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to their invasive nature and will often respond very well to palliative radiation therapy, which has a low risk of acute side effects. When removing tumours for purely palliative purposes, aggressive resection to achieve margins should not be a major factor in the approach but if margins are achievable without increasing morbidity this may be reasonable.
Nutritional support in cancer patients:
Maintenance of adequate nutrition is a key factor in assessing quality of life in dogs and cats with many illnesses, including cancer. In the specific setting of palliative care in the veterinary oncology patient, both strategies
to increase voluntary intake and strategies bypassing
the need for voluntary intake (e.g. feeding tubes) may
be used, but clear consideration of goals and quality of life is required. Anorexia or hyporexia in dogs and cats with cancer may be caused by inflammatory response
to the tumour, pain or nausea, obstruction (oral or other
GI tumours), or effects of chemotherapy. Even in patients where caloric intake appears adequate, disordered metabolism can cause loss of condition (cancer cachexia), though this does not seem to be as common in dogs as in people. It may be more common in cats.
The first step in developing a nutritional support plan is
a baseline assessment including body weight, body and muscle condition score, and dietary history. Weight alone is not sufficient to fully assess nutritional status as weight gain with significant loss of body and muscle condition may be seen due to e.g. tumour growth or ascites.
If nutritional supplementation is required, resting energy requirement (RER) must be calculated. There are several formulae for this. One approach, used at the University of Melbourne, is:
· RER in kcal/day =
· Body weight (kg) x 30 + 70 for dogs and cats
· 70 x Body weight (kg)^0.75 for dogs > 45kg
An alternative approach for lean/active cats < 5kg cats is: RER = Body weight (kg) x 60
For hospitalised patients, aiming for RER is reasonable. Increased energy requirements are expected for more active animals at home or those in whom extensive tissue repair is taking place and maintenance energy requirements can vary from approximately 1.2-1.8 RER depending on activity level and neuter status. Regardless of which calculation or approach is taken, regular reassessment is required to assess whether current caloric intake is sufficient.
Recommended steps for increasing caloric intake in palliative care:
1. Address pain, nausea or other underlying causes where possible
2. Coaxing (e.g. hand feeding, dietary modification)
· Syringe feeding is usually not practical
1. Pharmacologic approaches (1) including:
1. Mirtazapine - can cause behavioural changes e.g. vocalisation or agitation. Should not be used concurrently with cyproheptadine. Is absorbed transdermally in healthy cats with effective appetite stimulation, although the appropriate dose has not been determined (2)
2. Cyproheptadine - may take a few days to be effective, may cause sedation or paradoxical hyperexcitability
3. Capromorelin - recently approved (in dogs), ghrelin receptor agonist. Can cause diarrhoea, vomiting, and excess salivation (3)
4. Prednisolone
2. Feeding tubes
In my opinion, feeding tubes should be considered in palliative patients only in select circumstances i.e. where other quality of life factors are considered good (e.g. pain is controlled, activity and mobility are acceptable) but inadequate caloric intake persists. Feeding tubes are not recommended where inadequate intake is due to effects of cancer that are not otherwise being addressed e.g.
in oral tumours where the animal is not eating well due to pain. Oesophagostomy and gastrostomy tubes are the most common approaches used. Oesophagostomy tubes typically last for weeks to months. Gastrostomy tubes should be considered when anticipated need is for > 6-8 weeks. Placement of gastrostomy tubes is more challenging than oesophagostomy tubes and typically requires either an endoscopic or surgical approach. Naso-oesophageal or nasogastric tubes are quick and non-invasive to place but are usually short term (days) and can only accommodate liquids. These approaches may be used in cases where a definitive diagnosis
is pending or while assessing for rapid response to treatment before making longer term decisions.
References: General:
Vet Clinics of North America Small Animal Practice Palliative Medicine and Hospice Care, 2011
Lascelles BD, Management of Chronic Cancer Pain, Withrow and MacEwen’s Small Animal Clinical Oncology 5th edition pp 245-259
Wakshlag JJ, Nutritional Management of the Cancer Patient Withrow
and MacEwen’s Small Animal Clinical Oncology 5th
edition pp 259-270
1. Agnew W, Korman R. Pharmacological appetite stimulation: Rational choices in the inappetant cat. J Feline Med Surg 2014;16:749-756
2. Benson KK, Zajic LB, Morgan PK, Brown SR, Hansen RJ, Lunghofer PJ, Wittenburg LA, Gustafson DL, Quimby JM. Drug exposure and clinical effect of transdermal mirtazapine in healthy young cats: a pilot study J Feline Med Surg 2017;19:998-1006
3. Plumb’s Veterinary Drug Handbook iPhone application, accessed 20th April 2018.
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