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Jane Lefler
Jane Lefler, Animal Behaviorist
Category: Dog Training
Satisfied Customers: 20171
Experience:  Dog breeder/Trainer and Behaviorist 18+ years
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I have a 8 year old Golden Retriever who has become aggressive

Customer Question

I have a 8 year old Golden Retriever who has become aggressive towards any one who comes into the house. He also has become aggressive with our other dogs. If I am talking to someone at the door he barks non stop. We have 4 other dogs who are all working dogs and over the last year he has changed towards them, it's although he is trying to protect me.
Recently he attacked our black lab and left the lab with a open wound on his face. He has started to bark non stop at anyone who arrives at our house. He seems to bully the younger dog and attempts to mount him. I have had retrievers all my life and love him dearly but he is causing so much disturbance to the other dogs life's that I wonder what the best answer is for him. I feel I do not trust him around children anymore.
Submitted: 4 years ago.
Category: Dog Training
Expert:  Jane Lefler replied 4 years ago.
Hi JaCustomer,
My name is Jane. I have been working professionally with animals especially dogs in both health and behavioral issues for over 18 years. I have over 14,000 satisfied customers. It will be my pleasure to work with you today.
I can think of a couple of things that might be going on. One thing is that he may be experiencing Cognitive Dysfunction Syndrome (CDS). It has been seen in dogs younger than yours and I've seen in Goldens as young as 5-6 years of age.. There is a wonderful site that explains it well and also explains how to document your dog's behavior and discuss it with your vet.
The good news is that there is a drug called L-Selegeline (Anipryl (R)) which has been recently approved for use in the clinical indication of cognitive dysfunction (CDS) in dogs.
Please see this site for more information and other causes that may exhibit the same symptoms.
Then there might be another medical cause for it such as hypothyroidism or even pain if he is suffering from arthritis. Hypothyroidism is known to cause sudden aggression in dogs. You can read about these here:
While this might be strictly behavioral, given that this has come on suddenly and his age, I would start with a senior checkup on his specifically checking for a thyroid conditon as well as other painful conditions.
If this is not medical in nature, you will need start obedience training with him again and see if you can't get him under control. I would keep both the male dogs leashed and if one dog even looks at the other dog, a correction should be done. Any sign of aggression including a prolonged look, hair raised on the shoulders, a growl or even a stiff legged walk, should be corrected. A correction is a quick tug of the leash and a firm low toned "NO". Once you have done this couple of times, you should notice the dogs ignoring each other. When that happens, you will want to reward them for the desired behavior. Again, use tasty treats like the hot dog slices. This teaches the dogs that you WILL not tolerate fighting in YOUR pack.
You will also want to get him a basket style muzzle to wear when guess or children are present to prevent any bites at least until you find out if is medical or not.
I hope this information is helpful to you and you are satisfied with my response. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have .