Disease Description:
FIP is a complex disease of cats caused by FIPV, a coronavirus related to transmissible gastroenteritis virus (TGEV) of pigs, enteric coronavirus of dogs, and respiratory coronavirus of humans.1
Although scientists do not completely understand its pathogenesis, they believe that FIP is an immune-mediated disease. FIPV first multiplies in epithelial cells of the upper respiratory tract and intestine.2 Clinically apparent FIP occurs after the virus crosses the mucosal barrier and spreads throughout the cat in infected macrophages and monocytes.
Primary FIP may be mild, consisting of fever and a slight nasal and ocular discharge. While most cats with the primary form of FIP recover, others become chronically infected carriers. Secondary FIP may develop following primary infection and appears in 2 forms: (1) Effusive or wet form, characterized by peritonitis and pleuritis with ascites and pleural effusion, and (2) Noneffusive or dry form, characterized by granulomatous inflammation of various organs and little or no exudate.3,4 Both forms may appear together. Once clinical symptoms occur, FIP usually takes a fatal course. The most commonly diagnosed clinical manifestation is accumulation of fluid within the peritoneal cavity with progressive, painless enlargement of the abdomen. Infected animals also may experience difficult breathing, have an elevated temperature, appear depressed, and lose weight. Other clinical symptoms, such as ocular involvement, disseminated intravascular coagulation, and renal involvement, are observed occasionally.5 Exudate obtained from body cavities by paracentesis appears pale yellow or golden in color and is relatively clear. Hemograms of cats with FIP typically indicate a stress response. There may be a mild to moderate anemia and leukocytosis attributed to an increased percentage of neutrophils.
FIP most frequently occurs in young cats between the ages of 6 months and 2 years of age. Incidence of disease is also higher in older cats, between 11 and 15 years of age.
Safety And Efficacy:
Comprehensive tests were conducted to demonstrate the safety of Fellocell® FIP.
In these tests, Fellocell® FIP did not cause illness in cats when administered intranasally. It did not cause illness in cats infected with feline leukemia, in cats exposed to feline enteric coronavirus, in dexamethasone-immunosuppressed cats, in nonvaccinated cats that survived FIP challenge, or in kittens.
Fellocell® FIP did not interfere with the development of an antibody response to any of the following feline vaccine antigens: feline leukemia virus, feline rhinotracheitis virus, feline calicivirus, feline panleukopenia virus, and Chlamydia psittaci. Conversely, none of these vaccine antigens interfered with the immunogenicity of Fellocell® FIP.
Efficacy of Fellocell® FIP also was demonstrated in a series of tests.
In the first of 2 immunogenicity studies, 20 seronegative cats were vaccinated with a 2-dose primary regimen (given 3 weeks apart). All vaccinates developed FIPV antibody titers, and 17 of the 20 (85%) survived an FIPV challenge that caused FIP in 12 of 12 (100%) nonvaccinated controls. Ten of the 12 controls died. Sixteen of the 17 (94%) vaccinated cats that survived the first challenge survived a second challenge, which caused FIP in 4 of 6 nonvaccinated controls. In the second immunogenicity study, 20 of 20 seronegative cats developed FIPV antibody titers after primary vaccination with 2 doses given 3 weeks apart. Fifteen of 20 (75%) vaccinates were protected against a challenge of immunity in which 7 of 10 (70%) nonvaccinated control cats died of FIP. All but 1 of the surviving vaccinated cats from the first challenge survived a second challenge, which killed 6 of 6 nonvaccinated controls.
In addition to protecting against homologous challenge, Fellocell® FIP also protected cats against a heterologous challenge strain (WSU-1146). Clinical FIP symptoms of vaccinated cats were significantly lower (P<0.05) than symptoms of control cats following WSU-1146 challenge. Eight of 10 (80%) vaccinated cats survived a challenge of immunity with the WSU-1146 strain of FIP in which 3 of 5 (60%) nonvaccinated controls died of FIP.
References:
1. Lutz H, Hauser B, Horzinek MC: Feline infectious peritonitis (FIP)-the present state of knowledge. J Sm An Pract 27:108-116, 1986.
2. Stoddart ME, Gaskell RM, Harbour DA, et al: The sites of early viral replication in feline infectious peritonitis. Vet Microbiol 18:259-271, 1988.
3. Holmberg CA, Gribble DH: Feline infectious peritonitis. Diagnostic gross and microscopic lesions. Feline Pract 3:11-14, 1973.
4. Montali RJ, Strandberg JD: Extraperitoneal lesions in feline infectious peritonitis. Vet Path 9:109-121, 1972.
5. Weiss RC, Dodds WJ, Scott FW: Disseminated intravascular coagulation in experimentally induced feline infectious peritonitis. Am J Vet Res 41(5):663-671, 1980.
