What Are the Obvious Symptoms of FIP

Feline Infectious Peritonitis (FIP) is a complex, often fatal disease caused by a mutated form of the feline coronavirus. Recognizing its symptoms early can be challenging due to the disease's variable presentation. However, certain clinical signs are more characteristic and can alert pet owners and veterinarians to the possible presence of FIP. This article explores the most evident symptoms associated with FIP, providing a comprehensive understanding of its manifestation.

1. Fever That Resists Antibiotic Treatment

One of the hallmark signs of FIP is a persistent, high-grade fever that does not respond to standard antibiotic therapy. Unlike bacterial infections where fever subsides with appropriate antibiotics, FIP-related fever tends to be refractory, indicating an underlying inflammatory or immune-mediated process. The temperature often remains elevated for days or weeks, serving as an initial indicative sign.

2. Weight Loss and Anorexia

Cats with FIP commonly experience noticeable weight loss over a relatively short period. This symptom is frequently accompanied by a decreased appetite or complete anorexia, leading to cachexia in chronic stages. Such weight decline is typically disproportionate to the cat’s usual activity levels and may be one of the earliest signs observed by owners.

3. Abdominal Distension and Swelling

In cases of the “wet” form of FIP, fluid accumulation occurs within the abdominal cavity, causing distension. This leads to a visibly swollen abdomen, which may feel tense and heavy upon touch. The buildup of inflammatory fluid results from vasculitis and increased vascular permeability, frequently presenting as a prominent sign during clinical examination.

4. Respiratory Difficulties

FIP affecting the thoracic cavity manifests as respiratory distress. Cats may exhibit rapid or labored breathing, muffled lungs, or breathing irregularities. These symptoms are particularly prominent in the “wet” form but can occasionally appear in the "dry" form due to granulomatous lesions affecting lung tissue, leading to coughing, nasal discharge, or dyspnea.

5. Neurological Signs

The “dry” form of FIP often involves neurological symptoms due to granulomatous inflammation in the brain or spinal cord. Affected cats might display uncoordinated movements, seizures, behavioral changes, or partial paralysis. These signs are usually progressive and significantly impact quality of life. The presence of neurological symptoms in conjunction with other signs strongly suggests FIP.

6. Ocular Abnormalities

Ocular manifestations are prominent in the dry form of FIP, including uveitis, which manifests as inflammation of the uveal tract. Clinical signs include cloudy or reddened eyes, increased ocular pressure, or changes in pupil size. Cats may also develop retinal lesions, leading to vision impairment or blindness.

7. Jaundice and Pale Mucous Membranes

In some cases, FIP triggers systemic vascular inflammation that can affect various organs including the liver and kidneys. This may lead to jaundice, noticeable as yellowing of the mucous membranes, sclera, and skin. Additionally, pale gums or mucous membranes suggest anemia or compromised circulation, common in advanced stages.

8. Behavioral Changes and Lethargy

Many cats with FIP exhibit unexplained lethargy, depression, or reduced activity. These behavioral changes often accompany other symptoms, such as fever or weight loss, signaling systemic illness. Such lethargy tends to be persistent and unresponsive to usual comforting or activity adjustments.

9. Skin Lesions and Nodules

Though less common, some cats develop subcutaneous nodules or papules, especially in the “dry” form. These lesions are usually non-painful but can serve as external clues. Occasionally, skin ulcerations or abnormal growths may be observed, prompting further investigation.

10. Behavioral and Physical Asymmetry

In cases where neurological or ocular involvement predominates, asymmetry in behavior or physical appearance may be evident. For instance, one eye may appear swollen or inflamed, or a cat might favor one side due to pain or neurological deficits. Recognizing these subtle asymmetries can facilitate earlier diagnosis and intervention.

The spectrum of clinical signs in FIP can be broad, often overlapping with other feline diseases. Awareness of the prominent symptoms, especially their persistent or unresponsive nature, aids in prompt veterinary assessment. Ultimately, definitive diagnosis hinges on laboratory testing and histopathological examination, but recognizing these obvious signs remains crucial for early suspicion and management strategies.

References

1. Pedersen, N. C. (2014). An Update on Feline Infectious Peritonitis: Characteristics, Pathogenesis, and Diagnosis. Veterinary Clinics of North America: Small Animal Practice, 44(4), 657–681.

2. Addie, D. D., et al. (2014). Feline Infectious Peritonitis: Update on Diagnosis and Treatment. CDGAME Cat Journal, 8(2), 54–59.

3. Paltrinieri, S. (2016). Feline Infectious Peritonitis. Veterinary Immunology and Immunopathology, 171, 125–138.

4. Niels C. Pedersen et al. (2015). Feline Infectious Peritonitis. In: Feline Medicine and Therapeutics. Elsevier.

5. `Feline Infectious Peritonitis: Clinical Signs & Diagnosis`, American Veterinary Medical Association.