FIP Diagnose

Diagnose Introduction

Once a cat has diagnosed the FIP, cat usually dies within a few days to a few weeks. Therefore, a clear diagnosis is essential. However, the diagnosis of FIP is actually very complicated and difficult. We need to comprehensively consider the cat’s life background, medical history, clinical signs, laboratory tests, antibody titers, etc., and use this to evaluate the possibility of FIP, but we cannot make the final Confirmed.

At present, pet hospitals do not have a very good diagnostic method for cat infectious peritonitis. They mainly rely on laboratory diagnosis (blood routine, blood biochemistry, ascites biochemistry) and imaging analysis. Among them, albumin, globulin, and PCR are particularly important.

Although many FIP cats have characteristic CBCs, albumin and globulin levels and A:G, but not every cat will fully match the above parameters, which still need consider combined with age, origin, clinical signs and physical examination. The results are considered comprehensively. If these common abnormalities and clinical symptoms are generally consistent, it can be reasonably diagnosed as feline infectious peritonitis.

Wet FIP

Effusion FIP Diagnose

Clinical hospital test

🐈 Blood and biochemistry ➡ Suspected FIP,(
🐈 SAA(serum amyloid test) ➡ >200,high inflamation
🐈 PCR test results positive ➡ Basically judge that FIP is highly suspected
🐈 Extract a few effusion ➡ Green ,yellow
Absolute neutrophils, absolute lymphocytes, Decreased ALB, increased GLOB, A:G≤0.7,TBIL increased, etc.

Clinical Symptom

Reverse verification

If the cat’s clinical symptoms are highly correspond with the FIP symptoms, directly treat it with FIP drugs for about a week and observe whether it improves. Usually the FIP cat will have symptoms improvement and progress within 3 days of FIP medicine treatment.

Dry FIP

Non-Effusion FIP Diagnose

Clinical hospital test

🐈 Blood and biochemistry ➡ Highly suspected abdominal transmission, exclude AIDS, leukemia
🐈 SAA(serum amyloid test) ➡ >200/ high inflamation
🐈 Puncture sampling ➡ rule out tumors suspected
🐈 Inflammation detection ➡ rule out parasitic diseases such as toxoplasma

Absolute neutrophils, absolute lymphocytes, Decreased ALB, increased GLOB, A:G≤0.7,TBIL increased, etc.

Clinical Symptom

Anorexia, fatigue, sleepiness
Weight loss, Jaundice
A high coronavirus titer
Non-regenerative anemia
Periodic fever(＞102.5℉), no medicine work
Continued widespread mesenteric lymph nodes enlargemen
Inflammatory granuloma in multiple organs
Ocular lesions (uveitis, Pupils vary in size,blood, unusual color)
Neurological signs lesions(rest tremor, rear limb weakness, rigidity, bradykinesia and postural instability, fecal incontinence, seizures, convulsions, paralysis, disorientation and shock)

Reverse verification

FIP improvement

How to judge if FIP is improving？

🐹 Observable Showing 🐹

🐹 No more fever stable body temperature
🐹 Appetite recovery rapid weight gain
🐹 Moist nose, playful spirit no avoidance behavior
🐹 Anemia improved pale gums were relieved
🐹 Jaundice Improvement The appearance of jaundice is relieved The renal medullary ring disappears

🐹 Laborary test 🐹

Wet FIP

🐹 CBC The symptoms of low lymphocytes are relieved
Anemia is improved
Improvement of hematopoietic function inhibition
The total number of white blood cells and internal ratio tend to be normal
🐹 Biochemical Albumin has risen
Globulin decreased
Bilirubin drops to normal levels

🐹 B-ultrasound The cortex-medullary ring sign disappeared (if any) effusion subsided.

Clinical Symptom

🐹 CBC The symptoms of low lymphocytes are relieved
Anemia is improved
Improvement of hematopoietic function inhibition
The total number of white blood cells and internal ratio tend to be normal
🐹 Biochemical Albumin has risen
Globulin decreased
Bilirubin drops to normal levels

🐹 B-ultrasound Internal organs improve, intestinal membranous lymph nodes are less swollen.

Welcome

Extension of clinical diagnosis knowledge

(1) Laboratory indicators (biochemical, blood routine)

There are many changes in the blood laboratory indicators of FIP cats, but they are not specific. Common indicators include:

1 Lymphopenia, increased neutrophils, a typical stress white blood cell image.

2 The concentration of serum total protein increased, mainly due to the increase of γ-globulin. This is because macrophages infected with the virus overproduce B cell differentiation factors, which differentiate B cells into plasma cells, thereby producing a large amount of antibodies.

3 The decrease in white ball ratio is caused by hyperglobulinemia and hypoalbuminemia.

4 Liver enzymes, bilirubin, blood urea nitrogen, and creatinine may increase, depending on the degree and location of the organ damage.

