Mast Cell Tumour in Dog - Stelfonta injection

[Whenworld]

My dog has a MCT on her muzzle, probably the worst place to have it. My vet is investigating whether a new injection that kills the cancer cells could be the best treatment. It’s a new drug but none of the trial dogs had a MCT on the muzzle. Has anybody out there had their dogs tumour treated with this injection?

Hi, was wondering what the follow up was regarding your pup's MCT muzzle tumour and if he/she was a candidate for Stelfonta? Any help would be appreciated. We are battling something similar with our pup.

My vet said it was too risky. I went to the Fitzpatrick clinic for a consult and they outlined my options. This didn’t include Stelfonta so I asked about it. None of them had used it but had chatted to other vets about it and they had had mixed reviews; it’s said that only the tumour dies and is shed, but in reality quite a bit of surrounding tissue is affected so the wound can be quite big and there is no control once the injection has been done. I opted to have the tumour removed by surgery (specialist soft tissue surgeon at my practice) which meant some of her nose had to go and a skin flap from her cheek created to replace the lost skin near the nose. The vet did an amazing job, she managed clear margins of 5mm around the tumour and 3mm u Dee it. It was grade two(intermediate level) with a low mitosis, so very good news. The option I didn’t choose was to remove the tumour and, as a precaution, the lymph node at the same time. I’m glad I didn’t go for this option because it was really hard work looking after her after the surgery but at least there was only one area to protect. With luck, that’s the end of the matter and Roxy will not have a recurrence. A FB contact used Stelfonta on her dogs ‘elbow’ and it was a small tumour - about 1cm and she shared the daily photographs with me. The wound was about 3cm large, rather gruesome but healed very well. Please let me know how you get on, and if there’s anything else I can help with, please ask. I’ll see if I can add photos tomorrow but can’t promise I can deal with the technicality of that. Posting without proofreading!

Sorry, I didn’t ask where your dogs tumour is located. Personally, I think Stelfonta is worth a try if the option is an amputation. On the face, I wouldn’t risk it. Additionally, I should say that I wouldn’t have gone ahead with the operation if they would have had to remove too much of her nose because she’s a small dog and walks with her nose on the ground! Dogs without noses get chest infections. As my vet said, there’s a lot we can do, but it doesn’t mean we should. Added a recent picture. Will add a post op picture too.

Recent picture

This has been extremely helpful. We don't know what to do and it has been nerve racking to say the least, which I'm sure you know. My dogs tumor is tiny and located on his lower muzzle near his lip. One oncologist said she wouldn't recommend surgery because it could disfigure him, but another oncologist disagrees. The tumor has not metastasized which is good news, but if we opt not to do surgery then radiation is the only other option and that would mean daily treatments for a month and we just can't do that to him, plus the cost is astronomical. I got really excited when I read about the Stelfonta. Looking at pictures of your dog it looks like surgery went quite well and did not disfigure at all. Where was the tumor located and how big? Thanks again for your help! I'm going to try and post a pic too if the technicality is not too hard. ha ha!

oh, and just to clarify, did you opt not to remove lymph node?

@whenworld she looks lovely! Glad all went well.

I chose not to have the lymph node done at the same time because I had not had her scanned or X-rayed and therefore didn’t know if the cancer had spread. Decided I’d deal with that after the op and biopsy. As the mitosis level was one, we assumed it hadn’t spread so left it at that. No one ever talked to me about radiotherapy but I wouldn’t have gone down that route because of the daily anaesthesia and visits to the ‘hated’ wets. She just wouldn’t be happy being taken away from me so often, and of course with lockdown humans are not allowed through the door. I’m aware that Roxy could get another tumour but I cross my fingers everyday and hope for the best. Age is always a factor; she’s eight so has plenty of life left in her. Here she is with the tumour.

Do you live anywhere near Guildford? I went for a second opinion there. Consult cost £240 I think. It was good to do that because I was almost at the point of doing nothing. I can’t quite remember, but I’m sure they said radiotherapy wasn’t an option.

