shitztzu aggressive when upset

Question
my shihtzu maggie is 3year old and spayed. She has become very aggressive when she is accidently bumped ar tripped over She will snarl and bite.   She has also started attacking peoples feet for no reason this is also very aggressive.My vet suggested I take a fly swatter to her and give a good swat when she does this Is this the right punishment Thank you Murielle.

Answer
Has her eye sight been checked?  Often times when a dog just suddenly starts doing these things it is due to them looseing their eye sight.  I wouldn't use the fly swat route.  I would instead go to the store and get a squirt bottle.  Fill it half water and half lemon juice.  When she gets upset like that, one squirt on the face should do.  Most do not like being squirted in the face and she will learn to associate the squirt with her bad behavior and it should help to stop it.  Using the fly swat may just make her more aggressive.  If you need further help there is a wonderful group called Everything_Shih Tzu.  Just go to www.yahoogroups.com and in the search for groups type Everything_ShihTzu .  It should pull the group up.  Just click join this group.