Chemotherapy for Dogs: What to Expect
Cancer. For pet parents, it’s one of our worst nightmares to get a diagnosis of cancer in our canine companion. For veterinarians, it’s one of the hardest conversations we have with clients. Unfortunately, cancer is the leading cause of death in senior dogs, so it’s a conversation many pet parents will have with their veterinarian.
Luckily, the treatment options for cancer are always evolving and improving. If you’re staring down a diagnosis of cancer in your dog, your veterinarian may discuss chemotherapy as a treatment option with you. Here, we’ll discuss types of chemotherapy for dogs and what you should expect if you pursue chemotherapy for your pet..
What Is Chemotherapy?
Simply put, the term “chemotherapy” refers to drugs used to kill cancers or slow cancer growth and spread. These drugs can be given as oral medications, as injections, or as intravenous infusions.
The medication or combination of medications that your veterinarian recommends will depend on what cancer your dog has and your dog’s individual health.
Chemo in dogs is different from chemo in humans. In humans, chemotherapy protocols are extremely aggressive and typically aimed at curing cancer. For dogs, we are focused on ensuring the pet has a good quality of life for as long as possible. The veterinarian will not tolerate adverse effects and will likely alter protocols if the pet is not tolerating chemotherapy well.
When Is Chemotherapy Recommended for Dogs?
Whether chemotherapy is recommended for a dog depends on the type of cancer the pet has, how aggressive the cancer is, and the pet’s overall health.
Chemotherapy is a common recommendation for many types of dog cancer, particularly if the cancer has already spread (metastasized) or is a type of cancer that frequently metastasizes, such as lymphoma or osteosarcoma.
For example, with osteosarcoma, which typically affects one of the bones of a leg, most oncologists will recommend surgery to remove the limb with the primary tumor, as well as chemotherapy to address spread of the cancer. This is because most osteosarcomas have already metastasized on a microscopic level by the time they are discovered.
Your veterinarian may also recommend chemotherapy if the tumor is unable to be removed surgically. Sometimes, chemotherapy may be used to shrink large tumors prior to surgery or as a follow-up to surgery if microscopic cells are left behind.
Access to radiation treatments is also very limited currently, with few specialty centers currently having the capability to perform radiation. As a result, pets who may have benefitted from radiation therapy may end up relying more on chemotherapy.
Dog Chemotherapy Medications
Veterinarians use a wide range of chemotherapy medications used to treat cancer in dogs. In the table below, we list some of the common chemotherapy medications used in dogs, examples of cancers they can be used for, and their method of administration.
| Name of Drug | Uses | How It’s Administered |
| Doxorubicin (Adriamycin) | Lymphoma Osteosarcoma Splenic hemangiosarcoma Soft tissue sarcomas Mammary gland carcinoma Carcinomas and sarcomas | Intravenous infusion |
| Vincristine (Oncovin) | Lymphoma Mast cell tumor Transmissible venereal tumor | Intravenous injection |
| Vinblastine (Velban) | Mast cell tumor Lymphoma Carcinomas | Intravenous injection |
| Cyclophosphamide (Cytoxan, Neosar) | Lymphoma Lymphocytic leukemia Carcinomas and sarcomas | Intravenous injection or oral medication |
| Prednisone/Prednisolone | Lymphoma Mast cell tumor Myeloma Chronic lymphocytic leukemia | Oral |
| Cisplatin | Osteosarcoma Transitional cell carcinoma Squamous cell carcinoma Other carcinomas | Intravenous infusion (usually with IV fluids for several hours before and after administration) |
| Carboplatin (Paraplatin) | Osteosarcoma Melanoma Carcinomas and sarcomas | Slow intravenous injection. An infusion |
| Mitoxantrone (Novantrone) | Lymphoma Transitional cell carcinoma | Intravenous infusion |
| Dactinomycin / Actinomycin-D (Cosmegen) | Lymphoma Bone and soft tissue sarcomas Carcinomas | Intravenous infusion |
| Chlorambucil (Leukeran) | Lymphoma Chronic lymphocytic leukemia Mast cell tumor IgM myeloma | Oral |
| Cytosine Arabinoside / Cytarabine (Cytosar-U) | Lymphoma (myeloproliferative) | Intravenous infusion, some protocols involve subcutaneous (under the skin) administration |
| L-Asparaginase (Elspar) | Lymphoma | Intramuscular or subcutaneous injection |
| Lomustine / CCNU (Gleostine, CeeNu) | Lymphoma Mast cell tumors Brain tumors | Oral |
| Rabacfosadine (Tanovea) | Lymphoma | Intravenous infusion |
| Toceranib (Palladia) | Mast cell tumors Anal sac adenocarcinoma | Oral |
Injectable medications are given in a veterinary clinic – most often at a specialty center. Oral medications are typically given at home, and dosing instructions vary by drug.
