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3 CE CREDITS CE Article Feline Infectious Peritonitis ❯❯ T eresa L. Goodson, DVM, DACVIM (Small Animal Medicine) ❯❯ S usan C. Randell, BVSc, DACVIM (Small Animal Medicine) ❯❯ L isa E. Moore, DVM, DACVIM (Small Animal Medicine) Affiliated Veterinary Specialists Maitland, Florida At a Glance Causative Agents Page E1 Pathogenesis Page E1 Signalment Page E2 Clinical Signs Page E2 Diagnostic Tests Page E3 Treatment Page E5 Prognosis Page E6 Prevention Page E6 Abstract: Feline infectious peritonitis (FIP) frequently results in death in cats. It is caused by a mutated, highly contagious coronavirus, and it is more common in indoor cats in multicat households. A complex interaction between the coronavirus and the feline immune system causes disseminated vasculitis, which is the hallmark of FIP. New tests are being developed, but the antemortem diagnosis of FIP continues to be difficult and frustrating. Current treatments are crude and involve supportive care and immunosuppression. Minimizing exposure is the best method of preventing infection. F eline infectious peritonitis (FIP) is caused by a mutated coronavirus and frequently results in death in cats. The difficulty of establishing the diagnosis and the lack of effective treatment options have frustrated veterinarians since FIP was identified more than 40 years ago.1 Research is clarifying the complex pathogenesis of FIP. This review addresses the pathogenesis and clinical signs of FIP, as well as the current diagnostic tests and management recommendations. Causative Agents Feline coronavirus is a large, enveloped RNA virus that exists in two forms: feline enteric coronavirus (FECV) and feline infectious peritonitis virus (FIPV). FECV is virtually nonpathogenic, whereas FIPV is almost invariably fatal.1 All FECV carriers have the potential to develop either enteritis or peritonitis, although only about 5% of infections develop into FIP.1 Currently available diagnostic tests cannot differentiate FECV from FIPV with 100% accuracy. Multicat households have a much higher prevalence of FECV (75% to 100%) than single-cat households (25%).2–4 Animal shelters and catteries facilitate the transmission of FECV because of high environmental stress and sharing of contaminated litterboxes.4,5 Increases of up to a millionfold in fecal shedding of FECV were seen in FECV-positive cats after entering an animal shelter.6 Half of the cats that were originally FECV negative were shedding FECV within 1 week of entering the shelter.6 Pathogenesis FECV, which is highly contagious, is transmitted primarily via the fecal–oral route, although it may also be transmitted by inhalation.1 It replicates in the epithelial cells of the intestinal tract. Fecal shedding begins within 2 days of infection, and seroconversion occurs within 18 to 21 days after exposure to the virus.1 FECV replicates only in enterocytes. It can exist in the systemic circulation but cannot sustain viral production there, so progression to FIP does not occur.7 However, if a crucial deletion mutation (typically of the 3C or 7B gene) occurs, the virus can be taken up by macrophages and gain access to the systemic circulation, where it transforms into the highly pathogenic FIPV.8 FIPV infection is sustained in monocytes and macrophages, where the virus undergoes replication and spreads systemically.7 Traditionally, FIP has been divided into two distinct clinical forms: effusive (wet) and noneffusive (dry). Approximately three times as many cats present with the wet form as with the dry form.9 However, these divisions are not absolute, as a combination of both forms is often present in cats with FIP.10 The macrophage is the key inflammatory cell in both forms of FIP.11 Cats that are infected with FECV but do CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® E1 ©Copyright 2009 Veterinary Learning Systems. This document is for internal purposes only. Reprinting or posting on an external website without written permission from VLS is a violation of copyright laws. FREE CE Feline Infectious Peritonitis Box 1 Breed Prevalence