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Open Sore on back of my cat

15:26:20

Question

Photo of cat Sore
Hi Jessica; i know you are not a vet but I thought I would ask this question
anyway; our cat Allie was diagnosed with Mammary cancer a few weeks ago;
we were fortunate to catch it VERY early, and she underwent what has, thus
far, been considered a successful surgery to remove the mass as well as half
of her lymph nodes/glands on the cancerous side; post surgery biopsy's and
x-rays have indicated no found cancerous tissue; she is scheduled for chemo
beginning next week.
Tonight while petting her, I found an open sore on her back which appears to
be like a very small crater; not a lot of hair loss but some around the sore. It
doesn't appear to hurt her - do you know what this might be? I am hoping it
is just a skin irritation and not another indication of more cancer. We have a
call into the vet and will be following up with this for sure; I was wondering if,
prior to this, you had any experience with this type of condition.

thanks is advance.

Lenny

Answer
Hi Lenny.  Glad you were able to catch her cancer early!

I have seen a couple things cause such a distinct circular sore.  One is ringworm.  And I know every time I bring a cat in with the sore, the vets say, "That doesn't look like ringworm,"  because the typical appearance of this fungal infection is a crusty round spot or even sometimes a true reddish ring.  I have found that the intense itching leads some cats to lick it excessively.  So instead of the classic crustiness, they are left with complete rawness and even bleeding.  Some vets carry a Wood's Lamp, a type of green fluoroscent light that illuminates some strains of the ringworm fungus.  Sending out a culture of surrounding hair and skin samples is more accurate.  Ringworm can be treated with topical creams, oral medications or shampoos/dips.

Another condition I have seen cause this is an abscess, most often caused by some sort of puncture.  The entry wound closes up and infection builds underneath.  But then in some cases, the overlying skin finally dies and sloths off, leaving a crater underneath where the infection was.

Skin cancer could be a possibility, but I think it would be a completely separate issue from the mammary cancer, since when mammary cancer does spread, it tends to stay within the chest, lymph nodes and bones.  A tissue biopsy will probably be recommended when you see the vet unless they recognize it as something right away.  The biopsy can help determine if it's cancer, allergies, autoimmune disease, bacterial infection or fungal infection.