Dry FIP in Cats: Symptoms, Diagnosis, and Treatment
- CURE FIP™ USA
- Sep 3, 2023
- 7 min read
Updated: Jul 30
Summary
Dry FIP is a form of Feline Infectious Peritonitis without fluid buildup, primarily affecting internal organs, the nervous system, or the eyes.
It’s caused by a mutation of the feline coronavirus (FCoV), which triggers a severe inflammatory response in the cat’s body.
Symptoms vary widely and may include neurological signs (e.g. seizures, wobbly movements), ocular changes (cloudy or dilated pupils), or organ-specific signs like jaundice and enlarged lymph nodes.
Dry FIP is harder to diagnose than wet FIP because it lacks obvious fluid buildup; vets rely on clinical signs, blood tests (notably low A/G ratio), and sometimes imaging or eye exams.
A definitive diagnosis often comes from excluding other illnesses, such as lymphoma, toxoplasmosis, or fungal infections.
GS-441524 is currently the most effective treatment for dry FIP, especially in neurological or ocular cases, due to its ability to cross the blood-brain and blood-ocular barriers.
Early diagnosis and proper antiviral treatment significantly increase a cat’s chance of survival and full recovery.
Understanding Dry FIP: A Hidden and Dangerous Form of Feline Infectious Peritonitis
Feline Infectious Peritonitis (FIP) is one of the most feared viral diseases in cats, historically regarded as a death sentence. While the more widely recognized "wet form" involves fluid accumulation in the chest or abdomen, Dry FIP is a more insidious and often misdiagnosed variant.
Dry FIP, also known as non-effusive FIP, does not produce fluid buildup. Instead, it manifests through granulomatous lesions in various organs, especially the eyes and central nervous system (CNS), making it harder to detect. Because of its vague and varied clinical signs, it often delays diagnosis and treatment.
The Root Cause: Mutation of Feline Coronavirus
FIP begins with feline enteric coronavirus (FECV), a benign virus present in 80-90% of multi-cat environments (Pedersen, 2009). In rare cases, this virus mutates inside the cat's body, enabling it to infect macrophages, triggering systemic inflammation and immune-mediated damage.
Once mutated, the virus targets different organs. In Dry FIP, the damage is localized and often affects:
Eyes (ocular FIP): inflammation of the iris, anterior uveitis, retinal detachment
Brain and spine (neurological FIP): seizures, ataxia, nystagmus, behavior changes
Organs: liver, kidneys, lymph nodes, resulting in systemic signs
Felten & Hartmann (2019) and Addie et al. (2022) support that these organ-specific lesions are typical of Dry FIP.
Signs and Symptoms of Dry FIP
Dry FIP symptoms depend on which organs are affected, but common clinical signs include:
Ocular Symptoms:
Anisocoria (unequal pupil size)
Sudden vision loss
Cloudy or inflamed eyes (uveitis)
Retinal hemorrhage or detachment
Neurological Symptoms:
Head tilt
Ataxia (loss of coordination)
Seizures
Circling or falling to one side
Personality or behavior changes
General Symptoms:
Fever unresponsive to antibiotics
Weight loss
Lethargy
Poor appetite
These signs often progress gradually and may be misdiagnosed as toxoplasmosis, lymphoma, or other infections.
Diagnosing Dry FIP: Challenges and Tools
Diagnosing Dry FIP is complex and typically requires a combination of clinical suspicion, exclusion of other conditions, and supportive laboratory tests:
Bloodwork: shows elevated total protein, low albumin, anemia, or lymphopenia
A:G ratio: a low albumin-to-globulin (A:G) ratio (<0.4) is a red flag for FIP (Hartmann et al., 2022)
Ocular examination: reveals retinal or iris inflammation
Neurological exams: can identify central nervous system involvement
PCR testing: can detect FCoV RNA in cerebrospinal or aqueous fluid
Imaging: MRI or CT scans may reveal CNS lesions
While histopathology remains the gold standard, real-world diagnosis often combines symptoms with supportive lab data.