of FIP 21 Increased risk Abyssinian Bengal Birman Himalayan Ragdoll Rex QuickNotes FIP occurs primarily in indoor cats housed in large groups. E2 No increased risk Burmese Exotic shorthair Manx Persian Russian blue Siamese TNF-α, IL-6, and IL-12 appear to be associated with disease progression.15,17–19 The role of all of these cytokines in the development of humoral (Th2) and cell-mediated (Th1) immune responses may be instrumental in understanding the pathogenesis of FIP.15,19 Signalment All felids are susceptible to FIP. Among nondomestic cats, cheetahs are particularly vulnerable.20 Among domestic cats, young cats aged 3 months to 3 years and geriatric cats older not develop FIP are believed to mount a strong than 13 years are most frequently affected.9,12 cell-mediated response, although other, unde- Sexually intact cats, males, and purebred termined factors are likely involved.1,12 A lack cats have a higher incidence of FIP.9,21,22 of cell-mediated immunity, combined with a Susceptibility to FIP is a polygenic inherited strong humoral response by the host, leads trait in Persians and Birmans.23 However, a to the effusive form of FIP.12 Host antibodies recent study revealed differences between and viral antigens form immune complexes breeds in the prevalence of FIP21 (Box 1). that are deposited on the vascular endothelium, causing vasculitis with resultant leakage Clinical Signs of proteinaceous fluid. Adhesion of infected FECV infection may manifest as a benign monocytes to the endothelium activates com- illness limited to mild diarrhea that rarely plement, causing the release of vasoactive requires veterinary attention.1 Some cats show amines that retract the vascular endothelium, no clinical signs of infection. allowing further protein and fluid exudation.1 Cats with wet FIP are typically ill and When virus-infected monocytes enter tissue, debilitated.1,10 Fever or uveitis may be presthey attract antibodies that fix complement, ent.1,10 These cats exhibit abdominal distendrawing in more macrophages and neutrophils tion, pallor, tachypnea, dyspnea, or muffled and creating a perivascular pyogranulomatous heart sounds as a result of fluid accumulation in the peritoneal or pleural cavities1 (Figure 1). inflammation.1 Experimentally infected monocytes and Pericardial effusion is less common.1 Effusion macrophages do not express surface viral pro- into body cavities is a nonspecific finding teins; rather, viral proteins are rapidly inter- without cytologic evaluation of the fluid; siminalized following exposure to FIPV-specific lar effusions occur in a variety of diseases antibodies. This allows the virus to evade (e.g., lymphoma, hepatic neoplasia, cholangantibody-dependent lysis, so the humoral iohepatitis, congestive heart failure, bacterial response fails to clear FIPV infection.13,14 peritonitis/pleuritis). If a partial cell-mediated response is mounted, Clinical signs of the dry form can be vague the noneffusive form of FIP results, and large and nonspecific, including lethargy, poor pyogranulomas form in many organs.12 The appetite, weight loss, icterus, and an intermitvasculitis present in dry FIP is not severe tent fever that does not respond to antibiotics.1 enough to cause the effusion that occurs in Kittens may have stunted growth and diarrhea. Ocular lesions include iritis, uveitis, and cuffwet FIP.1 The patterns of expression of various ing of the retinal vasculature1,24 (Figure 2). Cats cytokines in the peripheral blood monocytes, with neurologic involvement frequently exhibit macrophages, lymphoid tissue, and ascitic ataxia, nystagmus, and seizures.25 Abdominal fluid of cats with FIP are being studied exten- palpation may reveal enlarged lymph nodes sively. Tumor necrosis factor (TNF)-α, inter- and irregular organ surfaces, especially the feron (INF)-γ, interleukin (IL)-6, IL-10, and kidneys. Less commonly reported clinical signs IL-12 appear to play roles in the develop- include intestinal granuloma (often colonic), ment of FIP.11,15–19 Increases in INF-γ and IL-10 massively enlarged abdominal lymph nodes, may be protective,11,15,18 whereas