A fresh row has erupted over the merits of vegan pet diets after new analysis argued there was only a “minimal” link between the approach and animals’ health.

Researchers at the University of Liverpool say other factors are more critical to owners’ perceptions and they can draw “no firm conclusion” on which diet is best.

But the lead author of the original paper has stood by its findings, claiming to have even greater confidence in them now following the latest work.

Based in UK

The new paper, published in the Plos One journal, re-analysed data from more than 2,300 dog owners, of whom a substantial majority are based in the UK.

A study of the same cohort, which was published in the same journal two years ago, concluded that vegan-fed dogs had fewer health disorders than their counterparts who ate conventional or raw meat diets.

It also claimed that “nutritionally sound” vegan diets were the “healthiest and least hazardous” feeding choice for dogs, suggesting indications that raw-fed dogs fared slightly better than the vegan group may have been influenced by a younger average age within the raw group.

‘Negligible’

But the new paper argued that diet choice was a “negligible” factor in canine health, with age, frequency of veterinary visits and receiving medication found to be the most important indicators instead.

That conclusion is based on the development of two new variables based on whether either any health problem or a significant illness was reported in individual cases.

Alex German, one of the authors of the new paper, said the suggestion that vegan diets were healthier than alternatives was “not accurate”, because the original study’s reliance on survey data meant that it could only indicate “a possible correlation and not causality”.

‘Nuanced insights’

His co-author, Richard Barrett-Jolley, argued that the current approach provided “more nuanced insights” on the subject than the earlier analysis.

Prof Barrett-Jolley said: “Crucially, we cannot draw a firm conclusion as to what diet type is actually best for dogs; this was never possible given the nature of the original dataset and study design.

“However, we can conclude that variables other than dog diet are more strongly associated with owner opinions about the health of their dog.”

Swift response

But the paper’s publication on 15 May prompted a swift response, which branded the new research as a scientific attempt to “undermine” vegan diets and suggested it had backfired.

Andrew Knight, the lead author of the original study, said: “I was relieved to see confirmation that feeding vegan diets had minimal impact on owner opinions about health. This increases my confidence in the reliability of the owner opinions we analysed.

“The large number of health parameters we studied, and the very large number of dogs included, provide a high degree of confidence in our results.”

In response, Prof German described the confirmation claim as “surprising”.

‘Ecological grounds’

Prof Knight also argued that what he described as “substantial dietary change” was now essential on ecological grounds, following a paper published last year that calculated that more than 450 million more people could be fed through food energy savings if all the world’s dogs were put on to a vegan diet.

The new research is also likely to further intensify interest in the outcome of an ongoing BVA review into its diet policy.

Last month, officials indicated a report from the work of the Companion Animal Feeding Working Group that was set up last year could be released as early as this summer.