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Extending quality of life for cancer patients
Assessing nutrition, pain management key components to palliative care


DVM360 MAGAZINE


How aggressively to provide nutritional support depends on the severity of the animal's nutritional deficiencies. Minimal deficiencies can be overcome by offering palatable foods such as commercial nutritional support diet or boiled chicken and rice. The latter is not nutritionally balanced, and additional supplements are needed if this diet is going to be used long-term.

For moderate anorexia, appetite stimulants such as prednisone, cyproheptadine and mirtazapine can be used. If food intake is thought to be reduced because of nausea, gastroprotectants such as famotidine and sucralfate may be considered. Anti-emetics such as metoclopramide, dolasetron, ondansetron and maropitant are indicated to help control nausea and vomiting.

If voluntary food intake cannot be restored or maintained, then supplemental feeding is needed. Whenever possible, it is preferable to use the GI tract. This way, the nutrients provided are digested and metabolized through normal pathways.

In addition, food within the intestine plays a critical role in maintaining gut health and function. The most commonly used feeding tubes are esophagostomy tubes and gastrostomy tubes. Both can be left in place indefinitely. The main advantage of an esophagostomy tube is the ease of placement — they can be placed quickly and easily under light general anesthesia without any specialized equipment. In contrast, gastrostomy tube placement usually is done surgically or with endoscopic guidance.

The main advantage of a gastrostomy tube is that it is wider in diameter and can accommodate a wider variety of foods. Additionally, low-profile gastrostomy tubes can be used to eliminate the need for cumbersome and potentially uncomfortable bandages.

There is ongoing discussion about so-called "cancer diets." Their general features include low quantities of simple carbohydrates, moderate quantities of highly digestible proteins rich in arginine and glutamine and relatively high quantities of lipids and omega-3-fatty acids.

However, the use of such diets has been evaluated primarily in dogs with lymphoma. It is more important for an animal's diet to be palatable and nutritionally balanced. Changing an animal's diet to a cancer diet should be considered only if caloric and general nutritional requirements are being maintained without any difficulty.

Get the animal to eat first; worry about what it is eating second.

Pain management

Cancer pain is one of the most important factors affecting overall quality of life. In human oncology, it is estimated that cancer pain is experienced by 30 percent to 50 percent of people undergoing active cancer treatment and 70 percent to 90 percent of people with advanced disease. It is difficult to accurately assess the prevalence of pain in veterinary cancer patients, but it is reasonable to assume that it is comparable to that.

Cancer pain likely is underappreciated in veterinary cancer patients because it is relatively difficult to assess objectively. Physiologic variables such as heart rate, respiratory rate and pupil size are not reliable indicators of pain. Instead, pain assessment is based primarily on behavior. Subtle changes in activity level, attitude, appetite or grooming can be early signs of pain. As pain becomes more severe, aversion to petting/palpation may be noticed. Vocalization usually is seen only when pain is severe.

Because the owner sees the dog or cat every day in its own environment, he or she is best able to assess behavior changes. Therefore, it is crucial to educate the owner about what signs to look for, to ask the owner for feedback on a regular basis and to trust the information provided by the owner.

It is very important always to be aware of the potential for cancer pain and to take a proactive approach with respect to its diagnosis and treatment. Pain can be prevented far more easily than it can be reversed. Chronic pain induces physical changes in the spinal cord that alter the way pain signals are processed, resulting in hyperalgesia and allodynia. These changes decrease the efficacy of analgesic medications, making it much more difficult to alleviate an animal's pain. Additionally, even if the pain eventually is controlled, the physical changes in the spinal cord are not necessarily fully reversible.

Dog and cat owners do not want their beloved pet to be in pain. Do something about it.

Pain management typically is most effective when multiple treatment modalities are used in combination. When animals present with mild pain, non-opioid analgesics such as nonsteroidal anti-inflammatory drugs (carprofen, deracoxib, meloxicam) may be attempted first. For moderate pain, a weak opioid such as codeine, buprenorphine or tramadol can be added.

For severe pain, strong opioids such as morphine or fentanyl are indicated. While veterinary analgesia involves primarily the use of nonsteroidal anti-inflammatory drugs and opioids, the adjunct use of additional drugs such as gabapentin and amantadine is gaining popularity.

In addition to using analgesics, several other treatment modalities should be considered and used whenever appropriate. Local anesthetic nerve blocks are very useful for orofacial tumors and for phantom pain associated with amputation. Using a mixture of bupivacaine, lidocaine, methylprednisolone and serapin can be a good locoregional pain control enduring for up to one month per injection.

Bisphosphonates are drugs that prevent bone resorption by inhibiting the formation of new osteoclasts, inhibiting the ability of mature osteoclasts to resorb bone, and inducing osteoclast apoptosis.

By inhibiting tumor-associated osteolysis, bisphosphonates can help reduce the pain associated with both primary and metastatic bone tumors. Pamidronate currently is the bisphosphonate used most commonly in veterinary medicine. A dosage of 1.0-2.0 mg/kg every four weeks has been reported. To minimize the risk of renal toxicity, the pamidronate dose should be diluted in 250 ml 0.9 percent NaCl and then administered intravenously over two hours.

In one study, 12 out of 43 dogs (28 percent) with appendicular osteosarcoma experienced clinically significant pain relief that persisted more than four months. There is anecdotal evidence that the oral bisphosphonate alendronate may be beneficial for dogs with osteosarcoma, but its routine use is not recommended because of poor absorption from the gastrointestinal tract.


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Source: DVM360 MAGAZINE,
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