increases in orchitis, skin lesions, and pneumonia.1,26–30 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com FREE Feline Infectious Peritonitis CE Diagnostic Tests FIGURE 1 No single sensitive, specific, noninvasive diag nostic test for FIP is currently available. Therefore, test results must be combined with the history and clinical signs to establish the diagnosis. The complete blood cell count (CBC) often reveals lymphopenia, neutrophilia, nonregen erative anemia, and thrombocytopenia. Lympho penia is due to virus-induced apoptosis of lymphoid tissue.31,32 Neutrophilia characterizes a stress leukogram secondary to infection.10 Nonregenerative anemia is due to chronic inflammation.10 Thrombocytopenia may be due to immune-mediated destruction or decreased bone marrow production of platelets.33 Cat with FIP showing emaciation and abdominal fluid distention. Hyperglobulinemia is observed in more than 70% of patients with FIP. Elevated serum FIGURE 2 globulin levels may be due to the antibodies produced during the host’s humoral immune response to the virus, as well as the presence of complement and immune complexes.34,35 Mild hypoalbuminemia may be due to decreased albumin production by the liver or increased loss from endothelial leakage. The serum albumin:globulin ratio (A:G) should be calculated: a value of <0.8 indicates that the cat likely has FIP (92% positive predictive value [PPV]), whereas a serum A:G >0.8 makes FIP unlikely (61% negative predictive value [NPV]).10 An elevated bilirubin level is likely due to liver necrosis. Liver enzyme levels are frequently normal.1 Additional serum biochemical abnormalities reflect the organs Anterior uveitis due to FIP. affected by vasculitis and subsequent lack of blood supply. Disseminated intravascular coagulopathy and coagulopathies caused by unclear, but the protein may prove to be a liver necrosis and increased platelet reactivity useful biomarker.37,38 Serum amyloid A (SAA), another acute-phase protein, increases 10-fold can also be seen.36 Serum protein electrophoresis may reveal a in the serum of cats with FIP compared with polyclonal or a monoclonal gammopathy, so healthy cats exposed to FECV.1,38 SAA may also this test does not help distinguish FIP from other be useful as a biomarker in the future. At this time, no validated commercial test is available diseases that cause hyperglobulinemia.10 Alpha-1-acid glycoprotein (AGP) is an acute- for routine evaluation of AGP and SAA levels. phase protein, the serum level of which is elevated in many infectious and inflammatory Analysis of Effusion Fluid diseases. AGP controls lymphocyte produc- FIP effusion fluid is typically a straw-colored, tion of cytokines by modulating neutrophil modified transudate that contains a high level and lymphocyte responses. Levels of AGP in of protein (>3.5 g/dL) and few cells (<5000 serum and effusions increase twofold to five- nucleated cells/mL; Figure 3).1 The fluid may fold in cats with FIP, more than in diseases also be classified as an exudate or, rarely, as such as neoplasia and cardiomyopathy. The chyle.39 The high protein content comes from role of AGP in the development of FIP is leakage of globulins across the damaged CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® E3 FREE CE Feline Infectious Peritonitis FIGURE 3 Abdominal effusion fluid removed from a cat with FIP. QuickNotes No single sensitive, specific, noninvasive diagnostic test for FIP is currently available. vascular endothelium. Neutrophils and macrophages in the fluid are consistent with pyogranulomatous inflammation. The A:G ratio of the effusion should be measured: a ratio of <0.5 is strongly correlated with FIP, with a PPV between 66% and 95%, depending on the prevalence of FIP in the cat’s environment.3 An A:G ratio >0.81 has a 100% NPV, essentially ruling out FIP.1,3,12,40 In some cases, the results of the CBC, serum chemistry, fluid analysis, and cytology—combined with a thorough history and physical findings—may be sufficient for a presumptive diagnosis of FIP. Rivalta’s test can be performed to exclude FIP as a cause of effusion.3,10 