How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Terri Your Own Question
Terri, Feline Healthcare Expert
Category: Cat
Satisfied Customers: 32666
Experience:  Expert in feline health and behavior. 20 years experience with cats.
Type Your Cat Question Here...
Terri is online now
A new question is answered every 9 seconds

A fast growing mass (tumor?) in the lower right hind leg of

Customer Question

Hi. A fast growing mass (tumor?) in the lower right hind leg of my 13 year old cat.
JA: I'm sorry to hear that. This sounds like it might be serious. I'll let the Veterinarian know what's going on ASAP. Is there anything else the Veterinarian should be aware of about the cat?
Customer: We noticed that the lower leg was twice the size of the left leg last Thu evening. Brought him to our vet on Fri. She took xrays and thought it looked like cancer. Chest xrays looked clean. We brought him to specialty hospital on Tue for a consult. The radiologist there confirmed that the chest xrays looked clean, too. They also took an ultrasound of his intestinal area; that looked clean. Biopsy is scheduled for next Wed. The cat started limping Tue evening, after the exam.
Submitted: 11 months ago.
Category: Cat
Expert:  Terri replied 11 months ago.

Hello, My name is Terri.
It is my pleasure to assist you today!
I am reviewing your question right now and will reply in a few minutes.

Customer: replied 11 months ago.
Forgot to mention that blood work (done on Tue) came back looking good. I.e. White blood cell count is in normal range - no signs of fighting an infection.
Expert:  Terri replied 11 months ago.

I am sorry your cat has this trouble.

Does he have any other known medical issues or take any medication?

Did this swelling appear suddenly?

Any chance he was bitten, stung or has an abscess?

any fluid in the leg?

You say his labs were unremarkable, does that include a normal temp?

is he in pain?

Customer: replied 11 months ago.
He has kitty asthma, seasonal allergies. It seems that the swelling was sudden. But hard to say, as we never noticed any changes in gait or size of leg as he moved around normally, and has so much fur on him (he's a Maine Coon mix), that we didnt notice the growth until he was lying down and we were playing with his feet. He is an indoor only cat who gets along well with his 4 "sisters", so there was no bite. Yes, his temp was normal.
Expert:  Terri replied 11 months ago.

Thanks so much for your very helpful reply.

The good new is this does not sound like cancer because that disease does not present with a sudden onset.

It sounds more cellulitis caused by an allergic reaction or an injury.

If he has any fluid retention his DVM can script a diuretic.

In the meantime try an antihistamine (IF he is not taking asthma meds)

add one quarter of a 4 mg chlortrimeten to a tablespoon of baby food chicken or turkey with no onion or garlic.

Give it every 24 hours. It is very tiny so he will not detect it

Any of these are also acceptable:

Benadryl at a dose of 1/2 of a 25 mg tablet given twice daily or

Chlorpheniramine at a dose of 2-4 mg twice a day or

Claritin (Loratadine) at a dose of 2.5-5 mg/cat or

Zyrtec (cetirizine) 5 mg once or twice a day

It is important to ensure that the formulations used contain ONLY the antihistamine and are not combination products (e.g. Claritin-D contains pseudoephedrine, which could cause very significant adverse effects in a cat).

Please let me know how he is doing. Just reply here or if you prefer, we can speak on the phone.

Please be so kind as to rate my answer with positive feedback, as that is the only way I receive recognition from the site for my assistance. Thank you!

Providing a positive rating will not end our conversation, should you need me for any follow-up. Simply click 'Reply' for clarification or additional information, if needed and I will always be here for you and your kitty.

Kind regards,


Customer: replied 11 months ago.
Would cellulitis cause a hard mass?
Expert:  Terri replied 11 months ago.

It could here's a link:

On palpation the skin feels hard and sometimes hot.

Customer: replied 11 months ago.
Can cellulitis affect the bones? Our vet thought that there was bone involvement based on the X-rays...
Expert:  Terri replied 11 months ago.

