You have just brought home a thin little cat you found by the bus stop. She purrs in the carrier, and your own cat is already sniffing at the door, curious about the new smell. You want them to meet and become friends.
Not yet. A little patience now, and a quiet room of her own, will keep both cats safe.
Many stray animals have never been vaccinated, so they are more likely to carry infections, and some of these spread easily to other pets. This does not mean you should avoid helping strays. It means taking a few simple precautions to protect yourself and the animals already in your home.
Only a veterinarian can diagnose these illnesses. The signs below are for awareness, not for making a diagnosis yourself.
- Keep the new animal separate. Use its own room and its own things for at least two weeks, and until a vet has checked it.
- Wash your hands, change your clothes. Some viruses travel on hands, clothes and shoes.
- Clean first, then disinfect. Tough viruses like parvovirus and panleukopenia survive a long time and many cleaners do not kill them.
- Most stray illnesses affect only animals. A few, like ringworm, some worms and rabies, can affect people. See a doctor after any bite or scratch that breaks the skin.
- Know the urgent signs. Vomiting, diarrhea, weakness or breathing trouble means call a vet now.
When to go to a vet urgently
Contact a veterinarian right away if a rescued animal shows any of these:
- Repeated vomiting or diarrhea, especially with blood
- Refusing food for more than a day (for a young kitten or puppy, even a few missed meals)
- Weakness, collapse, or being very cold to the touch
- Difficulty breathing or breathing with an open mouth (for cats)
- Seizures, twitching or loss of balance
- Eye problems, such as a cloudy eye or an eye held shut
- Any illness in a very young kitten or puppy
Common diseases in cats
The most common are panleukopenia, cat flu, FeLV and FIV, parasites and ringworm. Vaccination protects well against the most dangerous one.
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Feline panleukopenia (feline distemper)
A highly contagious virus that attacks the gut and the immune system. It is especially dangerous for young kittens and unvaccinated cats, and it can kill quickly.
- Signs: vomiting, diarrhea, fever, low energy, refusing food, dehydration. A very young kitten may die suddenly.
- How it spreads: through the droppings, vomit and other body fluids of sick cats, and on anything they touch: bedding, bowls, litter trays, and people’s hands, clothes and shoes.
- Why it is hard to control: the virus can survive indoors for many months, up to about a year, without proper disinfection, and many common cleaners do not kill it.
- Good news: vaccination protects very well. It is not known to infect people or dogs.
Cat flu (upper respiratory infection)
Very common in strays and shelters. It is usually caused by feline herpesvirus or feline calicivirus, sometimes together with bacteria.
- Signs: sneezing, runny or crusty eyes and nose, squinting, drooling, mouth ulcers, fever, loss of appetite.
- Why it matters: cats with a blocked nose cannot smell their food, so they often stop eating. Kittens can become seriously ill quickly.
- Carriers: most cats that recover from herpesvirus carry it for life. Stress, such as a move to a new home, can make the virus active again, and the cat may start sneezing again.
- It spreads only between cats, not to people or dogs.
FeLV and FIV
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) both weaken the immune system over time.
- FeLV spreads through close contact: mutual grooming, bites, and shared bowls and litter trays. Mothers can pass it to their kittens.
- FIV spreads mainly through deep bite wounds, so cats that fight often are most at risk.
- A veterinarian can test for both. Results sometimes need a second test to confirm. These viruses affect only cats.
Parasites and ringworm
Fleas, ear mites, ticks and intestinal worms are very common in strays. Ringworm is not a worm but a fungal skin infection. It often causes round patches of hair loss with scaly skin. It can spread to other pets and to people.
Common diseases in dogs
The most common are parvovirus, distemper, kennel cough, parasites and skin disease. Vaccination is very effective against parvo and distemper.
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Canine parvovirus (“parvo”)
A highly contagious virus that attacks the gut and the immune system of dogs. Puppies younger than about four months and unvaccinated dogs are most at risk.
- Signs: severe vomiting, diarrhea (often with blood), low energy, refusing food and fever.
- How it spreads: through direct contact with infected dogs and their droppings, and through contaminated ground, objects and people. The virus can survive for a long time, especially in dark, damp places.
- Treatment: there is no medicine that kills the virus. Dogs need intensive supportive care from a veterinarian, and the chances are best when treatment starts early.
Canine distemper
A serious virus that can affect the lungs, the gut and the nervous system.
- Signs: thick discharge from the eyes and nose, coughing, fever, vomiting and diarrhea. Later, some dogs develop twitching, poor balance or seizures.
- How it spreads: mainly through close contact and droplets when infected dogs cough or sneeze.
- Vaccination is very effective. There is no specific cure; treatment supports the body.
Kennel cough
A contagious infection of the airways that causes a harsh, honking cough. It is usually mild, but puppies, older dogs and dogs with other illnesses can become more seriously sick.