This test has an 86% PPV and a 97% NPV for FIP.10 One drop of 98% acetic acid (not vinegar) is mixed into a test tube containing 5 mL of distilled water.3,10 One drop of effusion fluid is gently added to the mixture. If the drop dissolves and disappears, the result is negative, so FIP can be ruled out as the cause of effusion. If the drop holds its shape due to high levels of protein, fibrin, and inflammatory mediators, the result is positive.41 Diseases other than FIP that produce positive results on Rivalta’s test are lymphoma and bacterial peritonitis, which can usually be distinguished by cytologic evaluation of the fluid.10 Rivalta’s test is not frequently used because 98% acetic acid is not readily available in most veterinary practices. a very low PPV for FIP (44%).3 However, a very high titer (1:1600) has a 94% PPV for FIP.3 A negative titer has a 90% NPV for FIP.3 The magnitude of the coronavirus titer may be helpful when evaluated in conjunction with clinical signs and other test results.3 Viral titers do not always correlate with fecal shedding of FECV.43 A commercial test for the 7B antibody is available, and it initially showed promise in differentiating FIPV from FECV. However, additional studies showed the 7B antibody test to have false positives in some healthy cats with FECV infection. Because this test cannot reliably differentiate between FIPV and FECV, it has little diagnostic usefulness.44 Testing for anticoronavirus antibodies in effusion fluid may be more useful than testing serum. Detection of anticoronavirus antibodies in effusion fluid has a PPV of 90% and an NPV of 79% for the diagnosis of FIP.3 Laboratories vary widely with regard to reporting anticoronavirus antibody titer results, making interpretation very difficult.10 Antibody titers should be interpreted carefully and should never be used as the sole test to diagnose FIP. The diagnostic value of anticoronavirus titers in cerebrospinal fluid (CSF) for the diagnosis of FIP involving the central nervous system (CNS) is questionable. A recent study45 demonstrated anticoronavirus antibodies in the CSF of cats with neurologic FIP, cats with FIP not involving the CSF, and cats with brain tumors. The cats with positive titers in the CSF also had high serum titers. This finding is consistent with blood contamination of the CSF sample. Detection of anticoronavirus antibodies in the CSF offers no diagnostic advantage over serum titers, which are of limited value. Polymerase Chain Reaction Reverse transcription polymerase chain reaction (RT-PCR) can identify feline coronavirus in effusion fluid, feces, tissue, or blood.10,42,43,46 Serology Messenger RNA (mRNA) is only present when Many commercial assays are available to detect the virus is replicating, which is important anticoronavirus antibodies in serum. However, in differentiating between FIPV and FECV.46 none can distinguish among FECV, other non- Although FECV can be present in the circulavirulent coronaviruses, and FIPV. Healthy cats tion, it does not replicate within monocytes, so exposed to nonvirulent coronaviruses (e.g., no mRNA should be identified.46 When FIPV is canine coronavirus, transmissible gastroen- circulating and replicating within monocytes teritis virus) will be seropositive. Conversely, and tissue macrophages, it produces mRNA, cats with fulminant, effusive FIP can be falsely which can be identified using RT-PCR.46 Beseronegative.1,42 A positive titer (all levels) has cause it can be difficult to work with mRNA, E4 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com FREE Feline Infectious Peritonitis CE a DNA copy (cDNA) is created in RT-PCR by reverse-transcribing the mRNA. The cDNA is then amplified using primers specific for the highly conserved M gene so that large quantities of cDNA are available for identification of the virus.46 Of cats with confirmed FIP, 93% tested positive with RT-PCR, and no false positives occurred in the study group.46 However, RT-PCR results may be incorrect. False negatives can occur because of degradation by RNases, ubiquitous enzymes that can easily contaminate a sample. Laboratory