This list is not all-inclusive of chemotherapy medications for dogs. Your veterinarian may recommend other chemotherapy medications or choose a specific chemotherapeutic agent for a different use than we’ve listed. Some medications may have other names that are not included on this chart.
If your veterinarian’s recommendations differ from the information included above, you absolutely should follow the recommendations from your pet’s doctor.
What to Expect During Treatment
How many doses your dog will get and over what length of time varies a lot based on the type of cancer, the stage, the drugs used, and your dog’s health. It’s possible that your pet may be receiving chemotherapy for the rest of their life. It’s also possible that your pet may stop treatment if the cancer goes into remission.
The oncologist or veterinary professional will determine which medications your dog receives, how often they receive the medication, and for how long they undergo chemotherapy.
Appointments last anywhere from under an hour to most of the day. Some treatments, such as cytosine arabinoside infusion, may require overnight hospitalization. Most injectable chemotherapy protocols involve a set number of treatments that are spaced out every 1-3 weeks. Chemotherapy treatments can last several months to over a year.
Prior to administering the next dose of chemotherapy, the veterinarian will run blood work to ensure your pet still has an adequate number of white blood cells and is tolerating the protocol well. If your pet is receiving injectable chemotherapy, your pet will likely have a shaved area on their leg where the veterinarian placed the catheter.
It’s very important that intravenous injections make it into the vein and do not leak into surrounding tissues. This means the placement of the catheter will require a clean needle stick. Although most dogs don’t have to be sedated for treatment and will rest comfortably during the infusion, sedation is sometimes necessary to make the treatment safe for the dog and the veterinary team.
Cost of Chemotherapy for Dogs
The cost of chemotherapy for dogs varies depending on the specific protocol recommended, how well your pet is tolerating and responding to their protocol, and whether other treatments are recommended. Prices differ between private practices that do chemotherapy, specialty clinics, and universities. Prices can range anywhere from $3,500 to well over $10,000.
Keep in mind that even if you cannot afford the “gold standard” chemotherapy protocol, there may be other options that will still improve your pet’s quality of life. If you do wish to pursue treatment but are struggling to afford it, other suggestions could include:
- Asking the veterinarian about alternative protocols that may be more affordable
- Running a fundraiser for your pet
- Looking for clinical trials that your pet could join
- Applying for CareCredit to help you pay for treatment in affordable monthly installments
If you already have pet insurance, some companies will cover the cost of cancer treatment. This may be a good reason to consider purchasing pet insurance while your pets are young and healthy.
Chemotherapy Side Effects for Dogs
Most dogs have minimal to no side effects from chemotherapy treatments. As a reminder, negative side effects are generally not tolerated by the veterinary profession. If your pet is showing negative effects of chemotherapy, you need to follow up with their doctor.
Your dog may be more likely to experience negative side effects if they have pre-existing gastrointestinal, kidney, or liver disease. Underlying conditions may affect which drugs can be given and how often. Make sure to discuss your pet’s health history with the veterinarian prior to beginning a chemotherapy protocol to reduce risk.
When side effects do occur, they’re commonly related to the gastrointestinal tract or bone marrow. Common GI tract side effects include vomiting, diarrhea, nausea, and loss of appetite. Decreased production of white blood cells in the bone marrow can result in immunosuppression, making your dog prone to secondary infections. In most cases, the white blood cell count will be at its lowest 7-10 days after treatment. If your pet’s white blood cell count is too low, they may be placed on antibiotics to prevent infection. This can also impact their ability to receive their next injection as scheduled.
