Rats (and mice) are often the animals of choice to try and model human conditions, treatment and body functions - even though we know that using animals to try and model people fails over 90% of the time.
Mice and rats are commonly used due to their small size, low maintenance (i.e., they are easy to house and care for), short life cycle, and ability to breed quickly (allowing large numbers to be generated for studies).
They also share many of our genes.1 However, that's not surprising. Even cats share many of our genes.2
Rats are used is some of the most gruesome experiments that involve things like force-feeding, poisoning, oxygen deprivation and invasive surgery.
Rats in NZ have been used for:
- Drug research, including safety and efficiency testing.
- Teaching purposes in schools, mainly dissections.
- Investigating ways of killing wild rats. (i.e., research into effective poisons and traps).
- Medical research, including research into the development of severe diseases (i.e., stroke, diabetes, cancer), modelling neurological disorders (i.e., Schizophrenia, Autism), modelling mood disorders (i.e., example, anxiety, and depression) and research into tinnitus.
- Drug addiction research including research into the development and suppression of addictions and the impacts of drug use.
- Basic biological research, including research into digestion, aging, nerve damage, obesity and how the brain functions.
Places that use rats for science in NZ include crown research institutes, private companies and universities. In fact, most universities have their own breeding colonies. Otago University states on its website that they have a dedicated rat testing room in the Behavioural Phenotyping Unit.3
Rats used for science in NZ are sourced from breeding units, public or commercial sources, the wild (captured) and they are imported from overseas.
Discover real-life examples of how rats have been used in NZ below!
Studying selenium metabolism
Cats and dogs were fed diets with different selenium supplementation for three weeks in individual metabolic chambers. A liver biopsy was taken under anaesthesia.
Monitoring wild cats via GPS collar
Wild cats were caught and fitted with GPS collars. After an average of 9.75 days, there were recaptured to retrieve the collars.
Testing new toxin against stoats and wild pets
Dogs, cats and stoats were fed different versions of toxic bait. Symptoms and time of death were monitored. Four dogs and two cats survived, but their fate is not stated.
Testing the efficacy and shelf-life of a toxin
Captive wild cats were used to compare the efficacy of different toxin formulations and the effect of more extended bait storage. Cats were fed the toxin bait or pipette-fed toxin directly as control. Symptom onset and time of death were monitored.
Investigating how worms spread between lambs and calves
Lambs and calves were infected with worm eggs to see if parasites from cattle can infect sheep.
Testing a fertility treatment
Cows with fertility problems were treated with hormones for ten days or left untreated. All were then artificially inseminated.
Testing a supplement for more calcium intake
Pregnant cows were fed with or without a specific feed additive. After birth, all were fed the same diet. Blood samples were taken in the weeks around birth.
Checking endometritis rates in dairy herds
Some cows in several dairy herds were selected, and their vaginal discharge was measured and sampled. They were then impregnated as per standard agricultural practice.
Comparing weight gain with different diets
Newborn calves were raised on various milk, pasture, and pellets combinations. They were slaughtered at two years old, and their “quality” was measured.
Testing pain meds for disbudding
The horn buds of young calves who were slightly sedated were burned off with a hot iron. Half of them received pain meds beforehand, and blood samples were taken before and after. After 24 hours, the second group received pain meds, too.
Studying Ikeda infection and treatment
Regular blood samples were taken from cows on three different farms. Only some were treated against the parasite. Milk production and fertility were recorded.
Studying diarrhea infection
New mother cows had blood samples taken. If the sample was negative for a diarrhoea virus, they were sampled again after a while.
Studying genes for body size
Udders of dairy cows were slightly cut with a scalpel, and a tissue sample was taken with a biopsy needle.
Testing toxicity of a potential new fertiliser
Pregnant cows were fed a toxic ingredient to see if it is toxic.
Studying stress around birth
Blood samples were taken from cows with a high or low risk of health concerns after birth.
Studying genetics of a missing tail
Cloned foetuses were implanted into female cattle to research taillessness. Some of them were killed during pregnancy to examine the foetuses. One tailless animal was killed at age 4, and one of the cloned calves died after birth.