contamination and cross-reaction with other coronaviruses (e.g., canine coronavirus, transmissible gastroenteritis virus) can produce false-positive results.1 Auburn University’s College of Veterinary Medicine Molecular Diagnostics Laboratory is the only laboratory to offer the FIP mRNA Multi Test. Samples of whole blood, effusion fluid, and tissue/aspirate of an affected organ are submitted for RT-PCR testing. The PPV and NPV of this combined test are both reportedly close to 100%.47,a Cerebrospinal Fluid Analysis and Central Nervous System Imaging Neurologic abnormalities are present in approximately 35% of cats with FIP.25,48 CSF analysis may reveal an elevated protein content or pleocytosis (lymphocytes and neutrophils).10,49,50 FIP should be strongly suspected in a cat with inflammatory CNS disease and hydrocephalus identified on magnetic resonance imaging or computed tomography.25,48,51 Histopathology Histopathology is the gold standard for the diagnosis of FIP.3,12 Without histopathology, any diagnosis of FIP is considered presumptive. However, cats with FIP are extremely debilitated, making exploratory surgery for biopsies risky and impractical. Fine-needle aspiration and Tru-Cut biopsy of the liver and kidneys have been evaluated as diagnostic tests for FIP. Lesions consistent with FIP can be identified using these techniques, and combining fine-needle aspiration and Tru-Cut biopsy of the liver has the highest sensitivaMore information about this test, including pricing and shipping methods, may be obtained at the Auburn University College of Veterinary Medicine Web site (www.vetmed.auburn.edu). ity (86%). However, false negatives and inadequate samples are common, yielding a very low diagnostic sensitivity (11% to 38%).52 In many cases, lesions are observed only at necropsy. The classic lesions are pyogranulomatous inflammation that has caused vasculitis, necrosis, and fibrosis.12 The wet form of FIP affects a large number of blood vessels, causing the typical effusion, and small plaques form on the surfaces of abdominal and thoracic organs. In the dry form, larger pyogranulomas affect the kidneys, liver, eyes, and CNS.19,50 Solitary mural FIP lesions of the colon or ileocecocolic junction may be grossly mistaken for neoplasia.26 Meningitis, ependymitis, and hydrocephalus are seen in the neurologic form of FIP.25,50 Lymphoid depletion is commonly observed in the spleen and lymph nodes of cats that succumb to FIP.32 Lymphoid tissue is hyperplastic in cats that survive infection.32 Immunofluorescent staining identifies the coronavirus within macrophages in effusion fluid or tissue. This test is 100% specific but only 50% sensitive for FIP when performed on effusion samples.3,10 In other words, FECV should not be found in macrophages in effusion samples, so a positive result indicates that the cat has FIP. Low numbers of macrophages with insufficient virus to create fluorescence can lead to a false-negative result.10 RT-PCR can also be performed on tissue that has not been preserved in formalin.47 QuickNotes The macrophage is the key inflammatory cell in the development of FIP. Treatment No curative treatment exists for FIP. Therapy is directed at suppressing the formation of immune complexes and thus trying to control the vasculitis that characterizes the disease. Supplemental therapies to increase the overall well-being of the cat, including fluids and nutritional support, should be provided. If an owner or breeder chooses to test healthy cats, cats identified as FECV seropositive should not be subjected to stress because the onset of clinical signs is frequently seen after events such as elective surgery or introduction to a new home.1 Avoiding stress in group-housing situations is especially important. Cats with diarrhea suspected to be due to FECV should be managed with supportive care to maintain hydration, weight, and intestinal bacterial balance.1 Because the immune system of cats with FIP CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® E5 FREE CE Feline Infectious Peritonitis QuickNotes Reverse transcription polymerase chain reaction