Very sad diagnosis -- how common is this?

Question
QUESTION: Dear Dr. Krempels,

I've had my 8 year old mixed breed rabbit, Newbie, since he was a tiny bunny.  He has been in perfect health his whole life, although for several reasons I wasn't able to have him neutered until he was 4 years old.  I'm not sure if that's relevant.

Last week I found a mass in his ear, which had not been there when I checked his ears two weeks before, and a biopsy just confirmed that it's malignant melanoma.  The prognosis is beyond bad, and my heart is breaking.

But I can't help but wonder about the odds of a rabbit developing this kind of cancer.  I have never in all my reading about rabbit health encountered any mention of melanoma.  Tumors in the internal organs or reproductive organs, yes.  But malignant melanoma?

Also, I had thought that at 8 years old Newbie was "getting up there," but from reading some previous questions and answers on this website, I've learned that a properly fed, neutered, indoor rabbit should live to be 10 years and older.  I've given Newbie my most devoted love and the best care and feeding I can, but now I'm wondering if he's dying too young, from a disease he shouldn't have.

Please help me understand this awful thing that's happening to my bunny and me.

Sincerely,
Sadie

ANSWER: Dear Sadie,

I have heard of a few cases of rabbits developing melanomas, and they usually are on the ears.  But here's the good news.  Newbie does *not* have to die from this!

Strangely enough, all the rabbits I know of that have had these melanomas removed (with good margins, and even if it leaves a hole in the ear or requires removal of part of the ear) have *not* had recurrence or metastasis!  For some reason, melanomas in rabbits may not be as metastatic as they are in humans.

So don't despair.  Find an experienced rabbit vet here:

www.rabbit.org/vets

and discuss the surgical options.  It could be that your little guy will have a perfectly successful surgical removal of the lesion, and that it will never return or spread.  It is certainly worth a try, or at least discussion with the vet.

I hope this helps.

Dana

---------- FOLLOW-UP ----------

QUESTION: Dear Dr. Krempels,

Thank you very much for your prompt reply.  I've already given myself over to grieving for what I thought was the inevitable, so your answer has left me a little confused, to say the least.

Is there a test or a scan that would reveal metastases, if there are any?  The vet who saw him (a new vet, since I recently moved) offered to amputate the affected ear, but cautioned me that it would probably do no good.  But if what you say is true, I might consider amputation -- obviously only if I knew the cancer hadn't spread yet.  Is there a way to determine if it has?

Yours truly,
Sadie

Answer
Dear Sadie,

Radiographs of the chest and abdomen could reveal metastases, but it would be very difficult to determine whether there were any mets to the central nervous system, which is a common place for melanoma to spread.

Because this is a fairly rare thing in rabbits, relatively few vets are aware of the tendency of rabbit melanomas not to readily spread.  I'm not saying it's impossible that the cancer has spread, but I am saying that--based on the experience of others with this same problem in their rabbits--the prognosis can be very good if the lesion is removed with good margins.

I am not sure it's necessary to remove the entire ear, but if the vet thinks that's the only way to get good margins, then it's better to lose an ear than a life.

I can say only this:  If Stewie were my rabbit, I'd give the removal a try.  I'd also try to opt for as little removal as possible, as long as reasonable margins can be attained.  

I wish I could give you a more definite answer...but there really isn't one.  It's just a "give it a try" and hope for the best.  From what little I've heard from others with melanoma rabbits, it's not unreasonable to hope!

I'd suggest perhaps you join EtherBun, a listserve of more than 5000 rabbit lovers who range in expertise from newbie to rabbit veterinarian and rabbit rescuer/expert.  There may be people in that community who have experience with rabbit melanoma, and can offer their help and tips.  To join EB, go to:

www.bio.miami.edu/hare/etherbun.html

It's free.  You don't have to stay subscribed any longer than it takes to get the info you need.  

I hope it will help.

Dana