5 Biggest Health Problems of Indoor Cats vs. Outdoor Cats

Pay attention to signs that your cat needs immediate veterinary attention. Here are the top problems we see with indoor cats and with outdoor cats.

Even indoor cats can suffer from flea allergies. By: mlcollins

Cats are fabulous creatures and usually lead long and healthy lives.

Though sturdy little beasts, however, they are still prone to certain syndromes and diseases.

Luckily, cats respond well to medical intervention if we can figure out the root cause of what’s bugging them and how best to treat it.

Part 1: The 5 Biggest Health Problems of Indoor Cats

A typical week full of cat appointments might look something like this:

  • Leo, 5-year-old DSH, vomiting for 2 days.
  • Oscar, 7-year-old DSH, check runny eyes.
  • Annabelle, 2-year-old Persian, not using the litter box for 1 month.
  • BamBam, 5-year-old DSH, scratching himself, just like last year.
  • Pumpkin, 4-year-old DLH, sneeze/cough.
  • Juno, 14-year-old DSH, possibly losing weight and drinking more water.

1. Vomiting

Young. Old. Healthy. Debilitated. Vomiting is not picky when it wants to bother a kitty.

Everyone is familiar with that full-body undulation giving way to a projectile spewing of recycled cat food in various stages of digestion. Cats often pick your dinnertime or when guests arrive to grace the carpet or your favorite piece of upholstery with vomitus, often accompanied by a war-cry vocalization. Then, some might go back to the food bowl and see if there’s more to eat.

While occasional vomit deposits are normal for many cats, vomiting is a symptom of many feline diseases. The differential list (causes) for vomiting is longer than this page.

Cats like to eat or chew on stupid stuff, often causing an intestinal blockage. Swallowing foreign objects that lodge in the GI tract is a common cause for vomiting. Cat toys, a needle and thread, 35 pieces of self-adhesive strips from envelopes, chipmunk heads, Christmas decorations – I never know what I’ll find when I cut into that intestine.

When you bring your kitty into the vet because they’ve been vomiting for a week to a month and you think there’s a simple answer, there’s not. In 1 week alone, I saw cats vomiting from inflammatory GI disease, kidney disease, hyperthyroidism, constipation, eating a rodent, eating house plants and a few cases still undiagnosed.

Diagnostics for vomiting include radiographs and blood work, advanced imaging, diet trials and possibly GI biopsies, to name a few. Treatment depends on the cause. Although there are palliative medications to perhaps make a vomiting kitty feel better, don’t take the Band-Aid approach if your cat continues to vomit. We need to find out why.

Veterinary pearl of wisdom: Although hairballs are considered a cause of vomiting in the cat, a normal cat develops hairballs and passes them without excessive vomiting. A cat vomiting frequently, even if that cat appears healthy, has an underlying condition. Have it checked out.

2. Lower Urinary Tract Problems

Many cats are affected by lower urinary tract disease, sometimes referred to as cystitis. If cats are mildly affected, they exhibit occasional straining to urinate in the litter box or they stop using the box.

The urine is often blood-tinged (hematuria), and the cat is passing small amounts of urine frequently (stranguria). In the worst case, the cat cannot pass urine (urinary blockage), which is an extreme medical emergency. This is a multi-factorial disease, meaning diet, dehydration, viral and bacterial infections, genetic predisposition, metabolism, stress and more may play a role.

Basic diagnostics include blood work and urinalysis, a urine culture, radiographs and sometimes ultrasound. Treatment may include dietary changes, pain and anti-spasmodic medications and antibiotics. A kitty with a urinary blockage must be unobstructed and catheterized. Bladder stones may have to be removed surgically.

Veterinary pearl of wisdom: Change to an all-canned or mostly canned diet if your kitty has experienced any symptoms of lower urinary tract disease. Offer multiple sources of clean, fresh water. Keeping your cat as hydrated as possible may prevent recurrence of problems.

Know which plants are poisonous to cats and keep them out of your home. By: tommyhj

3. Respiratory Diseases

Cats are frequently plagued by diseases that cause anything from a mild sneeze to respiratory distress. Symptoms include runny nose and sneezing, tearing eyes, ocular discharge, conjunctivitis, cough, fever or difficulty breathing.

Upper respiratory disease is often caused by viruses. Bacterial infections can come secondarily. Theses infections can be mild and self-limiting, chronic or sporadic, or serious. Kittens, geriatric and immunocompromised kitties are at greater risk of developing serious respiratory infections.