is a promising test for the accurate diagnosis of FIP. E6 is impaired, immunosuppressive therapy may vector (e.g., litterboxes) when housing groups be contraindicated.53 However, prednisone, of cats. One litterbox should be provided for intracavitary dexamethasone, and cyclophos- each cat, and the litterboxes should be cleaned phamide may be used to control the immune daily to reduce fecal contamination.59 response to the virus and temporarily improve Queens should be isolated from all other the cat’s quality of life.1,10 Ribavirin is an antivi- cats 2 to 3 weeks before delivery. Strict isolaral agent with activity against FECV, but its use tion and sanitation should be continued until is limited by its severe toxicity in cats, which the kittens are weaned at 5 weeks of age. The causes hemolysis, bone marrow suppression, kittens should be maintained in isolation until and liver damage.54 they are removed from the cattery. Infected Various supplements have been used anec- queens can produce kittens negative for FECV dotally with variable reports of success. High- if the kittens are strictly isolated and weaned dose injectable human INF-α (104 to 10 6 IU/kg early.60 No cat that produces two or more kitSC q24h) inhibits viral nucleic acid and protein tens with FIP should be bred, since a genetic synthesis. Cats develop neutralizing antibodies predisposition has been shown.21,23 to human INF-α within 3 to 7 weeks, limiting Any cat entering a cattery should be its usefulness.55 Low-dose oral human INF-α (1 screened with FECV serology or fecal RT-PCR to 50 IU/kg PO q24h) has immunomodulatory and isolated before introduction to the geneffects that may cause progression of FIP and eral cat population.43 Kittens can be screened is not recommended.56 Feline INF-ω inhibits as young as 10 weeks of age.1 Cats with high FECV in vitro and is available in some coun- titers, low titers, and negative titers should tries. A recent report described a small num- be housed separately. As its titer decreases, a ber of cats with suspected (not definitively cat can be housed with other nonshedders.2 diagnosed) FIP that were treated with gluco- Chronic shedders should be removed to elimicorticoids as well as feline INF-ω.57 No well- nate a source of FECV in the cattery. A cat, and controlled studies have been performed to ultimately a cattery, may be considered FECV assess the effectiveness of feline INF-ω against negative after 5 consecutive months of neganaturally occurring FIP. Propionibacterium acnes tive fecal RT-PCR tests and serology tests.43 is a nonspecific immunostimulant that may enhance cell-mediated immunity, but no effi- Individual Households An exposed, seropositive, ill cat should be cacy against FIP has been documented.58 suspected of having FIP and should be approPrognosis priately evaluated, isolated, and treated. A Because there is no definitive treatment, the healthy cat that has been exposed to a cat that prognosis for FIP is grave.59 Cats with the effu- succumbed to FIP should be carefully monisive form of FIP usually survive less than 2 tored for any clinical signs of illness. FECV can months after presentation and sometimes for remain infectious in the environment for more only days or weeks.1,12 The clinical signs are than 7 weeks.1 Therefore, an owner should devastating and rapidly progressive, so eutha- wait at least 3 months before introducing nasia is justified when the cat has a diminish- another cat into the house.10 ing quality of life.1 The average survival time for cats with noneffusive FIP is unpredictable, Vaccination with clinical signs waxing and waning for An intranasal, temperature-sensitive vaccine that stimulates mucosal immunity against weeks to months.1 FECV was released in 1991. In field trials, the Prevention vaccine appeared to be safe and effective Catteries and Shelters for cats that had not been exposed to FECV Minimizing exposure is the mainstay of pre- before vaccination.61,62 The efficacy of the vacventing the spread of this highly contagious cine is questionable in cats already exposed to disease. Cats should be housed in groups FECV