TL;DR: My 9-year-old pit bull mix, Mylo, has cutaneous lymphoma that's turned into an aggressive large-cell (likely T-cell) form. He's gone through CCNU, L-asparaginase (x2), Tanovea, doxorubicin, and as of today vincristine/modified CHOP — and it keeps coming back faster each time. Lesions are now ~5x bigger than two weeks ago and spreading all over his body and into his mouth. He's still eating, drinking, and being himself. His oncologist says any further response will likely be short, and that planning a peaceful goodbye soon is a reasonable, compassionate choice. I'm looking for honest input: anything we haven't tried, second opinions/trials worth chasing, or whether others would stop here and focus on comfort.

About Pet

• Breed/age/sex: American Pit Bull Terrier mix, 9 years old, male neutered
• Weight: ~36 kg (~79 lb), stable — no cancer weight loss
• Location: Washington, DC area
• Other history: bilateral TPLO (knee surgeries) years ago; has arthritis in a rear leg

Diagnosis

• Cutaneous (skin) lymphoma, originally diagnosed by cytology with our primary vet and managed initially as the epitheliotropic (cutaneous T-cell) type.
• In April, a new, more aggressive large-cell / high-grade lymphoma was confirmed by cytology — the pathologist said it looked different from the original cells and was "compatible with stage V disease."
• Immunophenotype (B-cell vs T-cell) was never confirmed by flow cytometry or PARR — it's been presumed T-cell based on the cutaneous origin and the aggressive, drug-resistant behavior. (Open question: is it worth confirming at this point?)
• It's now behaving as a multicentric / mucocutaneous lymphoma — skin nodules across his body plus lesions in his mouth/gums.

Treatments tried (in order)

1. CCNU (lomustine) — started 2/18; complete response after one dose.
2. Relapse with a new large-cell lesion → L-asparaginase (Elspar) — complete response.
3. Tanovea (rabacfosadine) — disease progressed (new lip lesion)
4. L-asparaginase again — only minimal response.
5. Doxorubicin (single agent, the strongest CHOP drug) — started 5/20; disease still progressed.
6. Vincristine / modified CHOP — started June 4, with cyclophosphamide planned next week if he tolerates it.

So he's been through essentially every standard and rescue option, and each remission has been shorter and harder to get than the last.

Current status (right now)

• New nodules appearing all over his body, and existing ones are growing — roughly 5x bigger than two weeks ago. Some are ulcerating; one on his chest is open and he keeps licking it.
• Lesions inside his mouth/gums (crusted, not currently stopping him from eating).
• Still eating and drinking normally — appetite unchanged through all treatment.
• Urinating and defecating normally, no diarrhea, no vomiting, normal stool.
• No obvious pain/whining, though the chest and mouth lesions seem itchy/uncomfortable.
• Mobility: moving on his own but slower, with less energy than usual. Still loves sitting outside watching people and animals, greets us at the door, wants to be in the same room.
• Breathing: fine at rest, but he'll pant with an open mouth after about a 5-minute walk.
• My parents saw him fall on his back and get back up on Sunday — no obvious cause.
• A couple of lymph nodes are slightly enlarged (could be the lymphoma or inflammation from the ulcerated skin lesions).

Current meds

Prednisone, gabapentin, amantadine (added June 4 for cancer-related pain), Benadryl (for itch), Cerenia as needed for nausea.

What the oncologist has said

He's been honest and kind: the disease is progressing faster than expected even with chemo, and while lymphoma can still respond, any response now would likely be short (possibly only a couple of weeks). Without treatment, he estimated a likely decline within about two weeks, given how fast things are moving. He said both continuing chemo and stopping to focus on comfort are reasonable, and that planning a peaceful goodbye on a good day — rather than waiting for a crisis — would be a compassionate choice.

Where I'm at / my plan

I had him treated with vincristine June 4, hoping to shrink the bothersome lesions and keep him comfortable and stable. He has a scheduled in-home euthanasia this Friday (easily movable), on a good day, before I have travel coming up in ~10 days. My biggest fear is a medical emergency forcing me to rush him to the ER and say goodbye in a panic, on a bad day. I understand that even if treatment works, I'm only buying time and it will come back.

What I'm hoping to hear from you

• Has anyone seen a durable response in rapidly progressing, multi-drug-resistant cutaneous (especially T-cell) lymphoma? What worked?
• Are there rescue protocols, clinical trials, or specialists/second opinions (East Coast / DC area) worth pursuing at this stage?
• Would it change anything to confirm the B-cell vs T-cell phenotype now?
• For those who've been here: did you continue treatment or stop and focus on comfort — and what do you wish you'd done?
• Any comfort/wound-care tips for ulcerated, itchy skin and mouth lesions?

Photos of his nodules attached - https://imgur.com/a/best-friends-lymphoma-PKxmZ85

Thank you kind people. He means the world to me. He's been my bestfriend for 8+ years and I just want to make the right call for him.