American Fancy Rat & Mouse Association

This article is from the Sep.–Dec. 1994 AFRMA Rat & Mouse Tales news-magazine.


Squamous cell carcinomas

From Karen Robbins
On September 14, 1994, I took Likkity to the vet for a swelling on the left side of her face below the ear. The vet determined it to be an abscess and lanced and cleaned it (surgery no. 1). She sent me home with Betadine solution (to be diluted 1:10) and syringe to flush the wound out twice a day. She made a great “tip” for the syringe by taking a tom-cat catheter and cutting it in half (this tip would work great as a feeding tip for baby mice or rats). She also gave me Amoxidrops to give Likkity twice a day. Since the Los Angeles County Fair was in progress, I took her with me to the Fair every day (I was staying at my mom’s during this time since she is closer to the fairgrounds).

September 19 I noticed some blood coming from Likkity’s ear and took her in to my Riverside vet, Dr. Mark Farrar, the next day (see Vet Referral). There was still pus in the abscessed area every time I cleaned it, so he did a second operation on her and installed a cloth drain and gave her a different medicine of Ditrim (0.2 cc orally twice a day) and recommended I also give her yogurt for the flora in her intestines. I was to continue the flushing of the wound twice a day. There was no real change in the appearance/swelling of the area from the initial operation. Dr. Farrar had me come in the following week to remove the drain—thought things were looking okay. He suggested I put “hot packs” on the area twice a day to help the swelling after flushing. He told me he had seen some abscesses take several weeks to heal and assurred me that she should be okay but it may take a few weeks.

Squamous cell carcinomas are usually located on the face and head, and tend to be highly invasive but not metastatic.

October 3 I took her in for a recheck. Dr. Farrar thought the area looked better than the time before (I thought there wasn’t really any change) and had me continue the Ditrim and flushing. I was still getting pus every time I cleaned the wound and the swelling was still there.

Two days later she was looking worse and there was pus in her ear canal, so I took her in and he did a third operation on her, this time putting in a plastic drain and did some exploring of the area to try to determine if the abscess was being caused by something. He used Isoflorane gas with both surgeries and she was awake and about right after. He had me contine the Ditrim and flush the drain twice a day.

The following Monday (October 10) I took her in to my original vet (Dr. Robison) for the drain to be removed and for a recheck as the Fair was over at this time. She took the drain out and sent me home with instructions to continue cleaning the wound twice a day. I continued this for several more days, always flushing out some pus, but never really seeing much improvement as far as swelling. After a week of this continued cleaning, it finally got to the point this wasn’t working so I decided not to flush or mess with it and see if it would heal on its own.

Then, October 22 she started having problems breathing. By evening she was really distressed so we took her to the Emergency Animal Clinic in Sherman Oaks as Dr. Robison was closed at this time (usually how it works!). The vet, Dr. Sauer, told us he thought it could be a tumor causing the abscess. He checked her over, listened to her lungs, and probed the abscess. He said he could put her on oxygen (he couldn’t really tell but thought her lungs may be compromised with pneumonia or tumors) then perform another surgery on the abscess and send in a sample for a biopsy. Likkity was having so much trouble that even though he had these suggestions on performing another surgery, I didn’t feel her chances of surviving were that good, especially if her lungs were gone. He admitted that it wouldn’t do much good to take the tumor off her cheek if she had tumors in her lungs, plus she was 2 years 3 months old. We decided the best thing for Likkity was to put her down and have the vet take samples of the abscessed area and her lungs and send them in for diagnosis. I wanted to know once and for all what was causing the abscess not to heal. This was the most painful decision for me as I had grown quite attached to her during the past month of caring for her plus she was our very special pet. Just earlier that week I had to put down Star and Lizzie. With Likkity gone it only left Little Squirt of the four original girls, and our newest pet T.B. (we just had him neutered Septembert 26 by Dr. Farrar—THAT surgery came out great!).

The results of the biopsy came back “The appearance of squamous cell carcinoma, cells highly anaplastic. Prognosis poor. Lungs severe to moderate congestion, no tumor cells seen.” From what Dr. Sauer told me about this was these tumors are common from skin to mouth/eye/etc. These are invasive tumors to internal organs though none were seen in her lungs. From reading my Laboratory Animal Medicine book it states, “Papillomas and squamous cell carcinomas occur infrequently, but have been reported in many stocks of rats. Squamous cell carcinomas are usually located on the face and head, and tend to be highly invasive but not metastatic [movement of bacteria or disease from one part of body to another]. Most of these arise as sebaceosquamous tumors from the glands of Zymbal in the ear. Similar tumors occur on the prepuce and clitoris. In females from most stocks and strains, the mammary gland is the most frequent site of neoplasia [abnormal growth], with incidences of 30–60% being common. These tumors occur in males but much less frequently. Benign fibroadenomas are the most common type, but adenocarcinomas may also occur. Fibroadenomas have ductal epithelium [cellular substance of skin and mucous membrane] and periductular connective tissue components and tend to be less vascular than carcinomas. Adenocarcinomas [tumor/cancer of a gland] can metastasize to regional lymph nodes and the lung. Tumors of the mammary gland, which may arise at any site from the neck to the inguinal region, often attain a very large size.

Nutrition is well known as a factor that influences the development of neoplastic disease. For instance, it has been shown that a high fat diet enhances tumorigenesis, that the protein–calorie ratio influences the occurrence of some tumors, and that restricted food intake of postweanlings for 7 or more weeks decreases tumor risk (Ross and Bras, 1971).”

This was all the information I could find on squamous cell carcinomas. If you get a rat with a swelling/abscess on the head area, by all means have a biopsy done to determine if it is more than an abscess. If we would have known to have a biopsy done right away at the first office visit, we may have been able to save Likkity, let alone not gone through all we did to try and “cure” it.

Likkity in April 1994. Such a sweet rat. She got her name because she gave kisses to everyone.

  • Fox, James G., et al, (eds.). Laboratory Animal Medicine, Academic Press, Inc., San Diego, CA, 1984, pp. 116–7. *

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Updated February 12, 2015