Neurological FIP: The Most Complex Form of Dry FIP
Neurological FIP is the most severe form of dry FIP and can develop when the virus penetrates the central nervous system (CNS). According to Pedersen (2009), CNS involvement occurs in roughly 5–10% of FIP cases, although it may be underdiagnosed due to its subtle and diverse clinical manifestations.
Symptoms of Neurological FIP
Neurological FIP can affect multiple parts of the nervous system. Common signs include:
Ataxia (wobbly or uncoordinated walking)
Seizures
Head tremors or twitching
Nystagmus (involuntary eye movement)
Abnormal behavior or personality changes
Incontinence or difficulty using the litter box
Spinal pain or sensitivity
These symptoms may appear gradually or suddenly and often worsen over time. Unlike ocular FIP, neurological FIP significantly affects quality of life and requires immediate intervention.
Diagnostic Imaging
MRI and CT scans may reveal CNS inflammation, ventricular enlargement, or other abnormalities suggestive of neurological FIP. Cerebrospinal fluid (CSF) analysis can also detect elevated protein levels or the presence of coronavirus RNA via RT-PCR.
Reference: Dickinson PJ, et al. (2020). “Clinical and Diagnostic Features of Neurologic Feline Infectious Peritonitis.” Journal of Feline Medicine and Surgery, 22(11): 1049–1061.
How Dry FIP Is Diagnosed
Diagnosing dry FIP is more challenging than the wet form, as there is no effusion to sample. Diagnosis is typically based on:
Clinical symptoms (neurological or ocular involvement)
Blood tests: including elevated total protein, hyperglobulinemia, and anemia
Imaging: to detect organ granulomas or CNS inflammation
RT-PCR or immunohistochemistry: on biopsy or cerebrospinal fluid
Unfortunately, a definitive diagnosis can often only be made post-mortem. However, veterinarians increasingly rely on pattern recognition and exclusion of other diseases to begin presumptive treatment when FIP is strongly suspected.
How GS-441524 Treats Dry FIP
The breakthrough antiviral GS-441524, a nucleoside analog, works by inhibiting the replication of feline coronavirus inside cells. While initially developed as a precursor to Remdesivir, GS-441524 has shown remarkable efficacy in treating both wet and dry forms of FIP.
Clinical Evidence
A landmark study by Pedersen et al. (2019) treated 31 cats with GS-441524 at 4–10 mg/kg for 12 weeks. The success rate was over 80%, with most cats making a full recovery. Subsequent clinical data show that higher doses (up to 15 mg/kg) and longer durations are needed for neurological cases.
Reference: Pedersen NC, et al. (2019). “Efficacy and Safety of the Nucleoside Analog GS-441524 for Treatment of Cats with Naturally Occurring Feline Infectious Peritonitis.” Journal of Feline Medicine and Surgery, 21(4): 271–281.
Dosage Guidelines
Ocular FIP: 8–10 mg/kg once daily
Neurological FIP: 12–15 mg/kg once daily, for 84+ days
Treatment may be given as an injection or oral formulation, depending on the cat’s condition and tolerance.
At CureFIP™, both injectable and oral GS-441524 formulations are available, including specific guidance for ocular and neurological FIP cases. Our support team can help determine the right dosage for your cat’s condition.
What to Expect During Treatment
Cats with dry FIP, especially those with neurological symptoms, may take longer to respond to treatment than those with wet FIP. Here’s what pet owners should monitor:
First 1–2 Weeks: Reduction in fever, improved appetite, better mobility
Weeks 3–6: Gradual return of energy, stabilization of weight
Weeks 6–12: Resolution of ocular and neurological symptoms, if reversible
Supportive Care Is Key
Treatment for dry FIP should be accompanied by supportive care:
Anti-inflammatory medications (under vet supervision)
Supplements to support immune health and organ function
Regular bloodwork to monitor treatment response
Hydration and nutrition support
Prognosis: Hope Is Real
While dry FIP used to carry a grim prognosis, outcomes today are significantly better with timely GS-441524 treatment:
Ocular FIP: Excellent prognosis when treated early
Neurological FIP: Guarded but improving — many cats fully recover with high-dose, long-term treatment
Thousands of cats with dry FIP have gone on to live healthy, normal lives.
