Most biomedical scientists were trained on two species: humans and mice. Veterinary research works across dozens, and it overlaps with human biomedicine far more than its separate schools, journals and funders suggest. The next pandemic is more likely to start in an animal than a person, dogs get many of the same cancers people do, and some of the most instructive gene-editing and pharmacogenomics stories of the past twenty years happened in animals.
This is an introduction for people coming from the human side: what veterinary medicine covers, where molecular work fits into it, and what changes when your subject is not a mouse.
What veterinary medicine covers
The field is usually divided by the kind of animal, because each one brings different economics, regulation and research questions:
- Companion animals. Dogs, cats, and an increasing number of exotic pets. This is where most clinical vets work, and where individual patients get treatment approaching human standards, including chemotherapy, MRI and specialist surgery.
- Food animals. Cattle, pigs, poultry, sheep, goats and farmed fish. The patient is often the herd rather than the individual, and the questions are about productivity, prevention and food safety.
- Horses, which sit between the two: individually valuable, and with their own sports medicine and drug rules.
- Wildlife and zoo animals, where conservation and disease surveillance meet.
- Laboratory animal medicine, the vets who run animal facilities and sit on the committee that approves your animal protocols. If you have ever worked with mice, you have worked with one.
In the US, a vet holds a four-year professional degree (DVM or VMD). Specialists then do a residency and board certification, much like physicians. The specialty most useful to a molecular lab is veterinary pathology. Board-certified veterinary pathologists are trained to read tissue from many species, mice included, and a lot of mouse-model histology is read by them. If your phenotyping depends on histology, that is a collaborator worth having.
Who regulates what
US regulation is split in a way that surprises people from human medicine. Animal drugs are regulated by the FDA Center for Veterinary Medicine. Vaccines and other biologics for animals are regulated by the USDA, through its Center for Veterinary Biologics. Some parasite treatments that go on the skin fall under the EPA, as pesticides. Internationally, the World Organisation for Animal Health (WOAH, formerly OIE) sets standards for reporting animal disease.
That last point matters at the bench. Some animal diseases are legally reportable. If your sequencing finds one of them in a sample, notifying the authorities may not be optional, so know the list for your species before you run a diagnostic assay on field samples.
Where molecular research shows up
Outbreak diagnostics and surveillance
Much of applied veterinary molecular biology is diagnostics: PCR panels, sequencing and serology run by veterinary diagnostic labs. It becomes visible during an outbreak. In 2024, highly pathogenic H5N1 avian influenza was confirmed in US dairy cattle, a species not previously considered a meaningful host. Infected cows lost appetite and milk production. Cats on the same farms that drank raw milk or colostrum developed fatal systemic infections. The virus had moved between farms with transported cattle, which pointed to cow-to-cow spread.
Zoonoses and One Health
"One Health" is the idea that human, animal and environmental health are one system and should be studied together. The numbers behind it are stark. An analysis of 335 emerging infectious disease events between 1940 and 2004 found that 60.3% were zoonoses, diseases that jump from animals to people, and that 71.8% of those came from wildlife.
Antibiotic resistance follows the same logic. Colistin is a last-resort antibiotic for some human infections, and resistance to it was thought to arise only through chromosomal mutations, which do not spread between bacteria. Then routine surveillance of E. coli from food animals in China found mcr-1, a colistin resistance gene carried on a plasmid, first isolated from a pig, that transferred readily between bacterial strains. Agricultural antibiotic use and human medicine share a single pool of resistance genes, and that discovery came from an animal surveillance programme.
Comparative oncology
Pet dogs develop cancer spontaneously, with intact immune systems, in the same homes and environments as their owners. Their tumours share histology, genetics, molecular targets and treatment response with many human cancers. Osteosarcoma, lymphoma and melanoma are common examples. A mouse xenograft is a human tumour growing in an immunodeficient host; a dog with lymphoma is a real patient with a real disease, treated in a veterinary clinic, whose owner can consent to a trial.
