For its health and yours, keep the cat indoors

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At least one running argument among cat lovers is now over: Whiskers, Lucy and Tigger are definitely better off staying indoors, scientists reported Wednesday.

Pet cats allowed outdoors, in fact, are nearly three times as likely to become infected with pathogens or parasites than those confined to quarters, they reported in the Royal Society journal Biology Letters.

Two-legged house-mates should also take note because cats—a.k.a. Felis catus—can transmit some of those diseases to humans, the authors said.

Intriguingly, the farther domesticated felines are from the equator, the more likely they are to be afflicted by some kind of bug or virus, if they spend time outdoors.

"Each degree in absolute latitude increased infection likelihood by four percent," said lead author Kayleigh Chalkowski, a researcher at the School of Forestry and Wildlife Sciences at Auburn University in Alabama.

"You think of as just having more wildlife, more parasites," she told AFP. "But it turned out that latitude had the opposite effect."

To settle the indoor-vs-outdoor question once and for all, Chalkowski and colleagues combed through nearly two dozen earlier studies in which the prevalence of one or more diseases was compared across interior and exterior environments.

All told, the new study looked at 19 different cat pathogens in more than a dozen countries, including Spain, Canada, Australia, Switzerland, Germany, Pakistan, Brazil, the Netherlands and St. Kitts.

'Keep your cat indoors'

"This is the first time outdoor access as a risk factor for infection in cats has been quantified across a wide range of geographic locales and types of pathogens," Chalkowski said.

The effects were consistent for almost all of the diseases, including feline roundworm and the single-cell parasite that causes toxoplasmosis, both of which can affect humans.

This held true regardless of how they were transmitted—whether from soil, other cats, or prey such as mice and birds.

"Basically, no matter where you are in the world, keeping your cat indoors is a great way to keep them healthy from infectious diseases," Chalkowski said by way of summary.

This is especially good advice, she added, "considering that many of the pathogens cats carry can actually be spread to humans".

Other domesticated animals transmit to their caretakers—dogs, for examples, spread rabies, and cattle carry Cryptosporidium parvum, a parasitic disease that attacks the intestinal tract.

Wild cats were likely first drawn to human communities in search of rodents, and were domesticated some 5,000 years ago. In ancient Egypt, they were associated with gods and prominently featured in hieroglyphics.

There are some 90 million in the United States, and an estimated 500 million worldwide.

Explore further

Should you feed wild birds in winter?

More information: Kayleigh Chalkowski et al. Who let the cats out? A global meta-analysis on risk of parasitic infection in indoor versus outdoor domestic cats ( Felis catus ), Biology Letters (2019). DOI: 10.1098/rsbl.2018.0840
Journal information: Biology Letters

© 2019 AFP

Citation: For its health and yours, keep the cat indoors (2019, April 17) retrieved 17 August 2019 from
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User comments

Apr 17, 2019
So that means, at a 4% increase for each degree of latitude, that cats at latitudes 25° and over are doomed the moment they stick their noses out the door. Sounds a bit too extreme to me...

Apr 17, 2019
No. A 100% increase merely doubles the unstated likelihood. Epidemiology is difficult wether human or veterinary.

Apr 17, 2019
But are the cats happy being confined?

Apr 17, 2019
Cats accustomed to going outdoors will be miserable if subsequently confined and their destructive behaviors will make their owners miserable, too. Vaccinate for the pathogens and let them take their chances.

Apr 17, 2019
And, in other news. Cat lovers discover, that locking them indoors, make them want to eat your face.

Apr 17, 2019
@Doug_nightmare: I'm not an epidemiologist, but I'm pretty good at math. A 100% chance of getting infected is pretty self explanatory, and doesn't double anything (other than a 50% chance, that is). If you get a 100% salary raise, that doubles your chance of being very happy, but if you have a 100% chance of getting fired, you're toast.

Apr 17, 2019
But are the cats happy being confined?

It depends on the amount of love, affection, attention, good food and clean water they are given daily. Also they need a way to exercise safely and a chance to explore until their curiosity is satisfied and they are tired out. A nice comfortable bed and clean litter box are also important. Cats seem to enjoy going inside a clean paper bag and looking out at their indoor world. If you gently poke the top of the bag, the cat will react to that challenge also. Long, sharp nails need to be gently and carefully cut with special nail-clippers made for cats. If not done by a professional, it's important to not cut into the colored portion of each nail. And have a bottle of blood clotting powder for cats on hand just in case you cut into the "quick" and causes him/her to bleed.
Make sure that he or she gets all her vaccinations for rabies, etc.
Vacuum often.

Apr 17, 2019
My cats are well adjusted and happy and fear the outdoors, including the one I took off the street. He would not willingly go back. I make sure to let them look (and more importantly smell) out through open screened windows when the weather is clement, and even sometimes when it's not. They get plenty of enrichment and enjoy it.

Apr 18, 2019
Come on. We all know the truth. This story was concocted by dogs so that they wouldn't have to deal with their pesky feline rivals.

Apr 19, 2019
So that means, at a 4% increase for each degree of latitude, that cats at latitudes 25° and over are doomed the moment they stick their noses out the door.

It does not mean that at all, obviously.

First, the abstract says "absolute latitude trended towards significance such that each degree increase in absolute latitude increased infection likelihood by 4%." That means it is a relative comparison between the two groups with increased likelihood of getting infected of 1.04 at a degree higher latitude.

Second, the paper took that odds ratio estimate into a fit of proportion total infected cats (all cats, all parasites) between 0 to 60 degrees (figure 2 b), where it goes between ~ 0 to 0.3 at 60 deg absolute latitude, i.e. the proportion infected cats increased 0.7 %/deg. (Possibly you can derive the proportion outdoor cats and their infection rates from that.)

Apr 23, 2019
Once again an article that exaggerates. One thing is letting a cat roam around the neighborhood, another is allowing you cat to play in your fenced yard or if not, to wear a leash just like dogs and keep an eye on him. Cat's natural habitat is NOT a house and even less a small apartment. It's like a human being confined for life to keep safe for all possible accidents and contamination by other humans.

Apr 23, 2019
Keeping cats and dogs indoors is cruel. Which means they shouldn't be kept at all.

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