No, not commonly can you post the xray here?

Can he do a needle biopsy?

Customer: replied 11 months ago.
I don't know how to post jpeg files here. I actually have 2 images (top + side views) of the mass. Would it be possible to email them to you?
Expert:  Terri replied 11 months ago.

see if you can use the paper clip icon to post them

Customer: replied 11 months ago.
The problem is that I'm on my ipad. The images are on my usb stick and accessible via the app that reads it. I'll have to take a few mins to see if there is some way that I can get them off the app and into this discussion. The other option is to somehow continue this discussion on my pc. It's much easier to move files around on the pc...
Expert:  Terri replied 11 months ago.

There is no hurry, I can wait as long as you need.

Would you be able to text a pic to my cell phone?

Customer: replied 11 months ago.
Yay! I'm able to resume this conversation on my pc! Let me try to add the 2 images...
Expert:  Terri replied 11 months ago.


Customer: replied 11 months ago.
The 2 images are attached...
Expert:  Terri replied 11 months ago.

Thanks so much for the radiographs, they are very informative.

I do see a shadow on the bone but that does not mean it is cancer.

I understand a biopsy is scheduled for Wednesday. That is going to diagnose the issue.

In the meantime the attending DVM should script clindamycin in case it is cellulitis.

Please stay in touch and let me know what is found and how he is doing.

Customer: replied 11 months ago.
Would it hurt our boy if clindamycin is not prescribed until biopsy results are returned? Or, could this drug reduce the inflammation (tumor?) if it is cellulitis? Supposedly, biopsy results should arrive 48 hrs after the procedure...
Expert:  Terri replied 11 months ago.

Clindamycin is a broad spectrum antibotic that is commonly used where there is an inflammation of the flesh.

It cannot hurt him in any way. It will treat cellulitis if that is the problem. If not, nothing will be affected adversely.

Customer: replied 11 months ago.
That sounds like a very reasonable way to go. Thanks for your time and feedback! Keeping my fingers crossed for Wed...
Expert:  Terri replied 11 months ago.

You are more than welcome. It is my pleasure to help such a wonderful person.

I will be praying for your boy on Wednesday and always.

Please be so kind as to rate my answer so I am credited by the site. Rating will not close our conversation. I will still be here for you at no additional charge.

Best wishes and prayers,


Expert:  Terri replied 11 months ago.
I'm just following up on our conversation about your pet. How is everything going?
Customer: replied 11 months ago.
Hi. The tumor continues to grow. It's now about twice as big as when we 1st found it, making the lower leg about 3-4x as big as the normal leg. Anything that grows this fast is cancer, I would think. Got a call into the vet who will be doing the biopsy on Wed. This biopsy may need to be an amputation, as well, particularly if the dr thinks it looks like cancer. We do not want this thing to metastacize! Saving our boy's life is top priority!
Expert:  Terri replied 11 months ago.

I completely understand. Of course the biopsy will lead to a definite diagnoses

Yes, saving his life IS the top priority.

If, God forbid there is an amputation, I want you to know that a cat that loses a leg usually adjusts well and quickly and does just fine.

Best wishes, love and prayers,


Customer: replied 11 months ago.
Thank you for the support! I do have faith that our boy will be ok, even if he has to live with 3 legs. We have been preparing for the possibility of amputation, so will be there for him as he recovers and adjusts to his new configuration. Just got a callback from the vet hospital. Wed biopsy is now going to be an amputation. The surgery center coordinator agrees that this kind of aggressive growth is most likely cancer, so will be the best course of action to save the boy's life. Now we have to get used to this reality...
Expert:  Terri replied 11 months ago.

You are more than welcome. I have see several cats with this situation adjust very well. Most are up and getting around quickly after surgery. I am praying for a speedy recovery.

If I can help you through this in any way please do not hesitate to write.

Customer: replied 11 months ago.
Thanks, ***** ***** the support!
Expert:  Terri replied 11 months ago.

You are very welcome!