Dog genetics makes this unusually productive. Breeds are closed populations with long stretches of shared DNA, which the 2005 dog genome paper mapped across breeds. That structure means a genetic association study in dogs can find disease genes with far fewer animals than the equivalent study in people.
Pharmacogenomics
One of the cleanest pharmacogenomic stories comes from collies. A subset of them suffer severe neurological toxicity from ivermectin, a common antiparasitic. The cause is a 4-base-pair deletion in the MDR1 gene, which encodes P-glycoprotein, the pump that pushes drugs back out of the brain at the blood-brain barrier. Dogs with two copies of the deletion make no working pump and are sensitive; dogs with one copy are not. A simple genetic test now lets vets check at-risk breeds before prescribing ivermectin and other P-glycoprotein substrates, which is genotype-guided prescribing of the kind human medicine is still working to make routine.
Antivirals
Feline infectious peritonitis, caused by a mutated feline coronavirus, was until recently almost always fatal. A 2019 field trial treated 31 cats with GS-441524, the nucleoside that remdesivir is built on. Five cats with severe disease died or were euthanised in the first month. Of the 26 that completed treatment, all but one were healthy at publication, several only after relapsing and being treated again at a higher dose. This was a veterinary result published before remdesivir became famous in human medicine.
Livestock genomics and gene editing
Animal breeding was an early adopter of genomics. A 2001 paper proposed predicting an animal's genetic value from dense genome-wide markers, a method called genomic selection, which went on to reshape dairy cattle breeding. Closely related statistical methods are now used for polygenic risk prediction in people.
Gene editing in livestock is often aimed at disease resistance. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most costly diseases in pig farming, and it enters cells through a receptor called CD163. Pigs with the CD163 gene knocked out were protected from infection when challenged with the virus. It is a clear case of an edit with an obvious mechanism and a measurable benefit.
Ageing
Dogs live a fraction as long as people, share their environment, and get much of the same veterinary care a person would. The Dog Aging Project is a long-term study of tens of thousands of companion dogs, collecting surveys, veterinary records, genome sequences and blood and faecal samples, with the data released openly. It is one of the largest open datasets on ageing in a genetically diverse species living outside a lab.
What changes when your subject is not a mouse
- Reagents. Most antibodies are validated for human, mouse or rat. For a dog, cat, cow or pig, you will often rely on predicted cross-reactivity, which is not the same as validation. Budget time to validate your key antibodies on the species you are using, or use methods that do not depend on them, like RNA sequencing or mass spectrometry.
- Genomes. The major domestic species all have good reference genomes, but annotation is thinner than for human or mouse, and gene names do not always map one to one. Check which assembly a dataset used before you compare across studies.
- Cell lines. There are far fewer, and many are poorly characterised. Some are excellent: MDCK, a dog kidney line, is used to grow influenza for cell-based vaccine production. For most questions you will work with primary cells or tissue.
- Patients have owners. In companion animal studies the subjects are client-owned pets, recruited through veterinary teaching hospitals, with owners giving consent. Expect diverse genetics, diets and histories, which makes results more realistic and sample sizes harder to reach.
- Large animals are expensive. Housing cattle or pigs, especially under biocontainment for infectious disease work, needs specialist facilities that only some institutions have.
Who funds it
In the US, the main federal funder for agricultural animal research is the USDA's National Institute of Food and Agriculture. NIH funds veterinary work where it bears on human health, comparative oncology and ageing in particular. Private foundations, such as the Morris Animal Foundation and the AKC Canine Health Foundation, fund companion animal health directly. If your project sits between human and animal health, you may be eligible for more of these than you expect.
Getting started
If your work could benefit from a veterinary angle, the quickest entry point is usually people, not literature. Talk to the nearest veterinary school: its pathologists, its clinical trials office, and its diagnostic lab. They know which samples exist, which patients come through the clinic, and which species-specific assays are already validated.
When the work needs capacity you do not have, such as large-animal housing, species-specific assays or veterinary pathology, it is often faster to commission it from a facility that already does it than to build it from scratch.