Feline asthma (also known as bronchitis or allergic bronchitis) is another common respiratory disease. Asthmatic cats can cough, wheeze, gag, stretch their necks out as if to gasp or draw in a breath and/or exhibit true respiratory distress. Cats experiencing a severe asthmatic attack require emergency intervention, medications and an oxygen cage.

Treatment for respiratory disease can include antibiotics, antivirals, steroids, bronchodilators, inhalers, decongestants and eye medications.

Veterinary pearl of wisdom: Never ignore difficult breathing in a cat. Early intervention can truly be life-saving. Your veterinarian will have to differentiate upper airway disease from lower airway disease, rule out a heart condition and treat appropriately.

4. Dermatologic Disease

Cats are very prone to allergies that cause itchy skin, particularly flea allergic dermatitis.

Indoor cats can get fleas. Most veterinary dermatologists believe flea allergy is behind a great deal of cat scratching until proven otherwise. Cats can also be allergic to inside and outside environmental allergens and be food allergic. When a cat is itchy, they will over-groom, bite, scratch and give themselves serious skin lesions.

There are many other dermatologic diseases in cats including parasitic, neoplastic, bacterial, fungal, autoimmune and inflammatory.

Diagnosis starts with a good history from the cat’s human and a thorough exam. If fleas are found or suspected, for example, treat these first. Skin scrapes, fungal culture for ringworm, food elimination diet trials and possible biopsy are all diagnostic tools in getting to the heart of the itch.

Treatment depends on the diagnosis. This can include a change in diet, steroids, non-steroidal drugs, antibiotics and anti-parasitics.

Veterinary pearl of wisdom: If a cat starts scratching and incurring lesions, this itch will not stop until you discover the cause and treat it. Waiting means worse trauma to the skin, a longer recovery time, more medications and bigger vet bills.

Here are more signs to watch out for if you think your cat is ill:

5. Kidney Failure

Many house cats develop kidney disease and failure, particularly as they age. Kidney disease is more prevalent in our felines than in our other pets.

The most common cause of kidney disease and failure in cats is age. Not every older cat has kidney disease, however, and younger cats can be affected. Exposure to toxins that damage the kidneys, infections, dehydration, poor diet and stress on the body caused by other illnesses can all affect the kidneys. Congenital kidney disease and cancer also occur.

Advances in veterinary care, particularly how we care for our aging population of felines, have made kidney disease much more rewarding to treat. Diagnosis is largely through blood work. A full workup including radiographs and/or ultrasound, culture of the urine and blood pressure monitoring.

Modifications in diet, multiple medications and additional sources of hydration help the kitty in kidney failure.

Veterinary pearl of wisdom: Don’t ignore subtle weight loss, mild lack of appetite or increased thirst in your kitty. Kidney disease can behave like a cat burglar, sneaking up on your cat, so don’t disregard the early warning signs.

Parasites your outdoor cat brings into the house may put you at risk. By: Jorge Gonzalez

Part 2: The 5 Biggest Health Problems of Outdoor Cats

Part 1 of this article focused on the common maladies of indoor cats. Outdoor cats get their turn now.

The outdoor cats I see come in 2 varieties:

  • There are the indoor/outdoor cats who get veterinary care and have a good home but go outside.
  • And then there are the “good ol’ barn cats” or the strays who pretty much fend for themselves.

Here are the top 5 health problems of outdoor cats that I see:

1. Parasites

Cats who live outdoors share their bodies with lots of other little creatures: parasites.

  • Endoparasites live inside the body, invading the GI tract, the lungs and the heart.
  • Ectoparasites live on the outer body, invading the skin and the ears.

When a cat has GI parasites (roundworms, hookworms, tapeworms), their symptoms usually include vomiting and/or diarrhea, weight loss and anorexia. Some of these parasites can also create a cough because they migrate through the lungs.

Identified by a fecal test, these buggers are treated with drugs called anthelmintics. Unfortunately, many outdoor cats don’t get the benefit of being “wormed” and live their lives with parasites. Although many adult cats can live with a certain burden of parasites, a heavy worm burden in young kittens or immunocompromised cats can be life-threatening.

Parasites such as lungworm and heartworm are also prevalent in outdoor cats and more endemic in some areas of the country more than others. Many of these cats suffer from a cough, but the damage done to the lungs can be life-threatening in some cats.

Lungworms can be treated with the proper anthelmintic medication. Heartworm is not easily treated in the cat, but the cough and lung damage it causes can be helped with medications. These cats usually present as having “asthma.”

2. Fleas and Other Ectoparasites

Outdoor cats can have fleas even in Alaska. They can also have ear mites, lice, ticks and, less commonly, maggots or cuterebra.

