bump on skin

Question
QUESTION: Sandra,
I have a 2.5 year old intact male rat.  I recently noticed a bump on his skin which is around the size of a large pimple.  It's located just behind and below his shoulder, on his side.  It is hard and raised, it has no scab, and it doesn't seem to be sore to the touch.  There is no discoloration, but there is no hair growing over it.  My rat has had a large abscess before, but this doesn't look anything like that did - this one is much harder and it feels like it's closer to the surface.  I'm not sure how long the bump has been there, but I would guess no longer than a week or so.  Do you have any idea what it could be?  Would you recommend I make an appointment with my veterinarian?
Thanks,
Mary Beth

ANSWER: Hi Marybeth

Before I can decide what this bump/lump/mass may be, I wanted to get a better vision in my head first.  You said there is no fur where the lump is so that means you can clearly see it and its flesh toned and not hidden under the fur like a common tumor would be?  

If this is the case, this tells me that this bump has either grown from the outside of his body, or has grown from the inside and has grown out through the skin.  A general tumor, such as a mammary tumor, usually is hidden under the fur and cannot be seen right away unless its huge of course, so I am wondering if your dealing with something more along the lines of a cyst.

If your gut tells you to see professional medical attention, by all means, go with your gut. I always tell any of my readers or clients at the Vets office to always go with your gut first, no matter how petty it may seem to others.  

You can, of course, wait a bit also, just to see how fast it grows or what changes it may make, such as shrinking on its own etc... sometimes if its a cyst the may burst on their own and of course as you stated earlier in your post, you have experience with abscesses and do not feel this is one since it isnt following the typical pattern the other abscesses have followed.  You may be surprised though, sometimes these things end up being abscesses and they just dont form a head right away.

It is, however, in a prime location where mammary tumors are found.  Even though females are prone to mammary tumors, unfortunately, our males are not exempt from them. They have mammary tissue minus the nipple.  The good news is that they usually do not continue to grow back after one is removed, unlike some females, that once you start removing them, it seems they start to appear left and right. I have seen new growth start on these poor girls develop sometimes before they are even done healing from their previous surgery....still have stitches in them and they are growing mammary tumors elsewhere. Its frustrating!!  This isnt usually the case with males, which is the only good news about these pesky tumors.

Anyhow let me know about the way the tumor looks as far as the fact that the area has no fur etc...
if you can take a picture that would be even better!!
You can send it to sandyscrittercity@yahoo.com.

On a final note, I forgot to ask if you have a vet that is an exotic vet and well prepared to treat rats?  If not, I can find you someone, all I need is your zip code.

Talk soon

Sandy

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

QUESTION: Sandy,
I did take him to the vet, and unfortunately the veterinarian suspects that it is either a cyst or skin cancer.  Given his age, cancer is most likely.  The vet put him on Zithromax and Baytril for his recurring respiratory problems, and said that with the antibiotics if the lump decreases in size within the next week we'll know it's a cyst but if it's cancer it'll probably grow quickly.  Even if it is cancer, I don't think I'll have it removed, since he's old and his respiratory infection puts him at risk during the anesthesia.  He's still so full of energy, it's hard to imagine he could be sick at all!  He turns three in July, so I'll still hope that it's only a cyst and maybe he'll make it to his third birthday, but I also know how rare that is.  Thanks for you help, you convinced me to see a vet so now at least I can start preparing.  
-Mary Beth

Answer
Hi


I am glad you went to the vet....I am a bit confused though, about the cyst. If it is a cyst, unless there is infection present, antibiotics wont shrink it. Cysts contain fluids, solid material, or both.
With males, it is common for them to develop sebaceous cysts that are often retention cysts that contain oils from the sebaceous glands and are found in the areas that the sebaceous glands are more commonly active, which is the back or the side of the rat, which is where you had described the lump to be on your rat: on his side.

If infection is present, the cyst may reduce in size but it doesnt always go away, like an abscess would if treated with antibiotics.

As for cancer, the fact it is flesh tone tells me it is probably benign. Most cancers (which are not real common with our rats, you will be happy to know) on the skin are not flesh toned and instead, they can be bright red, dark lesions that are crusty in texture; some appear as uclerations on the skin (sarcomas) and others often contain a mass under the discoloration which would be a tumor more invasive to the organs. Many cancerous growths are slow growing where the mammary tumors (benign) can grow at astonishing fast rates. Cysts and abscesses also can grow pretty fast,depending on the source.

A cyst can be aspirated or exised and treated with antibiotics to prevent infection, but if it is not hurting anything, you can often let it go and treat the rat with steroids and antibiotics.

As for surgery, keep in mind that regardless of age, anesthesia is always a risk. If the rat is otherwise healthy,anesthesia doesnt become any great risk than it would in a healthy 1 year old rat. What does put the rat at risk is, like you suggested, the fact he has respiratory infection that is active. Even if he was a younger rat, he would still be at risk. Often, with surgery and a rat that is not healthy, anesthesia isnt always the danger. Post op infection can be a bigger danger than anesthesia
Age is a number, never a disease. We have had rats undergo surgery as old as 3 and a half and have been under up to 90 minutes, which is pretty darn long, and have recovered with flying colors.  It depends on the over all health of the rat, not the age of the rat. I agree with you though, I would not risk it because of his current health status.  

I am glad you took him to the vet and have him on medication for his infection.  I feel pretty strongly that this is a sebaceous cyst, though, but again, I dont usually see cysts shrink from antibiotic therapy unless it is caused by underlying infection.  I am keeping my fingers crossed for you both!