Roxy looks amazing. I love a happy pet outcome. Hope she has many happy years with you.

I actually live in the USA (Los Angeles). I was able to talk to someone directly from the company that manufacturers Stelfonta and they put me in touch with a few veterinarians in my area. There were only 4 in all of Southern California that had purchased the product and one of them was a veterinarian just a few miles from our home and happened to be a place we have visited before. Long story short, I called them and the Dr. is very interested in doing the procedure and thinks my pup is a good candidate. He did his first treatment today for another dog. He was very surprised when I asked him about it because he said the drug had just been released 15 days ago. We have our 1st consult in a week. If you are interested I can keep you posted.

Here is a pic of my dog. The tumor is on his lower lip.

I hope all goes well. Yes please, keep us updated. I’m sure this thread will be viewed again. Fingers crossed.

How are things? Did the op go well?

My little 3 lb Yorkie was diagnosed today with a rare mast cell tumor on the tip of her nose. I am devastated. Our vet in the Cirgin Islands put her on prednisone not knowing what it was. It came back and grew quickly. Vet today said ask an oncologist about Stelfonya. We are also in Los Angeles. She has bo other symptoms, it is Grade II, m-4

I am also in Los Angeles. My Yorkie baby was diagnosed today with a mast cell tumor on the tip of her tiny nose. Vet said look into Stelfonta because she is 4 pounds and too small for surgery. May I ask what vet you found, and whether you know if it is costly. Thank you

I’m sorry to hear about your dog. The other person who posted from the States hasn’t given an update but I’m sure you could track her down if she has used her real name. I think you need to get your vet to speak to the producers of the drug to ask about the injection on such a small dog. From the pictures I’ve seen, the wound site is quite a bit larger than the tumour and bigger than the literature indicates. It would need to be done by someone who has had specific training in giving this injection because it is very important that the drug only goes into the tumour and not through it (layman’s understanding). It’s heart breaking isn’t it and there’s so much to take into consideration such as the age of the dog. Best wished to you.

Hi everyone. I am posting here because this is the site that came up when I searched for "Stelfonta reviews." My dog had this treatment two days ago. I guess if the option is that your pet has a low chance of survival, you might want to try it. But I do not recommend it otherwise. I wish someone had told me it was new, and that there are many unknowns and risks. Our dog has a small cutaneous mast cell tumor on the side of her rear leg above her knee. The vet didn't give us choices, he just said "we can give her an injection and the tumor will die and slough off over time." I wish we asked more questions! We gave her steroid two days ahead of time as told. After the injection, she had a bad reaction. Her leg swelled to 3-4 times its normal size. She couldn't walk and was sick, not eating or drinking. We took her back to the vet and he said "I wasn't expecting this." She now is on 5 medications 2-3 times a day. Steroid, antihistamine, pain med, antacid, antibiotic (the last as a precaution). She will now eat a small amount of wet cat food if we hand feed her (normally that would be a wonderful treat). We are supposed to massage her leg to help reduce inflammation, but the open wound from the Stelfonta is running blood and fluid and inflamed so she won't let us touch it. My husband sleeps on the couch near her at night and I stayed home from work. We try to keep her from licking it and help her walk out to go to the bathroom. She cannot walk on her own; she falls if she puts weight on it. Now that the injection is in her, there is nothing we can do but let it take its course and pray she gets through it. Our vet even said not to take her to the emergency clinic because they "won't understand what is happening" because this process of killing tumors is so new. This should only be a last resort for inoperable tumors, in my opinion. We took a healthy 5-year-old dog with a tumor the size of the end of a pencil eraser and put her, and ourselves, in hell. (I just had to stop typing to help her; she was falling off the bed. There is blood all over the sheets, and her skinny little leg is bloated all the way up to her hip.) I wish I had known the risks. The treatment alone causes a painful, weeping, open wound; that plus the reaction is too much for us. I wish I could go back in time and not do it. A surgery would have been a much safer choice in her situation. I do NOT recommend it! My dog is suffering and I am afraid she will not pull through. I will pray that your dogs will be okay.

