— Written by Tim Marzullo —
All vertebrate animals have hearts (and many invertebrates too), and many have EKGs that can be non-invasively recorded as commonly done in humans. We have fairly hairless bodies, so we can easily put sticker electrodes on our wrists or chests to record our EKG.
However, many of us share our households with furry four-legged creatures that bring us joy, companionship, humor, protection and pest control. Could we record their EKGs too? We know that the smaller the mammal, the faster the heart rate, but can we see this trend in our own pets, and in a way that minimally annoys our household friends? Yes we can. Ladies and gentlemen, the Dog and Cat EKG.
For our dog EKG investigations, we chose a two-year-old Vizsla dog named “Santina”, cared for by BYBer Florencia Edwards. This dog has very short hair and a gentle disposition, making it ideal for our pilot experiments. We modified our EEG headband by using tennis wristbands instead, inserting metal buttons into the wristbands (the buttons we find in jeans and wallets), and slipped them on her front two legs (signal electrodes), and one rear leg (ground).
We then applied a bit of gel between the metal buttons and the short-furred skin of Santina, and voila! It worked in an instant. Of course, we don’t want to hurt human’s best friend; these sweatband electrodes are non-invasive and are the same as wearing clothing. Florencia gently caressed Santina’s head while we put on the electrode sweatbands, and we did a 40-second recording using our Heart and Brain SpikerBox and our program SpikeRecorder. As expected, given Santina’s smaller size than humans, her resting heart rate was 90 bpm (beats per minute). You can analyze the data using our SpikeRecorder program by downloading Santina’s recording here.
Check out a video of Santina’s EKG in action below!
Dogs want to make their owners happy (for the most part), but cats are famously uninterested in us, mere human mortals. Cats do not tolerate sleeves on their legs (or anything on their legs – try touching their paws and see how your cat responds), so how can we record EKG that is minimally annoying for a cat? After a few prototyping rounds, we converged on a design using foot paw copper pads covered with electrode gel. It is very easy to make, taking only about 10-15 minutes and less than $5 in materials.
We visited our feline friends at our local cat cafe “Cat Playground” in Myeong-Dong, Seoul, South Korea, that we have been frequenting, and we have become good friends with the owners. They were kind (and curious) enough to let us run an EKG test on their beloved cats. We chose a docile 6.5-year-old female Scottish Fold cat named Harang with a lovely calico coat pattern. We placed some electrode gel on the copper pads, and Harang tolerated the owner placing her paws on the pads for about 20 seconds, long enough for us to get a stable reading. We gave her some treats afterward. Thanks Harang!
Harang’s two front paws were on the upper two copper pads as signal electrodes, and her rear right leg paw was placed on the rear ground copper electrode. Examining her data in SpikeRecorder, we observed that her resting bpm was faster than Santini’s, around 160. For reference, a cat’s resting heart rate is approximately 150 and can get up to 250 when physiologically excited.
These dog and cat EKGs are probably the cutest projects Backyard Brains has ever embarked on, and we feel a cat owner could rapidly train their cat to sit on the copper pads so they could measure their EKG regularly if they are a curious budding veterinarian or just wonder what their cat’s EKG looks like. The dog sweatband bracelets are also quite easy to make and are easily tolerated if you have a similar interest in your dog’s EKG. The NeuroRevolution is here. Let us know if you are interested in recording EKGs in your human or furry friends!
In sum, we observed what we expected: the smaller the mammal, the higher the bpm. The human author of this blog’s resting bpm was 65, Santini the dog’s resting bpm was 90, and Harang the cat’s resting bpm was 160. Rats and mice can get even faster, at 250 and 500, respectively, and a large whale can have a resting bpm as low as 10!
Science is all about collaboration, and we close this blog by saying Harang visited us as we were writing this on our computer at the cat cafe, and she wanted to contribute too. This is what Harang added (her real text):
Our team of cat cryptographers continues to try to decode this using the most advanced AI we have available. Stay tuned, and thanks for reading!
Disclaimer: These experiments were non-invasive and did not harm the dog or cat. They were designed to show the principle to students that the smaller the mammal, the higher the resting heart rate. The owners were present during the experiments. They care very much for their pets, and the owners agreed to and monitored the measurements.