Studying Ikeda (parasite) infection
Blood samples were taken from dairy cows and their calves directly after birth before separating them. After four months, the calves were sampled again.
Studying Osteoporosis in cows
Young female cattle who had given birth for the first time were sent to slaughter. Half of them had broken bones for between 2 and 10 days. Blood samples were taken before slaughter, and bones were collected after.
Testing a tuberculosis vaccine
Male calves were infected with bacteria. Two groups were vaccinated before or after the infection, and the third group was left untreated. All were killed and dissected 13 weeks later.
Testing feeding plans for better immunity after calving
Pregnant cows were fed either a bit too much or a bit too little. Blood samples were taken before, at, and after calving. Researchers also took liver samples with a 20-cm biopsy needle and vaginal samples with a small brush and a scoop at these dates, except for the date of birth.
Testing a “Kiwiball” to teach kiwi aversion to dogs (2014)
Dogs were exposed to a device mimicking a kiwi bird, getting an electric shock upon touching it. The learning effect was tested several weeks later.
Testing a morphine alternative for pain
Dogs undergoing castration were treated with different pain relief and their pain response was measured. During surgery, EEG was measured to see differences in response to the process. After surgery, the pain level was determined through a behavioural assessment several times.
Studying selenium metabolism
Animals were fed diets with different selenium supplementation for three weeks in individual metabolic chambers. A liver biopsy was taken under anaesthesia.
Studying selenium metabolism
Cats and dogs were fed diets with different selenium supplementation for three weeks in individual metabolic chambers. A liver biopsy was taken under anaesthesia.
Testing treatment of a neurodegenerative disease
Dogs with Mucopolysaccharidosis (MPS IIIA) received medication, either from birth or 12 weeks to 23 weeks of age. One group received a placebo. Drugs were given under anaesthesia, either as injections into the vein or close to the brain. At 23 weeks old, all puppies were killed and their brains removed.
Evaluating the efficiency of kiwi aversion training
Dogs who had experienced either none, one or two times of kiwi aversion training with shock collars were observed near a caged live kiwi.
Testing a “Kiwiball” to teach kiwi aversion to dogs (2010)
Dogs were exposed to a device mimicking a kiwi bird, getting an electric shock upon touching it. The learning effect was tested several weeks later.
Trying out genetically sick dogs as models for human disease
Dogs with Mucopolysaccharidosis (MPS) IIIA were bred within an experimental colony. As part of characterizing them as a model for testing, the dogs were killed for dissection.
Testing new toxin against stoats and wild pets
Dogs, cats and stoats were fed different versions of toxic bait. Symptoms and time of death were monitored. Four dogs and two cats survived, but their fate is not stated.
Testing a pesticide as dog poison
Pound dogs were fed poison in different concentrations and different bait. More than half died within 4 hours.
Using fish to study the impacts of Climate Change
Fish were either bought or caught and killed so that they could be dissected.
Overfeeding Zebrafish to learn about obesity
Normal and transgenic zebrafish were fed normally or way too much. The fish were taken out of the water for glucose tests and blood samples.
Studying gut bacteria in fish
Nine fish were caught by underwater spearing and killed so that samples could be collected from their digestion tracts.
Studying the sleep of sharks
Sharks were caught and kept in outside tanks. For the experiments, they weren't fed for at least 4 days, of which they spent 3 days in a measuring chamber not much bigger than the shark. Oxygen consumption and behaviour were continuously recorded for the last 24 hours.
Infecting fish larvae as a potential model for humans
Zebrafish larvae were injected with bacteria to test how their immune system responds. This was repeated to test how well the immune system reacted and how long the effect lasts.
Finding a “growth gene” in snappers
Snappers were caught from the wild and bred. Around eighty-thousand of their offspring were hatched and raised. At regular “grading” events, injured and deformed fish were disposed of. At just under a year old, around twenty-two-thousand were left and transported to a sea pen, where they were raised to 17.5 months old before harvesting.
Testing how much fat you can feed fish
Fish in aquaculture were divided into groups and fed diets with different fat content. Fish were anaesthetised and faeces samples squeezed out of them.
Testing fish for mercury contamination
Wild fish were caught, measured and frozen to be analysed.
Measuring how stress affects fish
Fish were exposed to chronic stress for four weeks, while 57 non-stressed animals were kept as a control. Signs of stress were noted. At the end of the experiment, all were chilled to death.
Exposing fish to herbicides
Zebrafish were kept in tanks that were contaminated with different herbicide concentrations for 10 days. They were then mated to herbicide-exposed or control fish. Both generations were tested on behavioural changes at around 4 months of age. 24 fish per treatment were killed and dissected.
Testing supplements as protection from toxins in over 1,000 fish embryos
Embryos were harvested and kept in Petri dishes for toxicity and treatment tests. Embryos were treated with an antioxidant, a gold salt or both on the first day, and abnormal development was measured on day 5.
Studying effects of drying rivers on mudfish
Water depth and quality were measured at 24 different sites. Several traps for fish and invertebrates were set at 8 visits, sampling and mostly killing the caught animals (including 15 individuals of the endangered Kōwaro).
Studying bacterial spread in fish larvae
Bacteria were genetically modified and made fluorescent. Zebrafish were bred, and their larvae were infected with the bacteria. The fish were killed for analyses or used for live imaging under a microscope (and then killed, most likely).
Investigating effects of invasive fish removal
Using fyke nets and electrofishing, fish were caught on four occasions. Fish were marked with fin clippings around one big removal event where 3 tonnes of fish were caught. In recaptures a week after each marking event, invasive fish caught were killed after the examination.
Studying fish life cycles
Fish were sedated and their blood and ovarian tissue were sampled three times.
Developing a model for thermal stress in humans
Guinea pig pups were lightly anaesthetised, connected to devices measuring heart activity and breathing, and wrapped in a temperature-controlling blanket. Their body temperature was either forcefully raised or dropped.
Testing how too much fructose is bad during pregnancy
Female guinea pigs were mated; some were fed additional sugary water until birth. The pups were used for several glucose tolerance tests and X-rays. All pups were killed in the end.
Testing a seizure medicine for preterm babies
Pregnant guinea pigs were induced to give birth early, to test medication on their pups.
Testing the effects of sedatives
Young guinea pigs were treated with different sedatives. Their heart rate and blood pressure were measured before and during each treatment.
Testing a refined way of anaesthesia in guinea pigs
Guinea pigs were made to inhale anaesthetic gases. Different probes were inserted and attached to the animals to measure responses.
Studying the effect of fructose during pregnancy
Guinea pigs were fed either normally or supplemented with fruit sugar before and during pregnancy until birth. Mothers and pups were tested for glucose tolerance.
Studying the effects of meth
Guinea pigs were injected with sedatives, caffeine, and later meth. Under anaesthesia, their livers were cut out before they were killed.
Studying preterm birth effects on the brain
Pregnant guinea pigs were grouped to give birth normally or be induced early. The pups were put through behavioural tests and then killed for dissection.
Studying trauma and treatment of cochlear implants
After destroying their hearing with noise, guinea pigs were fitted with cochlear implants. Treatment success was tested before they were killed.
Testing the measurement of pupil reflexes in Alzheimer’s research
Guinea pigs were repeatedly flashed in the eyes with a phone light to record the pupil responses.
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
Investigating mechanisms slowing down the heart rate
Young guinea pigs were injected with blood thinner before being anaesthetised and dissected.
Testing a device to assess hearing
Young guinea pigs were anaesthetised, electrodes placed under their skin, and their brain's response to sound was measured. All guinea pigs had one ear damaged, some both ears, before all were killed.
Studying changes in the inner ear due to inflammation
Guinea pigs were injected into the ear with bacteria. Medical scans were done after injecting chemicals, and most were killed for dissection.
Studying the effects of medication on memory
Guinea pigs were force-fed different drugs and later tested in a water maze before some were killed. Another group was exposed to carbon dioxide and decapitated.
Studying how anaesthetics affect intestine movement
Guinea pigs and rats were anaesthetised, then dissected, and then killed, in that order.
