenario for treatment. Phenotyping, completed either by the oncologist or by the primary care veterinarian, allows the veterinarians and client to better gauge the prognosis, how aggressive the cancer is, and what kind of treatment is indicated.

With an oncologist, Dr. Galligher said it’s important to have an open line of communication and also be very transparent with the clients about who is in charge of what part of the patient’s care. The general practitioner and oncologist want to provide consistent, comprehensive care.

“We want the experience in our practice and the specialty hospital to be cohesive,” she said. “We let the specialist work on their advanced oncology services, and we can focus on family medicine.”

Dr. Clifford said if the client is willing to see an oncologist, that’s a good sign that they will be willing to move forward with a treatment plan. “If they’re going to make their way to the specialist, they’re likely going to treat because the primary care doctor usually has a good idea of what general costs are and relays that to the client,” he said. “Very few cases come in just for a consult, meaning they want to hear about the information, but they’re not going to treat. Most of the cases, by the time they make it to me, they already kind of have an idea they want to treat.”

Linking data to care

Early detection can be amazingly impactful in treating cancer in pets. That’s why pet insurer Nationwide has been conducting research using its population base with the intent of releasing a solution that will allow pet owners and veterinary healthcare teams to access critical information about specific breeds and specific ages, and specific areas.

In the interim, Nationwide announced some initial results of analyses it has conducted and what it means for certain segments of the pet population. For instance, an analysis in 2022 of Nationwide’s pet health insurance policy and claims data for 1.61 million dogs revealed that the risk of cancer claim increases with dog size.

Nationwide’s white paper, “About the Size of It: Scaling Canine Cancer Risk,” builds on findings in two previous white papers from Nationwide’s Pet Health Analytics and Insights team that examined cancer risk in crossbreds vs. purebreds and in the 25 most popular purebreds. This analysis of policy and claims data for 1.61 million dogs over a six-year period (2015-21) focused on the risk associated with dog size and shows that cancer risk increases significantly with dog size. This finding was consistent across all dogs, purebred and mixed, and across almost all body systems commonly affected by cancer, Nationwide said in a release.

Based on its research, the veterinary team at Nationwide made the following suggestions for pet owners:

• Wait-and-see can be a risky approach to limping: “Large and extra-large dogs are at increased risk of bone cancer as early as 6 years old. Knowing what to look for could help pet families have more treatment options and better long-term pet health outcomes.”
• Timing of routine diagnostics can be guided by data analysis: “Pet families with medium, large, and extra-large dogs looking to catch liver cancer early, for example, may want to consider routine diagnostics from age eight or younger.”
• Not all cancers are “old dog diseases”: “Lymphatic cancers (e.g. lymphoma) are a significantly higher risk to dogs in their middle years than other forms of cancer.”

Dr. Jules Benson, BVSc, MRCVS, chief veterinary officer, Nationwide, said there are many practical implications for how a veterinarian can use data for the benefit of a pet’s health. For example, if you have a 5-year-old Rottweiler, being able to access information that reveals this breed has a 10 times greater risk of bone cancer and then explain what that means from a pragmatic point of view to the pet owner could prove invaluable. Veterinarians could explain during a routine preventive screening that if the pet owner’s dog is limping at any point throughout the year, not treat it like regular lameness. Instead, the Rottweiler owner should bring the dog in “because if we can catch osteosarcoma early, that has massive impacts on successfully treating the disease.”

The same example could be used with bladder cancer in beagles or canine lymphoma in Golden Retrievers and Labradors. “As we started talking about very specific capabilities of the healthcare team to intervene, the more that we can make the pet parent and the pet family a partner in that in terms of early detection, that’s what we’re aiming for,” Dr. Benson said.

The other benefit of this data is its ability to increase the efficiency of the vet team by taking more off their plate. Nationwide believes it can play a role in either providing the information to the pet family so that they can ask about it or creating tools that will allow the healthcare team to hit on the right preventive measures during the pet’s routine visits.

Cancer was a good place to start with the data analyzed because it’s so heavily genetic, Dr. Benson said. For example, analysts saw the differences between the Golden Retriever and Labrador breeds and hybrids like doodles. The degree by which cancer prevalence decreases with hybrid breeds was surprising, he said. In the “Oodles and Doodles” white paper researched, there was a 75% reduction in relative risk between the standard breeds and the offspring. “I don’t think any of us expected it to be so high,” Dr. Benson said. “We thought there would be some reduction in cancer risk because of that dilution of potentially negative genes. Talking to the targeted oncology people, when they talked about the genetic risk of cancer, they talked about it probably being a multifactorial thing, so you could have 15 genes that are responsible for increasing the prevalence of types of cancer. But the fact that you’re diluting so many of them I don’t think we expected the rest to go down that much.”

