There are quite a few reasons why dogs sneeze. The most obvious reason may be particles getting in their nose. Dog noses are quite sensitive, so this explanation certainly makes sense.
You may have also noticed your dog sneezes when you pet him and wondered what may be causing this. As humans we spend quite a lot of time and resources trying to understand our canine companions, and the truth is that we don't always have or are able to discover the answers. But we try!
Let's explore why your dog sneezes when you pet him and if it's something to worry about or not. In many cases, it's not necessarily a bad thing.
As previously mentioned, dogs have sensitive noses. Something you are wearing like an angora sweater, or body lotion and perfume, might trigger the sneezing reflex in your dog while you are petting him. Some common allergies in dogs include grasses, pollen, mold, dust mites, cigarette smoke, feathers, chemicals, pests, medicines and more. Perfume, for example, contains chemicals and ingredients that can become a problem. If you've recently put on perfumed hand lotion, this may also cause your dog to develop a sensitivity or simply react by sneezing without having developed an allergy. The truth about perfumes and fragrances is that a loophole allows manufacturers to keep the ingredients they use a secret. So obviously you have no idea exactly which chemical ingredient is causing this reaction. If your dog has a sneezing fit while you're petting them, it may just be because of a fragrance and you may want to stop using it while interacting with your dog.
A playtime response
Dogs can also sneeze quite often when they are playing. This is not cause for concern as it means that they are simply enjoying themselves. A sneeze while playing can be a calming signal, in that it can calm the dog itself and other dogs. It's a harmless signal to dogs that actually puts them at ease. So, since a dog sneezes during playtime to indicate she's having fun, it stands to reason that she sneezes when you pet her because she's enjoying herself and also enjoying being the recipient of your attention and affection. These are really just playful sneezes and not cause for concern. You may have also noticed your dog grunts or makes other vocalizations when you pet them. This is another sign that they are enjoying themselves. Basically, don't worry if your dog sneezes a few times while being petted - it's perfectly normal.
When to see a veterinarian
Excessive sneezing and sneezing a lot in general, or even a runny nose while sneezing, may be signs of a bigger problem, and might necessitate you to consult your veterinarian. Your vet will do a thorough checkup of the dog's nasal passage and determine if there is something perhaps lodged in there (for example, foxtails can often burrow their way through a nostril and into the nasal passage causing a lot of irritation). Your vet may also be able to determine if your dog is allergic to any type of fragrance you may be using. Don't wait too long before visiting your vet if the sneezing is excessive and won't stop because if it's a foxtail or other item stuck in the nasal passage, it can be quite dangerous.
Keep in mind that your dog's sneezes are not necessarily an indication of a problem. Dogs show their happiness in a number of ways, including sneezing. It seems strange to us humans because we don't sneeze when we're happy (usually), but dogs can't express themselves by talking, so they have developed other ways of showing happiness, pleasure, or gratitude. Naturally, though, if you sense something is wrong because the sneezing is excessive or won't stop, trust your gut. Only you can know whether the sneeze is normal or possibly an issue. Consult your veterinarian to rule out any problems immediately.