Testing motherly instinct towards foster pups
Mice of different “status” (never pregnant, pregnant, new mums) were made to rescue foster pups they didn’t know from several places. Transgenic mice lacking a prolactin brain receptor were tested for anxiety behaviour in the standard elevated-plus-maze.
Testing new cancer vaccines
Mice were injected with cancer cells, followed by one of several potential vaccines. They were killed when tumours reached a certain size, or it became otherwise inhumane to keep them alive.
Testing if pregnancy affects the healing of teeth
Pregnant and non-pregnant mice were taken. After the pregnant ones gave birth, all mice were anaesthetised. Some of their teeth were forcefully moved. Two weeks later, all were killed.
Testing the effect of obesity during pregnancy
Pregnant mice were fed high-fat diets and had their babies removed via caesarean section. The foetuses were decapitated. Other newborn mice were separated to record their calls.
Testing how motherly mice are
Transgenic mice were compared to “normal” mice on rescuing pups and how they care for their babies. They were mated, gave birth, and then put through behavioural tests involving newborn mice. After a few weeks, they were killed.
Testing a medicine against drug addiction
Mice's tails were dunked in hot water. Rats were put through cycles of drug-seeking and withdrawal using self-injection of cocaine. Other rats were injected, and their behaviour was tested (with the notorious Forces Swim Test, among others).
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
Testing the viability of xenotransplantation using islet capsules
Newborn piglets were killed for their pancreas. Encapsulated pancreas cells were then implanted into young mice, who were killed later to retrieve the capsules.
Harvesting colon tissue for laboratory tests
Pigs were killed and their colon tissue was used for laboratory testing.
Testing if pigs can be fed by-products from biofuel and food processing
Pigs were fed a standard diet or a diet containing by-products from other industries. They were slaughtered to compare meat growth and quality.
Studying starch digestion in pigs to try and model humans
Pigs were fed different diets containing durum wheat or rice. Some had regular blood samples taken through a catheter. All the animals were killed at the end.
Validating a treatment for stomach muscle dysfunctions
Pigs were anaesthetised, their bellies were opened, and electrodes were placed on their stomach walls before and after damaging some stomach tissue with heat. All pigs were killed.
Assessing pigs as digestion models for humans
Titanium tubes were implanted into pigs’ intestines. Digested food was collected through the tube for 9 hours.
Testing the effect of different species’ milk on brain gene expression
Piglets were fed different kinds of milk from other species for 15 days. They were killed to dissect their brains.
Testing transmitter implantation on wild pigs
Wild pigs were captured, and three different tracking devices were fixed to or implanted into each one. After 104 days, they were tracked down and killed.
Investigating oxygen content in the gut
Pigs were fed diets with different or no protein sources as a control. After a week, all were killed.
Testing a UV treatment for bacterial eye infection
Pigs’ eyes were acquired for testing a new treatment, followed by tests on live mice, most of whom were killed.
Testing the effect of different species’ milk on protein digestion
Piglets were fed different kinds of milk from other species for 15 days. They were killed to dissect their stomachs.
Testing the strain on a temporary surgical implant
A surgical implant was screwed to a severed pig head, and measurements were taken via laser scanning.
Investigating intestine movements
Young pigs and NZ White rabbits were anaesthetised. A part of their intestine was pulled out far enough to record its movements and signalling.
Harvesting rabbit and pig eyes for lab tests
The eyes of slaughtered rabbits and pigs killed for experiments were used to analyse the structure of the cornea.
Harvesting eyes for lab tests
The eyes of pigs and rabbits killed for experiments were used to analyse the structure of the cornea.
Testing a treatment for stomach muscle dysfunctions
Pigs were anaesthetised, their bellies were opened, and electrodes were placed on their stomach walls before and after damaging some stomach tissue with heat. All pigs were killed.
Testing how electric stimulation affects stomach movements
Nine pigs were anaesthetised, their bellies were opened, and electrodes were placed on the stomach walls. Electric stimulation tests were performed before the pigs were killed.
Studying food intake in an autism "model"
Pregnant rats were injected to cause autism-like symptoms in their babies. The male babies were put through behavioural tests with control animals as well as a feeding study. Some were fasted for 16 hours and killed by flushing their hearts.