because mucosal immunity cannot proof five or fewer, with no contact between tect against viral mutation.61,62 Unfortunately, groups.10 Sanitation is extremely important, most at-risk kittens are already exposed to and attention should be given to any potential FECV before the vaccine can be administered Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com FREE Feline Infectious Peritonitis CE starting at 16 weeks of age. The American Association of Feline Practitioners lists the FIP vaccine as “not generally recommended.”63 Conclusion FIP is a devastating disseminated vasculitis in cats that results from a complex interaction between a mutated FECV and the feline immune system. The virus is highly contagious, so the disease is more common in multicat households and in purebred cats in catteries. Researchers are continuing to elucidate the complex pathophysiology of the dis- References 1. Addie DD, Jarrett O. Feline coronavirus infections. In: Green CE, ed. Infectious Diseases of the Dog and Cat. 3rd ed. St. Louis: Saunders Elsevier; 2006:88-102. 2. Barr MC. FIV, FeLV, and FIPV. Interpretation and misinterpretation of serological test results. Semin Vet Med Surg (Small Anim) 1996;11(3):144-153. 3. Hartmann K, Binder C, Hirschberger J, et al. Comparison of different tests to diagnose FIP. J Vet Intern Med 2003;17:781-790. 4. Addie DD. Clustering of feline coronaviruses in multicat households. Vet J 2000;159:8-9. 5. Addie DD, Dennis JM, Toth S, et al. Long-term impact on a closed household of pet cats of natural infection with feline coronavirus, feline leukemia virus, and feline immunodeficiency virus. Vet Rec 2000;146:419-424. 6. Pedersen NC, Sato R, Foley JE, et al. Common virus infections in cats, before and after being placed in shelters, with emphasis on FECV. J Feline Med Surg 2004;6:83-88. 7. Dewerchin HL, Cornelissen E, Nauwynck HJ. Replication of feline coronaviruses in peripheral blood monocytes. Arch Virol 2005;150:2483-2500. 8. Vennema H, Poland A, Foley J, et al. Feline infectious peritonitis viruses arise by mutation from endemic feline enteric coronaviruses. Virology 1998;243:150-157. 9. Rohrbach BW, Legendre AM, Baldwin CA, et al. Epidemiology of feline infectious peritonitis among cats examined at veterinary medical teaching hospitals. JAVMA 2001;218(7):1111-1115. 10.Hartmann K. Feline infectious peritonitis. Vet Clin North Am Small Anim Pract 2005;35:39-79. 11.Berg AL, Ekman K, Belak S, et al. Cellular composition and interferon-γ expression of the local inflammatory response in FIP. Vet Microbiol 2005;111:15-23. 12.McReynolds C, Macy D. Feline infectious peritonitis. Part I. Etiology and diagnosis. Compend Contin Educ Pract Vet 1987;19(9): 1007-1016. 13.Dewerchin HL, Cornelissen E, Nauwynck HJ. FIPV-infected monocytes internalize viral membrane-bound proteins upon antibody addition. J Gen Virol 2006;87:1685-1690. 14.Cornelissen E, Dewerchin HL, Van Hamme E, et al. Absence of surface expression of FIPV antigens on infected cells isolated from cats with FIP. Vet Microbiol 2007;121:131-137. 15.Kiss I, Poland AM, Pedersen NC. Disease outcome and cytokine responses in cats immunized with an avirulent FIPV and challengeexposed with virulent FIPV. J Feline Med Surg 2004;6:89-97. 16.Gelain ME, Meli M, Paltrinieri S. Whole blood cytokine profiles in cats infected by FCoV and healthy non-FCoV infected SPF cats. J Feline Med Surg 2006;8:389-399. 17.Takano T, Hohdatsu T, Hashida Y, et al. A “possible” involvement of TNFα in apoptosis induction in peripheral blood lymphocytes of cats with FIP. Vet Microbiol 2007;119:121-131. 18.Dean GA, Olivry T, Stanton C, et al. In vivo cytokine response to experimental FIPV infection. Vet Microbiol 2003;97:1-12. ease, which should eventually lead to more effective methods of prevention and cure. The recent development of RT-PCR testing is providing encouraging results for possible antemortem diagnosis of FIP, although the laboratory providing this test has not published any information regarding its validation methods. Current treatments are crude at best and involve supportive care and, sometimes, blanket suppression of the host’s humoral and cell-mediated immune responses. Minimizing exposure is the best method for prevention of infection. QuickNotes Minimizing exposure is the best method for prevention of infection. 