Individual Pain Management to Optimise Patient Comfort
Pain is a common symptom amongst cancer patients. Adequate pain assessment and management is critical to improve the quality of life and health outcomes in affected pets.
Pain management should always be considered as an integral part of the cancer therapeutic plan, even if the patient has no outward signs of pain.
Unrecognized or undertreated pain that progresses from acute to chronic in cancer patients can lead to treatment failure, death or premature euthanasia despite treatment of the cancer itself. The longer a cancer patient’s pain is ongoing, the more difficult it becomes to successfully treat both the underlying cancer and pain.
Clinical experience suggest
- Cancer pain generally progresses slowly until the patient’s physiological function is severely affected.
- As the cancer progresses and becomes more advance, pain may go undetected for some time before owners notice deficits in function or daily routine.
- Over time, factors that contribute to the progression of acute pain result in chronic pain, which becomes more difficutl to treat if no intervention occurs.
How Painful is Cancer in Animals?
Not all tumors are painful, and the amount of pain is likely to vary considerably from one animal to another, even with similar cancer types.
Tumors that are more likely to be associated with pain include those at the following sites: oral cavity, bone, urogenital tract, eyes, nose, nerve roots, gastrointestinal tract, and skin.
In additional to pain caused by the tumour itself, pain in cancer patients can also be caused by chemotherapy, radiation therapy, or surgery. Concurrent noncancerous disease, such as osteoarthritis, gingivitis and dermatological conditions can also contribute to the pain of a patient.
Estimating the incidence of pain in cancer patients is difficult. Recent studies have suggested a significant number of animals have not been receiving appropriate levels of analgesic medications. Approximately 70% human cancer patients report some degree of pain.
Assessment of Cancer Pain
Assessment of pain in animals is challenging. It is likely that the tolerance of pain by individual pets varies significantly and is further complicated by a patient’s ability to mask significant pain and disease.
The mainstay of pain assessment in cats and dogs suffering from cancer is likely to be changes in behaviour. In general, if a tumour is considered to be painful in humans, it is appropriate to provide an animal with a similar condition similar analgesics.
Changes an owner might notice in their pet include:
- Pets may become less active. Maybe there is less jumping or playing. Less interest in going outside on walks. A stiff gait or lameness. Slow to get up, or difficulties getting comfortable.
- Reduced appetite is frequently associated with chronic pain.
- Increase in aggression, dullness, shyness, increased dependence or being “clingy”
- Head hung low, squinted eyes in cats, sad facial expressions, low head carriage.
- Failure to groom
Response to palpation:
- Sensitivity, turning of the head, vocalization, hissing, biting - when an affected area is touched or manipulated.
- Increase in respiratory rate is often associated with acute and chronic cancer pain.
- Licking an area excessively, scratching or biting.
- Failure to use litter boxes in cats and accidents inside the house for dogs.
- Vocalization is rare with chronic pain. Whinning and grunting, just like in humans, however can been seen in some dogs. Occasionally cats will hiss, meow or purr in association with Cancer pain.
Management of pain
Discomfort and pain must be treated appropriately and the treatment adjusted continually with disease or therapy progression.
Multi-modal pain management is encouraged especially as the degree of pain increases with progression of cancer. For example, mild pain can be managed with Non-steroidal pain medicaitons (NSAIDs) +/- acupuncture. For more severe pain, a veterinarian may suggest NSAID, acupuncture, opioids, anxiolytics +/- radiation/surgery.
- Non steroidal anti-inflammatories (NSAIDs)
- NSAIDs (.e.g carprofen, deracoxib, meloxicam etc), provide mild to moderate anti-inflammatory and analgesic effects. Older nonspecific NSAIDs, such as aspirin, ibuprofen and ketoprofen may be associated with greater risk of side effects such as gastrointestinal distress and perforation. Newer NSAIDs (e.g. Carprofen, deracoxib) tend to be associated with less side effects. Regardless, liver and renal function should be evaluated periodically in all animals receiving these medications
- Opiods (e.g. sustained-release morphine, morphine, fentanyl, codeine, hydromorphone) can result in excellent analgesia with low to moderate behavioural changes, such as depression. These drugs are the most predictable and effective analgesics for use in cancer patients. Administration can be subcutaneously, intramuscularly, intravenously, or transdermally. Efficacy of oral opioids has not been clearly documented. Adverse reactions can include: lowered heart rate, diarrhoea, vomiting, constipation, and sedation.
- Palliative radiation therapy is commonly used to reduce discomfort associated with some tumours, especially ones that affect the skeletal system. When combined with low dose chemotherapy, the enhanced effected may be prolonged. In general, one-third of treated patients have good to excellent results, one-third have transient adequate responses, and one-third have no noticeable improvement in pain control.
- Acupuncture is used to treat many types of pain due to cancer or cancer therapy. It is often used on conjunction with pharmacologic agents to reduce their dosage and enhance overall wellness. Stimulation of acupuncture points induces the release of endogenous opioids and can aid in reducing nausea associated with chemotherapy, anaesthesia or administration of certain antibiotics.