Feline Infectious Peritonitis (FIP) is a disease with an almost 100% fatality rate, which is believed to occur when a non-pathogenic enteric coronavirus (FECV) in cats mutates into a virulent virus (FIPV) within the body. There are theories that suggest either FECV suddenly mutates into a stronger virus or that coronaviruses ranging from low to high virulence exist widely.
Since the inflammation of blood vessels causes various symptoms, it is said that the behavior of this virus is similar to coronavirus in humans.
FECV prevalence is around 40% in outdoor cats and around 90% in multi-cat environments. Therefore, it might be safe to assume that most cats acquired from breeders or pet shops carry FECV.
Even if a cat carries FECV, many cats remain healthy throughout their lives.
However, if it mutates into FIPV for some reason, the virus proliferates in organs throughout the body, leading to the development of FIP.
### 【Age of Onset and Breeds Prone to FIP】
FIP is said to be more commonly seen in cats under three years of age (particularly those aged 4-16 months) and in senior cats.
Reports indicate that over 70% of FIP cases occur in cats under one year old. This is thought to be because the immune system is still immature in younger cats, and it becomes less effective in seniors.
Also, purebred cats (especially Asian breeds like Himalayans and Birmans) are reported to be more susceptible to FIP than mixed-breed cats.
### 【Transmission Routes】
Since FIPV itself is very weak outside the body and quickly becomes inactive, there is no current evidence of FIPV itself infecting other cats (horizontal transmission).
FECV is transmitted via feces, which means that sharing litter boxes, grooming fur contaminated with feces, or licking saliva mixed with feces can cause infection.
Factors contributing to the mutation from FECV to FIPV include:
– Age (young cats with underdeveloped immune systems or senior cats with weakened immune systems)
– Multi-cat environments
– Stress
– Diseases that cause immune abnormalities such as Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV)
– Treatment with immunosuppressive drugs
### 【Symptoms and Types of FIP】
Initial symptoms include:
– Decreased appetite
– Weight loss
– Fever
– Gastrointestinal symptoms like vomiting and diarrhea
Since these are not specific to FIP and can occur in various diseases, it is often difficult to recognize FIP at this stage.
FIP can be classified into the following three types based on additional symptoms observed beyond the initial ones:
#### ① Wet Type (Exudative)
Most cases of FIP are the wet type.
Symptoms include dehydration, anemia, abdominal swelling due to ascites, breathing difficulties due to pleural effusion, and jaundice.
The ascitic and pleural fluid removed is usually yellow and viscous.
Most cats die within two weeks to one month after diagnosis, and the average life expectancy is said to be 7-10 days.
#### ② Dry Type (Non-exudative)
This type is characterized by the formation of granulomas in various organs such as the kidneys, liver, brain, and eyes.
Symptoms vary depending on the affected organs. If the brain is affected, neurological symptoms like seizures, behavior changes, abnormal behavior, difficulty walking, paralysis of elimination, or facial nerve paralysis may be observed.
#### ③ Mixed Type
This type combines features of both wet and dry types and progresses more slowly than the wet type alone.
### 【Diagnosis of FIP】
The diagnosis of FIP is mostly confirmed by detecting FIPV from blood, pleural fluid, or ascitic fluid through PCR testing.
For the wet type, diagnosis is relatively straightforward with tests on pleural/ascitic fluids and blood tests showing an Albumin:Globulin ratio (A:G ratio) of less than 0.8, and elevated total protein levels.
For the dry type, there is no definitive test for a 100% FIP diagnosis. Diagnosis often involves a combination of age, onset progression, symptoms, blood tests, imaging, antibody titers, and serum protein fractions.
### 【General Treatment for FIP】
Currently, there is no established effective treatment for FIP. Treatment is limited to symptomatic therapy to alleviate symptoms.
### Types of Symptomatic Therapies
– Steroids
– Interferon
– Immunosuppressants
– Antibiotics
– IV Drip
These are some of the symptomatic therapies available.
【Other Treatments for FIP】
In recent years, treatments for FIP have been evolving significantly.
However, since these treatments involve unapproved drugs within Japan, they can be costly and vary widely in safety that has not yet been fully established. Therefore, the decision to use them lies with the pet owners.
