This blood test detects cancer in dogs.

This blood test detects cancer in dogs.
A startup has just shown that its OncoK9 test accurately sounds the alarm for aggressive, advanced cancers. The catch? These often have no cure.
Cancer is the leading cause of death among dogs, especially the elderly. About half of all dogs 10 years and older die of cancer. Some types are particularly aggressive: lymphoma, in the white blood cells; hemangiosarcoma, in the blood vessels; and osteosarcoma, in the bone. Routine tests, such as CBC and urinalysis, often don't detect the disease before symptoms appear, so veterinarians often can't diagnose it until it's too late. Even if they suspect a tumor, surgical tests to confirm it can be invasive, expensive, and dangerous to vital organs.
Flory and Grosu began developing the first multi-cancer liquid biopsy for dogs, which they called OncoK9. The product was launched in 2021 and is available at about 400 veterinary clinics by prescription only. PetDx markets the test as a routine tool for older dogs and high-risk breeds, and to confirm suspected cancer when other evidence exists.
Today, in a paper published in PLOS ONE , they detail the performance of their liquid biopsy in a trial that began in 2019. For about a year and a half, 1,100 dogs had their blood collected by veterinarians who partnered with PetDx.
Some dogs already had cancer diagnoses. The rest were presumably cancer-free. Then the PetDx lab examined this blood using an in-house genomic analysis that looked for mutations or other cancer biomarkers in the DNA floating around in the bloodstream. They concluded that when analyzing the blood of dogs known to have the three most aggressive canine cancers, their algorithm correctly sounded the alarm 85% of the time. It was more modestly effective overall, catching about 55% of all cases.
The prospect of blood-based cancer screening for dogs provokes both enthusiasm and caution by experts and veterinary ethicists. "It could really help a lot of patients and could be very exciting," says Lisa Moses, a veterinarian who has specialized in palliative care for 30 years and is currently a bioethicist at Harvard Medical School, "but it really has to be used carefully."
Because blood tests are non-invasive, they are safer and cheaper than surgery to confirm that a pet has cancer, especially for hard-to-reach tumors in the spleen or liver. But in cases where an early diagnosis still doesn't offer much hope for treatment, is knowing earlier worth the stress?
For an OncoK9 test, once the vet collects blood, they send it to the PetDx lab, where the team centrifuges it to separate the plasma, then mixes the plasma with special beads that adhere to the cfDNA and isolate it. They then sequence the genetic material and run the sequencing through an algorithm that looks for changes previously associated with human and canine cancers, including mutations and extra or missing segments of chromosomes - known as copy number variations.
This algorithm was designed to detect these genetic indicators in many breeds of dogs with different forms of cancer: say, a bloodhound with lymphoma or a golden retriever with hemangiosarcoma. When the PetDx team began their study, they used blood from 224 of the dogs - those known to have cancer or not - to refine their algorithm. This "training set" helped PetDx determine a threshold for each genomic variation, defining what they should call a signal rather than just noise.
Next, they ran the algorithm on data from the other 876 dogs. For each one, it would yield a binary answer: yes cancer or no cancer. (For most cancers, it wouldn't identify what form it was.) Pet owners and veterinarians already knew if their dogs had a cancer diagnosis, but the PetDx researchers didn't, so as not to influence their analysis. The team then compared their results with the veterinarians' previous diagnoses.
While canine cancer experts worry about the ethics of using the test too broadly, PetDx recommends it for only a few use cases: for high-risk dogs and as a diagnostic aid when veterinarians suspect cancer. PetDx hopes to expand use to monitor cfDNA during cancer treatment, to track how the treatment is helping.
For her part, Moses, the veterinarian and bioethicist, thinks that having a diagnosis is better than not having one, even if a dog's cancer is incurable. "I think for most people it's really helpful and comforting," she says. "I've rarely heard people say, 'I wish I didn't know.'"