Feline injection site sarcoma — the very last words you want to hear combined with your cat’s name. Chances are your cat has just been handed a death sentence, and cost for palliative care, just to keep them from suffering, can run into thousands of dollars.
I hate to start this off on such a negative note, but it can’t be avoided. Feline injection site sarcoma, or FISS, isn’t talked about enough, and even among veterinarians, information is lacking. Somewhere between one in 1000 and one in 10000 cats will receive this devastating diagnosis. That is a huge spread, and so far — at least in 2023 — no one has narrowed it down. And honestly, numbers aren’t that important when that one is the most important cat in your life — your own.
Why do I care about this so much? Because FISS can hit a disproportionate number of therapy cats. As you have probably guessed, one of the most common ways that a cat develops FISS is through vaccination, usually FeLV or rabies vaccines. And therapy cats are required by their organization to keep up on their vaccines. We cannot skip them if we want to keep working. And recently, one of my fellow therapy cats received this sad diagnosis. Let me tell you briefly about her.
About Basil
Like just about every other therapy cat I know of, Basil is a very special and personable cat. She a positively magical touch with those who need healing energy. When she and her human therapy partner lived in Portland, OR, she often worked at OHSU Doernbecher Children’s Hospital. And she is one of just about 35 nationally accredited Animal-Assisted Crisis Response Teams utilizing a cat. Crisis Response animals help victims and first responders during events as big as natural disasters (earthquakes, fires, floods), or as intimate as domestic violence. It’s one of the most important things you can be called on to do.
Unfortunately, Basil was recently diagnosed with an inoperable feline injection site sarcoma, and it has already metastasized to her lungs. Her human is scrambling to come up with the funds for her radiation and chemotherapy — the only things that will keep her comfortable for the time she has left. Currently, she is unemployed. She lost her job a few months ago, and with her age and management positions she should be doing, it has been hard finding work in her field. If you’d like to help Basil, her GoFundMe is here, and you can follow her Facebook page for more ways to help.
But what about FISS and your cat? Here is what you need to know.
What exactly is feline injection site sarcoma?
FISS is a very aggressive sarcoma (cancer) which attacks starting in areas where a cat has received injections. It is usually discovered as a lump near the site, and can develop any time from two months to ten years after a cat has received a vaccine or other injection. Other ways a cat can develop FISS is through injectable steroids, antibiotics, microchips and suture material. But vaccines are most common and well known.
Because the tumor is aggressive, removal (if that is even possible) has to be equally aggressive. It may involve amputation of a limb, or a large area around the mass. And even so, the cancer may have already traveled to other parts of the cat’s body, where it continues its deadly work.
And while the risk of a cat developing FISS increases with more vaccinations, it can happen after just one. So no cat receiving an injection is completely safe.
What is the life expectancy of a cat with FISS?
This varies on how far the sarcoma has spread, and how aggressive the treatment is. With aggressive surgery and treatment afterwards, life expectancy can be a year to year and a half. Longer is even possible if it looks like the cancer and its margins were removed completely. But it’s a hard cancer to catch in time and treat, and often cells have already invaded other parts of the cat’s body. It’s very rare for a cat to be cured from FISS.
What you can do to lessen your cat’s chances of developing feline injection site sarcoma
- Minimize injection exposure. Keep in mind that FISS is actually pretty rare, and vaccinating your cat is important. If your cat goes outside or interacts with other cats, they really need FeLV and rabies vaccines. And keep in mind that if your cat bites someone and they are not up to date on their rabies vaccine, they would have to be quarantined for 10 days. It’s better to be on the safe side. That said, you probably don’t need to vaccinate yearly. I opt for three year vaccines. Fewer vaccines over the years means fewer potential exposures to FISS. In addition, senior cats and cats with some medical conditions might forego vaccinations. Discuss vaccination schedules and protocols with your vet.
- Make sure your vet follows guidelines to inject different vaccines in different limbs, and preferably in the distal, or lower part of their limbs. While this doesn’t prevent FISS, it does improve the chances of removing all of the cancer through amputation.
- Examine your cat’s body regularly for any changes. If your cat is not initially comfortable with having their body felt and examined, acclimate them to it slowly, and with rewards, if you can. It is so important to be able to regularly examine your cat not just for lumps around or near injection sites, but also their mouths, paws, eyes, and behinds. The quicker you can find any irregularities, the faster you can get your cat treatment, and the better the outcome.
- Get pet insurance. FISS is just one of many illnesses your cat can develop that are very expensive to treat. Over the course of a cat’s lifetime, they are likely to have something happen that will result in big vet bills. So be prepared.
