photo of pills forming a question marke, sun, fork, knife, and plate to represent chemo drugs

In-patient Chemotherapy

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

In-patient Chemotherapy

Most people have had experience with cancer and cancer therapy, whether it is personal experience, with a family member, or through a close friend. Often, these experiences are not pleasant, despite having positive rewards at the end. Cancer in veterinary medicine, though, is treated differently than in human medicine. Our goal in veterinary medicine is not to achieve a “cure” but to achieve the best quality of life for our patients. We may be able to achieve a remission (different than a cure) with some diseases, but for others we aim to stop or slow down growth.

When a pet experiences a side effect from chemotherapy, it typically starts the second or third day after treatment. This period, from three to five days after treatment, is when symptoms occur with the GI tract.  The bone marrow can have problems as early as day three but it is typically six to eight days after when cell counts are at the lowest. If white blood cells get too low, opportunistic microbes can get a hold and make pets feeling sick. Symptoms can include problems with the GI tract as well as decreased energy and generally “not feeling well”.

Most of our patients (greater than 90%) will have absolutely no side effects from chemotherapy. That is unless you want to include feeling better and happier with the side effects. For the majority of our patients that receive therapy and have a response, this will be the only “side effect” they experience.

Of the remaining 5-10% than develop side effects, most will be mild in nature and easily controlled from home. The most common side effects reported include loss of appetite, low energy, nausea, diarrhea, soft stool, and vomiting. To help treat these, we send home medications for you to have on hand in case side effects occur. Typically, cats will get upper GI side effects (nausea, vomiting, and loss of appetite), while dogs can experience the whole range of symptoms. The medications can be used prophylactically (starting the night of therapy) or held in reserve and used only if symptoms occur. It is important to use these medications at the first sign of symptoms. If started early, side effects can be stopped before they become more serious. The medications we send home are safe to use and will not cause your pet any issues if they are given them but did not actually need them.

A small number (1-2%) of pets will require more intensive care to control their symptoms. This includes outpatient injectable medications or inpatient hospitalization with IV fluids and injectable medications. This typically occurs when the symptoms come on suddenly and at home medications are not adequate to control them, or due to an overwhelming response of the cancer to therapy that “floods” the body with dead cancer cells. This can cause your pet to feel sick while the body plays catch –up in filtering out the dead cells. If symptoms are not addressed quickly, your pet’s condition can deteriorate rapidly. In extreme situations, a pet can have a fatal event after receiving therapy, usually from suppression of the bone marrow (low cell count), compromised body systems (like kidney or liver), or untreated symptoms (vomiting, diarrhea, etc). If your pet is not responding to medications at home or has severe symptoms that come one suddenly, please seek immediate care here, your regular vet, or your local emergency center.

Ultimately, the primary goal of veterinary chemotherapy protocols is to provide good quality of life for our patients while managing the cancer for as long as possible. Thus, if a pet has a side effect we switch drugs, adjust doses, or stop treatment entirely. We do not want our patients getting sick any more than you want your pet to be sick. If you have any questions or concerns about sick effects and your pet, please feel free to discuss these with your doctor.

Marijuana and THC/CBD

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

Marijuana and THC/CBD

With the legalization of marijuana in Washington, there have been a plethora of companies that have started to target pets and their owners with the benefits of its use. Please use caution before giving your pet anything that has marijuana or any of its chemical compounds mixed in with it. Pets are more sensitive to some of the compounds (like THC) and can become severely ill if too much is ingested.

While we have no doubt that there are viable uses for this drug and some of its compounds, there are no peer-reviewed scientific papers that address which compounds are needed, in what combination, and how to properly dose it for various conditions. Until the time that we can safely dose and prescribe the appropriate compounds, we cannot make any recommendations about the use of this product besides not to use it.

If you are compelled to add any marijuana products to your pets treatment regime, please talk to your doctor before starting them so they can give you more detailed warning about what compounds need to be avoided and what side effects to watch for. Your doctor is also happy to talk with you if you would like more information in general about marijuana compounds.

photo of pills forming a question marke, sun, fork, knife, and plate to represent chemo drugs

Low-dose Chemotherapy

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

Low-dose Chemotherapy

A handful of oral chemotherapies can be given at home, either as a low-dose long-term medication, or at a higher dose for a short, specific amount of time. These drugs are prescribed for at home use because the risk of side effects (to both pet and human) at the prescribed dose are low and they must be given over a long enough period of time that administration in the clinic would be unrealistic.

Side effects of the drugs to your pet are similar to other therapies: low white blood cell count, changes to the liver or kidneys, vomiting, nausea, diarrhea, and/or soft stool. The first two will be monitored by blood work performed at specific intervals. The latter are watched for at home. In either case, if side effects are noted, the medications are either stopped or the dose is adjusted to avoid side effects. If there are any concerns specific to a medication, your doctor will let you know before prescribing it.

Below are a few precautions and recommendations in regards to your pet and their medications. These guidelines help to avoid chronic health affects to you as their caregiver and anyone else in the family.

  • Most important: It is perfectly safe for people and other pets to be around the pet receiving medications, even while they are being treated.
  • Direct handling of medications should be avoided.
    • Certain individuals should avoid contact if possible. This includes children, other pets, and persons who are pregnant, may become pregnant, or are nursing.
    • A single exposure is unlikely to cause an issue, especially if cleaned up quickly by washing the affected areas with soap and water. The concern is with chronic exposure and the changes it can cause over time.
    • Wear non-powered latex or nitrile gloves (available as most pharmacies) when handling medication or anything that might be contaminated with the medication.
    • Wash your hands thoroughly after administering the medication, even if you wore gloves.
  • Do not open the capsule or crush the tablet.
    • Chemotherapy should be given whole, unless you are specifically instructed to break or open the capsule/tablet.
    • Unfortunately, due to the great chance of contamination, liquid formulations are discouraged. Medications come as either tablets or capsules.
    • If your pet chews the medication while taking it, that is fine. If they spit it out chewed up, make sure to thoroughly clean the area with soap and water or a detergent cleaning spray.
  • Less than 1% of the medication will be excreted by your pet as the active drugs, typically through the kidneys (urine).
    • Most drugs are broken down by the liver and these breakdown products are excreted in the feces.
    • Most drugs are also sensitive to light and temperature, breaking down very quickly when exposed to the natural environment.
    • Frequent cleaning of the yard or litterbox is all that is needed.
    • At our dosing levels, there is no drug found in the saliva of pets.

Targeted Therapy

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

Targeted Therapy

There are many new drugs available to treat cancer (and various other diseases as well) that are not actual chemotherapy, but instead work by targeting the suspected genetic mutations involved in cancer cell growth. While there are new targeted therapies coming out all the time, the main three used here are masitinib, dasatinib, and toceranib. These medications can be used alone, but they work best when combined with other oral and/or injectable therapies.

Side effects to these medications are very rare and can often times be stopped with minor dose adjustments. We’ve also learned a lot about dosing over the years. We habitually dose below the ‘recommended’ amount without seeing a loss of efficacy, while also avoiding most/all of the side effects from the medication. Possible side effects to all targeted therapies include bone marrow suppression and GI upset, such as vomiting or diarrhea.

Some rare side effects that we monitor for that are specific to commonly used targeted therapies:

  • Masitinib can also cause a protein losing nephropathy (protein loss through the kidneys), so watch for a change in drinking and urination habits at home. We will monitor for any changes in blood work here at the clinic.
  • Toceranib can cause ulcers and bleeding of the GI tract that you would see at home as frank (red) blood in the vomit or stools, ‘coffee ground’ appearance to vomit, or stools/diarrhea that are tarry and/or dark. If you notice any of these side effects, please let you doctor know right away.
  • Dasatinib is especially prone to causing diarrhea, nausea, and vomiting so we typically prescribe an ‘antidote’ that is given one hour prior to the dasatinib to help prevent these side effects. However, if your pet still has trouble tolerating the medication, a dose adjustment often takes care of the issue.

photo of pills

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in veterinary medicine to help treat pain and inflammation. These drugs are in the same class that Tylenol and Advil are for us, but they are safe for pets to receive. There are many different types available based on what your pet needs. While the brand name varies, some of these drugs include carprofen, deracoxib, meloxicam, robenacoxib, and firocoxib. Some of these drugs are only available at veterinary hospitals, while others are available through neighborhood pharmacies as well.

