Refinement measures to improve animal welfare can ease the ethical dilemma between human benefit and animal harm in research with animal models of neurodegenerative diseases. To evaluate the potential for refinement, as well as its implementation in research, we analysed papers on murine models of Huntington's disease (HD) published between 1999 and 2009 (n = 233). Each study was classified according to a four-level severity scale, in terms of the disease stage that animals were allowed to reach, the execution of invasive procedures, and the implementation of refinement. Reports of ethical approval, and regulatory compliance in general, followed a clear rising trend over the years reviewed (p < 0.001). However, the proportion of high-severity studies did not change over that period. Also, of the studies for which approval was reported (n = 120), 36% were attributed the highest severity level. The observed discrepancy between the rising motivation to affirm regulatory compliance, and the unaltered proportion of studies allowing animals to reach severely distressful stages, raises both ethical and methodological issues, which we discuss in this paper.
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