What Your Cat's FIP Blood Test Results Really Mean During Treatment: A Guide for Filipino Cat Parents

The chat notification arrives before you have even had breakfast. Your vet just sent the blood test results. Three weeks into FIP treatment, your cat has been eating again — climbing onto the bed at night, grooming, asking for food. You were starting to breathe again.

FIP Blood Test Results During Treatment Explained

Then you open the results. And the numbers do not look anything like what you hoped.

Globulin is still way above normal. ALT has gone up. The white blood cell count is flagged. You screenshot everything, post it in your FIP Philippines Facebook group, click the Live Chat button at the bottom right of the page to reach the BasmiFIP support team, and try to get your vet on the line — all before 8 in the morning.

Here is the thing most Filipino cat parents find out too late, and wish they had known from day one: most of those numbers are not telling you that your cat is failing treatment. They are telling you exactly what happens inside the body of a cat who is responding normally to GS-441524 therapy. Blood test results during active Feline Infectious Peritonitis (FIP) treatment look alarming — and they are frequently misread, including by veterinarians who have not handled many FIP cases before.

In the Philippines, where FIP specialist experience can vary significantly between clinics — especially outside Metro Manila, Cebu, and Davao — understanding these results yourself becomes part of how you protect your cat.

This guide explains every major blood parameter, what it does during treatment, and when a result is expected versus when it actually needs urgent attention.

Why Blood Tests Are Your Most Reliable Tool Throughout Treatment

Feline Infectious Peritonitis (FIP) starts when the feline coronavirus mutates inside your cat's body into a form that attacks the immune system itself. GS-441524 interrupts that process by blocking the virus from replicating. But the inflammation, protein imbalances, and immune system disruption that built up over days or weeks do not simply vanish once the virus starts being suppressed. The body heals at its own pace — and blood tests are the only objective way to track that healing.

For many cat parents across the Philippines — particularly those in Visayas, Mindanao, or areas without a nearby specialist — blood work is often the most accessible way to know whether the treatment is working, separate from clinical signs alone.

Blood tests during FIP treatment do three essential things:

• Confirm the disease is actually retreating — inflammatory markers are falling, protein ratios are rebalancing

• Catch early side effects — particularly on the liver and kidneys, before they cause visible symptoms

• Guide dosing decisions — when response is slower than expected, the panel tells the treatment team whether an adjustment is needed

The standard protocol used by BasmiFIP Philippines follows the same schedule that clinical research has validated: a baseline panel before treatment starts, checks at weeks 4 and 8, and a final panel at day 84. After the 84-day course ends, the post-treatment observation period calls for additional blood checks at weeks 4, 8, and 12.

No single draw tells the complete story. What matters is the direction each value moves across multiple tests over time.

Breaking Down the Key Values

Globulin

What it is: Globulins are immune proteins the body produces to fight infection. In cats with active Feline Infectious Peritonitis (FIP), they are almost always very high — commonly between 50 and 90 g/L — because the immune system has been working in overdrive for an extended period.

What to expect during treatment: Globulin is consistently the last value to normalize. It is completely normal for it to remain elevated at the week-4 and week-8 blood draws, even in cats who are clearly improving in every visible way. The number that matters is not the absolute level — it is whether that level is trending downward.

When to be concerned: Globulin that keeps rising after week 8, alongside clinical signs that are also worsening, may indicate the current dose is not suppressing the virus adequately. This is a conversation to have with the BasmiFIP team or your vet — not a reason to stop treatment without guidance.

Albumin-to-Globulin Ratio (A:G Ratio)

What it is: The A:G ratio compares albumin — a structural protein produced by the liver — to total globulins. In a healthy cat, this ratio sits above 0.8. In cats with active Feline Infectious Peritonitis (FIP), it commonly falls below 0.5, sometimes as low as 0.3.

What to expect during treatment: A rising A:G ratio is one of the earliest and most reliable signs that GS-441524 is working. As globulins start falling and albumin starts recovering, this ratio climbs back toward normal. Seeing the A:G ratio improve at week 4 — even when the individual values are still outside the reference range — is a meaningful positive signal.