Some cats tolerate fleas and the like, and learn to live with them. Others are super sensitive, scratching themselves, giving themselves swollen ears and living very uncomfortable lives. It goes without saying that some of these parasites are a risk to you and your home environment as well.

Once identified, all of these ectoparasites can be treated, but the cat may need other supportive treatment as well. Medications to stop the itch and treat the skin or ear infections take time and a dedicated human. That good ol’ barn cat needs some TLC to get better.

Fleas are also the biggest source of tapeworms and can transmit blood parasites. If your cat goes outside, I believe in treating fleas proactively every month. House cats can also get fleas from other animals who go out, from hunting rodents in the house or by spending time near outdoor areas. Talk to your veterinarian about risk and prevention.

Outdoor cats may contract FeLV and FIV via fights with other outdoor felines who are infected. By: hkase

3. Retroviruses: FeLV and FIV

Your outdoor cat can contract these serious viruses from other infected cats. Kittens can contract them from the mother. Adult cats contract the viruses from another cat either by friendly grooming, unfriendly contact (such as cat bites and fights), sharing dishes and food, and any other contact with bodily fluids.

Cat bites are a big cause of feline immunodeficiency virus (FIV) transmission. Tomcats who fight inflict deep puncture wounds, and the saliva from the infected cat transmits the virus to an opponent.

Vaccinating your cat against feline leukemia (FeLV) is helpful but not 100% protective. The FIV vaccine is much more controversial.

Cats can live with these viruses for several years before becoming sick. FeLV is a more serious disease and usually causes severe anemia, tumors (lymphoma) and other syndromes associated with immunosuppression. FIV cats may live long lives without symptoms, but the virus can also create an acquired immunodeficiency syndrome with associated health problems.

Keeping your cat away from infected cats is the best way to prevent transmission of retroviruses, but this is virtually impossible if your cat goes outside.

4. Trauma

An outside cat is at great risk for trauma. They face wild predators, other cats and vehicles. They get caught in fences, locked up in garages or outbuildings, fall from high places — the list goes on.

Lots of clients talk themselves into a false sense of security by thinking their indoor/outdoor cat “just stays by the house.” At some point, most of these sensible or street-savvy kitties get into some kind of trouble. If you let your cat outdoors, you must be willing to accept the consequences. All outdoor cats are at risk for trauma.

Do you know where your outdoor cat goes?:

5. Vomiting

Just like our house cats, outdoor cats can suffer from many diseases and syndromes that cause vomiting, not to mention the fact that they are at risk for eating many disgusting or toxic things.

Diagnosis and Treatment

An outdoor cat that comes to me sick or vomiting is a true challenge because the differential list (causes of the illness) is very long indeed. Particularly if our vagabond cat about town has not been to the vet recently or ever, I have to start from scratch.

  • Has Wildling lost weight? How much and in what period of time?
  • What is the FeLV/FIV status of Targaryen? Even if previously tested negative, he could have contracted one of these viruses recently from a warring enemy.
  • What does Dragon eat? Assume anything.
  • How long has Jon Snow been sick? Since last winter? Depending on how little the human sees Jon, this question often can’t be answered.

Unfortunately, these kitties are often on the budget health plan. There is still a population of barn cats out there who are not considered true pets by their humans. A “stray” might be brought in by a Good Samaritan who has “fed him through the winter,” but “he’s not really my cat.”

So say Jamie is brought in — flea-infested, coughing and sneezing; an old wound on his paw; thin and not eating the food Mrs. Human has been offering him this week. An estimate for a FeLV/FIV test, other blood work, X-rays, wound treatment and other supportive care as indicated can shock Mrs. Human. Add to this the cost of flea medication, ear mite treatment and worming. Did I mention he’s not neutered and is now under a rabies quarantine?

Oh, boy — Jamie might not live to see next season. This might be time for one of my fabulous technicians or myself to adopt him or get help from our terrific regional shelter or the state program. No wonder most of us in the veterinary world have at least 5 cats.

When at all possible, keep your cat close to you in their own kingdom.


This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was last reviewed Sept. 6, 2017.

Dr. Debora Lichtenberg, VMD

View posts by Dr. Debora Lichtenberg, VMD
Dr. Debora Lichtenberg, VMD, is a small animal and exotics veterinarian who has split her time between a veterinary practice in Pelham, Massachusetts, and her studio in New York City. Dr. Lichtenberg is a graduate of the University of Pennsylvania School of Veterinary Medicine with 30 years of experience. Her special interests are soft tissue surgery and oncology.

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