The following are a reasonably complete list of likely symptoms of allergies in dogs.

This article is the base article of bad reactions that dogs can have to allergies, more detail on each specific reaction will be dealt with later

They are not in any specific order nor ..

Itchy, red, moist or scabbed skin and Increased scratching of dog

Different allergies will have different sites of symptoms in the dog though some are reactions for almost any time of allergy cause. For instance contact allergy with grass or plants will have a dog specifically licking their feet.

But as the rest of their bodies react, they may end up scratching their ears that might make you think the allergy is connected with an ear symptom. They may also scratch their ear and spread the allergen to the inside of the ear giving it a genuine primary site of allergic reaction.

Note taxing of the immune system can allow secondary infections such as bacterial or yeast skin infections to flourish that also need to be treated.

Itchy, runny eyes, Sneezing

This is usually caused by airborne allergens that humans suffer from such as pollen during spring time. And sometimes the same antihistamines that owners used can be used on your dog, but consult a vet first.

Itchy back or base of tail (most commonly flea allergy)

Often a dog will roll on its back on grass to scratch an itch, but if it is allergic to the grass then it will only increase that itch. The base of tail itch is an interesting one. It can be worm related or cling on poo around the anus. Alternatively it can be an allergy related symptom such as a might or flea bite, which may turn into a hot spot and take a lot longer to heal.

Paw chewing/swollen paws

This is one of the most common allergies in dogs, and those dogs that have light colored coats, you can see discoloration on the paws from saliva from constant licking

Itchy ears & ear infections

This can be contact allergy related, airborne allergen or food related. Curiously I have read that some food related allergies can cause allergies and licking of the feet, that are self perpetuating.

The problem with this is that if the dog continues to lick and breaks the skin and gets a secondary infection, the white blood cells in its body that try to fight off a possible infection, coupled with the extra load that histamine swelling is causing in the body allow a dogs ears bacteria and fungal levels to sky rocket and a primary infection occur in the ear that is far worse than the feet will ever be.

dog Snoring caused by an inflamed throat

Like humans some dogs can just have problems with their throat architecture that as they get older hangs down and causes snoring. If you sleep with a dog in your room you will soon be aware of loud dog snoring and want to fix it. Finding out that the snoring is caused by an inflamed throat and that it is caused by an allergy rather than a virus can be a lot more difficult.

Constant licking by the dog

Dogs with allergies on their feet constantly lick that, but some dogs with general body allergies (all over their skin) may lick all over their body and fur, giving you the impression they are preening like a cat. Dogs do not preen like cats and this is a clear sign that something is wrong, potentially an allergy.

Vomiting, Diarrhea

These are very severe dog allergy reactions that are often food allergy related. Both can cause many secondary symptoms including malnutrition, strained stomach muscles etc. These are very serious symptoms that regardless of the cause, if they continue for any length of time in a single day should be monitored by a vet.