It must be springtime in Wisconsin - about 75% of the people I saw this week were sneezing or congested. We certainly get seasonal allergies; pets do, too.
A dog with grass or pollen allergies may sneeze or have watery eyes. The whites of the eyes (sclera) can get red and there can be discharge from one or both eyes. Pollen gets on the fur coat and some dogs will be itchy on their skin. Paws are also frequently affected, since they are in contact with grass. Licking of the paws is a common clinical sign of allergies in dogs.
Veterinary dermatologists "grade" itchiness on a scale of 1 to 10. The occasional lick or scratch is probably about a 1, stopping on a walk to scratch is about a 6 and waking you up at night slurping on the paws is probably a 10! If your pet is showing only mild signs of allergies (grade 2-4), you can try over-the-counter antihistamines, like diphenhydramine (Benadryl) or loratidine (Claritin). Diphenhydramine is dosed at 1 mg/pound dog's body weight, rounded to the nearest 12.5 mg. You can give it every 12 hours. Some dogs do get a little sleepy on it, but overall it is a pretty safe drug. (Overdoses can cause seizures, respiratory depression, and possibly death, however). The main problem with OTC antihistamines is that they aren't very effective in dogs.
Frequent baths or rinsing your dog's fur and paws can be helpful if the allergies aren't too bad. A moisturizing dog shampoo or ones made for itchy dogs can be used once or twice a week. If you are using a topical flea/tick preventative, frequent bathing will decrease the effectiveness by the end of the month and you should re-apply the medication every 3 weeks instead.
When the itchiness is getting to the 5-6 range on the scale, your pet needs something more effective and should be seen by your veterinarian. Licking and scratching can cause both yeast and bacterial skin infections. These infections are itchy on their own, making the dog even more miserable. Medicated shampoos or mousse may be helpful at this point, as well as omega-3 fatty acids, to help improve the skin barrier. By treating the itch at this intensity, hopefully you will prevent your dog's skin (and misery) from getting any worse.
If your dog's itching and licking is almost constant, please don't wait any longer to take him/her into your veterinarian! At-home treatments won't be enough to help the itch at this point. Besides allergies, your dog could have Sarcoptic mange (which is very itchy), ringworm, Demodectic mange with a secondary bacterial infection, a Staph infection or a Malassezia (yeast) infection. Anticipate starting your dog on antibiotics, antifungal medication, medicated shampoos, and more effective anti-itch medication (Apoquel or Cytopoint). If your dog also has an ear infection, the ears will likely be thoroughly cleaned and a medication placed in the ear (there are long-lasting medications now, such as Claro, so you don't have to treat the ears at home!)
Seasonal allergies are miserable for everyone involved. You don't like sneezing and feeling congested and your dog doesn't like licking his paws or scratching his side all the time. Hopefully the allergy only lasts for a few weeks to a couple months and responds well to treatment. But in that time period, your dog can do a lot of damage to his skin, so please get treatment started at the first sign of itching or licking. Your dog will be very appreciative (and you won't wake up in the middle of the night to that slurping sound!)