Pain is one of the most prevalent symptoms in veterinary patients with cancer. Pet owners are increasingly concerned with how much pain their pets may be experiencing. In people, a full 40% of patients with early or intermediate stage cancer, and 90% with advanced cancer, have moderate to severe pain, with bone pain the most common type.1
Pain in the cancer patient often occurs from the tumor compressing or infiltrating surrounding tissues, or from skin, nerve and other changes caused by hormone imbalance or immune response. The presence of pain often depends on the type, location and stage of the cancer, as well as the pain tolerance of the individual animal. Treatments such as surgery, radiation therapy and/or chemotherapy may also cause pain.
Most chronic pain in the cancer patient is caused by the cancer itself, whereas acute pain is more often caused by treatment or diagnostics. However, in some patients, radiation and chemotherapy can cause painful side effects that persist long after treatment has ended.2,3
PAIN – THE FOURTH VITAL SIGN
Pain is now considered to be the fourth vital sign – after temperature, pulse, and respiration (it’s the fifth vital sign in humans, after blood pressure), and should be integrated into patient evaluations so that the veterinarian can recognize, assess, prevent and treat the pain.4
Traditionally, pain has been categorized as acute or chronic, based on duration. The more contemporary approach is to consider pain as either adaptive or maladaptive.
• Adaptive pain is a normal response to tissue damage. It includes acute inflammatory pain that often occurs with surgery or trauma. Inflammatory pain may also occur in chronic pain states such as osteoarthritis or cancer. If adaptive pain is not appropriately managed, physical changes occur in the spinal cord and brain, leading to pain that is termed maladaptive.
• Maladaptive pain includes neuropathic and central pain. Pain-induced changes can occur in the nervous system causing it to become more sensitive rather than less sensitive. The longer pain is unmanaged, the more likely the neurophysiologic processes involved will result in a switch from adaptive to maladaptive pain, which is more serious and difficult to control.4 Acupuncture can be an important adjunct to managing the maladaptive pain often associated with cancer.
THE ROLE OF ACUPUNCTURE
A recent systematic review of 33 randomized human clinical trials, evaluating the effectiveness of acupuncture in palliative care for cancer patients, suggests promising results. It also showed that acupuncture may help reduce the side effects of chemotherapy or radiotherapy.5 Auricular acupuncture in humans has been shown effective in treating neuropathic pain in cancer patients.6 The use of acupuncture in 286 patients with bone metastasis of cancer, meanwhile, reduced the need for analgesic or sedative drugs.7 The National Comprehensive Cancer Network (NCCN) guidelines for adult cancer pain now recommend acupuncture as an integrative intervention in conjunction with pharmacologic intervention, especially in frail, elderly and pediatric patients in whom standard pharmacological interventions may be less tolerated.8 In addition to pain management, additional benefits of acupuncture include enhancement of immunity9,10; alleviation of side effects from Western therapies (chemotherapy and radiation therapy)11; alleviation of symptoms of the cancer itself; and improvements in response to Western therapies.
Approximately 70% of human cancer patients do not receive adequate pain relief. Many dog and cat cancer patients are “stoic” and do not always exhibit recognizable signs of pain, so it is likely that both owners and veterinarians underestimate a patient’s pain. Many conventional medication options exist for treating pain in veterinary patients. However, these medications may have side effects, and some owners are resistant to the idea of overmedicating their pets. Additionally, some patients do not experience adequate pain relief with conventional therapies at maximum doses, and additional therapies are needed to improve pain control and quality of life.
Acupuncture is a useful adjunct for pain management in the veterinary cancer patient. It can greatly reduce pain and the doses of conventional pain medications needed, thereby enhancing the patient’s quality of life. In many animals, a better outcome may be achieved if a combination of acupuncture and conventional pain medications is used. Acupuncture may also be beneficial in reducing the side effects of conventional pain medications, such as constipation, pruritis and nausea/vomiting.
HOW IT WORKS
The physiological responses associated with acupuncture for pain include serotonin release from the upper brain stem region and hypothalamus, and stimulation of endogenous opiate release (B-endorphin, enkephalin, endomorphin and dynoprhin), which can then alleviate pain.12 In addition, some neurohormones like g-aminobuyrin acid and glutamate, neuropeptide Y and brain-derived neurotrophic factor can lead to euphoric sensations and treat the psychological aspects of pain in cancer patients.13,14
The main mechanism of the analgesic effect caused by acupuncture may be related to its ability to decrease substance P and upregulate plasma B-endorphin levels. In Traditional Chinese Medicine, Qi deficiency (weakness of immune function) is the fundamental or root pattern for cancer. Pain is a manifestation of the tumor and is associated with Qi or blood stagnation. Qi deficiency with blood stasis is a key factor leading to the development of tumor and metastases.15 Triggering acupuncture points promotes the flow of Qi and blood and regulates visceral function.
Dry needle, aquapuncture and/or electroacupuncture techniques may be used in the veterinary cancer patient. Care is taken to avoid needles directly in or around a malignant tumor. When using electroacupuncture, care must also be taken to avoid crossing the electroacupuncture wires over the tumor. Between ten and 20 acupuncture needles are placed on the body, depending on the tolerance levels of the patient. Acupuncture sessions are 20 to 30 minutes long, with sessions repeated every one to three weeks, depending on the severity of the patient’s pain and his duration of response to the acupuncture treatment. Initially patients may be treated more frequently until improved pain control is achieved; then, intervals between sessions are lengthened. Patients with osteosarcoma, an extremely painful cancer, generally require more frequent treatments.
In summary, acupuncture is a useful adjunct for the treatment of pain in veterinary cancer patients. In combination with conventional pain management, acupuncture may improve pain control and enhance quality of life. It may also decrease the side effects associated with conventional pain medications, and may allow for decreases in overall dosages of pain medications. Additional benefits include enhanced immunity, decreased side effects from chemotherapy and radiotherapy, decreased symptoms from the cancer, and improved response to Western therapies.
ACUPUNCTURE POINTS FOR QI AND BLOOD DEFICIENCY
These points are selected for treating the main pattern of Qi or blood deficiency and the manifestation of Qi or blood stagnation (pain):
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