Do you suffer from any food allergies? Your dog can also suffer from an allergic reaction to certain types of food and hair loss can be an indicator of that.
If you dog starts to show signs of a reaction after eating it could be a sign of worse to come and scratching could lead to infections and skin problems.
There are solutions however.
If you suspect an allergic reaction it can basically be a case of trial and elimination to try and identify the foods which your dog cannot get along with and then removing the perpetrator from his diet.
A trick you might try to aid identification and possible diagnosis is to start to give your dog food you have made yourself from natural ingredients.
If he is fine with that it could mean that he is allergic to something in the shop-bought dog food you normally feed him on - a chemical or preservative ingredient perhaps.
If you are going through the identification and elimination process to try and narrow things down it is suggested that you try to cut out any other sources of food from your dog's diet.
By that I mean the occasional treat from friends and the like.
Then, when you think you have found the food you believe him to be allergic to stop it totally from his diet.
If your dog now shows no adverse reaction to his food you know you've done the trick.
The identification and elimination process can be frustrating and time consuming though is in the best interests of your dog in the long term.
Food related allergies are just one of the causes of hair loss in dogs.
Once you have removed the offending food you should see an improvement in his demeanour and much less itching and scratching.