It works, but you have to find the exact spot (antennas from vets scanner devices are much bigger and therefore easier to get a read)
Look at the yellow LED and if you see it, search closer in that area. That’s what ultimately helped me find the chip.
Good Luck
Tried with my Siberian Husky but no way, fur is too dense I guess 
Sometimes the Chip is moving. Unfortunately nobody can say in which direction.
For older dogs it always helped me to start with ‘Read ASK’ from the left shoulder, near the neck and go back until the LED goes yellow. For long fur it goes more often yellow, but after scanning twice, you’ll get a feeling for false positive.
Right now (with a lot help from my wife) I was able to scan every dog.
And a friend of mine, in the Tattoo and Beauty business was so interested in Flipper and now got registered for human NFC/RFID implants… Soon I can start scan myself
Additional, how Avid (Manufactor of Animal Tags) recommend to move the scanner:
Source: https://www.avidid.com/sites/default/files/product_manuals/AVID1034-3_MT3_Manual.pdf - Page 3 (with more explanation, I won’t copy here, because of copyright)
The issue with that is that Flipper can’t read tags while in motion, the antenna doesn’t have enough time to settle. You have to keep it completely still for 2-3s, then move it a bit, and then keep it still again
Good point. Haven’t thought of this limitation.