Read this first: Bite Prevention: Understanding your dogs communication system
What to do and how to respond if your dog growls, or snaps:
Thank Your Dog for Growling - growling is nothing more than communication from you dog that s/he's uncomfortable. Pay attention! And never punish your dog for letting you know!
Click here to learn more about the most effective Techniques used for modifying aggressive behavior
In addition to the modification techniques demonstrated at the link above, Behavior Adjustment Training (BAT) is also very effective. This innovative approach helps dogs learn to use calm pro-social behavior/s, rather than reactive/aggressive behaviors to satisfy their needs when they're worried about what's happening around them. The technique first identifies the "function" of the behavior (in other words, what purpose the behavior serves for the dog) then combines reinforcement and desensitization during "sub threshold" exposure (meaning non-reaction producing) to the "trigger". When done properly this technique helps the dog feel more comfortable, and ultimately learn to make better choices in behavior. https://www.youtube.com/watch?v=E1lVAFHlhGA
Thresholds: Knowing what your dog can handle without feeling the need to resort to the use of aggression
One of the most important concepts for you to understand as you begin working to help your dog learn to feel better about the thing/s that currently cause him to aggress is that of "thresholds". In other words, your dog has "limits" for exposure that he can effectively handle without using aggressive behavior. Putting (or continuing) to put your dog into situations where he's exposed in a way that force him beyond his threshold/limit only makes matters worse. So for starters, be sure to only expose your dog to whatever he's aggressive toward at a level of intensity that is well below his limit/the point that he becomes aggressive. Click the following link to learn more about thresholds and how to control your dogs environment more effectively now - it's the first step in the modification process and one that you really need to understand: http://www.whole-dog journal.com/issues/16_4/features/across-a-threshold_20726-1.html?ET=wholedogjournal:p80468:50034870a:&st=pmail&s=weekendtip041313&t=tl
After you've read the article above on thresholds, click on this link http://www.successjustclicks.com/trigger-stacking-but-hes-normally-fine/ It's a terrific article from a human perspective about what happens to stress thresholds when too many anxiety producing events occur at the same time. A concept within the realm of behavior modification known as "trigger stacking".
How easy it is for us humans to overlook signs of fear and stress in dogs! This article is a must read! https://thesciencedog.wordpress.com/2015/06/09/fear-itself/
Stop Dog Aggression Before It Starts
By Dr. Sophia Yin, DVM, MS
Dogs Bite When Humans Greet Inappropriately
By Dr. Sophia Yin, DVM, MS
DINOS = Dogs In Need Of Space!
If You're Aggressive, Your Dog Will Be Too, Says Veterinary Study
Relationship Help: Our Dogs Just Don't Get Along!
Training your dog to love wearing a muzzle may be a very good addition to your behavior modification plan, but it must be done properly. Click here for an excellent video that shows the proper way to train a dog to happily wear a muzzle: http://www.youtube.com/watch?v=1FABgZTFvHo
This section provides information about the behavior known as resource guarding, which is characterized by a dog's (or pup's) defensive reaction i.e., running away, stiffening, growling, snarling, snapping when in possession of a valued resource such as food, toys, chews, sleep/resting space, etc. It is a very common (and normal!) behavior in both adult dogs, and puppies.
Resource Guarding - What It Is, How to Prevent It
Watch https://www.youtube.com/watch?v=2nyt2WLdQGs&feature=em-subs_digest for a prevention exercise to get started on with your puppy (or adult dog)
Teaching your pup (or an adult dog) to drop objects (happily!) on cue:
Building trust will lead to decrease in guarding behavior: https://www.youtube.com/watch?v=f8F471ykE_w&feature=emb_logo
Thank Your Dog for Growling - Growling is nothing more than a communication from your dog that s/he's uncomfortable with what's happening. Pay attention, and never punish your dog for letting you know!
Concerning behavior at food bowl while eating
Help for a Resource Guarding Puppy (this is a Q&A regarding a 6 month old dog, but the same applies for an older/adult dog)
The Q&A at the following link discusses growling from a dog when her human tries to pet her while she's eating. This Tip also mentions tension between the dogs who live together in the home (also resource-related); Click here to learn more.
**For more information about dog/dog resource guarding (also a very common problem!) click Housemate Problems