I took my dog to the vet like 2 weeks ago for a vaccine (rabies). Yesterday I felt a small mass just before his knee. Could this be caused by the vaccine or should I be worried?. I know I have to take him to the vet. I just need to save some money. The mass is soft and it does not causes him any pain. What could it be?

I doubt this is from the vaccination.Please get the dog to the vet ASAP. Could be something simple as a fatty tumor, but also could be something very serious as Osteosarcoma ( bone cancer ). Good luck and I hope it is the first that I have mentioned.

No, it would not be caused by the vaccine. The lump that you are feeling could be many things...take him to the vet as soon as you possibly can.

Dogs and cats can certainly have a localised reaction to vaccines(or any injection) however it would only occur at the sight where the vaccine was given and would happen within one week of the injection.A soft mobile mass on the leg could be a tumour either malignant or not. Lipomas are benign tumours that develop on dogs, they usually develop slowly over months to years. However a fast growing mass would usually indicazte something more serious. Watch the mass and if it grows rapidly or changes in anyway take to vet for a fine needle aspirate to be taken and they will look at the cyctology of it under microscope. If it looks fatty it will be a lipoma and no need to worry unless it causes trouble for your pet, however if they see cells they will need to send the cytology sample to a pathologist so that they can work out what kind of mass it is and whether surgery is required.If I was you (and this is what I would tell clients) watch for 1-2 weeks if changes occur in size, shape or the skin near it then bring in, if not keep watch and get it looked at at next vaccination.

I would say at least call the vet where you had the vaccine done and tell them. They may just tell you that it is a normal reaction to the vaccine and will go away on it's own. If nothing else it will put your mind at ease a bit. I know that if there is anything going on with my dog that i'm not sure about, I call the Vet immediately!