Question:
Could this be related to chocolate poisoning?

His vet indicated that it could be an infection or cancer and wants to do some diagnostic tests. The dog has no other symptoms, is 12 years old & 80kg. He stole a large chocolate bar off a chair and ate it the day before we went to the vet. I didn't remember this until after leaving the office.

If not, then is there an initial test to determine if an infection (parasite or tic or whatever) is present without the x-rays and biopsy recommended?

Answer:
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I doubt it is chocolate related within the time frame you indicate.
At the age and weight of the dog ( more age than weight related) I think it is a very inexpensive investment to have the x-rays and biopsy performed so you are not wandering in the dark and letting the possible cancer gain more ground.
A dog that has given you 12 years of companionship seems worthy of a few dollars investment. I have an older - larger dog with cancer and when she starts to show signs it is bothering her I will have to put her to sleep to save her from suffering. I chose not to give her chemotherapy as I would not chose it for myself either.
Woody

Answer:
Did you mention the chocolate to the vet?

What type of chocolate? The higher the content of coacoa the larger the effect of poisoning.

I dont' think as Woody indicates it has anything to do with the chocolate bar.

I think tests would give the vet a better understanding of what is going on.

Answer:
Originally Posted by Geordi
Could this be related to chocolate poisoning?

His vet indicated that it could be an infection or cancer and wants to do some diagnostic tests. The dog has no other symptoms, is 12 years old & 80kg. He stole a large chocolate bar off a chair and ate it the day before we went to the vet. I didn't remember this until after leaving the office.

If not, then is there an initial test to determine if an infection (parasite or tic or whatever) is present without the x-rays and biopsy recommended?

Where are the lymph nodes involved located?

If under the neck or behind the jaw bone this could be from the teeth or throat. You are very vague with info...I, myself would not worry about the chocolate so much....
The lymph system is an indictator of infection or the body trying to fight something lurking about..total lymph involvement can alert a vet to other more serious disease's, such as lymphoma.
On the good side., have the blood work and tests done...this is needed to help your vet find anything amiss., kinda like mapping the body from the inside..

Could be an infected tooth, ear infection. If rear hind legs or thigh glands are swollen it could be a sign of an on going anal gland infection.

Please give this further thought..

Answer:
Most likely it means that your dog's body is trying to fight infection in this area.

Answer: