My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
Often dogs when they get older do experience a little more discomfort when moving. Many older dogs develop arthritis at a younger age then this. Often they will exhibit little growly sounds when they experience pain on moving. It would be rather normal for Reagan to have a little arthritis. You might want to try glucosamine chondroitin (a supplement) and see if that helps him. Many senior foods have glucosamine in them for joint health. You can read about this here:
Buffered aspirin can be given to a dog with a dosage of up to 5-10 mg per pound every 12 hours for pain. Keep in mind that a dog's body does not metabolize aspirin in the same way as a human and thus should not be given more than a day or two without contacting your Vet. The aspirin may need to clear your dog’s system before other medications can be given, so keep that in mind if you decide to give aspirin and be sure and tell your vet when your dog is seen. Read side effects and precautions here.
Aspirin can not be used full time so you will need to see the vet about a more appropriate medication for inflammation and pain if aspirin seems t help.
Depending on where they x-rayed, they may have missed something as well. If they x-rayed the chest and lungs they might not have seen issues in the discs or hips (arthritis) and if they did x-ray those, they might not have x-rayed the throat,etc.
If he is like many goldens, he has gained a little weight and may even have a little snore that sounds like a growl. Rotties often exhibit a growl like noise as a way of "talking". For talking the growl changes pitch and tone, where a real growl tends to be a low growl all the same tone.
Depending on you level of worry and finances, you might want better imaging done the next time REagan goes in. Perhaps an MRI or CT scan especially if he starts to experience issues with going up and down stairs or jumping. It is likely just normal changes and discomfort that older dogs like older people experience, but I did want to let you know some other possible causes.
I hope this information is helpful to you. 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 . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.