Some medications, such as doxorubicin, can cause tissue sloughing if they escape the vein and leak into surrounding tissues (extravasation). Other chemotherapeutic agents, such as carboplatin, can be locally irritating. The veterinarian will monitor for extravasation and manage accordingly if this occurs.
Other side effects can be related to the specific drug. For example, doxorubicin results in heart toxicity over time and cyclophosphamide can cause bloody urine (sterile hemorrhagic cystitis). Your veterinarian will be aware of these drug-specific side effects and will alter their plans based on how your pet is handling their medications.
Prednisone commonly causes increased drinking, urination, and appetite. You may also see muscle wasting if your pet is on this medication for a long-time.
Most dogs will not lose their fur during chemotherapy, though you may see fur loss in curly-coated and wire-haired breeds. It’s also possible to see the loss of whiskers and eyelashes.
Make sure to contact your veterinarian if you are noticing any side effects in your dog.
Chemotherapy Alternatives for Dogs
Other treatment recommendations could include surgery, radiation, and immunotherapy. Surgery is typically performed if there’s an isolated tumor, such as a mast cell tumor, that can be removed. For some cancers, like lymphoma, surgery is not typically recommended.
Radiation therapy is generally recommended for tumors that cannot be completely removed surgically or are not surgically accessible. Importantly, radiation treatments require full sedation for each treatment. Limited practices currently offer radiation, and the travel in addition to the treatments can be costly
Immunotherapy is a developing cancer treatment option. Immunotherapy uses the dog’s own immune system to destroy cancer cells. An example of this is Oncept, which is a vaccination for melanoma in dogs. Research is ongoing into the use of immunotherapy for other cancers, such as osteosarcoma, hemangiosarcoma, and transitional cell carcinoma.
Things to Consider Before Chemotherapy for Dogs
Before considering chemotherapy for your dog, it’s best to have a candid conversation with your veterinarian about the process, risks, and benefits. Consider asking for a referral to a veterinary oncologist, which is a veterinarian who specializes in cancer treatment, for at least a consultation.
Remember that many factors can play into your pet’s response to chemotherapy, such as their underlying health, the specific cancer they have, and how aggressive their cancer is.
Questions you can discuss with your veterinarian and the oncologist prior to moving forward with treatment could include:
- Does my dog have other underlying conditions that may complicate cancer treatment?
- Does the veterinarian expect my dog to have a good response to chemotherapy?
- How long does the veterinarian expect chemotherapy to extend my dog’s life?
- Is chemotherapy potentially going to cure my dog, or do we expect relapse?
- What will chemotherapy cost, and can I afford this without negatively impacting the bond I have with my pet?
There are other considerations to keep in mind, as well. Not all dogs respond to chemotherapy the same. While your veterinarian can tell you what they expect, your dog may do better or worse than the average pet. If you pursue chemotherapy, this is a risk you must accept.
Additionally, consider how your pet is behaviorally. If you have a highly anxious or stressed dog, a dog prone to aggression in the veterinary office, or a dog who can’t have their blood drawn or an injection administered without sedation, the process of chemotherapy will likely be very stress-inducing for your pet. Additional sedatives or anti-anxiety medications may increase the cost.
Receiving a diagnosis of cancer can bring up a lot of painful feelings, as well. It’s emotionally taxing not only to receive the diagnosis but also to go through chemotherapy with your pet. This is totally normal, and your veterinarian will understand that this isn’t an easy decision to make. Consider finding support groups, pet grief counselors, or a therapist to help you throughout the process.
Is Chemotherapy for Dogs Worth It?
Whether chemotherapy is a good option for your canine family member depends on your individual dog, the type of cancer your dog has, and your personal finances.
In some cases, chemotherapy can extend a pet’s life by well over a year. In other cases, chemo may only buy you a couple extra weeks or months. In both situations, it’s likely to be quite costly.
If your family is unable to afford chemotherapy or can’t accommodate the many rechecks and treatment appointments, it’s okay to discuss other options with your veterinarian. In most cases, veterinarians just want to find an option that works for your family and preserves the bond you have with your dog.
Importantly, remember that chemotherapy is generally tolerated better by our canine companions because the goal of chemo in dogs is to preserve quality of life for as long as possible. Rest assured that if you are pursuing chemotherapy, your veterinary oncologist and primary veterinarian will work together to ensure your pet continues to feel great for as long as possible.