Parasites and skin disease
Fleas, ticks, intestinal worms and mange mites are common. Mange causes itching, hair loss and thickened skin.
Diseases that can affect people
Diseases that pass between animals and people are called zoonoses. Most common illnesses in strays affect only animals, but a few can affect people.
Simple habits protect you: wash your hands with soap after handling any stray, its bowls or its litter; wear gloves for cleaning up droppings; keep scratches and bites clean; and see a doctor after any bite or scratch that breaks the skin. See how to approach a stray safely.
See which diseases can affect people
- Rabies. A virus spread through bites and scratches. It is almost always fatal once symptoms start, but prompt treatment after exposure is very effective. Whether it is a risk depends on where you live, so always ask a doctor after a bite.
- Ringworm. Causes itchy, ring-shaped patches on the skin.
- Roundworms and hookworms. Eggs in animal droppings can contaminate soil. Young children who play in soil are most at risk.
- Toxoplasmosis. A parasite that some cats pass in their droppings. It is a particular concern during pregnancy. If you are pregnant, ask someone else to clean litter trays, or wear gloves and wash your hands well, and talk to your doctor.
- Wound infections. Bites and deep scratches, especially from cats, often become infected.
Quarantine: protect the pets you already have
Set up a separate room before you bring a stray home, or as soon as you can, and keep it going for at least two weeks.
Read the full steps
- Choose a separate room that is easy to clean, such as a bathroom or spare room with a hard floor. Keep the door closed.
- Give the new animal its own things: bowls, litter tray, bedding and toys. Do not share them with your pets.
- Care for your own pets first, then the new animal. Wash your hands afterward and change your outer clothes, or wear a cover-up that stays in the room.
- Keep the quarantine going for at least two weeks and until a veterinarian has checked the animal. Some illnesses do not show signs at first.
- Check your own pets’ vaccinations are up to date before the new animal arrives.
- Visit a veterinarian soon for a health check, parasite treatment, and advice on tests and vaccines.
Cleaning and disinfection
Clean away the dirt first, then use a disinfectant that is known to kill tough viruses.
How to clean and disinfect safely
- Clean first, then disinfect. Remove droppings, vomit and dirt, and wash with detergent and water. Dirt stops many disinfectants from working, and good cleaning removes much of the virus on its own.
- Use a product known to kill tough viruses like parvovirus and panleukopenia. The Cornell Feline Health Center suggests household bleach diluted 1:32 (about half a cup of bleach in 4 liters, or 1 gallon, of water), left on hard surfaces for at least 10 minutes. Ask your veterinarian about other suitable products.
- Follow the contact time on the label. Wiping a disinfectant off too early reduces its effect.
- Never mix bleach with other cleaners, use it only in a well-aired room, rinse surfaces afterward, and keep animals away until they are dry.
- Wash bedding and fabrics on a hot cycle. Items that cannot be cleaned well, such as cardboard or scratched plastic, are best thrown away.
Myths vs facts
A healthy look does not always mean a healthy animal.
Read more
- Myth: “Strays that look healthy are not carrying anything.” Fact: some animals carry viruses or parasites without showing signs.
- Myth: “My indoor pet cannot catch anything.” Fact: these viruses can travel on your hands, clothes and shoes.
- Myth: “Cat flu can spread to my dog or to me.” Fact: the main cat flu viruses affect only cats.
Frequently asked questions
Can I catch a disease from a stray cat or dog?
A few infections, such as ringworm, some worms, toxoplasmosis and, in some regions, rabies, can spread to people. Most common stray illnesses affect only animals. Good hand washing and seeing a doctor after any bite or scratch greatly lower the risk.
How long should I keep a rescued animal away from my pets?
At least two weeks, and until a veterinarian has examined it and advised you. If the animal is sick, your vet may suggest a longer period.
Is it safe to bring a stray home if my pets are vaccinated?
Vaccination greatly lowers the risk from diseases like parvovirus, panleukopenia and distemper, but it does not cover every illness, and very young or sick pets may be less protected. Keep the new animal separate until your vet says it is safe.
What does bleach kill, and what does it not?
Correctly diluted household bleach, left on long enough, kills parvovirus and panleukopenia on clean hard surfaces. It works poorly on dirty surfaces and cannot be used on most fabrics or carpets. Ask your vet for advice on what to use on other surfaces.
Sources
- Cornell Feline Health Center – Feline Panleukopenia Virus
- Cornell Feline Health Center – Feline Leukemia Virus
- VCA Animal Hospitals – Herpesvirus Infection in Cats (Feline Viral Rhinotracheitis)
- VCA Animal Hospitals – Distemper in Dogs
- Maddie’s Fund – Preventing parvovirus and panleukopenia in foster homes
- World Health Organization – Rabies (fact sheet)
This guide is general information and not a substitute for veterinary advice.