How to use it alongside individual values: A cat whose globulins dropped from 72 g/L to 55 g/L while albumin climbed from 15 g/L to 21 g/L is responding well to treatment — even though neither number has crossed back into normal territory yet. The A:G ratio captures that recovery in a single number where individual values may not show it clearly.

ALT (Alanine Aminotransferase)

What it is: ALT is a liver enzyme that rises when liver cells are under stress or damaged. In FIP cats, elevated ALT can come from the disease itself — or from GS-441524, which is documented to cause moderate, typically temporary ALT increases in a portion of treated cats.

What to expect during treatment: A moderate ALT rise in the first four to eight weeks of GS-441524 therapy is a known and well-documented finding. It does not mean your cat has liver failure. It does not mean the treatment is failing.

When to act: An ALT that rises to more than three to five times the upper limit of the reference range, or that continues climbing after week 8, needs closer evaluation. If your cat also develops jaundice — yellow coloring of the gums, the whites of the eyes, or the inner ear skin — contact your vet or the BasmiFIP Philippines team the same day.

Never stop treatment based on ALT alone without speaking to a professional first. Stopping GS-441524 prematurely dramatically raises the risk of relapse — a risk that, in the vast majority of cases, far outweighs the risk of a moderate, monitored enzyme elevation.

ALP (Alkaline Phosphatase)

What it is: ALP is another liver-related enzyme that is commonly elevated alongside ALT during Feline Infectious Peritonitis (FIP) treatment.

What to expect: Mild ALP elevation during the treatment course is common and usually resolves on its own during or after the 84 days. If ALP remains persistently elevated after confirmed remission, additional liver evaluation is warranted.

SDMA and Creatinine (Kidney Function)

What they are: SDMA (symmetric dimethylarginine) and creatinine are markers of how well the kidneys are filtering waste. SDMA is a more sensitive early indicator — it can detect a reduction in kidney function before creatinine rises.

What to expect during treatment: Transient SDMA elevations have been documented in some cats during GS-441524 therapy. GS-441524 is processed through the kidneys, and certain functional changes can happen without causing permanent damage.

When to act: SDMA rising alongside elevated creatinine, decreased urine concentration, or noticeably increased water consumption needs veterinary evaluation. Cats with pre-existing kidney problems require more frequent renal monitoring throughout the full treatment period.

Complete Blood Count (CBC): White Cells and Differential

What it is: The total white blood cell count and the breakdown of each cell type — neutrophils, lymphocytes, eosinophils, monocytes.

What to expect during treatment:

• Lymphocytosis (elevated lymphocytes) has been documented during GS-441524 treatment and generally has no clinical significance when it appears on its own

• Eosinophilia (elevated eosinophils) is a known transient finding and does not by itself point to parasites or allergies unless accompanied by other symptoms

• Neutrophilia (elevated neutrophils) in early treatment reflects the active systemic inflammation of Feline Infectious Peritonitis (FIP) itself — this should gradually normalize as treatment takes effect

A CBC that is trending toward the reference range between weeks 4 and 8 is encouraging. Persistent or worsening neutrophilia — especially if your cat is also running a fever or going off food — may indicate a secondary bacterial infection or insufficient viral control at the current dose.

Hematocrit (PCV) and Red Blood Cells

What it is: The proportion of red blood cells in circulation. Many cats with Feline Infectious Peritonitis (FIP) are already anemic at diagnosis, due to immune-mediated destruction of red blood cells and bone marrow suppression.

What to expect: Anemia improves gradually as the viral load decreases and the immune system stabilizes. Full normalization in the first two to four weeks of treatment is not a realistic expectation. Cats who remain severely anemic beyond week 8 may need a discussion with their vet about supportive options.

Total Protein and Fibrinogen

What they are: Total protein is albumin and globulins combined. Fibrinogen is an acute-phase inflammatory protein that rises significantly during active systemic inflammation.

What to expect: Total protein normalizes as albumin rises and globulins fall. Very high starting values — above 90–100 g/L — are typical of active Feline Infectious Peritonitis (FIP). A sustained downward trend across the 84-day course is what to watch for.