There have been cases where alternative therapies combined with conventional treatments and supplements combined with conventional treatments have achieved remission. Nonetheless, these do not compare to the remission rates of unapproved drugs within Japan.
The following introduces treatment options other than conventional treatments.
①GS-441524
This is a precursor to GS-5734, an antiviral agent that inhibits RNA virus replication in humans, and it has shown potential for high antiviral efficacy against FIPV.
A paper published in 2019 by Dr. Pedersen’s group at the University of California, Davis, stated that treatment with GS-441524, a novel substance that inhibits replication synthesis, achieved more than 80% long-term survival.
Previously, only injectable forms were available. However, since last year, an oral formulation of GS-441524 can be purchased in the UK and can now be imported into Japan for use in animals.
②MUTIAN (currently Xraphconn)
This drug was developed by China’s MUTIAN company as a GS-441524 analogue. While MUTIAN was available in capsule form, the current Xraphconn (Lapcon) comes in tablet form.
It appears to be more widely used compared to GS among unapproved FIP drugs in Japan. However, the cost is higher than GS, and it can vary depending on the type and severity of FIP and the weight of the animal, with total treatment costs ranging from 1 to 2 million yen or more.
③CHUANFUNING (CFN)
This drug is manufactured by a company founded by former employees of MUTIAN and is said to have the same manufacturing method and ingredients as the previously circulated MUTIAN.
The number of cases treated with CFN is increasing, and treatment results comparable to MUTIAN have been confirmed. When comparing the published data, CFN seems to have a slightly higher improvement rate than Xraphconn.
The above mentioned options ①～③ are unapproved drugs within Japan that are currently widely adopted. As a standard method, treatment is administered for 84 days, followed by a three-month observation period, after which tests are conducted to confirm whether remission has been achieved.
④Remdesivir
This is a treatment for the human novel coronavirus. It has also begun to be used for FIP treatment in Australia and the UK on a case-by-case basis, with reports of an 85-90% efficacy rate in over 400 cases.
The International Society of Feline Medicine (ISFM) has introduced a protocol for FIP treatment that combines GS-441524 and Remdesivir. In Australia, there has been a treatment record of approximately 500 cats from October 2020 to November 2021.
⑤Molnupiravir
This is a drug that has begun to be used domestically for the human novel coronavirus and has also shown reports of efficacy against FIP.
It costs about one-tenth of GS-441524, but its safety for use in cats has not yet been confirmed, and it is less effective in terms of anti-FIP viral activity compared to GS.
Additionally, Molnupiravir poses concerns about mutagenicity and carcinogenicity, making it unlikely to be a first-choice medication at present.
In the future, it may be used for animals that have developed resistance to GS formulations.
⑥5-Aminolevulinic Acid (5-ALA)
In 2021, there were reports from a collaborative study between Kitasato University and Neopharma Japan confirming the suppressive effect of 5-Aminolevulinic Acid (5-ALA) on the replication of feline coronavirus.
Since these results are still from laboratory experiments, its use as a therapeutic drug is yet to come. However, since the safety of the ingredient in the body is already established, there is a reasonable expectation that it may be approved as a treatment for FIP in the future.
7. Homeopathy and Chinese Medicine
There are cases where using a combination of conventional treatment and alternative therapies has led to remission or symptom control.
The types of homeopathy and Chinese medicine prescribed can vary depending on the treating doctor, so specific types are not mentioned here.
8. Supplements
To combat the virus, it is crucial to have a properly functioning immune system.
Therefore, using supplements that support the immune system can be expected to help manage symptoms.
In cases where there is an accumulation of pleural effusion or ascites, a deficiency of amino acids in the body can occur. Thus, BCAA supplementation is recommended. Additionally, supporting liver function can promote albumin production, so liver care supplements (such as placenta) are also advised.
Considering that unapproved drugs are metabolized in the liver, providing liver care can support the body during treatment with unapproved drugs.
Furthermore, since FIP presents systemic symptoms due to viral-induced vasculitis, it is recommended to take EPA/DHA for inflammation care.
Although new treatments are emerging, they are still not widely common, and the treatment costs are high, so not all cats are able to receive these treatments.
I earnestly hope that one day, FIP treatments will become equally accessible to all cats.
