According to the Humane Society of the United States, there are more than 70 million feral and stray cats roaming the streets. Because stray cats often carry dangerous diseases, the best thing that you can do to protect your domesticated cat against serious illness is to keep it indoors. By staying inside, your cat is less likely to fight with other animals and risk the chance of spreading diseases through wounds. You’ll also reduce their exposure to infection-spreading parasites, including fleas and ticks, and prevent the kidney failure that can come as a result of ingesting poisonous substances such as antifreeze.

Outdoor cats and those that live in multi-cat homes have the highest risk of disease. However, indoor cats and “only cats” can get sick, too. Most cat illnesses are easily preventable, but once your cat contracts an illness, it can be very difficult to treat. It’s also important to keep in mind that even minor ailments can suggest major health problems. But some cat diseases are more dangerous than others. Read on to learn about some of the most serious ones.

5: Feline Leukemia Virus

Feline leukemia is a disease that spreads through urine, nose discharge and saliva. Cats can catch the disease through bites, sharing food, water bowls and litter boxes, and from grooming eachother. Mother cats can pass the disease along to their kittens, and kittens are more likely to contract the disease than adult cats.

Some cats will immediately become ill upon contracting the virus. In other cats, symptoms of the disease will not manifest for several weeks or even years. Feline leukemia can result in a number of conditions, but ultimately will attack the immune system and lead to bone marrow failure.  Any illness can be a sign of feline leukemia.

Although there is no cure for feline leukemia, the disease is easily preventable. Keeping cats indoors, restricting exposure to other cats, maintaining a clean living environment and ensuring your cat is vaccinated can all help prevent feline leukemia.

4: Feline Immunodeficiency Virus(FIV)

FIV is primarily spread through bite wounds, and outdoor cats and territorial tomcats are most susceptible to infection. Casual contact through sharing food and water bowls doesn’t significantly the increase risk of contracting FIV. A mother cat may rarely pass the virus along to her kittens.

Once the virus enters the bloodstream, it can remain dormant until it progresses into an active disease. FIV is terminal, and because it targets the immune system, cats that have the disease run an increased risk of common infections. To prevent FIV, keep your cat indoors and have them neutered to prevent fighting.  There is currently no effective vaccine against FIV.

3: Kidney Disease/Renal Failure

Renal failure is one of the leading causes of death in older cats. Causes for renal failure include age, genetics and environmental factors such as ingesting poisonous substances. Renal failure in cats can take two forms: acute or chronic. Acute renal failure is associated with a sudden stop of kidney function, while chronic renal failure results from a progressive deterioration of kidney function.

A number of symptoms can show up as a result of renal failure, including excessive urination, increased thirst, nausea or vomiting, dehydration, constipation, loss of appetite, weight loss, halitosis (bad breath) and lethargy. If your cat is experiencing any of these symptoms, your veterinarian can test for renal failure.   Blood tests can be checked for elevations in the kidney function values.  Unfortunately, these tests will only be elevated once there has been at least a 75% loss of function. A urinalysis tests to check for loss of protein and to see if the cat’s urine is diluted can detect disease at earlier stages.

Although there is no cure for feline renal failure, it can be managed through adjustments to your cat’s diet, medication and hydration therapy.  Well managed patients may be able to survive for long periods of time.

2: Feline Panleukopenia (Feline Distemper)

Feline panleukopenia is a highly contagious viral disease, primarily seen in kittens born from unvaccinated mothers.  Kittens almost always die, even if given treatment, after contracting the disease. It can spread through bodily fluids, feces and fleas, and is usually transmitted by contaminated food and water bowls, litter trays and clothing.

Feline distemper affects the intestinal tract and attacks the immune systems. Cats suffering from the disease are likely to experience diarrhea, vomiting, dehydration, malnutrition,anemia and usually death within a few days.   A veterinarian can diagnose feline panleukopenia through blood tests.

Treatment of feline panleukopenia is rarely successful.  In order to prevent feline panleukemia, you should vaccinate your cat.

1: Feline Rabies

Cats are reported rabid more often than any other domesticated animal in the United States. Because of their curious nature and instinctual hunting skills, they come into contact with carriers of the disease more than other pets.  Rabies is one of the most dangerous  diseases because it doesn’t infect just cats, it can be passed along to humans, too. Rabies usually spreads to cats through bites from or ingestion of wild animals.  With indoor cats, this can occur with bats or rodents that have gotten into your home. This debilitating and degenerative disease attacks the nervous system.

The normal incubation period is 10 days, but rabies can be deceptively slow-moving.  The disease can incubate in a cat’s system for weeks, or even years in rare cases.  Symptoms include poor coordination, yowling, drooling, fever, and any strange behavior.

There is no treatment or cure for feline rabies.  Vaccines are highly effective in prevention, and all pets should receive them regularly.  Keeping your cat indoors will reduce the risk of exposure to infected wildlife.