Understanding Results Week by Week

Before Treatment Starts (Baseline)

This panel is the reference point for everything that follows. Expect elevated globulins, low albumin, a depressed A:G ratio, possible anemia, and disrupted inflammatory markers. Every subsequent result is compared to this baseline — not to the healthy reference range of a normal cat.

Week 4 (Day 28)

In cats responding to treatment, the week-4 draw typically shows:

• A:G ratio improving, even when individual values are still outside reference limits

• Globulins lower than baseline (often still elevated in absolute terms)

• CBC beginning to normalize

• Partial improvement in anemia

• ALT possibly elevated but stable — not continuing to rise

If globulins have not moved and clinical signs have not improved, contact the BasmiFIP team to verify the current dose against your cat's actual current body weight. You can check the BasmiFIP Philippines FAQ page for dosage guidance before concluding that treatment is not working.

Week 8 (Day 56)

A cat responding well at week 8 should have values clearly moving toward the reference range. Globulins should be measurably lower than at week 4. ALT and ALP, if elevated, should be stable or falling. Albumin should show a clear upward trend.

If values at week 8 are still moving in the wrong direction, share the full panel results with BasmiFIP Philippines — do not adjust the dose or stop treatment without professional input.

Day 84 (End of Treatment)

The goal at day 84 is clinical remission with a clear trend toward normal — not necessarily perfectly normal lab results across every value. Globulins in particular may still be slightly above the reference range. The criteria for ending treatment are:

• Clinical remission: normal appetite, stable or increasing weight, normal activity, normal body temperature

• A:G ratio at or approaching the reference range

• No active fluid accumulations

• No other markers of ongoing active disease

For a detailed overview of the recovery milestones expected at each stage of treatment, read the FIP treatment guide for the Philippines.

Post-Treatment Observation: Weeks 4, 8, and 12 After Day 84

The post-treatment period requires continued blood monitoring. At each checkpoint, values should continue normalizing. Any value that moves in the wrong direction after treatment ends — particularly globulins rising again, or albumin falling — must be reported to BasmiFIP or your vet immediately. This pattern can signal relapse, and how quickly you respond directly affects the outcome.

Common Misreads — Set the Record Straight

"ALT went up. I should stop the medication." In most cases, no. Moderate ALT elevation during GS-441524 therapy is an expected, documented finding that generally resolves on its own. Stopping treatment prematurely is one of the most preventable causes of relapse. Have the conversation with BasmiFIP or your vet before making any changes.

"The results are almost normal at week 4. Can we stop early?" No. Lab values normalizing does not mean the virus has been eliminated. The 84-day protocol exists because feline coronavirus persists inside macrophages — immune cells — even when blood markers improve. Stopping early is the most common cause of preventable relapses in Filipino FIP cases.

"Week 4 results didn't improve. The treatment isn't working." Clinical improvement — returning appetite, reduced fever, increased energy — almost always appears two to four weeks before blood test values normalize. If your cat looks and acts better but the numbers are still off, the treatment is most likely working. Evaluate the clinical picture and the blood results together.

"Globulins are still high at week 8. Something must be wrong." Globulin is the last parameter to normalize in virtually every successfully treated FIP case. Many cats still have elevated globulins at week 8 while heading toward full remission. A consistent downward trend — even a gradual one — is the positive signal to focus on.

FAQ: FIP Blood Tests During Treatment in the Philippines

What blood tests are needed to monitor FIP treatment?

A complete chemistry panel — total protein, albumin, globulins, ALT, ALP, creatinine, SDMA — plus a full blood count (CBC) with differential. The A:G ratio is calculated from albumin and globulins. Minimum recommended testing points: baseline before starting, week 4, week 8, and day 84 at end of the treatment course.

What does high globulin mean in a cat with FIP during treatment?

Elevated globulins during Feline Infectious Peritonitis (FIP) treatment reflect sustained immune system activation caused by the feline coronavirus. This is an expected finding in the early and middle phases of GS-441524 therapy. A consistently declining trend — even when values remain above the reference range — is a positive sign of treatment response.

