Shadow sacrifice of surplus laboratory animals

Animal welfare officer and veterinarian at the University of Auckland, Dr Jodi Salinsky, says euthanizing laboratory animals takes a heavy toll on animal care workers.

“People get confused all the time,” she says.

“We want to talk about the fact that this is difficult… We try to make the animals’ lives as good as possible, using as little as possible and replacing them when we can.”

Even when done as humanely as possible, ending the lives of laboratory animals is a challenging task for the people who have worked with them. It is especially difficult when dealing with otherwise healthy “surplus” animals that have been bred for research but not used because the technicians have cared for them since birth.

The issue of surplus animals has received worldwide attention thanks to the publication of five-yearly statistics in Europe. New data is imminent, with the latest count showing that 12.6 million surplus animals were bred and killed in one year, significantly more than the 9.4 million animals used in research.

In Australia, there are a surplus of mice and other laboratory mammals – bred for research but never used – in New South Wales and Victoria alone.

There are no national figures, but government reports show the surplus is more than double the amount used for science, education or product testing.

Most surplus animals are laboratory mice. The vast majority are killed humanely.

Professor Gilbert Schoenfelder is head of the German Center for the Protection of Laboratory Animals (Bf3R), an independent organization of the German government that researches and advises on animal testing and improving animal welfare.

He argues that reducing surplus animals is “the easiest way to reduce the number of animals used in the context of research in the short term.”

However, doing this requires transparent statistics and attention to the contributing factors: researchers’ preference for using male animals, breeding to maintain genetic strains, and the excess of animals in reserve is kept to meet short-term requests, or ‘just in case’.

How many surplus laboratory animals are there?

The Australian Animal Research Code requires breeding to be managed to avoid or minimize the production of surplus animals.

The experiences in Germany show the magnitude of the opportunities.

In 2021, Germany began publishing the number of surplus animals every year, surpassing European Union requirements to count every five.

In one year – between 2021 and 2022 – Germany recorded a 31% drop in the number of surplus animals, equivalent to a total of 785,123 fewer animals.

A combination of reasons contributed to the dramatic decline: transparent statistics along with increased scrutiny and legal action by animal welfare groups over whether scientists had “reasonable grounds” for killing surplus animals.

But as Schoenfelder says, the data shows what is possible. “If we can do about 700,000 in Germany alone, think about how many animals you can save worldwide.”

In New Zealand, where Salinsky is based, national statistics on animals in research have been published for more than a decade, including data on the number of animals “bred but not used.” In 2022, 58,193 mice, rats, guinea pigs and rabbits were used, compared to 116,078 mice bred but not used.

The RSPCA’s Chief Science Officer Suzanne Fowler says more transparent data and monitoring in Australia would promote greater research and awareness of animals used in research, and surplus animals.

“More data analysis and reporting is needed in Australia on animal breeding and the ratio between the number of animals used and the number of animals killed without use, and this should form a formal part of any project reporting that addresses breeding and maintaining specific lines of research,” she says. .

The RSPCA is calling for greater transparency, including consistent, accessible statistics on animal use, published by institutions and collected at state and national level.

Currently, available state data indicate that the surplus of animals is significant and far exceeds the number of animals used in research.

The latest data from NSW (2021) shows there were 263,767 surplus laboratory mammals (mice, rats, rabbits and guinea pigs) – used for livestock production and maintenance – approximately 2.3 times the number (114,071) used for research , education or product development. to test.

In Victoria in the same year, 945,096 ‘specified’ animals, including laboratory mice, rats, rabbits, guinea pigs and non-human primates, were kept in breeding colonies, double the number (458,462) used for research or teaching.

Addressing gender bias in animal research is a win-win

One solution has the potential to have a “huge benefit” for improving the quality of science and animal welfare, Schoenfelder says.

The male bias in the biological sciences and clinical studies is well documented and extends to studies involving animals. “Most of the animals used in experiments are male,” he explains.

Excluding one gender was mainly for convenience, he says. Mice and rats have an estrous cycle of two to five days. In the past, scientists who wanted to check the variability and influence of hormonal cycles in their data chose to use only male animals. The practice became widespread and entrenched.

Because mice produced offspring of both sexes in roughly equal numbers, the bias contributed to the surplus, with the females usually killed because they were not being used.

Practices change.

There is increasing recognition of the problems arising from gender-based bias, so major research agencies such as the National Institutes of Health in the US and the UK’s Research and Innovation now require experiments to use both genders as a standard.

Salinsky says that at her institution, any researcher who proposes using only men in an experiment will be heavily investigated and questioned by the animal ethics committee, and asked to use both sexes. “As we continue, this will hopefully become standard practice,” she says.

Still, too many animals can arise because the nests are unpredictable. You may only want six animals, but the animal produces a dozen.

In addition, the nature of breeding to produce certain genetic strains also contributes to the surplus, creating surplus animals that do not meet the required characteristics.

Where institutions do not require specific strains of live animals for a significant period of time, technologies such as cryopreservation and resuscitation can provide a solution.

Schoenfelder says cryogenic preservation can limit the total number of animals and strains housed and bred in facilities, as an alternative to continued breeding to maintain certain genetic lines.

“You can cryopreserve embryos and store them in liquid nitrogen. If you need the thrill, take them out, put them in a mother animal (a surrogate mouse mother), raise them and you can breed them.

“This is not a supermarket”

Reducing surplus animals also requires a cultural change in scientific practice.

A difficult issue is the way in which researchers, scientific journals and reviewers sometimes request animal testing at short notice. This means that facilities sometimes breed extra animals to have them on hand.

The loose attitude towards the use of animals is something Salinsky is working hard to change.

“We do have some extra numbers so that we have diversity and a timely offer for researchers. We really try to involve the research community in the fact that this is not a supermarket and that we are not just breeding animals,” she says.

Researchers are expected to communicate their requirements in a timely manner to breed the animals and avoid last-minute requests.

Fowler says, “There should be no breeding ‘just in case’ animals are needed.”

“The RSPCA is against breeding too many animals to meet fluctuating demand or to maintain lines where there is no clear intended use of the animals,” she said.

Besides the obvious costs to the animals, dealing with the surplus also has consequences for the staff.

“Unfortunately for staff, this often means caring for animals for weeks or months and then having to kill those same animals,” she says.

“This is definitely a challenge, especially if they have not been used for their intended purpose, for example in biomedical research, meaning there is little justification for their production in the first place. This can increase the challenging aspects of the role and make it difficult for staff to rationalise, potentially contributing to compassion fatigue.”

To manage these risks, Salinsky creates a ‘culture of care’ in the team, caring for the well-being of the staff as well as the animals. For example, if someone feels like they can’t euthanize animals on a certain day, another person will step in – no questions asked.

“I try to make sure that whatever we do, we do the best we can – for the welfare of people, the welfare of animals and the robustness and translatability of the research,” she says.

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