19.Gunn-Moore DA, Caney SMA, Gruffydd-Jones TJ. Antibody and cytokine responses in kittens during the development of FIP. Vet Immunol Immunopathol 1998;65:221-242. 20.Munson L, Marker L, Dubovi E, et al. Serosurvey of viral infections in free-ranging Namibian cheetahs. J Wildl Dis 2004;40(1):23-31. 21.Pesteanu-Somogyi LD, Radzai C, Pressler BM. Prevalence of feline infectious peritonitis in specific cat breeds. J Feline Med Surg 2006;8:1-5. 22.Holst BS, Englund L, Palacios S, et al. Prevalence of antibodies against feline coronavirus and Chlamydophila felis in Swedish cats. J Feline Med Surg 2006;8:207-211. 23.Foley JE, Pedersen NC. The inheritance of susceptibility to feline infectious peritonitis in purebred catteries. Feline Pract 1996;24(1):14-22. 24.Colitz CMH. Feline uveitis: diagnosis and treatment. Clin Tech Small Anim Pract 2005;20(2):117-120. 25.Foley JE, Lapointe JM, Koblik P, et al. Diagnostic features of clinical neurologic FIP. J Vet Intern Med 1998;12:415-423. 26.Harvey CJ, Lopez JW, Hendrick MJ. An uncommon intestinal manifestation of FIP. JAVMA 1996;209(6):1117-1120. 27.Kipar A, Koehler K, Bellmann S, et al. FIP presenting as a tumour in the abdominal cavity. Vet Rec 1999;144:118-122. 28.Siguroardottir OG, Kolbjornsen O, Lutz H. Orchitis in a cat associated with coronavirus infection. J Comp Path 2001;124:219-222. 29.Cannon MJ, Silkstone MA, Kipar AM. 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Evaluation of the safety and efficacy of a modified live FIPV vaccine under field conditions. Feline Pract 1995;23(3):83-88. 63.Richards JR, Elston TH, Ford RB, et al. The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel Report. JAVMA 2006;229(9):1405-1441. Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com FREE Feline Infectious Peritonitis CE 3 CE CREDITS This article qualifies for 3 contact hours of continuing education credit from the Auburn University College of Veterinary Medicine. Subscribers may take individual CE tests online and get real-time scores at CompendiumVet.com. Those who wish to apply this credit to fulfill state relicensure requirements should consult their respective state authorities regarding the applicability of this program. 1. Which is the key inflammatory cell in the development of FIP? a. T cell b. neutrophil c. macrophage d. eosinophil 2. Which breed of cat has a genetic susceptibility for the development of FIP? a. Persian b. Manx c. Siamese d. Ragdoll 3. What percentage of cats exposed to FECV develop clinical FIP? a. <10% b. 20% to 30% c. 50% to 60% d. 90% to 100% 4. What finding on brain magnetic resonance imaging is suggestive of FIP? a. hydrocephalus b. mass lesion in the cerebral cortex c. no visible abnormalities d. cerebral edema c. They may be falsely negative in cats with effusive FIP. d. all of the above 5. What A:G ratio in effusion fluid is suggestive of FIP? a. <0.5 b. 0.6 to 0.8 c. 0.8 to 1.0 d. >1.0 8. Why are indoor cats more at risk for developing FIP than outdoor cats? a. population density b. environmental stress c. shared litterboxes d. all of the above 6. What histologic lesion is not suggestive of FIP? a. perivascular inflammation b. hepatic nodular regeneration c. tissue necrosis d. lymphoid depletion 9. What nondomestic feline is most susceptible to FIP? a. lion b. tiger c. cheetah d. cougar 7. Why should anticoronavirus titers not be used to definitively diagnose FIP? a. They cannot distinguish between FIPV and FECV. b. Laboratory reporting of titers is inconsistent. 10. What type of immune response produces dry FIP? a. strong humoral response b. strong cell-mediated response c. partial cell-mediated response d. INF-γ CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® E9 ©Copyright 2009 Veterinary Learning Systems. This document is for internal purposes only. Reprinting or posting on an external website without written permission from VLS is a violation of copyright laws.