Is it normal for ALT to rise during GS-441524 treatment?

Yes. Moderate ALT elevation is a documented and typically transient effect of GS-441524. It does not automatically indicate liver damage or treatment failure. Regular monitoring is important, and any significant or sustained rise should be discussed with BasmiFIP Philippines or your vet before any treatment adjustment is made.

What is the A:G ratio and why does it matter for FIP?

The albumin-to-globulin ratio (A:G ratio) compares two protein fractions in the blood. In healthy cats it sits above 0.8. In cats with active Feline Infectious Peritonitis (FIP) it often falls below 0.5. A rising A:G ratio during treatment is one of the earliest and most reliable indicators that GS-441524 is working.

How often should blood tests be done during the 84-day FIP treatment?

Minimum recommended schedule: baseline before starting, week 4, week 8, and day 84 at end of treatment. After treatment ends, blood checks at weeks 4, 8, and 12 of the observation period confirm sustained remission.

Can blood work look normal but my cat still relapse?

Yes. Lab values can normalize before the virus is fully cleared. This is one of the primary reasons the complete 84-day treatment course and the full 12-week observation period are both necessary — regardless of how good the results appear at any point during treatment.

Blood results got worse at week 4. What do I do?

Click the Live Chat button at the bottom right of the page and share the full panel results with the BasmiFIP Philippines team immediately. Deteriorating values at week 4 may mean the current dose is too low for your cat's actual body weight, a product quality concern, or a form of FIP that requires a higher-dose protocol. Do not adjust the dose or stop treatment without guidance.

What happens to SDMA during FIP treatment?

Transient SDMA elevation has been documented in some cats during GS-441524 therapy and does not necessarily indicate permanent kidney damage. Cats with pre-existing kidney conditions require more frequent renal monitoring throughout treatment. SDMA that stays elevated or continues rising after treatment ends needs further investigation.

Where can I get blood tests done for my cat in the Philippines?

Most veterinary clinics in Metro Manila, Cebu, Davao, Iloilo, Cagayan de Oro, Bacolod, and other cities can run a full FIP monitoring blood panel. If you are in a province or island where access to veterinary labs is limited, BasmiFIP Philippines can advise on the most practical testing options for your area and help you coordinate with a clinic remotely. Click the Live Chat button at the bottom right of the page for guidance.

My vet does not have much FIP experience. How do I use blood results to guide them?

This is one of the most common situations Filipino cat parents face, especially outside major cities. The most helpful approach is to bring a complete chronological history of every blood panel from baseline onward when you see your vet — not just the latest result. Trends are what matter most. BasmiFIP Philippines also offers free consultation to help you and your vet interpret the results together and make informed decisions about the treatment protocol.

Keep Every Result. Understand the Direction.

Tracking blood work during Feline Infectious Peritonitis (FIP) treatment is not just about catching problems early — it is the most objective proof you have that treatment is doing what it is supposed to do. For many Filipino cat parents, the day when the A:G ratio first starts climbing, or when globulins drop meaningfully from one test to the next, is the first real confirmation that their cat has a genuine path to recovery.

Save every result. Keep a simple log of the key values over time so you can see the trend clearly. When you share results with BasmiFIP or your vet, send the full history — not just the most recent draw. The full picture is what allows accurate, confident guidance.

The Filipino cat parent community is one of the most connected and caring in Southeast Asia. The BasmiFIP Philippines Facebook community and live chat support exist precisely for moments like this. Click the Live Chat button at the bottom right of the page — a clear answer is there for you, no matter where in the archipelago you are.

If warning signs return after treatment ends — recurring fever, loss of appetite, unexplained weight loss, abdominal swelling, eye changes, or neurological symptoms — do not wait. Reach out to BasmiFIP Philippines immediately. The guidance you receive in those first hours can determine whether a relapse is caught early or allowed to progress. Learn more about treatment options by visiting the dual antiviral treatment guide for Philippine cat parents.

You have already shown up for your cat by choosing treatment and staying committed to the process. Understanding these results is the next part of that commitment — and you do not have to figure it out alone.