Palliative care

Overview

Unfortunately, cancer still remains one of the most common causes of death and euthanasia in veterinary medicine. With advancements in the diagnosis and treatment of cancer, many cancers can be aggressively treated to provide excellent extended quality of life, slow cancer progression and prolong life eg. osteosarcoma, lymphoma. But, a cure rarely results. For those patients that are not good candidates for cancer therapy, palliative care can provide a good quality of life for as long as possible.

Palliative care is supportive care that improves or maintains the quality of life without slowing the progression of cancer or prolonging life. Once a pet’s quality of life is sub-optimal and cannot be restored with palliative care, humane euthanasia is an option. 

Nutrition

Inadequate nutritional support is a common complication of cancer. Studies show that 68% of dogs with cancer experience weight loss. Referred to as cancer cachexia it is characterized by anorexia and wasting of the lean body mass. 

There are two main factors that contribute to cancer cachexia

1. Mechanical - A decrease food intake e.g. oral and stomach tumours can cause discomfort when eating so the pet stops eating or vomiting and diarrhoea associated with cancer can prevent nutritional absorption
2. Functional - A metabolic change in the body that reduces the efficient use of nutrients e.g. poor metabolism of carbohydrates, protein, and fats

The goal of nutritional support is to get the pet eating first, and then worry about what it is eating. 

Providing nutritional support

• Offering highly palatable foods e.g. boiled chicken and rice, prescription diets e.g. Hill’s a/d
• Appetite stimulants e.g. prednisone, cyproheptadine, and mirtazapine
• Gastroprotectants e.g. famotidine and sucralfate
• Anti-emetics to control nausea

In severe cases, supplemental feeding via a feeding tube will be required.

Pain Management

Managing pain associated with cancer is an important factor in the overall quality of life. In human cancer, 70-90% of people with advanced disease experience pain and 30-50% experience cancer pain during active treatment. 

Signs of pain in pets include:

• Behavioral changes
• Decreased activity
• Decreased appetite
• Decreased grooming
• Does not like being touched
• Vocalization

Pain can be prevented more easily than it can be reversed, so it is important to notify your vet if you notice any of these signs of pain. 

Pain management options include

1. Non-opioid analgesics e.g. nonsteroidal anti-inflammatory drugs (NSAIDS)
2. Weak opioids e.g. codeine, buprenorphine, or tramadol
3. Strong opioids e.g. morphine, fentanyl

With additional drugs such as gabapentin or amantadine

Local pain control by way of local anesthetic nerve blocks can offer pain relief for up to 1 month for mouth or facial tumors or following an amputation. 

Bisphosphonates e.g. pamidronate are drugs that can help reduce the pain associated with both primary and metastatic bone tumors e.g. osteosarcoma.

Palliative Radiation Therapy

This type of radiation therapy is administered with the intent of reducing the pain associated with an incurable tumor. These pets typically would not benefit from a more aggressive definitive course of radiation treatment. This form of therapy is used widely in dogs with osteosarcoma where 75-90% of dogs experience pain relief and improvement in mobility around 14 days from starting treatment. Pain relief usually lasts around 3-4 months. Other cancers that have benefited from this include oral tumors, nasal tumors, thyroid carcinomas, and soft tissue sarcomas.

Prednisone

Prednisone can be used as chemotherapy drugs for some cancers and the response can be quite dramatic in the short term. But, because prednisone can negatively impact more aggressive chemotherapy treatment, it is important to discuss both options with your veterinarian or specialist before starting either treatment. 

For example:

• 50% of dogs with lymphoma can reach partial or complete remission on prednisone treatment with a survival time of around 1-2 months. 
• 20% of dogs with mast cell tumors can reach partial or complete remission with a survival time from weeks to months.

Prednisone also can help maintain quality of life by reducing pain and inflammation, improving appetite and energy levels.

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