I decided to write a post breaking down what happened with my rat Tavish partly to process my feelings and partly to have a solid record of events. I researched online for hours, even going through all of the pet rat forums, and found nothing about Tavish’s particular ailment. So I hope that future rat owners who go through this will find this post useful. I hid the photos behind links. They are not graphic, but they may be intense for some people.

I adopted Percy and Tavish (they had different names when I got them; Tav is the one with the black blanket and white blaze) from Rattie Ratz, a rescue organization in the San Francisco Bay Area, on Valentine’s Day 2020. Tavish had been born about July 1, 2019 and Percy about August 1, 2019. Both were purchased from a pet store in the Central Valley by their first owner about a month apart. I suspect they were likely cousins, as the pet store purchased both litters from the same breeder. They came to me with the start of an upper respiratory infection, which is not uncommon for rats in shelters and rescues. After treating the URI with a course of antibiotics, I had both boys neutered on March 31, 2020.

Other than dealing with constant sneezing (not a full URI, his lungs were clear) which I treated on and off with antibiotics (doxycycline and enrofloxacin combination) and dry feet which I treated with silver sulfadiazine cream, Tavish was very healthy.

July 2021
About every two weeks I give both rats a full body check, including teeth, looking for tumors, skin issues, broken teeth, etc. I had checked both at the beginning of the month and found no issues. However, on the evening of Tuesday July 13 I realized that Tavish wasn’t eating as much of his kibble as he usually does (I feed my rats Oxbow Essentials Adult Rat Food, as recommended by my vet). I also hadn’t heard him brux or eye boggle in a couple days. I checked his teeth and discovered a large white-ish mass growing up behind his two lower incisors. The mass was pushing his teeth apart, making it hard to eat his kibble or grind his teeth. Photo here – although the photo looks weird, I’m not gripping him hard.

I got an emergency appointment at my vet, Santa Rosa Veterinary Hospital, for the next day. At first I thought it might be a third tooth growing, but that is not something that happens to rats (it’s not uncommon in rabbits, however). The vet thought it was a piece of wood or drywall (he was notorious for going at my walls, baseboards, and anything else he could chew a hole into) that got stuck between his teeth. Another theory was that it was a seed that had gotten stuck and calcified. The vet tried pulling the mass out with tweezers, but Tavish was too stressed. Tavish was the kind of rat who did not like being held or touched without consent, especially not by strangers. The vet then used gas to sedate him and tried again to remove it. The mass, whatever it was, appeared to be attached to his jaw. They trimmed his teeth down and we scheduled him for surgery to remove his two lower incisors and the mass. At the time, we assumed it was bone cancer. Removing the mass and teeth wouldn’t prolong his life, but it would make his remaining time more comfortable. The mass was painfully pushing apart his teeth, and removing them would ease the pain at least until the cancer returned.

To treat the pain, Tavish was put on buprenorphine. Unfortunately, he had a bad reaction to it, as many rats do. It triggered pica, or eating or chewing on inedible things. He spent most of the next 18 hours gnawing on towels. (It could’ve been worse. I had a rat who tried to eat his fingers off!) The stress of the previous day and the bad pain med reaction also triggered cystitis, or bladder inflammation, so by the next morning he was urinating frequently and in small batches and his urine was bloody. Despite those issues, we decided to go ahead with surgery on Thursday July 15. I agreed to a histopathology report so we could confirm the diagnosis.

During surgery, the vet decided not to remove the teeth after removing the mass. Photo here. The mass extended down into Tavish’s jaw and was so large in proportion to Tavish’s jaw that the process was technically a debulking.

After surgery, Tavish was prescribed gabapentin for the bladder inflammation (3 times a day for 21 days) and prednisone for the pain (2 times a day for 5 days, 1 time a day for the next 5 days, and then 1 time a day every other day until instructed to stop).

Tavish was also switched to soft foods. I try to make sure the bulk of their diet is still their kibble, so I grind that up and mix it into baby food or Ensure. He got soup, cooked pasta, fruit, chicken, tuna, and vegetables as additions. The soft food usually provides enough liquids to keep them hydrated. Tavish was very active, so he was hungry constantly. I fed him about every 2-3 hours for the next week. Photo here.

Note: If you have to switch to soft foods, I recommend purchasing a kitchen scale that measures in grams and weighing your rat daily to make sure they aren’t losing too much weight, as well as a mortar and pestle to grind their lab blocks or kibble into powder. Soft foods are not a long term solution. If you have to feed them soft foods for more than about 2 weeks, you may need to consider taking them in and having their teeth trimmed. You also have to be really cautious about what you’re feeding them. Keep track of their nutrition, as well as how often and how much you’re feeding. This will help you notice any changes in behavior, such as eating less or rejecting foods they once enjoyed. These are early warning signs. Here is a list of safe and unsafe foods for rats.

After surgery, he was back to normal. Usually with cancer, I can usually see a noticeable change in behavior, but Tavish was running and playing like he always did. On Wednesday July 21, I checked his mouth again. The mass had returned and was almost as large as it had been when it was removed the week before. In consult with the vet and vet tech, we decided to wait for the report. Photo here.

The histopathology came in Friday morning. Here is what the report said:

MICROSCOPIC DESCRIPTION: The gingival biopsy is bisected and totally submitted. Three serial step sections are examined. Along the deep border of the biopsy, there is reactive fibrosis associated with small spicules of mineralized woven bone. A few osteoclasts are associated with the bone. The lesion appears to be cavitated. The overlying mucosal epithelium is unremarkable.

MICROSCOPIC FINDINGS: Gingiva between lower incisors: Fibro-osseous proliferation.

COMMENTS: The exact nature of this lesion is uncertain. No definitive evidence of a neoplastic process is seen but the biopsy is small and may not be entirely representative; correlate with dental radiographs. This type of lesion could be found at the periphery of an odontogenic cyst.

Although these types of cysts are benign, they can grow so rapidly that they can actually break the jaw. Given his age (he turned 2 on July 1, 2021) and the diagnosis, it was decided that the best course of action was, unfortunately, to put him down. It was not an easy decision, by any means. I could tell Tavish was physically uncomfortable and would likely be in serious pain soon. I didn’t want to risk him suffering from a fractured jaw or his teeth being pushed too far apart. It wasn’t a choice I wanted to make, but it was the best choice for Tavish’s well-being. He passed on full of his favorite snacks and cradled in my arms on Sunday July 25.

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