Understanding Relapses and Remission Phases in Dogs
- Fruzsina Moricz
- Jan 6
- 11 min read
In canine lymphoma, up to 80–90% of dogs go into remission with standard chemotherapy. Yet the majority of those same dogs will relapse, often within about a year, and many families are caught off guard by how suddenly the “better” phase seems to end.[3]
On paper, this is expected biology. In real life, it feels like whiplash: your dog starts eating again, the swelling goes down, you exhale — and then the symptoms creep back. It can feel like the treatment “stopped working” or that you missed something important.
This article is about what’s actually happening in those remission and relapse phases: why they occur, what research tells us (and what it doesn’t), and how to think about decisions when your dog’s illness seems to move in waves rather than in a straight line.
First, some shared language
These terms come up often in chronic and cancer care. Having them in your back pocket makes veterinary conversations much easier.
Remission: A period when the disease is well-controlled: clinical signs are greatly reduced or absent. Your dog may look and act “normal,” even though the underlying disease risk is still there.
Complete remission (CR): No detectable disease using the tests and exams available. This does not mean every last abnormal cell is gone — only that we can’t find it.
Minimal residual disease: The tiny number of abnormal cells that can remain even in complete remission. They are often too few to show up on standard tests, but over time they can multiply and cause relapse.
Relapse: The reappearance or worsening of disease signs after a remission. In cancer, this might be new lymph node enlargement; in immune-mediated disease, it may be pain, lameness, or fever returning.
Second remission: A new remission achieved after a relapse, usually with “rescue” or salvage therapy. Second remissions are often shorter and harder to achieve.
Maintenance therapy: Ongoing treatment during remission, often at lower doses or less frequent intervals, to prolong disease control.
Salvage (rescue) therapy: Treatment used after relapse to try to regain control of the disease. Often involves different drugs or combinations than the first protocol.
These aren’t just technicalities. They describe a pattern of illness that is cyclical rather than linear — and that can change how you think about “success.”
Lymphoma: why “doing well” and “relapsing” both belong to the same story
Lymphoma is one of the most studied cancers in dogs, and it gives us a clear window into how remission and relapse usually unfold.
What typically happens with first treatment
With a multi-drug chemotherapy protocol such as CHOP-L (a combination of cyclophosphamide, doxorubicin, vincristine, prednisone, and sometimes L-asparaginase):
First remission rates: about 80–90% of dogs achieve remission.[3]
Average first remission length: around 8–12 months.[3]
In one study, the median time to progression (time until the disease worsened again) was about 329 days, and 79% of dogs relapsed within the follow-up period.[1]
So if your dog responded well, that’s not a fluke — it’s consistent with the data. And if your dog then relapsed months later, that is also, heartbreakingly, consistent with the data.
A useful way to hold this in mind:
First remission is often a very real success — and still usually temporary.
Why relapse happens even after “complete” remission
Even when we can’t see any cancer on exams, bloodwork, or imaging, minimal residual disease may still be present. A small number of lymphoma cells can survive chemotherapy:
Some are naturally more resistant to drugs.
Some hide in places that are harder for drugs to reach.
Over time, those cells can divide and re-establish noticeable disease.
This is why “complete remission” is not the same as “cure” in most canine lymphoma cases. The treatment has dramatically reduced the cancer burden and given your dog meaningful time with good quality of life — but it rarely eliminates every single malignant cell.
Second remission: possible, but usually shorter
When lymphoma relapses, your vet may suggest salvage (rescue) protocols. These often use different drugs or combinations than the first protocol.
What research shows:
Response rates for second remission:
Roughly 30–50% of dogs respond to rescue protocols, achieving a second remission.[3]
Duration of second remission:
Commonly 60–100 days (about 2–3 months), though there is variation.[3]
Some dogs do better than these averages; some do worse. Second remissions are, on the whole, harder to achieve and shorter than the first.
That doesn’t mean they’re meaningless. For some families, a few additional good months are deeply valuable. For others, the burden of more treatment, side effects, and appointments feels too high. Both responses are valid.