What if my cat gets feline injection site sarcoma?
You become their advocate, same as if you developed cancer yourself, or a close family member did. You discuss all the details with the veterinarian and oncologist, ask a lot of questions, discuss options, and learn everything you can. You take into account your cat’s personality and their ability to tolerate the recommended treatment. Your cat needs you more than ever, so you are with them every step of the way.
FISS is one of many truly awful medical issues that can happen to cats. I hope you and your cat never have to deal with it.
Have you ever known someone with a cat that had FISS? If you have, please discuss it in the comments.
Tabby’s FISS Fibrosarcoma – A brief history (Tabby’s tumor is currently the size of a golf ball, is very hard and stationary, but I have yet to see signs that Tabby is in pain or suffering systemically. I have no idea how much longer I have before I have to choose euthanasia for ending my 10-year adoptive relationship with Tabby, but I can assure you this entire experience has been the most emotionally devastating trauma I’ve ever had and I’ve been a multiple cat owner for over 20 years. The following is an email I recently sent to the American Association of Feline Practitioners (AAFP).
One of my cats (Tabby) has recently revealed a growth / mass that appears to be an FISS sarcoma precisely at the site of a rabies vaccination he received the first week of January, 2023. I’d like to present a brief history, some of the actions I’ve taken, some of the resources I’ve found and a few comments regarding this episode.
Over the Christmas holidays, Tabby exhibited a very noticeable increase in his level of activity and his appetite, leading me to suspect hyperthyroidism. I took him to the vet the first week of January for a diagnosis that revealed an abnormally high T4 level and conferred with the vet as to his recommended options for treatment. I chose to schedule Tabby for radioiodine therapy as a preferred treatment and thought that, since he hadn’t been vaccinated recently and Alabama requires annual rabies vaccination, he should get a one-year Purevax non-adjuvanted subcutaneous rabies vaccination in his right flank prior to taking him in for radioiodine. As it turns out, this was a MAJOR mistake in part resulting from my ignorance of Tabby’s risk for FISS.
Tabby is a 10-year-old neutered male domestic shorthair cat that I adopted when he was a six-week old kitten. He’s been an indoor / outdoor cat for the past ten years but has never strayed beyond the fence or my ability to call him for dinner. This tumor growth was completely unexpected since neither Tabby nor my other cats have had a similar response and my understanding (erroneously) was that only 3-year adjuvanted vaccines could put a cat at risk for an injection site sarcoma.
The growth appeared two months after the vaccination (the first week in March) and one month after the radioiodine treatment, and I brought him to the vet for a confirmatory diagnosis. A fine-needle biopsy was unable to confirm the tumor and it was recommended that I take him home and monitor the tumor for growth. There are no veterinary oncologists within 100 miles of Madison, Alabama, where we live. Without access to an oncologist, and without the ability to safely biopsy the growth, I chose to try to understand why Tabby would get a FISS type tumor in this stage of his life and began an intensive internet (Google) search for a cause or causal relationship. This research is ongoing, but there are a few possible causal associations that I have discovered and would like to share.
I discovered one comprehensive comparative study that revealed that 10-year-old male domestic short hair cats were the prime age/sex/breed cats that had the highest predisposition for FISS sarcomas. I have been somewhat frustrated by the lack of comprehensive findings for any specific cause of FISS, resulting in the current status that it could be any type of injection that caused an inflammatory response in some cats that subsequently resulted in a histopathalogically distinct growth that could become metastatic.
Here is a comment that reflects a little of my frustration. FISS sarcomas / fibrosarcomas have been observed increasingly in cats for the past 30 years resulting in tens of thousands of cats either dying, being euthanized or having a surgically amputated limb with subsequent chemotherapy and/or radiation. I have found no comprehensive parametric evaluation of cause other than it was originally suspected to result from an aluminum adjuvant in the vaccine and then later to be an idiopathic response to the inflammation at the injection site.
Possible contributing risk factors for FISS include age, sex, breed, heredity, exposure to herbicides or insecticides, number of prior vaccinations, whether these were adjuvanted or unadjuvanted, health status when vaccinated, etc. To this day, none of the local Madison vets I use are aware of any specific risk factors other than the adjuvanted vaccines that have been historically used. To my knowledge, none of the local vets that administer vaccinations to companion animals provide any FISS warning to cat owners whose cat may be at an increased risk for this specific cancer due to any specific risk factor. I understand how difficult it is to do epidemiological studies on cat populations, but nevertheless (in my humble opinion as an owner and caretaker), it really needs to be completed for other owners to establish any definitive causal relationship with potential risk factors within the affected population.