That finding, and the link between breed size and cancer prevalence, were two big insights that Nationwide hopes veterinarians and pet owners can use immediately, with the goal of releasing more helpful information in the future.

When the client says no

Even with earlier detection, not all clients will want to see an oncologist. The reasons vary – cost, age of the pet, or previous experiences on the human side with the cancer treatment of a loved one. For those clients, it used to be that a general practitioner could offer very little in the way of treatment besides prednisolone. Yet even that option isn’t much of one for some clients. Prednisolone can lead to side effects that are offensive to both the pet and owner. For instance, large dogs taking prednisolone could have to eat and pee frequently – causing accidents in the house. And, sometimes prednisolone is contraindicated because the dog has other health issues.

Recently, another option was made available when the FDA conditionally approved the first oral tablet to treat lymphoma in dogs. In early 2022, Dechra Pharmaceuticals acquired the rights to Laverdia™-CA1 (verdinexor), a novel treatment for canine lymphoma. Laverdia was developed by Anivive Lifesciences, a pet health technology company, to address the obstacles that commonly prevent dogs from receiving cancer treatment, including cost, convenience, and concerns about side effects. Laverdia-CA1 tablets, available by prescription from veterinarians, can be administered at home and empower more pet owners to pursue treatment when they find out their dog has lymphoma.

Dr. Galligher said clients have reported that their pets feel better when taking Laverdia. She does have to caution them that treatment with Laverdia is not the same as the gold standard multi-adjuvant chemotherapy. But it is a new option, and it’s nice to have options more than steroids alone. Dogs on Laverdia have tended to clinically do well, even though their lymph nodes may not always shrink.

“When you have a loved one who has an advanced disease, it is not uncommon for family members to compulsively monitor lymph node size and panic when fluctuations are noted. This is a very important part of monitoring while undergoing chemotherapy,” she said. “But if they’re not undergoing chemotherapy and are taking Laverdia, I try to let the dog guide the care versus the size of the lymph nodes if they’re clinically doing well. They’re happy, they’re active, they’re eating, they’re playful, but their lymph nodes may be big.”

Laverdia’s mechanism of action is different than chemo. Dr. Clifford views chemotherapy as a shotgun in that it kills everything growing, good and bad. Most normal cells in a body don’t grow, which is why people don’t grow to be 100 feet tall and don’t live forever. Cancer grows faster than any other cell in the body. “That’s what makes it uniquely susceptible to chemo,” Dr. Clifford said. “That’s the whole point. That’s why we give it.”

Laverdia works by a very different mechanism. Like the human brain tells the body what to do, a cell’s nucleus acts as its brain. Inside the nucleus is where DNA sits. Over the course of time, our DNA becomes damaged. That’s how we develop cancer. Fortunately, our bodies and those of our pets have fail-safes, including tumor suppressor proteins inside the nucleus. If the DNA becomes damaged, these proteins essentially tell the cell to stop growing and try to fix itself. If it can’t fix itself, then the cell needs to die through a natural pathway called apoptosis.

“What cancers learn to do is to take those proteins and shuttle them outside the brain, outside the nucleus,” Dr. Clifford said. They’re sitting in what’s called the cytoplasm of the cell, which is the body of the cell. When they’re in the body of the cell, they can’t tell the brain what to do. That’s a big advantage for cancer if it can find a way to shuttle as many of those proteins out of the brain as possible. Many cancers have systems to get rid of those tumor suppressor proteins.

But Laverdia is designed to block that from happening. The tumor suppressor proteins build up in the cell, and they exert their influence: Stop growing, fix yourself, or die.

Traditionally with lymphoma, either the cancer grows uncontrollably if the drugs aren’t working or it responds. Laverdia doesn’t do this, Dr. Clifford said. “With this drug, there is a subset of dogs that it just sits there, or it slowly grows over time, but the dog still feels well. These are very different concepts for an oncologist treating lymphoma. You either do one or the other; you do great, or you don’t, and it happens very quickly. But this drug is very different, and we can see a subset of dogs who remain stable for a period of time. To me, if the dog feels well, stable is a win.”

Essentially that’s what the practitioners are trying to find for the client – to better understand what a successful outcome looks like for them, and what options are financially available to create that outcome.

Dr. Clifford said one of the beauties of a treatment like Laverdia is that it fills an unmet need. “We can start to break into those untreated cases. To me, I don’t care if it’s being done by the primary care veterinarian or the oncologist. As long as pets are getting treated, we want to offer them something.”