4 min read


Can Dogs See Security Features in Money?



4 min read


Can Dogs See Security Features in Money?


Counterfeiters beware of Fido and Fifi - yes, dogs can actually see the security features on our money! Their vision, like their hearing, is super-duper! Did you know if a dog has an accident in the house and their staff, um we mean their person, doesn't clean it up fully, they will be able to see the outline of the ick left on the floor?  

Likewise, our pups can spot all the security features in our money. The U.S. Government has gone to great lengths to mark our paper currency to ensure it cannot be easily duplicated by counterfeiters.  

First: some facts about our money. U.S. greenbacks are comprised of 75% cotton and 25% linen, making it extremely more durable than regular paper, and the same company has been providing that paper since 1879.  Cool, right? Now, all $5.00, $10.00, $20.00 and $50.00, etc. have security threads and watermarks that need to be held up to ultraviolet light. The  $100.00 bills actually have a 3d holographic security ribbon woven to the right of Benjamin Franklin's portrait.  

Hold up a bill and move it back and forth and the bells actually change to 100s and move. Take that, counterfeiters - and dogs can spot these security features and watermarks easily and without an ultraviolet light - here is how.


Signs Your Dog Can See Ultraviolet Light

UV light is not seen by the human eye because we have a lens that blocks that light from reaching our retina and causing damage. UV light can be seen by animals, research shows. UV light vision helps animals in the wild - including reindeer to see polar bears, who, because of their color, often blend in with snow and ice.  

It helps animals see urine trails, which can help a predator find a juicy, meaty snack out in the wild - oh, cruel nature. Back to our household pups, who, thankfully aren't our predators. We, mere humans, have to use a separate UV light to see the security threads and watermarks on U.S. currency- dogs, do not.

Have you ever noticed your doggo acting strangely or chasing something you just can't see? Stalking, barking, pouncing, and tail wagging at nothing are signs your pup is seeing something and wants to play, capture it or warn you about it, or to clean it better if it is a pee-pee faux paw in the rug. Anyone who has loved a dog and truly understands the depth of our love for them will gladly take on a little (or a whole lot) of extra housekeeping for the ruff of their lives.

Body Language

If you think your dog has spotted something that you can't see, look for signs like:

  • Alert
  • Barking
  • Wag Tail
  • Stalking
  • Pupils Dilated
  • Play Bowing

Other Signs

More signs that your dog has seen something with their UV vision are:

  • Nose To The Ground
  • Pouncing
  • Howling
  • Pawing At The Ground

History of Dogs Seeing Ultraviolet


Mammals have been able to see "UV vision" since the first ancient canine/wolf/cavedog roamed the earth millions of years ago. This vision certainly assisted ancient animals to hunt, stalk and kill other animals for survival in the wild, or to notice the tracks through urine trails of other dangerous prey animals, like dinosaurs or saber-tooth tigers, and stay clear of their path.  

Insects like bees and other crawly, little critters, by using their UV vision, can see patterns on the plant-life they are scooting around on that will lead them to sweet nectar to eat. Rats follow urine trails to fine food or other garbage to eat, and as studies show, kitties and dogs can also see UV vision, which, for dogs, includes seeing those invisible to the human eye security threads and watermarks on U.S. currency.

Science Behind Dogs' UV Vision


Studies on mammal vision show that UV vision is simply something most mammals have naturally. But let's talk about light for a second.  Visible light has wavelengths of between 400 and 700 nanometers; ultraviolet light - or light the human eye cannot see - has much lower wavelengths and occurs on the opposite side of the spectrum.  

Humans can't see UV light because the lens of our eyes is designed to absorb this type of light so it cannot reach our retina and damage our eyes. Dogs can see UV light because their eyes are designed differently, with different light filters, or cones, than humans. UV light often affects a dog's eyes later in life in the form of cataracts.

Using UV Light to Train Dogs


Some trainers are utilizing UV light to help them train dogs to do basic everyday activities at home. You can purchase special sensors that emit UV light that can be seen by your dog in the dark. You can teach your dog to hit that switch to turn the light on for you! A little patience and an amazing doggy are all that you need! 

Are you looking to be sure all surfaces are free from urine or bacteria? We, mere humans, need to look at the surfaces under a black light but your furry friend can see it freely. If your dog is sniffing along the ground over and over, this may be an area you would want to clean more thoroughly.

Have questions or concerns about your pet?

Chat with a veterinary professional in the Wag! app 24/7.

Get Vet Chat

By a Smooth Coated Collie lover Mary Alane Whalen

Published: 03/26/2018, edited: 04/06/2020

Wag! Specialist
Need to upgrade your pet's leash?

Learn more in the Wag! app

Five starsFive starsFive starsFive starsFive stars

43k+ reviews


© 2023 Wag Labs, Inc. All rights reserved.