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You already know you can get sick from your pet. But did you know your pet can also catch your cold, flu, or COVID-19? Scientists now realize that human-to-animal disease transmission—reverse zoonosis—is happening more often than we thought. And the consequences could be bigger than we ever imagined.
A recent comprehensive review of documented reverse zoonosis cases reveals a growing problem that could have serious implications for our pets, wild animals, and even humans. I’ll break down these findings, discuss the risks, and share tips on how to keep your furry companions safe when illness strikes in your home.
Reverse Zoonosis vs Zoonosis: What’s The Difference?
Reverse zoonosis (or zooanthroponosis) occurs when humans transmit infectious diseases to animals. This happens when a virus, bacteria, or other pathogen mutates and adapts to a new host species. Unfortunately, reverse zoonosis is under-researched, but scientists are beginning to recognize its significance.
By contrast, zoonosis refers to humans contracting infectious diseases from animals. This is much better understood, as zoonotic diseases have been studied for decades. You’ve probably heard of many of them.
| Term | Definition | Example |
|---|---|---|
| Zoonosis | Disease spreads from animals to humans | Rabies, Lyme disease |
| Reverse Zoonosis | Disease spreads from humans to animals | COVID-19, Influenza |
Known Zoonotic Diseases (Animal To Human)
Scientists have long studied zoonotic diseases, but what about the diseases we pass to animals? Let’s start with what we already know—how illnesses spread from animals to humans.
Viral Diseases
Viruses are among the most well-known zoonotic pathogens. They can spread from animals to humans through bites, respiratory droplets, or direct contact with infected bodily fluids.
- Avian flu – Certain strains of bird flu have infected humans, typically through close contact with infected poultry.
- H1N1 (swine flu) – The 2009 pandemic was caused by a flu strain that jumped from pigs to humans.
- Rabies – Spread through the bite of an infected animal, rabies is almost always fatal once symptoms appear.
Bacterial Diseases
Bacteria from animals can infect humans, often through scratches, bites, or vector-borne transmission.
- Cat scratch fever (Bartonella henselae) – Transmitted by cat scratches or bites, this bacterial infection can cause swollen lymph nodes and fever in humans.
- Lyme disease – Spread by ticks, Lyme disease can cause joint pain, neurological issues, and fatigue.
- The plague – Transmitted by fleas, this infamous disease still exists today but is treatable with antibiotics.
Prion Diseases
Prion diseases are caused by misfolded proteins that damage the brain, leading to severe neurological conditions.
- Mad cow disease (bovine spongiform encephalopathy) – Caused by prions, this fatal disease can spread to humans through contaminated beef, leading to neurological decline.
The Latest Science: Why Reverse Zoonosis Is More Common Than You Think
A recently published comprehensive review by Dr. Benjamin Anderson at the University of Florida’s College of Public Health reveals that reverse zoonosis may happen more often than we realize.
“We’re starting to see a lot of examples of reverse zoonosis,” Anderson says. “Pets are more susceptible than, maybe, we previously thought.”
Because we live in close contact with our pets, it’s no surprise that illnesses can spread between species. The question is: What diseases are we passing to them?
What Diseases Can We Transmit To Our Pets?
Scientists are beginning to recognize that many human illnesses can spread to our pets, particularly those caused by viruses and bacteria. While most cases involve dogs and cats, transmission has also been documented in horses, ferrets, and parrots. Here are some of the most concerning human-to-pet diseases.
Viral Diseases
- Influenza A – Some human flu strains have been transmitted to pets, particularly cats and dogs.
- COVID-19 – Multiple cases of dogs and cats contracting COVID-19 from their owners have been documented.
- Swine flu (H1N1) – This virus has been passed from humans to pets, including dogs and ferrets.
Bacterial Diseases
- Dengue – Some reports suggest that humans can transmit dengue fever to mosquitoes, which could then spread the disease to animals.
- Human norovirus – The virus responsible for stomach flu has been detected in pet stool samples.
- Tuberculosis – Though rare, there are cases of human-to-animal tuberculosis transmission, especially in cats.
Why this matters: Mammals are at greater risk because they’re genetically closer to humans, making it easier for viruses to mutate and adapt to their systems.
Is Your Pet Sick Because Of You? Symptoms Of Reverse Zoonotic Infections
If your pet has been exposed to a sick household member, watch for these signs:
- Behavioral changes: Increased hiding, irritability, or decreased interaction
- Gastrointestinal issues: Vomiting, diarrhea, loss of appetite
- Lethargy and fever: Unusual tiredness, increased body temperature
- Respiratory symptoms: Coughing, sneezing, nasal discharge, labored breathing
If you notice these symptoms, consult a veterinarian, especially if the illness coincides with a sick household member.
Risk Factors for Reverse Zoonosis
Some pets are at greater risk of contracting diseases from humans, including:
- Young and senior pets – Puppies, kittens, and elderly animals have weaker immune systems.
- Pets with pre-existing conditions – Chronic illnesses like diabetes or heart disease can make them more vulnerable.
- Close-contact pets – Animals that sleep in beds, share food, or are frequently handled by sick owners are at higher risk.
Future Outlook: Can Reverse Zoonosis Lead To New Pandemics?
Reverse zoonosis isn’t just a problem for pets—it’s a potential public health crisis. Scientists are concerned for two significant reasons:
- Pets can become seriously ill from human diseases.
- Pathogens can mutate in animals and then jump back to humans in a more dangerous form.
Scientists fear that animal mutations could lead to more potent viruses that return to humans. Every time a virus spreads between species, the risk of mutation increases.
Are we one step away from the next pandemic? Researchers are now studying whether these mutations could contribute to future outbreaks, making disease tracking and surveillance more urgent than ever.
