The main scientific issue with animal experimentation lies in the crucial differences between species, making animals unreliable models to predict any human outcomes. Therefore,

• what works in animals often does not work in humans
• what is safe for animals can be dangerous for humans
• what doesn’t work in animals might be discarded instead of saving human lives.

Animal experiments are also expensive and take a long time.

Animal experiments don’t only harm animals, they are harmful to humans, too.

‍Crucial differences between species

‍Animals are unreliable models for trying to predict outcomes in humans. They are not tiny humans. There are fundamental differences between species, so how could they ever reliably predict medical outcomes for one another? Imagine going to a vet (instead of a doctor) when you are sick – it just doesn’t make sense!

To give some concrete examples:

Our hearts differ in many crucial ways,from the normal and maximum beats per minute, calcium sensitivity, responses to stress, and cell communication up to anatomical differences.¹ Dogs, pigs and sheep have more veins leading into the heart than humans and differ in the number and position of the valves.²

Our brains are obviously different in many anatomical ways, so they are not suitable models for research into human stroke (not even non-human primates are).³

• Immune responses to stroke are different in rodents and humans,⁴ and some even differ between mouse breeding lines.⁵
• So far, treatments aimed at “fixing” mice and rats mostly failed in humans.⁶

‍Only primates (including humans) possess a macula in their eyes.⁷ Macula degeneration is a major cause of vision-impairment in elderly humans. However, healthy, young mice are by far the most used model subjects.⁸

Wound-healing models use mice,rats and pigs, but:

• Rat and mouse skin is thinner and looser than ours, fur-coated with barely any sweat glands, and the healing follows a different process. We also react differently to burns.^9,10
• Pigs and humans differ in the skin’s elasticity,hair coarseness and sweat gland characteristics.¹¹ Pigs also do not form blisters in the same way as us.¹²

‍Chemicals can cause cancer in one species and not the other.¹³

• The common “laboratory animals” do not get skin cancer from arsenic, which humans do.¹⁴
• The lethal dose of arsenic to animals ranges around 10 to 500-fold the dose that would kill a human.¹⁵

‍Animal models for Type 2 Diabetes ignore the vast differences in metabolising sugar between rodents and humans.¹⁶

• Insulin is encoded in different genes.
• Their glucose transporters have different properties.
• The cell’s signalling for insulin works differently.
• The tissue where glucose is metabolised is different.
• The composition of the pancreas is different, and
• Type 2 Diabetes in humans progresses slowly, while the manipulated rodents get sick very fast.

‍Animal models of behavioural or mental disorders will never accurately copy the complexity of the human experience.

• The most prominent Schizophrenia symptoms (hallucinations, delusions and ‘impaired speech’) cannot be measured in animal models.¹⁷
• Depression is a highly complex subjective disorder that cannot be “measured” in animal models.¹⁸
• The U.S. National Institute of Mental Health discourages researchers from equating behaviours observed in animal“models” to human health conditions.¹⁹

Chimpanzees and macaques, the animals used to model HIV infection,react differently to the virus than us. This is why we have over 85 HIV vaccines for them, but humans still have none.²⁰

^‍What works in animals often does not work in humans

Animal tests (preclinical trials) are routinely conducted to try and prevent dangerous or ineffective new drugs from reaching human trials (clinical trials). However, there is a lot of robust scientific evidence proving that this isn’t working.

In fact, the use of animals to try and model human outcomes fails over 90% of the time: Learn more about this [link to new 90% page]

‍What is safe for animals can be dangerous for humans

Animal experiments failing to detect when compounds are toxic to humans have caused disasters in the past (and will likely cause more in the future). The examples below help highlight this risk.

• Macaque monkeys tolerate more than 10 times higher doses of paracetamol (acetaminophen) than would cause liver failure in humans.²¹
• A potential cancer drug (TGN1412) that tested safe in monkeys and rats caused the six human volunteers life-threatening complications on a minuscule dose.²²
• Thalidomide (for treating morning sickness) resulted in 8,000 to 12,000 babies being born deformed, of whom only 5,000 survived past childhood.²³ It was approved after safety testing on animals, many of which did not react with deformations even at doses ten times higher than what was given to humans.²⁴
• Thiazolidinedione drugs (for diabetes) have caused liver disease,²⁵ heart failure and stroke in humans²⁶ after testing safe and effective in rodents.²⁷
• Fialuridine (for Hepatitis B) seemed safe in mice, rats, monkeys, and dogs at high doses but caused severe liver failure in lower-dose human trial patients.²⁸
• Vioxx (for arthritis) proved safe in tests on mice, rats, squirrels, rhesus monkeys, rabbits, and dogs.²⁹ But between its approval and market withdrawal it caused at least 28,000 human deaths.³⁰
• A whole group of chemicals (called MMP Inhibitors) has been showing great success against aggressive cancers in animal models since the 1980s. But none of them has made it through clinical trials on humans, causing more damage than good if they even worked.³¹
• Between 1950 and 2014, there were 56 approved medications being withdrawn from the New Zealand market due to adverse reactions.³² Of these, 33 withdrawals were associated with patient deaths.