Testing the safety of a probiotic supplement
Rats were force-fed with a probiotic solution or control solution. After two weeks, they were killed for dissection.
Studying the effects of obesity and mussel powder on bone health
Rats were kept alone and fed different diets containing normal or high amounts of fat or sugar. Some were supplemented with Greenshell mussel powder. X-rays were done, and some rats' ovaries were removed. Ultimately, all were killed by bleeding them out.
Testing if a brain region controls memory
Some rats had their brains surgically heat-damaged. Electrodes were implanted to monitor brain activity and to stimulate the damaged parts with light. Rats then had to re-perform memory tests to see the impact before all were killed.
Studying the communication between inner ear and brain
Rats were anaesthetised, and their inner ear was partly removed, before parts of their brains were stimulated with wire electrodes. Reactions of the rat's eyes and brain were recorded. In the end, all rats were killed.
Testing a connection between tinnitus and brain function
Rats were anaesthetised and one ear was damaged with noise. Rats were taught that silence meant they would get electric shocks and freeze in fear. This was a test for tinnitus.
Testing diabetic rats’ hearts
Genetically diabetic fat rats and their lean littermates were anaesthetised. Ultrasound images were made from their hearts. All were killed and dissected.
Testing the effect of diabetes on pregnancy hormones
Rats were anaesthetised, and their brain was accessed through the mouth to measure reactions to stimulation. In the end, all rats were killed.
Trying to study schizophrenia
Half of a group of pregnant rats were injected to affect their babies' brain development. Some pups were allowed to grow up to test their behaviour.
Releasing a rat family into the wild to see where they go
A wild-caught rat was mated, fed a fluorescent dye, and released again with her pups. Traps, tunnels, and cameras were set up to track and eventually recapture the animals, which did not work 100%.
Comparing digestion of sheep versus cow milk yoghurt
Rats were fed cow milk, sheep milk, cow yoghurt or sheep yoghurt for two weeks. They were gassed with CO2 before their necks were broken.
Testing a rat poison that is unattractive for dogs
Rats were kept in small cages and fasted overnight. Then, they were given two food trays. One of them was scented with lion, tiger, or dog faeces.
Comparing digestion of sheep versus cow milk
Rats were fed a test diet containing beef protein and received cow milk or sheep milk instead of drinking water. After 28 days, all were killed.
Testing medication after heart attack
Rats were anaesthetised, and their hearts were exposed. A heart attack was simulated by blocking an artery. Some had dye injected into their brains, and some were injected with test drugs. All animals were killed.
Testing a medicine against drug addiction
Mice's tails were dunked in hot water. Rats were put through cycles of drug-seeking and withdrawal using self-injection of cocaine. Other rats were injected, and their behaviour was tested (with the notorious Forces Swim Test, among others).
Studying cell death in breast tissue
Mother rats had some of their newborns taken away, and several of her teats were sealed off after two weeks. They were killed after different waiting times to analyse the dying tissue.
Investigating how worms spread between lambs and calves
Lambs and calves were infected with worm eggs to see if parasites from cattle can infect sheep.
Using sheep to try and model how well humans will heal after dental surgery
Sheep had healthy teeth pulled out and the sockets treated in different ways to compare how well the body will heal after a tooth is removed when left untreated vs using a bone graft.
Preclinical testing of a gene therapy for Batten disease
Sheep with and without a specific gene mutation were checked and scanned regularly for nine months. Affected sheep received gene therapy at different ages. Treated sheep were killed.
Testing if blocking a cell signal can prevent foetal brain injury
Pregnant sheep were anaesthetised, and the foetuses fitted with electrodes. The umbilical cord was blocked for most of them, and half were treated with a test drug. Mothers and unborn lambs were killed three weeks later.
Testing the combination of drugs for congestive heart failure treatment
Sheep were anaesthetised and subjected to surgery. Electrodes were used to pace their hearts faster while testing the effect of different drugs.
Testing the best way to deliver gene therapy drugs
Sheep were anaesthetised. Their heads were drilled into, and their brains injected with test drugs. They were killed after three weeks.
