Does turkey tail as an adjuvant therapy improve the quality of life of canine lymphoma patients?

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Appraisal, application and reflection

Holliday et al. (2009) published a prospective case series about the effect of a mushroom-derived supplement, K9 Immunity™, to the health-related quality of life (HRQoL) of canine patients with lymphoma. K9 Immunity™ contains the derivatives of six species of mushroom, including turkey tail (Trametes Versicolor), and it was offered with K9 Transfer Factor™ which contains a mixture of immunoproteins. In this year-long case series, the quality of life was measured by appetite and attitude level, and the adverse effect of chemotherapy namely gastrointestinal (GI) toxicity.

In canine cancer patients, the management aim is to achieve and sustain a good HRQoL. Three studies (Iliopoulou et al., 2013; Lynch et al., 2010; and Yazbek & Fantoni, 2005) have looked into a validated measurement of HRQoL in these patients. They have developed sets of questionnaires for owners to measure the HRQoL of their pets. In these questionnaires owners have been asked to score their pets in terms of their mental status, attitude, appetite, perceived pain level, mobility and hygiene. Owners’ perception is useful to assess HRQoL of cancer patients as they are often the very first individuals to recognise behavioural changes when HRQoL starts to be compromised.

Holliday et al. (2009) only made an evaluation on ‘activity and appetite level’ with owners’ perception, and GI toxicity which is the side effect of chemotherapy. In the measurement of ‘appetite and attitude level’, Holliday et al. (2009) failed to use a clear and validated scoring system. The paper also failed to use the standardised VCOG grading systems to assess GI toxicity. It therefore makes comparisons to other or future studies difficult. Other aspects of HRQoL, such as perceived pain level and mental status, have not been addressed by them either. Therefore, their case series did not fully and effectively assess HRQoL of the canine lymphoma patients.

GI toxicity includes vomiting and diarrhoea which may impact patients’ HRQoL, as they create distress, pain and inappetence. However, Mellanby et al. (2003) reported that some owners perceived an improved HRQoL in their dogs despite the complication associated with chemotherapy. The measurement of GI toxicity may not truly reflect the HRQoL.

All dogs in the study received a mushroom-derived product and another product in conjunction with either chemotherapy or palliative treatment. There was no control group and therefore it impossible to establish the impact of mushroom-derived supplement on the adverse effects of chemotherapy and HRQoL

Unfortunately, the demographic data, such as age, sex and breed, was not specified. Together with the small sample size (n=21), it is questionable whether this case series represents the wider canine lymphoma population.

A potential conflict of interest is identified in this study. Three of the authors of this paper were employed by Aloha Medicinals Inc., which is the pharmaceutical company manufacturing the immune-enhancement supplement used. In addition, the study was funded by this company. Given a lack of control in this study, there is a risk of bias in data presentation which the readers should be cautious about.

The Holliday et al. (2009) case series should be considered a preliminary study that may show the potential of mushroom-derived supplements in improving the HRQoL of canine lymphoma patients. However, the overall strength of evidence is very weak due to the absence of a control population, incomplete assessment of patients HRQoL, failure to use the VCOG grading system for all side effects, questionable representativeness to the canine lymphoma population, and the limitations in the study design. This prospective case series is insufficient to support the use of turkey tail-derived products to enhance the health-related quality of life of canine lymphoma patients receiving conventional therapies.

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