Re: oral infection or oral cancer?
I've been down the is it infection or cancer road many times. Most recently with Riley and a lump that appeared within hours on his neck. I took him to the vet and asked doc to do a fine need aspirate of the area to look at under a microscope. With Riley he already had a history with cancer, and it was the cancer coming back. My vets have always just taken the FNA and looked at it under a microscope to see what is going on. They should be able to determine if the sample has infection or abnormal cells (cancer). I've also had to have FNA samples sent off for a proper pathology to determine what they were. Its the only way you get an exact diagnosis.
Oral cancers are common, unfortunately. The oral cancer I have dealt with progressed extremely rapidly though.