| SUPPORTIVE CARE FOR PETS WITH CANCER |
| Cancer pain in cats and dogs Not all cancers will cause pain to your pet and the amount of pain will likely vary from one animal to another, even for similar types of tumors. Human studies indicate that 20-50% of human patients experience pain upon cancer diagnosis and up to 90% of human patients experience pain with advanced or terminal cancer. Unfortunately, cancer associated pain has been largely overlooked by veterinary medicine but it is predicted that pets will experience cancer pain similarly to humans. Many veterinary hospitals now recognize the importance of treating cancer pain and offer cancer pain management plans tailored to each pet's unique needs. In addition to pain caused by the actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or chemotherapy. Untreated pain decreases quality of life in all patients, and prolongs recovery from the illness, treatment or injury. It is, therefore, essential that veterinary teams taking care of pets with cancer should also play a vital role in educating pet owners about recognizing and managing pain in their pets. It is of extreme importance to make your pet's life as comfortable and painless as possible and to discuss appropriate cancer pain management for your pet's unique condition with your veterinarian or oncologist. Veterinarians are ethically obligated to recognize, assess, prevent and provide pain relief to all pets under their care. While no formal clinical studies have been conducted to evaluate the effect of specific cancers on pain, the following tumors are most likely to cause pain.
Assessment of cancer pain in cats and dogs Because many cats and dogs may not show obvious signs of cancer pain and also tend to hide pain as a protective mechanism, identifying the degree of pain and the amount of suffering can be very difficult. The most likely indicators of pain are changes in the pet's behavior, as summarized below. The pet owners spend the most time with their pets and are, therefore, the only ones who can really pick up even on the slightest changes in their pet's behavior. The pet owners should bring up cancer pain management during veterinary visits and should ensure that their veterinarian is fulfilling his/her ethical obligation if the pet appears to be in pain. However, even if such indicators are absent and it is known that the same type of tumor causes pain in humans, the pets should be given the benefit of a doubt and be treated for pain as well. Likely indicators of pain in cats and dogs
Types of pain Pain is divided into acute and chronic forms, each requiring its own treatment. Acute pain is generally short-lived, lasting hours to days. Acute pain is usually a result of trauma, treatment therapies (e.g. surgery, radiation therapy), or some underlying disease. In contrast, chronic pain persists over longer periods of time, lasting weeks or longer. It continues beyond the expected period of healing and can be more difficult to detect compared to acute pain. Cancer pain management in cats and dogs There are two aspects of treating cancer pain in pets. The first aspect is focused on eliminating the source of pain - the tumor itself. This can be accomplished by a combination of several approaches that can include surgery, chemotherapy and radiation therapy. The second aspect is focused on treating pain in general and pain associated with the above treatments. Pain management will depend on the type of pain, the species, individual pain tolerance, and the overall health status of the pet. The best way to manage cancer pain in pets is to prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort. Sometimes the veterinarian will have to combine multiple pain therapies in order to successfully control the pain, a term referred to as multimodal therapy. Cancer pain management typically incorporates the following drug classes:
Important note: You should never administer any medication to your pet without first consulting your veterinarian to avoid harming your pet (the type of pain medicine and dose will depend on your pet's size, weight, what other medications your pet is taking and the specific medical condition). The World Health Organization has proposed a three-step analgesic ladder for controlling mild, moderate and severe pain in humans, which is now applied to treating cancer pain in pets. Using this model, mild pain is typically initially treated with nonopioid drugs. If the pain becomes moderate, the second step would be administration of weaker opioid drugs (e.g. codeine or tramadol). If that is unable to achieve pain relief and the pain becomes severe, the third step would be administration of strong opioid drugs (e.g. morphine). For situations where the cancer pain is difficult to control, additional techniques can be applied such as intrathecal administration of opioids (into the spinal cord), neurostimulation, peripheral neuroablation (nerve block), and central neuroablation. Nerve blocks refer to the procedure where local anesthetics are injected into or near nerves to control pain in that region. Strong opioid drugs Opioids are heavily utilized in humans with cancer and have become incorporated into pain management plans for cats and dogs with cancer. These drugs are usually used for treating moderate to severe pain, and can be administered in combination with other analgesics, including non-steroidal antiinflammatory drugs. The commonly used opioid is morphine, which can be given either as subcutaneous injection (under the skin), intramuscular injection (into the muscle), intravenously (into the vein), orally or epidurally. Other opiods include fentanyl (also available as skin patch), hydromorphone and oxymorphone. Side effects usually become an issue at higher doses and with long-term use, which can include sedation, constipation, respiratory depression, panting or vomiting. Depending on your pet's condition, the stage of the disease, and perceived discomfort, the veterinarian will prescribe appropriate pain relief medication(s) and doses. Pain medications vary in their strength and duration of providing pain relief, and as the level of pain increases with progression of disease, more powerful and quick acting drugs should be administered on a regular basis rather than on as-needed basis to maintain the pet's comfort. Pain resulting from cancer treatments As mentioned above, pets also experience pain from the cancer diagnostic procedures and treatments such as invasive biopsies, surgical removal of the tumor, radiation therapy and chemotherapy. Radiation Therapy Painful acute side effects of radiation therapy can include inflammation in the mouth, skin, eyes or intestine, which are typically seen more often with full-course radiation therapy. It is very important to prevent any additional damage to the area so Elizabethan collars should be used as needed to prevent pets from pawing or licking. Inflammation in the mouth can be treated with oral rinse solutions (e.g. a weak tea solution, chlorhexidine rinse, or mixture of viscous lidocaine, liquid diphenhydramine, and magnesium hydroxide). Veterinary radiation oncologists strive to minimize the side effects by using computerized planning of the radiation treatment along with using modern radiation therapy equipment. Chemotherapy Although chemotherapy is not painful itself, it can result in side effects that are painful. For example, commonly used drug called doxorubicin can cause colitis (inflammation of the intestine) or drug called vincristine can cause constipation in cats. Chemotherapy drugs can also cause painful tissue destruction if they leak out during administration. Additional pain management strategies In addition to administering pain relieving medication, pain management plan can also include other strategies. Some commonly used strategies include:
Your veterinarian/oncologist should work closely with you to develop an individualized cancer pain management plan that is best for your pet's needs, and should routinely follow up with you on the safety and effectiveness of that plan to ensure that your pet continues to be free of pain and discomfort. Finding a qualified veterinary oncologist to discuss cancer pain management for your pet To locate a qualified veterinary oncologist in your area who can discuss with you appropriate cancer pain management for your pet's condition, please visit the "Locate a veterinary oncologist" section. Other useful online resources about pain management in pets
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| Pain Management for Cats and Dogs with Cancer |
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 2/20/2017
KEY TAKE-AWAYS ON CANCER PAIN IN PETS
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| PET CANCER CENTER Comprehensive guide to cancer diagnosis and treatment in cats and dogs |
| Pain Management for Cats and Dogs with Cancer |
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