Yes, cats can get dogs sick. Several infections, parasites, and skin conditions pass between the two species, though the most common viruses each species carries (like feline leukemia or canine parvovirus) do not cross the species barrier. The real risks come from bacteria, fungi, parasites, and a handful of serious viral diseases like rabies that affect all mammals.
What Cats Can Pass to Dogs
The illnesses that move between cats and dogs fall into a few categories: bacterial infections, fungal infections, parasites, and one critical virus. Most species-specific viruses stay locked to their host. Feline leukemia virus (FeLV), for example, is specific to members of the cat family and poses no risk to dogs or humans. The same goes for feline immunodeficiency virus (FIV). Your dog cannot catch these from a cat, period.
What can cross over includes:
- Bordetella bronchiseptica: The bacterium behind kennel cough in dogs also infects cats. It is the least host-restricted member of its bacterial group, meaning it moves freely between cats, dogs, rabbits, and pigs. A cat carrying this bacterium can transmit it through aerosol droplets, nose-to-nose contact, or coughing. If your cat has an upper respiratory infection and your dog starts coughing a week later, this is a likely suspect.
- Ringworm (dermatophytosis): This fungal skin infection spreads through hair, dander, and contaminated bedding. The fungus Microsporum canis is the most common species involved, and cats are particularly effective carriers. Untreated cats can harbor the infection for months to years. Dogs generally pick it up from direct contact or shared surfaces, though they tend to be somewhat less susceptible than cats.
- Rabies: All mammals are susceptible. Cats are actually the most commonly reported rabid domestic animal in the United States, outnumbering dogs every year since 1990. Transmission happens through bites, when virus-laden saliva enters tissue. An infected cat can shed the virus in its saliva up to 10 days before showing any clinical signs, which makes it dangerous even when the cat appears healthy.
- Salmonella and Campylobacter: Both bacteria spread through the fecal-oral route and contaminated surfaces. If a cat with a gastrointestinal infection uses a shared space and your dog investigates that area, transmission is straightforward.
- Leptospirosis: Spread through body secretions, urine, and blood. Both species are susceptible, and a cat shedding the bacteria in its urine can expose a dog that encounters that urine.
- Bartonella (cat scratch disease): This is flea-associated and can spread between pets through flea bites rather than direct contact.
Parasites That Move Between Species
Parasites are one of the most common ways a cat makes a dog sick, often without the owner realizing the source. Roundworms (Toxocara) infect both cats and dogs and spread through contact with contaminated feces. A dog that sniffs or eats cat feces, whether from a litter box or the yard, can pick up roundworm eggs. Hookworms work similarly, with larvae capable of penetrating skin or being ingested from contaminated soil.
Toxoplasma gondii is a parasite that cats are uniquely responsible for spreading. Cats are the only definitive host, meaning the parasite requires a cat’s body to complete its life cycle. Cats shed the parasite in their feces, and dogs can become infected by eating contaminated cat feces or contaminated soil. In adult dogs, toxoplasmosis is often mild or symptom-free. In puppies, however, the parasites can spread throughout the body and cause fever, diarrhea, coughing, difficulty breathing, seizures, and in severe cases, death.
Then there are fleas. The cat flea, despite its name, is the most common flea infesting both domestic cats and dogs worldwide. A cat carrying fleas will seed your home environment with eggs, and those fleas will readily jump to your dog. Fleas feed rapidly, producing feces from the blood meal within 8 to 9 minutes of latching on. Beyond the itching and skin irritation, fleas also carry Bartonella and tapeworm larvae, creating a secondary infection chain.
How Transmission Happens in Your Home
Most cat-to-dog transmission doesn’t require dramatic contact like a bite. The everyday realities of a multi-pet household create opportunities. Shared water bowls can harbor bacteria. Dogs eating from or sniffing the litter box is one of the most efficient routes for parasite transmission. Shared bedding transfers ringworm spores and flea eggs. Even shared air matters for respiratory pathogens like Bordetella, which spreads through coughing and aerosol droplets.
Outdoor cats pose a higher risk than strictly indoor cats. They encounter wildlife, soil-borne fungi, and other animals carrying disease, then bring those pathogens home. A cat that hunts rodents may pick up Toxoplasma, leptospirosis, or intestinal parasites and introduce them to the household.
Signs Your Dog May Have Caught Something
The symptoms depend on the pathogen, but a few patterns are worth watching for if your cat has recently been ill. Respiratory infections show up as coughing, sneezing, nasal discharge, or labored breathing, typically within 5 to 10 days of exposure. Gastrointestinal infections cause diarrhea, vomiting, loss of appetite, or lethargy. Ringworm appears as circular patches of hair loss, often with scaly or crusty skin, and can take one to three weeks to become visible after exposure.
Parasitic infections are trickier because they can be silent for weeks. A dog with roundworms might show no symptoms initially, then develop a pot-bellied appearance, dull coat, diarrhea, or visible worms in the stool. Flea infestations are usually obvious from scratching, but the diseases fleas carry may take longer to surface.
Keeping Both Pets Healthy
Prevention in a multi-pet home comes down to a few practical habits. Keep both animals on regular parasite prevention, covering fleas, ticks, and intestinal worms. This single step eliminates the most common transmission routes. Keep your dog out of the litter box. Covered boxes, baby gates, or placing the box in a room your dog can’t access all work.
Clean shared items regularly. For anything that contacts feces or urine, the CDC recommends disinfecting as often as you would a bathroom. A diluted bleach solution (a quarter cup of bleach per gallon of water, soaked for at least 10 minutes) is effective against most pathogens. EPA-registered disinfecting wipes or sprays also work if you follow the contact time on the label. Let everything dry completely before your pets use it again. If you have a cat, avoid any disinfectant containing phenol, which is highly toxic to cats.
Vaccinations matter on both sides. Keeping your dog current on rabies and Bordetella vaccines, and your cat current on rabies, provides a critical safety net. If either pet shows signs of illness, separating them while symptoms are active reduces risk. This is especially important for respiratory infections, where shared airspace is the transmission route.
If your cat is diagnosed with something contagious like ringworm or a bacterial infection, let your vet know you also have a dog in the home. They can advise whether your dog needs testing or preventive treatment. Ringworm spores, for example, can persist in the household environment for months, so environmental cleanup is just as important as treating the infected animal.