large male with lump in jowl

Question
I have a large male iguana(9.5lbs) mature, at least 10 years old. I recently noticed a grape sized lump in his right jowl. It doesn't seem to bother him at all. He spends a number of hours each day running around the house.(he has carnal designs on one of my cats, so he gets lots of exercise. He has a good appetite and a large cage with basking light and UVA & B fixture. I try to keep it moist and his diet consists of soaked iguana kibble with lots of greens and fresh veggies and fruit. He doesn't seem to mind me poking at him, so it can't be too tender.(he's not a martyr) Any thoughts as to what the lump could be?

Answer
Lynda,

Based on what you have described, I am inclined to believe that the lump you are describing is either a harmless cyst, a malignant tumor or an abscess. The good news is that mast cell tumors and other malignant tumors, which are common in cats and dogs, are rare in reptiles. Whether or not reptile owners are failing to notice or treat tumors or whether or not they simply do not occur as often in reptiles is debatable. I, personally, do not believe they occur as often due to the major physiological differences in reptiles vs. mammals. This being said, it is still possible that you may be dealing with a malignant tumor, but most case studies I have come across dealing with green iguanas and malignant tumors occur in iguanas who have had years of poor diets, living conditions and/or poor overall health. From what you have described, I believe your iguana is receiving adequate care and a diverse diet and I think it is highly unlikely you are dealing with a life-threatening tumor.

Now, if you were to have said that your iguana's lump was painful to the touch, I would assume it was something more along the lines of a swollen gland/lymph node due to some internal bacteria/virus he was having trouble fighting off and that it may subside with antibiotics. Because you said he doesn't seem to be in pain and it doesn't seem to bother him, I am inclined to pass it off as a cyst or an abscess.

I think that since you are dealing with an older iguana, this just may be him showing his age...another thing along the lines of a cyst that is common in older iguanas is an abscess and this may be something to consider. A lot of times older iguanas will develop hard lumps under their skin, but this is usually along bones or joints, but it is not to say it couldn't happen on the jowl. An abscess in iguanas is hard and does not drain...they are unable to be popped because there is no fluid, just a chunk-like deposit under the skin. A veterinarian should be able to make a small incision in the skin and work the abscess out of the opening in one or a couple of pieces. Abscesses are far more common than cysts in iguanas and cysts are far more likely than tumors.

If this were taking place in one of my iguanas, I would keep an eye on it and watch that it doesn't grow bigger and that he doesn't start to show decreased appetite, lethargy and/or changes in temperament. If any of these issues arise, I would seek out an established herp vet or a veterinarian who has experience with iguanas and understands their physiology and inquire about conducting a biopsy. Please consider all I have said and make your best judgment call. I hope this helps!

Thank You,

Sara J Gwerder
President
Raptor Rescue Iguana Sanctuary
Shreveport, LA
www.RaptorRescue.org