Experimental approaches: vaccines and beyond
Research is exploring ways to improve what happens after relapse.
One example: a CD40-activated B cell cancer vaccine combined with chemotherapy.
In one study, among dogs that relapsed:
About 40% of vaccinated dogs achieved a durable second remission with salvage therapy.[2]
In comparison, only 7.7% of unvaccinated dogs achieved a similar second remission.[2]
Vaccinated dogs also had significantly better survival outcomes after salvage therapy (p = 0.025).[2]
This doesn’t mean such vaccines are widely available or a guaranteed solution. It does mean that the field is actively searching for ways to stretch those remission periods and make second chances more robust.
If your oncologist mentions clinical trials or new protocols, this is the kind of work they’re thinking about.
Immune-mediated diseases: a different kind of relapse story
Not all relapses are about cancer. Immune-mediated diseases — where the immune system mistakenly attacks the body’s own tissues — often follow their own pattern of flare and quiet.
Example: immune-mediated polyarthritis (IMPA)
Non-associative IMPA is a form of immune-mediated joint disease not linked to an obvious trigger like infection or cancer. Dogs may present with:
Shifting leg lameness
Joint pain
Stiffness
Fever
Lethargy
With immunosuppressive treatment, many dogs enter remission — their pain improves, fever resolves, and they move more freely.
But studies show:
High remission rates are achievable, yet
Relapse rates range from about 8% to 60% of cases, depending on the study and criteria used.[4][5]
Relapses can occur during treatment (for example, when doses are lowered) or after treatment is stopped.[5]
So if your dog’s IMPA flares again after a good phase, it doesn’t necessarily mean:
You did something wrong
The treatment was pointless
Your vet misjudged the situation
It often means you’re dealing with a disease that is inherently relapsing, and the long-term goal is careful adjustment rather than a simple “on/off” cure.
Why relapse in immune-mediated disease is so tricky
Unlike lymphoma, where we’re targeting a relatively defined population of malignant cells, immune-mediated disease is about retraining or dampening the immune system itself.
Relapse can be influenced by:
How quickly medications are tapered
Infections or other immune triggers
Underlying genetics
Unidentified environmental factors
Current research is exploring whether gene expression profiles (patterns of which genes are turned on or off in certain cells) could predict which dogs are more likely to relapse early, especially in B-cell lymphoma.[6] Similar tools may eventually help in immune-mediated diseases too, but they’re not yet in routine use.
For now, management is often a long conversation about:
What level of control is “good enough”
How much medication is tolerable
How to recognize early signs of a flare
A quick comparison: lymphoma vs. IMPA patterns
Feature | Canine Lymphoma (CHOP-L) | Non-associative IMPA |
Nature of disease | Cancer of lymphocytes | Immune system attacking joints |
First remission rate | 80–90%[3] | High, but exact % varies[4][5] |
Typical first remission duration | 8–12 months[3] | Not precisely defined; often months to years |
Relapse frequency | Relapse in up to 79% after ~329 days median[1] | 8–60% relapse, depending on study[4][5] |
Second remission (salvage) rate | 30–50% response to rescue protocols[3] | Not well-defined |
Second remission duration | Often 60–100 days[3] | Variable; depends on drugs and tapering strategy |
Long-term goal | Prolong good-quality life, not usually cure | Long-term control, minimize flares and drug side effects |
Understanding which pattern you’re dealing with — cancer vs. immune-mediated, high vs. lower relapse risk — can make the ups and downs feel slightly less arbitrary.
The anesthesia question: can procedures trigger relapse?
One of the more unsettling findings in lymphoma research involves anesthesia and relapse.
In a study of dogs in remission from lymphoma:
83% of dogs that underwent anesthesia while in remission relapsed shortly afterward.[1]
The median time to relapse after anesthesia was 73 days.[1]
Overall, dogs that had anesthesia during remission had a higher risk of relapse and a shorter time to relapse compared with those that did not.[1]
Why might this happen?