The target of NSAIDs is a class of enzymes called cyclooxygenase (COX). Some NSAIDs are specific for a particular COX (such as COX II), while others work more broadly against multiple COX enzymes. These enzymes make a group of compounds known as prostaglandins and prostacyclins. Both prostaglandins and prostacyclins, among other things, help stimulate and maintain the body’s inflammatory response. They also are known to directly stimulate the local nerve endings causing pain. Therefore, the actions of NSAID drugs are to inhibit these enzymes to help reduce the inflammation and pain associated with varying diseases, including cancer.

Recently, it has been shown that a certain percentage of dogs and cats with various types of tumors may have an up-regulation (increased expression) of COX enzymes. If a cancer does something purposefully, it is a good bet that by inhibiting this activity you might slow the growth or even kill the cancer. Therefore, NSAIDs may have some anti-cancer effects in the tumors that have increased expression of COX enzymes. At this time, it is hard to predict which pets will have tumors that will respond to this therapy (i.e. which tumor is over expressing COX enzymes) and if they respond, how long will this response last. Due to these uncertainties, the use of an NSAID in dogs and cats with various tumors is somewhat empirical. There are some tumor types that we know have a greater chance of over-expression, but it is still not a guarantee. A response to NSAIDs is definitely a positive prognostic factor.

No drug is without risk. While the rate of side effects from NSAIDs has decreased dramatically over the years, there is still a chance of negative effects on your pet. Here, we often dose lower than is typical because the effects were are looking for can be achieved at doses lower than those used for chronic or post-surgical pain. This has the benefit of allowing for longer use with a lower risk of side effects. Before starting and periodically during use, we will monitor your pet’s blood work for signs of kidney or liver toxicity. At home, you should watch for any signs of GI upset, including vomiting, diarrhea, or blood in the stool or vomit. If any of these side effects occur, stop use and please contact us or your regular veterinarian so that the side effects can be addressed and the medication changed if needed.

While NSAIDs can play well with some medications, they do not get along well with others. Please make sure any veterinarian you are seeing knows that you pet is on a NSAID, and do not start any other pain medications or steroids without specific instruction from a veterinarian as severe side effects can occur.

photo of pills

Steroids

The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.

Steroids

One of the more common at home medications used to treat various cancers is steroids. Steroids are a good therapy for immune-based cancers and, for some, can even cause them to go into remission. The downside to steroids is that with their continued use, the cancer cells become resistant to its lethal effects much in the same way some bacteria are resistant to certain antibiotics. This developed resistance often extends to resistance against most of the other drugs used in cancer therapy. The development of resistance can begin as early as 2-3 weeks after starting the steroid therapy. Thus while steroids are very helpful in making a patient feel better initially, they do not, in the long run, greatly increase their life expectancy.

There are several different types of steroids and formulations. While oral steroids (tablets and liquids) are most common, steroids also come in transdermal (absorbed through the skin) and injectable forms. What formulation is used will depend on the needs of you and your pet. Please be sure to discuss any concerns you have with your doctor.

If it is decided to start your pet on steroids, there is some important information you should know about side effects and drug interactions. Please be sure to tell your doctor about all medications and supplements your pet is currently taking, or has taken, in the past week. Depending on the medication, starting steroids may need to be delayed to allow a ‘wash out’ period so that negative drug interactions can be avoided. Your pet will also need to have blood work checked periodically to monitor for any negative effects on the liver. Below is a list of the more common side effects seen at home with steroid use.

Common side effects

  • Increased thirst and urination
  • Increased hunger
  • Increased energy
  • Weight gain (due to eating more food)
  • Panting and/or increased respiratory rate

These side effects are common when initially starting steroids and should decrease or stop as the dose is reduced. If the side effects are severe, please talk with your doctor about adjusting the dose.