Why Are Zoonotic Diseases Better Understood Than Reverse Zoonoses?
According to experts, reverse zoonosis (pets getting sick from humans) gets little attention from researchers and the general media because it’s much easier to track humans becoming ill from their pets than owners getting their pets sick.
- When a person gets sick, doctors can ask if they’ve been around animals.
- But when a pet gets sick, there’s no clear way to link it back to a human case.
That’s why reverse zoonosis has remained understudied—until now.
A New Initiative To Track Pet Diseases
The Centers for Disease Control and Prevention (CDC) and Trupanion Pet Insurance have partnered to develop a system that tracks diseases in companion animals. This initiative will immediately share data on pet illness trends to help detect potential health threats.
Several infectious diseases, including Covid-19, bird flu, and mpox — are zoonotic and reverse zoonotic, which means they can spread from animals to humans and back again. As Dr. Steve Weinrauch, the chief veterinary and product officer at Trupanion, told the New York Times (NYT), “The concept is to proactively detect potential threats to pets and public health.”
According to a NYT article posted on August 16, 2024, this new effort also includes academic scientists and other companies in the pet industry, but it’s still in the early stages. Initially, it will focus on bird flu, a virus spreading through dairy cows in the U.S. and spilling over into domestic cats.
The Role Of Veterinary Research In Reverse Zoonosis
Veterinarians and researchers are essential in understanding and tracking reverse zoonosis. Unlike human medicine, where public health officials monitor the spread of infectious diseases, veterinary research into human-to-animal disease transmission is still in its early stages.
Several key efforts are emerging:
- Genome sequencing of pathogens – Scientists are studying how viruses mutate once they jump from humans to pets to assess their potential for further transmission.
- Increased disease surveillance – More veterinarians are now testing pets for human-origin illnesses, particularly in homes where owners have been sick.
- Tracking outbreaks – Collaboration between veterinarians, the CDC, and pet health organizations like Trupanion is helping document disease cases in pets.
Expanding research in this area is critical to understanding how diseases evolve and ensuring that both pets and humans remain protected.
How To Protect Your Pets From Human Disease
If you have the flu or COVID, take precautions with your pets just as you would with family members. Here’s what you can do:
- Avoid sharing food, kisses, or bed space while you’re sick
- Dispose of tissues and masks properly to prevent contamination
- Keep up with their vaccinations and vet visits
- Separate bedding for sick owners to limit pet exposure
- Use air purifiers to reduce airborne transmission
- Wash your hands before petting or feeding them
- Wear a mask around vulnerable pets (e.g., elderly pets, those with weakened immune systems)
Minimizing transmission helps protect your pets—and could help prevent the emergence of new disease strains that impact both animals and humans.
Frequently Asked Questions
As awareness of reverse zoonosis grows, many pet owners have concerns about how diseases spread between humans and animals. Below are some frequently asked questions to help clarify risks and protective measures. Don’t see yours? Ask us in the comments.
Are Certain Breeds More Susceptible To Reverse Zoonosis?
While all pets can be at risk of contracting diseases from their owners, some breeds may be more vulnerable due to their genetics, physical traits, or underlying health conditions.
- Flat-faced (brachycephalic) breeds – Dogs with shortened airways, such as Pugs and Bulldogs, are more vulnerable to complications from airborne illnesses.
- Immunocompromised pets – Pets with chronic illnesses, such as diabetes, cancer, or autoimmune disorders, are more likely to suffer complications if they contract a disease from their owners.
- Toy breeds – Smaller dogs who have been selectively breed for miniaturization may be prone to weaker immune systems, putting them at higher risk for infection complications.
- Young and elderly pets – Just like in humans, puppies and senior dogs are less capable of fighting off infections and are at greater risk of severe illness.
Knowing if your pet is at higher risk can help you take extra precautions when you’re sick.
Can Humans Pass The Flu To Their Pets?
Several strains of human influenza have been documented in pets, particularly in dogs and cats. While animal symptoms may be mild, some cases can lead to severe respiratory issues. Limiting close contact if you’re sick with the flu is best.
Can Pets Pass Reverse Zoonotic Diseases To Other Animals?
Yes, once a pet contracts a disease from a human, there is potential for it to spread to other animals, especially in multi-pet households. Quarantining sick pets and maintaining good hygiene can help reduce the risk.
Should I Keep My Pet Away From Me If I Have COVID-19?
If you are diagnosed with COVID-19, experts recommend limiting close contact with your pet, just as you would with other family members. Wearing a mask, washing hands frequently, and keeping your pet in a separate area can help reduce the risk of transmission.
What Should I Do If I Think My Pet Caught an Illness From Me?
If your pet shows signs of illness, such as coughing, sneezing, fever, or lethargy, and you’ve recently been sick, contact your veterinarian. They can guide treatment and determine whether testing for specific diseases is necessary.
Can Dogs Catch Colds?
Yes, our pups can catch colds. However, there aren’t any documented cases that dogs can catch a cold from humans (unlike the flu and COVID). That’s good news, but the symptoms of a cold in dogs could indicate a more severe illness. If your pup is exhibiting symptoms of the common human cold, I encourage you to read my article on dog colds to see what other conditions could be present.
Why Trust Canine Journal?
Sally and her team at Canine Journal are committed to finding the most critical and relevant research about our furry friends to help our readers stay informed from valid science compared to what some other sites may share with you based on uninformed internet hearsay.
Sally has over 20 years of experience in human and pet health sciences communications. She specializes in analyzing scientific studies and debunking false information you can easily find on the Internet to bring our readers the most trustworthy information that can be applied to real-life situations for you and your pets.