Researchers suspect that:
The stress of surgery and anesthesia may temporarily suppress or alter immune function.
This could give any remaining cancer cells an opportunity to grow more quickly.
However, this is still an emerging area, and the exact mechanisms are not fully understood.
Crucially:
This does not mean dogs in remission should never have anesthesia.
Sometimes procedures (dental work, biopsies, emergency surgeries) are genuinely necessary.
It does mean the decision deserves a more detailed, individualized conversation.
A helpful way to approach this with your vet:
Ask how urgent the procedure is.
Discuss whether there are non-anesthetic alternatives or ways to delay safely.
If anesthesia is needed, talk about how your dog’s history of lymphoma might influence monitoring and follow-up.
The goal is not to be paralyzed by fear, but to let this information sharpen your decision-making.
Maintenance therapy: holding the line vs. over-treating
Once your dog is in remission, you may hear about maintenance therapy — lower-intensity treatment meant to keep the disease in check for longer.
What we know:
In some lymphoma protocols, maintenance therapy can modestly extend remission.[3]
But it can also add:
More clinic visits
Cumulative side effects
Financial and emotional strain
There is no single “best” answer about whether to use maintenance therapy. It depends on:
The specific disease and its behavior
Your dog’s age and other health issues
How your dog tolerated the initial treatment
Your own capacity (time, emotional bandwidth, finances)
Research acknowledges that the optimal timing and components of maintenance vary by case and are not fully standardized.[3] A thoughtful, case-by-case approach is more realistic than a strict rule.
How vets think about salvage therapy and “when to stop”
When relapse happens, you may be presented with options like:
A new chemotherapy combination
Different immunosuppressive drugs or doses
Palliative care only (focusing on comfort, not further remission)
From the outside, this can feel like a test: “Am I doing enough?” or “Am I giving up too soon?” Inside the medical discussion, there’s usually a quieter set of questions your vet is also holding:
How likely is a meaningful second remission for this specific dog?
What will the treatment cost — not just financially, but in side effects, clinic time, and stress?
What is this dog’s quality of life likely to be with and without further treatment?
Some of the tensions:
Aggressive treatment vs. comfort:
Rescue protocols can buy time but often come with more side effects and shorter benefits.
Hope vs. burnout:
The possibility of another remission can be both a lifeline and an emotional treadmill.
Cost-effectiveness vs. emotional value:
A few months of extra time may be priceless for some families and feel disproportionate for others.
There is no ethically “pure” choice here. There is only an honest weighing of:
What more treatment can realistically offer
What your dog is experiencing
What you, as a caregiver, can sustain
A good vet will make space for all of that, not just the lab values.
The emotional reality of relapsing disease
Research on canine chronic illness tends to focus on numbers. The lived experience is less tidy:
Whiplash:
The transition from “We’re in remission!” to “The cancer is back” can be brutally fast.
Guilt:
Owners often wonder if they missed early signs, waited too long to call, or triggered the relapse with a walk, a vaccine, a treat.
Decision fatigue:
Each relapse can bring a new round of choices: another protocol? different drugs? palliative care? euthanasia?
It may help to remember:
Relapse is usually about biology, not blame. In both lymphoma and immune-mediated disease, relapse is common — even with excellent care and perfect adherence.[1][4][5]
Remission is still real, even if it ends. The good months your dog has are not erased by what comes after. They are part of the value of treatment.
You’re allowed to change your goals over time. At first, your priority might be “do everything possible.” After a relapse, it might shift to “maximize comfort” or “avoid more hospital days.” That’s not giving up; that’s adapting to new information.
Talking with your vet: questions that can steady the ground
When you’re facing remission, relapse, or the possibility of salvage therapy, it can help to have some language ready. These kinds of questions are reasonable and welcome:
About prognosis and patterns
“Based on my dog’s specific case, what range of remission times would you consider realistic?”
