Suspect my cat has FIP? Let me take you through the veterinarian's diagnostic approach and examination process (extremely important: there is no simple method for definitive diagnosis!)

Comprehensive Assessment Process for Veterinarian Diagnosis of FIP: Collecting Clues Step by Step

When faced with suspected FIP cases, veterinarians usually follow a rigorous logical process and comprehensively use a variety of methods to assess: (the following is not necessary for all examinations, veterinarians will choose according to the specific situation)

1. Detailed medical history and basic information (Signalment & History)

This is a very important first step. The veterinarian will carefully ask about the cat'sage(FIP is more common in young cats under 2 years old and old cats over 10 years old),breed(certain purebred cats are considered to be at slightly higher risk),source(whether it comes from a multi-cat environment such as a cattery, shelter),living environment,vaccination and deworming history,symptoms(when did it start, how did it develop, specific manifestations),treatment response(whether it is ineffective for certain treatments), etc.

2. Comprehensive Physical Examination

The veterinarian will perform a very careful systemic examination, including: measuringbody temperature(whether there is a fever), assessingweightand body condition score, checkingmucous membrane color(whether there is pallor or jaundice), palpatinglymph nodesfor enlargement, carefullypalpating the abdomen(feeling for fluid accumulation, enlarged organs, or masses),auscultating the heart and lungs, performing a detailedophthalmological examination(FIP may cause intraocular inflammation) and necessaryneurological examination(to assess for neurological symptoms).

3. Important Blood Tests - Provide Clues, but Cannot Confirm Diagnosis

• Complete Blood Count (CBC):May find non-regenerative anemia, lymphopenia, and sometimes neutrophilia, which are non-specific manifestations of inflammation or chronic disease.
• Serum Biochemical Examination:This is a very important part, focusing on:
  • Significant increase in total protein (TP) and globulin:This is one of the most common hematological abnormalities in FIP, suggesting a strong chronic inflammation or immune response in the body. However, other chronic inflammatory diseases may also cause this.
  • Albumin levels may be reduced.
  • Albumin/Globulin Ratio (A:G Ratio) is significantly reduced:A low A:G ratio (e.g., below 0.4 or 0.6, the specific critical value needs to be combined with the laboratory and literature) is supportive of FIP diagnosisImportant clues, but is also not absolutely specific.
  • Bilirubin is elevated:If jaundice occurs, bilirubin will be elevated.
  • Other indicators: Assess liver enzymes, kidney function indicators (BUN, Crea), etc. to see if other organs are involved.
• Serum Amyloid A (SAA):SAA is a very sensitive acute inflammatory marker in cats. It is usuallysignificantly elevatedduring the active phase of FIP. Tashikin providesF. SAA detection test stripsto help veterinarians quickly assess inflammation levels.But please note: An elevated SAA only indicates the presence of inflammation, and many other diseases can also cause it to rise. It itself cannot diagnose FIP. [Learn about F. SAA testing ]
• Feline Coronavirus Antibody Titer (FCoV Antibody Titer): This test has very limited value for diagnosing FIP and may even be misleading!A positive result only indicates that the cat has been exposed to feline coronavirus (FCoV) in the past and cannot distinguish between harmless intestinal viruses and mutated viruses that cause FIP. A negative result cannot completely rule out FIP (especially in the late stages of the disease). Tashikin'sFIP Ab detection test stripsalso detect antibodies and have the same limitation. The interpretation of the results must be extremely cautious andmust notbe used as a diagnostic basis.[Learn about FIP Ab testing ]

4. Imaging - Finding "Traces" of Lesions

• X-ray:Helpful for checking for fluid in the chest cavity (pleural effusion), heart size, and lung condition. Abdominal X-rays may show unclear or enlarged organ contours, but the information is limited.
• Ultrasound:For evaluating the abdomen it isextremely important. It can clearly show whether there isascites, assess whether themesenteric lymph nodesare enlarged (a relatively common feature of FIP), check whether there are abnormal lesions (such as granulomas) in the liver, spleen, kidneys, and other organs, and assess the thickness of the intestinal wall, etc. It is especially valuable for the diagnosis of dry FIP.

5. Fluid Analysis - If there is pleural effusion or ascites, this is one of the most valuable tests!

If pleural effusion or ascites is found in the cat through ultrasound or palpation (feline ascites detection), the veterinarian will usually draw a small amount of liquid sample for analysis, which isvery helpfulfor FIP diagnosis:

• Appearance and physical characteristics:FIP exudate is usuallyyellow, viscous, clear or slightly turbid.
• Rivalta's Test:A simple and quick bedside test in which a drop of exudate is dripped into a test tube of water containing a trace amount of acetic acid. If the droplet retains its shape and sinks slowly (positive), it highly suggests that it is exudate (increasing the possibility of FIP).
• Biochemical indicators:The liquid usually hasa very high protein content, buta relatively low number of cellsto the diagnosis of FIP.
• Cytological examination:The cells in the liquid are mainly macrophages and neutrophils, with fewer lymphocytes.
• A:G Ratio:The A:G ratio in the exudate is also usually low.
• FCoV RT-PCR test (for exudate):Performing FCoV RT-PCR testing onexudatesamples, ifa high viral RNA loadis detected, combined with typical fluid characteristics and clinical symptoms, canvery strongly supportthe diagnosis of FIP.But please note that blood PCR testing for FIP is usually of low value.Tashikin'sFCOV Ag detection test stripsdetect antigens in feces and are used to screen for intestinal detoxification. They arenot directly relatedto the diagnosis of FIP.[Learn about FCOV Ag testing ]

6. Histopathology/Immunohistochemistry - the "Gold Standard" for Diagnosis (but usually difficult to obtain ante-mortem)

The most reliable diagnostic method is to obtainsamples of diseased tissue(such as enlarged lymph nodes, lesions on the liver or kidneys) through surgery or autopsy for histopathological examination. Under a microscope, FIP-characteristic perivascular inflammatory lesions are observed, and feline coronavirus antigens are detected in macrophages at the site of the lesions through special staining methods such as immunohistochemistry (IHC) or immunofluorescence (IF). However, this method is usually difficult to implement safely in cats before death.

7. Summary: How Does the Veterinarian Ultimately Judge?

So,how does a veterinarian diagnose FIP? The answer is:There is no shortcut!Veterinarians must, like a puzzle, integratemedical history, clinical symptoms, physical examination findings, blood test results (especially protein, A:G ratio, SAA and other patterns), imaging results, and the most valuable fluid analysis results (if there is fluid accumulation)all clues meticulously together, conduct a comprehensive, detailed, and exclusionary comprehensive assessment, and then finally arrive at aclinical diagnosis(that is, highly suspected to be FIP based on existing evidence).