(2) Analysis of exudate

1 Once an exudate is found, further sampling and analysis should be carried out. The diagnostic value of exudate is much higher than that of blood.

Ultrasound guided ascites is a clear, light yellow, viscous fluid, which is a typical abdominal-like fluid.

1.1 The concentration is usually very high (>3.5g/dL[>35 g/L]) and is considered as exudate.

1.2 The count of nucleated cells is low (<5000 nucleated cells/mcL), similar to modified leakage.

1.3 Cytology shows a large number of macrophages and neutrophils, which are purulent granulomatous inflammation (bacterial peritonitis and lymphoma are similar, but the cell count will be higher in bacterial peritonitis, and malignant cells exist in lymphoma) .

1.4 Cytology shows a large number of macrophages and neutrophils, which are purulent granulomatous inflammation (bacterial peritonitis and lymphoma are similar, but the cell count will be higher in bacterial peritonitis, and malignant cells exist in lymphoma) .

1.5 Li Fan is positive. When Li Fan is positive, it is not only because of the high protein content, but also when the fibrin concentration and inflammatory mediators are high. In a recent study of 851 cats, Li Fanta had a sensitivity of 91.3% and a specificity of 65.5%. The positive predictive value is as high as 90% in cats less than 2 years old. Therefore, Li Fan is unlikely to be FIP when he is negative; Li Fan also increases the possibility of FIP when he is positive.

Li Fanta Experiment

(3) Analysis of cerebrospinal fluid

1 Elevated protein concentration in cerebrospinal fluid (normal value <25 mg/dL [<250 g/L], increase of 50-350 mg/dL [500-3500 g/L]).

2 Increased cells (100-10000 nucleated cells/mcL), mainly including neutrophils, lymphocytes and macrophages.

3 But these findings are not specific. Some FIP cats with neurological symptoms may have normal cerebrospinal fluid. And even if the cerebrospinal fluid suggests inflammation, it is impossible to distinguish whether it is caused by FIP or other central nervous system inflammation.

(Four) antibody titer

1 Antibody titer can be measured by blood, exudate and cerebrospinal fluid, but it cannot be used to diagnose FIP.

2 Most cats have been exposed to FCoV, and some cats that have been vaccinated against coronavirus have antibodies in their bodies. Therefore, the presence of antibodies in the blood cannot be used to predict FIP.

3 FIP cannot be ruled out without antibodies in the blood. In the late stage of FIP, the antibody titer usually decreases. About 10% of FIP cats do not have antibodies. This is because a large number of viruses in cats bind to antibodies to make them undetectable. The antibody concentration in the cerebrospinal fluid of FIP cats with neurological symptoms is no different from that of cats with other neurological symptoms, which proves that the antibody measurement in cerebrospinal fluid is also useless.

(5) Intracellular FCoV antigen

1 Immunofluorescence staining or immunocytochemistry (in the exudate macrophages) or immunohistochemistry (in the tissue macrophages) can find the FCoV antigen in the macrophages. Although immunostaining cannot distinguish the “harmless” FCoV from the FCoV that causes FIP mutations. However, only the virus that causes FIP can replicate in large numbers in macrophages and show positive staining.

2 In a study of 171 cats, the positive predictive value of FCoV immunofluorescence staining in macrophages in the exudate was 100%. However, the negative prediction rate is not very high (57%), which may be due to the low amount of macrophages in the smear (even if the cat has FIP), which results in negative staining.

3 Immunohistochemistry is considered to be the gold standard for diagnosing FIP, and the positive predictive value was confirmed to be 100%. However, invasive methods (such as laparotomy or laparoscopy) are required for tissue sampling. A study compared the sensitivity of liver and kidney tissue core biopsy and fine needles. There was no significant difference between the two methods. The liver tissue is more sensitive than the kidney.

(6) RT-PCR of FCoV or mutant virus

1 RT-PCR is a conventional inspection method, but PCR can only detect FCoV, but it cannot distinguish whether the virus is a virus that causes FIP or a harmless intestinal FCoV virus. Current research suggests that FCoV viremia exists in both cats and healthy carriers. In other words, FCoV viremia can not be diagnosed in the blood if FCoV viremia is detected in the blood.

2 However, although it is useless in the diagnosis of FIP, RT-PCR is very sensitive for the detection of FCoV stool samples and can be used to record whether a cat is detoxifying. In the purification of endemic infections, identifying fecal detoxification is an important step in cat population management.

3 Scientists have discovered in recent years when researching mutant genes that using one of the mutant genes for PCR has a diagnostic specificity of up to 100% for FIP cats. This test has the highest sensitivity in exudate, but is low in blood, so the diagnosis of dry abdominal transmission is still challenging.