“If we see a relapse, what signs are we most likely to notice first?”
“How does my dog’s situation compare to the typical numbers you see in lymphoma/IMPA?”
About treatment options
“What are we aiming for with this treatment: cure, longer remission, or comfort?”
“If we try a rescue protocol and it doesn’t work, what would our next steps look like?”
“Are there any clinical trials or newer options we should know about?”
About quality of life
“What side effects should make me call you right away?”
“How will we know if the treatment burden is outweighing the benefit?”
“Can we talk about what a ‘good day’ looks like for my dog, and how many of those we can realistically expect?”
About anesthesia and procedures during remission
“How urgent is this procedure, given my dog’s history of lymphoma?”
“Are there any ways to reduce the need for anesthesia or delay safely?”
“If we go ahead, how might this affect relapse risk, and how would we monitor afterward?”
You’re not being difficult by asking. You’re participating in shared decision-making — which is exactly what long-term disease management needs.
What science knows, and what it’s still figuring out
It can be oddly comforting to know where the edges of knowledge are. Here’s how the current landscape looks:
Well-established
High first-remission rates in canine lymphoma with CHOP-L (80–90%).[3]
Most lymphoma patients eventually relapse, with a median time to progression around 329 days in one study (79% relapsed).[1]
Second remissions are usually shorter and harder to achieve (30–50% response, 60–100 day duration).[3]
Relapse is common in immune-mediated diseases like IMPA, with reported rates from 8% to 60%.[4][5]
The emotional toll on owners managing relapsing illness is significant, affecting decision-making and wellbeing.
Still uncertain or emerging
The true impact of anesthesia and perioperative stress on lymphoma relapse risk is suggestive but not fully proven; more data are needed.[1]
The best structure and timing for maintenance therapy are not standardized and depend heavily on individual cases.[3]
Molecular predictors of relapse (such as gene expression profiles in B-cell lymphoma) are promising but not yet routine tools in practice.[6]
Best practices for emotional support in veterinary oncology are evolving; many clinics are still building structures for consistent counseling and follow-up support.
Knowing that some questions do not yet have precise answers is not a failure of care. It’s a reminder that you and your vet are working inside a living, changing field.
Holding the whole picture
Remission and relapse can make time feel fractured: “before diagnosis,” “during treatment,” “when things were good,” “when it came back.” It’s easy to feel like you’re constantly moving between hope and loss.
From a scientific perspective, these phases are expected in many chronic and cancer conditions. From a caregiving perspective, they are the shape of the relationship you have with your dog now — a relationship that includes vet visits and lab reports, but also naps, walks, and small, ordinary joys.
Nothing in the statistics cancels out the fact that your dog’s good days are real. And understanding the patterns — how remission works, why relapse happens, what second chances realistically look like — can make those days feel a little more secure, even if they’re not guaranteed.
You don’t have to be endlessly optimistic or endlessly brave. You just have to keep asking clear questions, noticing how your dog is doing, and making the next decision with the information you have. That, in the world of relapsing disease, is exactly what good care looks like.
References
Frontiers in Veterinary Science – Study on anesthesia and lymphoma relapse in dogs, examining relapse risk and time to relapse in dogs undergoing anesthesia while in remission.
PLOS One – Evaluation of a CD40-activated B cell cancer vaccine combined with chemotherapy in canine lymphoma, including outcomes for second remission and survival after relapse.
DVM360 – Clinical overview of rescue (salvage) protocols for canine lymphoma, including remission rates, typical durations, and practical considerations for first and second remissions.
PubMed Central – Study of relapse patterns in non-associative immune-mediated polyarthritis (IMPA) in dogs, reporting remission and relapse rates.
Journal of Veterinary Internal Medicine – Research on relapse rates and long-term management of immune-mediated diseases in dogs, including IMPA and related conditions.
Journal of Veterinary Medical Science – Investigation of gene expression profiles as potential predictors of early relapse in canine B-cell lymphoma, exploring the role of molecular markers in prognosis.
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