I contacted the Alabama veterinary consultant responsible for the state-wide rabies vaccinations of companion animals, and it is his opinion that the biggest risk factor for FISS is the prior vaccination with an adjuvanted vaccine. Tabby had a 3-year adjuvanted RabVac vaccination in 2015 – his most recent vaccination – so from this perpective he had an increased tumor risk (but so do many cats who have had adjuvanted vaccines in the past and many/most of them do not get FISS response when they get a later Purevax injection).
I have subsequently discovered a few published veterinary opinions that a weakened / compromised immune response that may be associated with conditions such as hyperthyroidism (see attachments) may also be a contributing factor for FISS. I have not been able to find any published studies that confirmed this opinion, but Tabby was clinically hyperthyroid when he was vaccinated with the Purevax vaccine in January.
I have attached a few of the papers that I was able to research, but please keep in mind that I am not a vet, a veterinary pathologist or even a very well-informed pet owner and my research falls far short of a peer-reviewed scientific investigation. One of the not-yet-available R&D treatments that may soon be available is a non-invasive ultrasonic tumor destruction procedure at Virginia Tech called histotripsy ablation. I hope this proves successful soon and hope to see its development for the treatment of FISS.
Attachments
https://www.thesprucepets.com/vaccine-protocols-for-cats-552506
Fibrosarcomas in Cats (thesprucepets.com)
Epidemiological and Pathological Characterization of Feline Injection Site Sarcomas in Southern Brazil – PubMed (nih.gov)
VAS (sunnysidevetclinic.com)
Vaccine-associated feline sarcoma: current perspectives – PMC (nih.gov)
Medical Oncology: Feline Injection Site Sarcoma | Veterinary Hospital (ncsu.edu)
FAB (felineasthma.org)
doi:10.1016/j.jfms.2011.07.015 (psu.edu)
I am so very sorry to hear about Basil.
It is infuriating so many vets refuse to use the tail as the principal injection site for vaccines and a study was done which showed it was easy to perform this way and well-tolerated by the cats. It is also recommended worldwide by veterinary oncologists. The reluctance of a vet to change his or her protocol for this makes me wonder why they entered the veterinary profession in the first place…Do No Harm!!!
This is very sad and it makes me mad that we get forced to do this to our kitties.
Mee-yow this ISS a furry seereuss psot Summer an Miss J. Mee can meow to you BellaSita ONLY purrmitss Rabiess shot an shee iss only doin efurry 3 yeerss. Shee wantss to meow to youss’ so mee step aside….
**purrss** BellaDharma
Hello Summer & Miss J remember my darling NYLABLUE? She was a HUGE Candidate for FISS that last 1 1/2 years of her life. She had weekly injections…..it was like playing Russian Roulette. I was lucky she did not get FISS altho when she became Diabetic, I gave her 1 more week & then had to PTS. I couldn’t bear the twice a day shots. It was not fair on either of us.
The Vet at the time agreed with me.
With Purrince Siddhartha Henry I had to take him yearly for Rabies as his system could not handle 3 year dose…of course this is no longer an issue.
When I adopted BellaDharma I made it clear ONLY Rabies! The Vet is not happy about this but I refuse to over medicate her & run the risk of FISS.
I feel pressured by Vet whenever I take BellaDharma in so I avoid going.
I am so very sorry & sad for Miss Tina & her beloved Basil kitty girl….You both are in our prayers!
(((hugs))) BellaSita Mum aka Sherri-Ellen
This is a valuable post but also such a sad one. Not only about the therapy cats, but also that owners who consciously vaccinated their cats may find this has occurred.
For quite awhile it has been advised to give injections in the limbs, to allow for amputations of an affected part, yet I don’t see many vets doing this. And since the pandemic the cat is usually taken “in the back” even for an injection. (My vets used to give injections in the exam room but that went out of tyle during the pandemic I guess we owners must assert ourselves with a reminder to them. Our time together is short enough without inserting any added risks.
So sorry Basil and his owner have to go through FISS. I lost my beloved Long-haired cat, Tiger, may years ago to the same thing. Injection site mass on his shoulder/neck line area where the vet gave him the injection. After surgery for removal, the tumor continued to spread rapidly around his neck. He lasted only about a month after that. Following that tragedy, Beau Beau and Angie were minimally vaccinated and with non-adjuvanted vaccines when possible, and now Tommy and Teaghan only get their vaccinations in their tail. Even that is a horrible solution to the over vaccination of our animals. I could go on and on about this but it’s important that cat and dog owners educate themselves and read the most up to date studies about vaccines, and never use the adjuvanted vaccines. There are alternatives available, 3-yr rather than annual vaccines, and saying no to non-necessary treatments. Be proactive. Read the data.
