Q: I have a 5-month-old German Shepherd Dog who plays with our neighbor's dog who is about 5 or 6 years old. When she comes over to play with our puppy she is constantly foaming from the mouth. What could cause this? When they’re done playing, we have to wash our dog to get rid of the funky smell left behind. Our neighbor says that the dog has had all of her shots, yet this continues to happen. Should we be worried that our puppy could pick up something?
A: Foaming at the mouth has always been a classic sign of rabies, and I would initially share your concern. You will be relieved to know, however, that cases of rabies in dogs in the United States are rare indeed, with only 76 dog-related cases reported in 2005. Most of these were related to rabid wild animals, including raccoons and skunks. Also, if your neighbor's dog has been vaccinated, the vaccine is close to 100% effective. You might look for, or ask about, a rabies tag on the dog's collar as proof of rabies vaccination. If your neighbor's dog does have rabies, she will probably become very ill or die within 10 days, since rabies is fatal in dogs.
Other more common and less alarming reasons for foaming could include dental disease and hyperexcitability. Most likely, these are not concerns for your dog, except for the unpleasant odor you report. Just as you might not want your child playing with another child who has less-than-ideal hygiene, the same might apply to your dog. Consider keeping them apart if you think the neighbor’s dog is not being cared for appropriately.
Jon Geller, DVM