How to stop a dog’s nose bleed:
Sneezing from allergies, an infection, a foreign object, polyps, bleeding disorders — lots of things can cause nosebleeds in dogs. While ultimately you’ll need to find out what’s behind your dog’s nosebleed, in the short term, you’ll want to try and stop the bleeding. To do that:
–   Soothe your dog and keep it calm.
–   Cover the nostril that’s bleeding with something absorbent.
–   Apply a cold compress to the top of your dog’s nose, between the eyes and nostrils.
–   Don’t tilt your dog’s head back to slow the blood, or put anything inside your dog’s nostril.
–   Call your vet right away if bleeding doesn’t stop within a few minutes.