We’re so sorry about Basil. It’s scary that this can happen as a result of making sure our cats are protected from things like rabies and FeLV.
I’m so so sorry for sweet Basil and her human. Sending so many healing thoughts. Is it possible to shrink the mass to a point where they could do surgery?
It is basically inoperable… but shrinking it will give her better quality of life for a longer time.
This is so sickening and sad. These protocol like injecting in the tail or a place that can be easily amputated have been in place for years so to think that this could still happen makes me sick. Sending so many healing thoughts and prayers to little Basil. I hope that she can somehow survive.
I couldn’t finish reading this after hearing about Basil. Our kitties have to get vaccinated. It makes me sick thinking about it. My heart hurts for Basil and her human
We read up on this years ago on someone’s blog who had unfortunately contacted this. Healing purrz for pretty Basil and her human. After than blog post and after I became lethargic after receiving a vaccine, we decided no more. I’m an indoor kitty who inneracts with no one but my peeps.
I’ve done a lot of research on it and it petrifies me.
Thank you for this, I had never heard of it.
This is such sad news about Basil. She is a beautiful kitty. I try to avoid vaccines except for rabies which is a law.
Thank you for sharing the information about this. I’m so sad to hear that this is something that can happen because a cat is vaccinated.
I’m also very sorry to hear about Basil. She’s a beautiful kitty.
Hi there folks. I am Basil’s human. Firstly, THANK YOU SO MUCH to those who have already donated to her care and treatment! I’m so grateful for that generosity and compassion.
Like many of you, I had never even heard of FISS until it hit Basil. This is a great and informative article and I have become an advoCATe for educating cat owners about it now – and I will always be. The other thing to share is to make certain that you advoCATe for your cat when you get those vaccines. If your vet won’t go for injecting in the lower limbs or sub-q, allowing the vaccine to come to room temp before injecting, and rotating the vaccines to different sites for each… find another vet. I’m also a HUGE believer in using a cat-only vet. You can find ones nearest you through the American Association of Feline Practitioners at https://catvets.com/
Lastly, if your cat does develop FISS, GET THE VACCINE INFORMATION FROM YOUR VET. I received information yesterday that the manufacturers will pay a serious amount for this tragedy. And be careful to not over-vaccinate your cat. According to many many Vet and research articles that I have read, we do tend to do this. As mentioned here, Therapy Cats are especially at risk because it’s a requirement. Because of this, I don’t know that I will ever have another Therapy Cat… This is just too painful to go through.
Basil will not survive this… but if we can help educate others, I will, in her honor. My love and thanks to Janiss and Summer for this article!
I neglected to mention (in my comments above) that we are sending purrayers and Power of the Paw to you and sweet Basil. Purrs and love and thank you for the additionalinformation.
The medical industry (including veterinary) has become drug-pusher for Big Pharma. That powerful lobby gets legislation passed making their product mandatory. We are vaccinating ourselves and pets into chronic illnesses, and prescribed medicines which themselves are problematic. What we’ve witnessed with covid vax issue is prime example. I’ve gone to great lengths becoming informed, and protecting my loved ones.
Wow. Never heard of that. Doesn’t seem right that cats can
get cancer due to taking the required vaccinations. Basil looks
like such a sweet kitty. Thanks for the info.
Thank you for this info! Never heard of this and definitely will talk to our vet about minimizing risk. Super helpful!
I lost my sweet Jenny to this nearly 20 years ago, on May 3, 2003. I’m in New England, and we got the best care possible for her at Angell Medical in Boston. We drove an hour every day in each direction for six weeks for her radiation, after the first surgery and before the chemo. She had three surgeries all together – and was an absolute champ throughout the process. We shared a year and a half after diagnosis.
All the time I spent in the car driving with her has turned out to be one of my most cherished memories. She was a dilute tortie, full of personality (not unlike Binga), and remarkably accepting of all the treatment. It was an honor for me to have her in my life.
This is a good and informative post about a very scary condition.
Good informative post Summer. Cancer is very scary for any being that it attacks.
Purrs, Julie
We had never even heard of this before. Now Mummy is eating herself up with worry – and so are We!