When to Suspect Dry FIP
Contact your veterinarian or FIP support group if your cat shows:
Persistent fever and lethargy
Sudden vision changes or abnormal pupils
Uncoordinated walking, seizures, or tremors
Unexplained weight loss or enlarged lymph nodes
Early intervention is critical. Don’t wait for symptoms to worsen.
Need Help Now?
If your cat is showing signs of dry FIP, you don’t have to face it alone. Our team is ready to support you with:
Personalized guidance based on your cat’s symptoms
Treatment kits tailored to ocular or neurological FIP
Vet consultation and ongoing support throughout recovery
📱 Message us on WhatsApp today and speak with a real advisor who can guide you through the next steps.
References for Dry FIP Information
Pedersen NC (2014, 2019) – Clinical studies on FIP pathogenesis and GS-441524 treatment→ Source: Journal of Feline Medicine and Surgery (JFMS): https://journals.sagepub.com/home/jfm
Tasker, S. (2018) – Feline infectious peritonitis: Diagnosis and treatment updates→ Source: JFMS Review Article: https://journals.sagepub.com/doi/10.1177/1098612X18758592
Addie, D. et al. (2022) – Global guidelines on FCoV and FIP management→ Source: ABCD (Advisory Board on Cat Diseases): https://www.abcdcatsvets.org
Drechsler, Y. et al. (2011) – FCoV replication and viral mutation pathways→ Source: Veterinary Microbiology Journal
GIH, UC Davis (2020) – Neurological and ocular manifestations of dry FIP→ Source: UC Davis School of Veterinary Medicine: https://www.vetmed.ucdavis.edu
Izes AM et al. (2020) – Diagnostic challenges of non-effusive (dry) FIP→ Source: Pathogens Journal: https://www.mdpi.com/2076-0817/9/11/902
CureFIP Clinical Database (2021–2024) – Real-world treatment outcomes using GS-441524→ Internal reports & post-treatment case studies: https://www.curefipusa.com/
Frequently Asked Questions
Q: What is dry FIP in cats?
A: Dry FIP is a form of Feline Infectious Peritonitis without fluid buildup. It causes chronic inflammation in organs like the eyes, brain, liver, or lymph nodes.
Q: What are the early signs of dry FIP?
A: Common early signs include persistent fever, weight loss, lethargy, eye inflammation, and subtle neurological issues like tremors or ataxia.
Q: Can dry FIP be cured?
A: Yes. GS-441524 has been proven effective in treating dry FIP, especially with early diagnosis and correct dosing.
Q: Is dry FIP contagious to other cats?
A: No. Only the original feline coronavirus (FCoV) is contagious. FIP itself is caused by a mutation that is not transmissible.
Q: How is dry FIP diagnosed?
A: Diagnosis is typically clinical, supported by blood tests (A/G ratio, globulins), imaging, and the presence of neurological or ocular symptoms.
Q: Does dry FIP always involve the nervous system?
A: Not always, but many dry FIP cases progress to involve the brain (neuro FIP) or eyes (ocular FIP).
Q: How long does dry FIP treatment take?
A: Standard treatment lasts 84 days with GS-441524. Neurological or ocular cases may need higher doses.
Q: Is a biopsy or PCR test required to confirm dry FIP?
A: Not necessarily. Many diagnoses are clinical, and positive response to GS-441524 often supports the diagnosis in practice.
Q: Can a cat with dry FIP live a normal life after treatment?
A: Yes. Thousands of cats treated with GS-441524 go on to live long, healthy lives with no relapse.
Q: Where can I get GS-441524 for dry FIP?
A: CureFIP™ provides trusted access to GS-441524 under compassionate use for FIP-affected cats.