Total Protein in Cats: What High and Low Levels Mean
Last reviewed: April 2026
Normal total protein (TP) in cats is 6.0–8.0 g/dL. High TP in cats most often means dehydration or elevated globulins — and in cats specifically, FIP (feline infectious peritonitis) is one of the most diagnostically important causes of marked TP elevation. Low TP means protein is being lost through the gut wall (IBD, GI lymphoma) or the liver can no longer produce enough. Total protein alone tells an incomplete story — the albumin and globulin fractions, and their ratio, are what actually drive diagnosis.
Normal total protein (cat): 6.0–8.0 g/dL. Total protein = Albumin + Globulins. In cats, FIP creates a distinctive pattern: high TP with low albumin and a low A:G ratio.
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Analyze My Cat's Protein ValuesWhat Is Total Protein?
Total protein measures all proteins in the blood serum. It has two main fractions:
- • Albumin (~40–60% of TP): produced by the liver. Maintains oncotic pressure (keeps fluid inside blood vessels), transports hormones and drugs. Low albumin causes edema and fluid accumulation in the chest or abdomen.
- • Globulins (~40–60% of TP): a group including immunoglobulins (antibodies), acute-phase proteins, and complement. Produced mainly by the immune system and liver.
In cats, this distinction matters more than in most species because FIP creates a dramatic pattern: globulins skyrocket while albumin falls — and total protein may be high, normal, or only mildly elevated depending on how the two fractions balance. Always check albumin and globulin individually when evaluating protein status in cats.
Total Protein Reference Ranges
Hypoproteinemia — PLE (IBD, GI lymphoma), liver failure, or severe CKD. Investigate albumin and globulin fractions.
Normal range. FIP can present with TP in the high-normal range if albumin and globulin are balancing — check A:G ratio.
Dehydration (most common), chronic infection, or FIP with marked globulin elevation. Check albumin + A:G ratio.
Severe globulin elevation. With fluid and low albumin: highly suspicious for FIP. Also myeloma (rare in cats).
| Result | Range | Likely Meaning |
|---|---|---|
| Low | <6.0 g/dL | PLE (IBD, GI lymphoma), liver failure, or severe CKD. Check albumin + globulin fractions separately. |
| Normal | 6.0–8.0 g/dL | Normal. FIP can produce a normal TP if albumin drop is partially offset by rising globulins — always check A:G ratio in a sick cat. |
| High | 8.1–10.0 g/dL | Dehydration or elevated globulins from infection/FIP. Check albumin and A:G ratio. |
| Very High | >10.0 g/dL | Severe globulin elevation. FIP highly likely if low albumin and fluid present. SPEP indicated. |
What Causes High Total Protein in Cats?
Dehydration
The most common cause. As fluid leaves the bloodstream, all dissolved proteins concentrate — hemoconcentration. PCV/HCT rises at the same time. Extremely common in cats with chronic kidney disease (CKD), who are chronically volume-depleted. Rehydration brings TP back to normal without any specific protein treatment.
FIP (Feline Infectious Peritonitis)
FIP is the most diagnostically important cause of high TP in cats. The FCoV coronavirus mutation triggers uncontrolled macrophage activation and a severe inflammatory response. The liver massively overproduces globulins (acute-phase proteins and immunoglobulins), while albumin is simultaneously consumed by inflammation.
The result is a characteristic pattern: very high globulins + low albumin = high TP with a low A:G ratio. An A:G ratio below 0.4 in a cat with fluid accumulation is highly suspicious for FIP. A TP above 10 g/dL with effusion is almost pathognomonic.
Important: FIP can present with a normal or only mildly elevated TP in early disease if the albumin drop and globulin rise partially cancel out. Never rule out FIP based on TP alone — check the individual fractions and the A:G ratio.
Chronic Infections and Inflammation
Chronic bacterial, fungal, or immune-mediated conditions drive polyclonal globulin production. Unlike FIP (which creates a very high total protein with very low albumin), these conditions raise globulins more modestly while albumin stays relatively preserved. Examples: chronic pyothorax, deep tissue infections, immune-mediated disease.
Multiple Myeloma (Rare)
Malignant plasma cells produce a single immunoglobulin in large quantities, causing a monoclonal globulin spike and very high total protein. Rare in cats compared to dogs, but occurs. Serum protein electrophoresis (SPEP) shows a sharp monoclonal band.
What Causes Low Total Protein in Cats?
Low TP in cats (below 6.0 g/dL) means protein is being lost through the gut, not produced by the liver, or lost through the kidneys. The albumin/globulin pattern identifies which:
Protein-losing enteropathy (PLE). IBD, small cell GI lymphoma, and intestinal lymphangiectasia all cause the gut wall to leak both fractions equally.
Also: low cholesterol, low B12, weight loss, diarrhea
Liver failure (hepatic lipidosis, cholangiohepatitis) or protein-losing nephropathy. Liver specifically fails to produce albumin; globulin production is less affected.
Check liver enzymes, bile acids, urine UPC ratio
FIP pattern. TP may be normal or low overall, but the low A:G ratio (below 0.4) is the diagnostic clue.
