Welfare-Adjusted Life Years (WALY): A novel metric of animal welfare that combines the impacts of impaired welfare and abbreviated lifespan

Abstract

Currently, separate measures are used to estimate the impact of animal diseases on mortality and animal welfare. This article introduces a novel metric, the Welfare-Adjusted Life Year (WALY), to estimate disease impact by combining welfare compromise and premature death components. Adapting the Disability-Adjusted Life Year approach used in human health audits, we propose WALY as the sum of a) the years lived with impaired welfare due to a particular cause and b) the years of life lost due to the premature death from the same cause. The years lived with impaired welfare are the product of the average duration of each welfare impediment, reflecting the actual condition that compromises animal welfare, the probability of an incident case developing and impaired welfare weights, representing the degree of impaired welfare. The years of life lost are calculated using the standard expected lifespan at the time of premature death. To demonstrate the concept, we estimated WALYs for 10 common canine diseases, namely mitral valve disease, dilated cardiomyopathy, chronic kidney disease, diabetes mellitus, atopic dermatitis, splenic haemangiosarcoma, appendicular osteosarcoma, cranial cruciate ligament disease, thoracolumbar intervertebral disc disease and cervical spondylomyelopathy. A survey of veterinarians (n = 61) was conducted to elicit impaired welfare weights for 35 welfare impediments. Paired comparison was the primary method to elicit weights, whereas visual analogue scale and time trade-off approaches rescaled these weights onto the desired scale, from 0 (the optimal welfare imaginable) to 1 (the worst welfare imaginable). WALYs for the 10 diseases were then estimated using the impaired welfare weights and published epidemiological data on disease impacts. Welfare impediment “amputation: one limb” and “respiratory distress” had the lowest and highest impaired welfare weights at 0.134 and 0.796, rescaled with a visual analogue scale, and 0.117 and 0.857, rescaled with time trade-off. Among the 10 diseases, thoracolumbar intervertebral disc disease and atopic dermatitis had the smallest and greatest adverse impact on dogs with WALYs at 2.83 (95% UI: 1.54–3.94) and 9.73 (95% uncertainty interval [UI]: 7.17–11.8), respectively. This study developed the WALY metric and demonstrated that it summarises welfare compromise as perceived by humans and total impact of diseases in individual animals. The WALY can potentially be used for prioritisation of disease eradication and control programs, quantification of population welfare and longitudinal surveillance of animal welfare in companion animals and may possibly be extended to production animals.

West Highland White Terriers under primary veterinary care in the UK in 2016: demography, mortality and disorders

“…It is recognised that the life-long nature of the disease, its complications, and associated financial costs are challenging, even a burden, for affected dogs and their carers, and a challenge for clinicians [13, 14], despite the expanding treatment options for this disease [15]. A recent study that developed a metric to summarise welfare compromise and total impact of disease in individual animals estimated that atopic dermatitis had by far the highest score out of the 10 canine diseases studied, even though euthanasia due to the disease was not factored into the estimate [16]. The documented breed predisposition and impact of this kind of allergic skin disease is reflected in the focus on skin disease by the KC as a priority for the WHWT, although much of the current evidence has been derived from referral veterinary care and owner survey data sources [9].…”

Health-related welfare prioritisation of canine disorders using electronic health records in primary care practice in the UK

“…Disorders affecting dogs for extended periods pose greater risk of cumulative or lifelong pain and other welfare issues, even where daily levels of discomfort/pain, debilitation or distress appear relatively low. A recent report by Teng et al proposed and applied the Welfare-Adjusted Life Year (WALY), adapted from the human Disability-Adjusted Life Year (DALY) concept, as a measure of cause-specific welfare impact on individual dogs [53]. This complex metric puts strong emphasis on disorder duration as a component of overall welfare compromise, taking into account both time lived with impaired welfare due to a given cause and years of life lost after premature death from that cause (with weighting by perceived cause-specific level of welfare compromise).…”

Positive attitudes towards feline obesity are strongly associated with ownership of obese cats

“…The final model showed a good fit with the P-values of the approximated Hosmer-Lemeshow test >0.05 (i.e., 0.888 and 0.876 for models with binomial outcomes, underweight versus ideal weight and overweight versus ideal weight, respectively). 3 : Overweight and obesity 4 : Birds and large mammals 5 : Small mammals, insects, lizards and frogs 6 : Technical and further education 7 : Vocational education and training 8 : Or equivalent � : P-value < 0.05 https://doi.org/10.1371/journal.pone.0234190.t005…”

“…Research on overweight and obesity (O&O) has extended from humans to companion animals, with increasing recognition of the issue of O&O as a risk to health conditions, a shorter lifespan and impaired welfare of cats and dogs [1][2][3][4][5]. Studies investigating the risk factors for feline O&O can be categorised into two groups.…”