Testing the potency of pneumonia vaccines for sheep
Lambs were vaccinated twice and regular blood samples were taken for 34 weeks, to test different pneumonia vaccines for sheep.
Testing the effects and wash-out of painkillers
Lambs were treated with different painkillers or no painkillers at all before tail docking and castration. Their behaviour was monitored.
Developing “hyperimmune” milk
Sheep were injected with Covid-19 vaccines to see if they produced milk that could be marketed to consumers as providing immunity against certain diseases.
Studying the genetics of Batten disease on chimeric lambs
Sheep foetuses were removed. After swapping cells between them, they were inserted into other ewes. Lambs born were subjected to X-rays and, at one to three years old, were bled out for dissection.
Testing pacemaker adjustments
After causing them heart failure, sheep were surgically fitted with pacemakers and measurement devices. Those who survived the procedures were killed after six months.
Studying methane emission and meat quality
Lambs were tested and killed to assess the relationship between methane emissions, carcass weight and meat quality. Almost 2,000 were put through emission measurements. Over 17,000 were slaughtered.
Studying the effect of chemicals in normal and high blood pressure
Sheep were surgically fitted with a clip around an artery and compared with others without clips. Measuring devices were added before injecting different chemicals into the hearts of the conscious sheep.
Comparing success of muscle repair surgery with or without weeks of delay
Sheep were anaesthetised and one side of a pelvis muscle was detached. After several weeks, the muscle was repaired. How well the sheep then walked was noted before all were killed.
Comparing different designs of dental implants
Sheep were anaesthetised. One leg bone was exposed and fitted with several implants. After 12 weeks, all were killed.
Trying to model human brain injuries
To study changes in different areas of the brain after brain injuries. Sheep were used to study the effects of traumatic brain injuries in humans.
Investigating intestine movements
Young pigs and NZ White rabbits were anaesthetised. A part of their intestine was pulled out far enough to record its movements and signalling.
Harvesting rabbit and pig eyes for lab tests
The eyes of slaughtered rabbits and pigs killed for experiments were used to analyse the structure of the cornea.
Causing sinusitis in rabbits as a model
NZ White rabbits were anaesthetised, and a sinus tract in their nose was blocked for four weeks to cause sinusitis. After another ten weeks with regular samples, they were killed.
Testing a new vaccine
NZ White rabbits were injected with a new vaccine type several times before being killed.
Harvesting eyes for lab tests
The eyes of pigs and rabbits killed for experiments were used to analyse the structure of the cornea.
Testing the toxicity of some substances
Young NZ White rabbits were force-fed different doses of toxic substances. Blood samples were taken before and immediately after killing them at set time points (or to end their suffering).
Using a new imaging technology
One NZ White rabbit and rats were killed, and their eyes were removed to use for the study.
Measuring contractions in exposed rabbit uteruses
Pregnant rabbits were anaesthetised, and their uterus was exposed. Measurements were taken while contraction-inducing injections were given. Then they were all killed for dissection.
Mapping wave patterns of the small intestine
NZ White rabbits were anaesthetised, their intestines were used for electrode mapping, and then they were killed.
Studying presence of a virus in rabbits
Wild rabbits were shot, caught by dogs or trapped to test them for virus strains. The infectious solution was then fed to NZ White rabbits in a lab to kill them later.
Harvesting rabbit colons for lab tests
NZ White rabbits were anaesthetised, a part of their intestine was cut out, and then they were killed.
Harvesting rabbit bladders for lab tests
NZ White rabbits were anaesthetised, their bladder was cut out, and then they were killed.
Testing an antimicrobial eye medication
NZ White rabbits were treated with Manuka honey solution in one eye and a control solution in the other eye for five days. Different values like tearing and irritation were measured.
Using muscles of dead rabbits for imaging
Two NZ White rabbits were killed to use for detailed muscle imaging.
Measuring jaw bone growth in young rabbits
Young rabbits were anaesthetised and had holes drilled into their jawbones to implant small pieces of metal. X-ray scans were made, and the rabbits were killed.
Testing the welfare impact of pindone toxin
Three groups of young NZ White Rabbits received pindone-toxin pellets on different schedules. Any rabbit still alive after three weeks was killed.