I’m so sorry for you; I don’t know what to say. I would definitely go to another vet with your dog, this doesn’t sound right at all. The Fitzpatrick vets, which is one of the most advanced in Europe, said they had read mixed reviews. Go to another vet ASAP and get a second opinion and take photographs. I have seen photographs of a dog that had this treatment done and it was successful. The tumour was 1cm but the wound site was at least 3 cm. prepare yourself for a possible amputation. Thinking about you.

I'm so sorry about your experience and I hope your dog is doing better now. We are Day 7 post Stelfonta treatement. We were warned that it would be painful, but had no idea!! Dixie's tumor was on her back foot, subcutaneous mast cell tumor. Dixie's response was as you described, painful swollen foot, weeping, smelly wound that just got bigger and bigger and bigger. The reason they didn't want to cut the tumor out was because there wouldn't be enough skin to close. Her wound is so large, about 2 x 3 inches that I can't imagine how it will ever heal up. And there are multiple lesions, so it had begun spreading. The first 72 hours were excruciating for Dixie and for us. Thankfully we are retired so we could be with her 24/7. She is now walking around (still holding the foot up), eating, and occasionally wagging her tail, but the wound is heinous. Even given a shorter life span, I think the kindest thing we could have done for her would have been to do nothing. We feel so guilty for putting her through this. Unless a tumor is really small, I wouldn't recommend this drug. It's torture.

Thanks for posting on this thread. I think the real problem is that the amount of drug that is injected into the tumour is very small and it must not go through the tumour. Perhaps vets have not had first hand training. Who knows. Don’t be hard on yourself; the wound will heal and Dixie will soon forget about the pain. I think I was more traumatised after the operation than Roxy. The alternative would have been to have the leg removed, so either way it’s not an easy choice. Fingers crossed it heals quickly.

Hey,how is your dog after one year from the injection?

Hi everyone. My dog is fine today, but our experience was a very bad one. After I posted last year the wound continued to expand and was oozing blood and fluid. It ultimately was a couple of inches across and when she moved I could see her muscles on her bone all the way down inside her leg, as if her skin was a pants leg with a large hole. The vet was so worried that she would not live that he came to our house daily to check on her and was having us text photos to his personal phone. This went on for a few weeks. After the skin stopped dying, she had to have surgery to close the wound. He cut her leg open to her ankle, removed a strip of skin as wide as the wound, then pulled the two edges together and sewed the straight seam all the way down. He said it was good she had this treatment because the drug kills tumor cells and the reason the wound was so large is because the tumor was so large. If he had manually cut it out he said he never would have got it all. However, he admitted he made a mistake by only having her take medicine to prevent a systemic reaction before the injection. It is absolutely critical that the medicine be continued during and after the injection to prevent the life-threatening, systemic reaction my dog had. This reaction is caused by the mast cell tumors releasing histamine when they die. Also, you must know ahead of time that this injection kills tumor cells and causes them to bleed and fall off, no matter how extensive they are. You cannot see all the cells. So, if your dog has a small tumor, a small wound will form. But if your dog has a large tumor, a large wound will form. If the tumor cells are dispersed in your dog, it may die. Once the injection is given, it can’t be stopped. Please know this risk and that your dog may die. There are pros (killing tumor cells you didn’t see) and cons (could be fatal if there are too many cells). The whole process was painful for our dog and scary and upsetting for us. Make sure you have all the information about benefits and risks, make sure your vet knows what he or she is doing, and don’t let them do it unless they give you the medicine to prevent your dog from having an allergic reaction to degranulation of the tumor cells during and after the treatment. When all was said and done, our dog was fine. But it cost us thousands of dollars, she suffered, and the ordeal lasted for months. I’ll look for photos and come back to post them. The best advice I can give is read all the information on the patient leaflet that comes with the injection. It disclosed all of this, and even says that the vet should make sure the patient sees it, but our vet never gave it to us. Instead, they cut out the part that shows the pictures of a wound forming and healing, and left out all the information about risks.