A:G <0.4 + effusion = FIP testing immediately
| Pattern | Likely Cause | Supporting Clues |
|---|---|---|
| Both albumin + globulin low | PLE (IBD, GI lymphoma, lymphangiectasia) | Low cholesterol, low B12, diarrhea, weight loss |
| Albumin low, globulin normal | Liver failure (hepatic lipidosis, cholangiohepatitis) or PLN | Elevated liver enzymes or abnormal bile acids; elevated UPC for PLN |
| Albumin low, globulin HIGH | FIP | A:G ratio <0.4 + effusion = FIP testing immediately |
Protein-Losing Enteropathy (PLE) in Cats
IBD and small cell GI lymphoma are the two most common causes of PLE in cats. The damaged intestinal wall leaks protein non-selectively — both albumin and globulin fall proportionally, keeping the A:G ratio relatively normal. Low cholesterol and low serum cobalamin (B12) are common accompanying findings. Distinguishing IBD from GI lymphoma requires intestinal biopsy.
Liver Disease
Hepatic lipidosis and cholangiohepatitis reduce the liver's albumin production capacity. Because globulins are made elsewhere, the result is selectively low albumin with globulins preserved or mildly elevated. Total protein may remain in the low-normal range even as albumin falls to dangerous levels.
The Dehydration Problem in CKD Cats
A Common Masking Effect
Cats with CKD are often chronically dehydrated. Dehydration concentrates all blood values — including proteins. A CKD cat with genuinely low albumin (from poor nutrition or muscle wasting) may show a normal or even slightly elevated total protein because dehydration is masking the hypoproteinemia.
After subcutaneous fluid administration or IV rehydration, total protein drops — and the true low albumin becomes visible. This is why TP interpretation in CKD cats always requires considering hydration status.
What Happens Next?
When total protein is outside the normal range in a cat, your vet will typically:
- • Check albumin and globulin separately — the essential first step in all cases
- • Calculate A:G ratio — below 0.4 with fluid = FIP workup immediately
- • Assess hydration — PCV, skin turgor, mucous membranes; correct before re-interpreting TP
- • Liver panel (ALT, ALP, GGT, bile acids) — if albumin is selectively low
- • Urine UPC ratio — to rule out protein loss through the kidneys
- • Abdominal ultrasound — assess for effusion, intestinal wall thickening, lymph nodes, liver architecture
- • FIP testing — Rivalta test on effusion, PCR, FCoV antibody titers if A:G ratio is suspicious
- • GI workup / biopsy — if pan-hypoproteinemia and IBD vs lymphoma needs distinction
Key Takeaway
In cats, total protein is a starting point — always decompose it into albumin and globulin. High TP with low albumin and an A:G ratio below 0.4 is a red flag for FIP. Low TP with both fractions falling points to gut protein loss. Dehydration (very common in CKD cats) can mask low TP and make a sick cat's values look deceptively normal.
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Related Reading
Low Albumin in Cats
Why albumin drops in cats — IBD, GI lymphoma, FIP, liver disease, and the A:G ratio.
Globulin in Cats
What high and low globulins mean — FIP, chronic infections, and GI protein loss.
ALB/GLOB Ratio in Cats
How the albumin:globulin ratio distinguishes FIP from IBD and liver disease.
FIP in Cats
How FIP causes high globulins with low albumin — and what the A:G ratio means.
IBD in Cats
The most common cause of PLE and low total protein in cats.
Frequently Asked Questions
What is total protein in a cat blood test?
Total protein (TP) measures all proteins in the blood — primarily albumin and globulins. Normal range in cats is approximately 6.0–8.0 g/dL. Albumin makes up about half and is liver-produced. Globulins include antibodies, acute-phase proteins, and complement factors.
What does high total protein mean in cats?
Most commonly dehydration (hemoconcentration) or elevated globulins. In cats, FIP is a major and distinctive cause — it drives globulins dramatically high while albumin drops, creating a high TP with a very low albumin:globulin ratio. Chronic infections, lymphoma, and myeloma are other causes.
What does low total protein mean in cats?
Protein is being lost or not produced. Common causes: IBD or GI lymphoma (PLE — drops both albumin and globulin), liver disease (fails to produce albumin), and sometimes CKD. Note: CKD cats are often dehydrated, which artificially inflates TP and can mask underlying hypoproteinemia.
Can FIP cause high total protein in cats?
Yes. FIP causes markedly high globulins alongside low albumin — total protein may be high while albumin is critically low. The A:G ratio drops below 0.4 in cats with FIP and fluid accumulation. This pattern is highly suspicious for FIP and warrants FIP-specific testing.
Why is total protein high in a dehydrated cat?
Dehydration concentrates all blood components including proteins — hemoconcentration. PCV/HCT is elevated at the same time. Very common in CKD cats, who are chronically water-depleted. Rehydration normalizes TP. Always consider dehydration before concluding TP is pathologically elevated.
What is the difference between total protein and albumin in cats?
Total protein = albumin + globulins. In FIP, TP can be high while albumin is low — the globulin surge more than compensates. A normal or elevated TP does not confirm normal albumin. In cats, the albumin:globulin ratio is more diagnostically useful than total protein alone.