Young cottonmouth slips into screened lanai and leaves 15-year-old cat fighting for her life before homeowners share how to seal snakes out

A Reddit post about a pet emergency is drawing attention after an owner said their 15-year-old cat survived a bite from a young cottonmouth that got into a screened lanai.

What happened?

A cat owner recounted on Reddit that a young water moccasin — also known as a cottonmouth — made its way into the family's screened lanai (or outdoor living room) and bit their senior cat.

The owner said the cat eventually pulled through on antivenin after the emergency vet had initially given her "25% odds."

"Now I don't want to let my pets on the lanai at all," they wrote. "I know there's really no way to snake-proof a lanai. For those of you who let your pets out there, how do you keep them safe, or is it really not possible? I'm thinking maybe to remove everything that would give a snake cover, like potted plants, and only let pets out there during daytime for short times while I'm actively watching them."

Why does it matter?

In warm-weather states, screened outdoor rooms are not always completely sealed against wildlife. Small snakes can sometimes get in through gaps near doors, frames, and edges, especially in spaces built for ventilation rather than full exclusion.

Human development increasingly pushes homes, pets, and wild animals into tighter shared spaces. As yards, patios, and lanais expand into or near natural habitats, animals seeking shade, prey, or shelter may come into close proximity to people and pets.

These encounters can quickly turn dangerous. Beyond the immediate threat to animals, they can also cause panic, lead to costly emergency treatment, and raise concerns about human safety.

What are people saying?

Commenters had plenty of advice to offer the OP along with well-wishes. 

"I don't have any advice, but just thank god your cat is okay!" one wrote. 

"I replaced the bottom section of screen with kick plate so it's solid and it's caulked around the edges," another said. "Not foolproof, but less possible to get critters in."

"I am so sorry, it is scary how quickly these things happen," said one more. "Unfortunately, snakes are masters at wiggling into places so you will probably never be totally safe from them."

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