What doesn’t work in animals might save human lives

Not only are our differences regularly causing new medicines to fail, but who knows how many life-saving drugs we abandoned, just because they did not work in animal tests?

Many people know that dogs and cats should not eat chocolate or avocado, nor have coffee, grapes, raisins, onion,garlic, avocado, alcohol, nuts, or xylitol (contained in chewing gum)³³ while these are all enjoyable for humans.

Other examples:

If you have a pet rodent, you might know that Penicillin is:

• fatal for guinea pigs and hamsters³⁴
• effective in mice³⁵
• neurotoxic for rabbits and can cause seizures.³⁶

Yet it is one of the most commonly used and important antibiotics in human health.

How about over-the-counter pain medications?

• Aspirin is teratogenic in rats (causes birth defects or death of the foetuses).³⁷
• Aspirin and Ibuprofen cause ulcers and renal damage in both cats and dogs and can be lethal.³⁸

If you were lucky to survive a heart attack or stroke, you likely had Alteplase. It is an activator for specific enzymes that dissolve the blot-clotting fibres. The World Health Organisation included it in its list of Essential Medicines.³⁹ But had this drug been tested on pigs, it would not have advanced to human trials because in pigs this mechanism does not work.⁴⁰

Kidney transplantation is not tolerated in dogs but it saves countless human lives.⁴¹

Several medications we have today were approved and used for humans before studies showed that they caused cancer in“lab animals”.

• Phenobarbital (anaesthetic) causes cancer in mice and rats.⁴²
• Tamoxifen (breast cancer treatment) causes liver tumours in rats.⁴³
• Isoniazid (tuberculosis treatment) causes cancer in mice, rats and rabbits.⁴⁴
• Furosemide (diuretic) causes liver cancer in mice⁴⁵ and damages the kidneys of rats and mice.⁴⁶
• Metronidazole (antibiotic) causes cancer in rats⁴⁷and mice.⁴⁸

‍Sad fact: we simply don’t know how many life-saving medications we have abandoned because they did not work on animals.

‍Animal experiments are expensive and take a long time

Keeping, breeding, and testing on animals is incredibly expensive!

The cost of developing a new drug (which includes everything from the research stage to obtaining approval) costs approximately 1.5 billion USD (~ 2.5 billion NZD).⁴⁹

The time it takes to develop one drug (including both animal and human trials) can range between 3.6 and 14.4 years.⁵⁰

It shouldn’t cost this much or take this long to find usable treatments for suffering people.

Animal experiments are harmful to animals and humans

Every year, several thousand animals are made to endure extreme pain or discomfort during experiments in New Zealand alone. Hundreds of thousands of animals who are used or bred for science are also killed.⁵¹

Additionally, animals are often kept under the bare minimum of housing conditions. Rodents in stacked, small cages,often alone and without toys. These animals are most likely under stress which impacts biomedical study results.⁵²

And that is unacceptable.

But the people conducting animal experiments and looking after these animals can be negatively impacted, too. Researchers performing harmful procedures on animals often find it hard (emotionally). The psychological burden can significantly impact their well-being.⁵³

The people working with these animals regularly form a bond with them and are affected by the animal’s level of stress or pain. Yet, the social stigma related to their kind of work often results in low social support, which increases traumatic stress and burnout risk.⁵⁴

Having to kill an animal you care about is associated with work-to-family conflict, depressive moods, and substance use.⁵⁵

Animal researchers often subconsciously cope with cognitive dissonance.⁵⁶

As we know from our struggle to get information about animal experiments released to the public, researchers conducting animal experiments can be terrified of public scrutiny. Not only are they at risk of harassment and becoming targets of personal attacks. They also cannot openly talk about their work and may worry about their confidentiality restrictions.

While only a relatively small percentage of animal researchers have been affected by animal rights activism, violent protests do occur, making animal researchers, in general, feel more unsafe.⁵⁷

We want to emphasise here that NZAVS is a peaceful organisation, and we do not condone violence or abuse of any kind, verbal or otherwise. We have never met a researcher who likes harming animals. They would prefer non-harmful research if they believed it to result in equal or better scientific outcomes.

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