Metronomics: At-home Cancer Care

Metronomics: At-home Cancer Care

The purpose of metronomic therapies is to slow the growth of new blood vessels and possibly control the growth of cancer stem cells. If one or both of these objectives can be met, tumor growth can be slowed down or sometimes even stopped. Depending on the disease, tumors can also shrink or disappear on metronomic therapies.

All tissues (including tumors) need blood vessels to obtain oxygen, nutrients, and to take away waste products. The first thing a tumor must have to grow is new blood vessels. Only then can it spread out and get larger. Growth will continue until the tumor out grows its blood supply or once it reaches a physical barrier that prevents its growth. If we can control how fast and how many blood vessels the tumor cells can make, then we can slow down or stop the growth of the tumor. Without adequate nutrients and oxygen, tumor cells will begin to die.

Stem cells are cells that have the potential to become almost any cell in the body. Some stem cells have more freedom to become different types of cell than others. In normal tissues, stem cells are typically few in number and rarely divide. As a whole, they act as a reservoir of functional cells for an organ or body system. Stem cells are naturally and genetically resistant to the influences of drugs and toxins. This makes them safe from damage and allows them to act as a reservoir for cells. Many organs of the body, especially the immune system, use stem cells as a part of their normal function. Ultimately, they are also the source of an organ’s ability to heal from an injury or disease. Stem cells function by dividing when needed into two separate cells. One of these new cells will continue to act as a stem cell and no longer divide. The other new cell will continue divide, with each subsequent cell division the resulting cells become more mature and specialized. This maturation and cell division process will continue until there are enough cells of a specific cell type to perform whatever functions are needed by the body.

It is thought that tumors also have a type of stem cell. There are likely only a few cancer stem cells within a tumor; especially in comparison to the more mature tumor cells. Cancer stem cells are thought to be naturally or genetically resistant to cancer drugs. Their resistance is also likely because of their slow growing nature. Many cancer therapies are designed to kill only fast growing (dividing) cells.  That means these therapies are targeting the more mature tumor cell, and not the cancer stem cells. Recurrence or progression of a cancer could therefore be due to the naturally resistant cancer stem cells repopulating the tumor. Cancer stem cells could act as a reservoir of cells for the tumor, only stimulated to divide when there is a signal that the level of mature cancer cells has been depleted, such as after being treated by a traditional therapy.

Metronomic protocols are designed to target the formation of blood vessels in tumors and possibly target the slow growing stem cell population within that tumor or cancer. How this protocol causes an effect is by providing a continual low amount of therapy over a long period of time. By delivering the drugs in this manner, you ensure that there is a constant level of drug in the blood at all times. This constant level of drug ensures that cells who divide rarely will be exposed to these drugs at the critical times during their division. These protocols do not typically provide fast ‘results’ but instead help slow growth over a period of time or maintain the results achieved during traditional therapies. In most cases, the amount of time needed for efficacy is 4 to 12 weeks. During this period of time, tumor cells can continue to grow and the tumor can progress. If there is no significant growth or progression during this time, metronomics have been shown to provide longer surgical and clinical remissions, or even stabilize tumor size, than those animals that receive no therapy or even receive other types of therapy. If there is gross disease present (an obvious tumor) at the time of starting this protocol, in rare cases, the protocol can cause shrinkage of the tumor. Most commonly, tumors will continue to grow very slowly. Lastly, there is always a chance metronomic protocols will not work or will suddenly stop working and the cancer will progress.

If your doctor recommends a metronomic protocol and you choose to pursue it, your pet will typically need an exam and blood work checked at two weeks, six weeks, and three months after starting this protocol. These appointments will allow us to assess whether there are any problems with the protocol and how the tumor is responding to the therapy. At the three month appointment, if all is going well, we will continue with the every three month appointments to recheck an exam, repeat blood work, and any other needed diagnostics to monitor the cancer or for cancer recurrence. This schedule is variable, however, and is ultimately based on what your pet’s specific needs are and how they respond/tolerate the therapy.