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Wet/Ocular FIP

Lung Lesions
Viral Resistance to GS
GC376/GS441524 Therapy

Boris, a 3.5‐month‐old intact male Maine Coon cat obtained from a breeder, presented with lethargy, inappetence, abdominal ascites, coughing, anemia and neutrophilia.  No chemistry panel was done at diagnosis.


Boris was treated at 6 mg/kg GS-441524 SC SID for 8 weeks.   Six weeks into treatment, xray revealed nodules in his lungs, and at 8 weeks hyperglobulinemia persisted. The dosage of GS-441524 was then increased to 8 mg/kg SC SID for 4 weeks. Only minor improvement in bloodwork and xrays were noted, and the dosage of GS-441524 was increased to 12 mg/kg SC SID for 4 weeks, followed by an increase to 17 mg/kg for 11 weeks, 25 mg/kg for 4 weeks, and 30 mg/kg for 4 weeks.


At 25 weeks into treatment, ultrasound noted pleural irregularities on the left side, and xrays showed no improvement in lung nodules.  Additionally uveitis and retinal detachment were noted in the right eye. Lung aspirates were obtained, showing inflamation consistent with FIP.

Viral resistance to GS-441524 was suspected.


At 33 weeks into treatment, 20 mg/kg SC BID GC376  was added to the regimen, and the combined GS-441524 and GC376 therapy was continued for 12 weeks.  Increased activity was noted within days of commencing therapy with GC376.  Within 5 weeks, weight gain accelerated, coughing decreased, and energy level increased.   Bloodwork showed improvement in the A/G ratio and chest radiographs showed reduction in nodules in the lungs. Uveitis was also resolved.


After 84 days of GC376 and GS-441524 combined antiviral therapy, treatment was stopped. The A/G ratio was 0.85 and Boris appeared clinically normal.  Boris is currently 1 year post treatment with no signs of relapse.


Before Treatment



After Treatment

6 weeks 

GS-441524 therapy

38 Weeks total

5 weeks after starting GC376 Treatment

12 Weeks

GS-441524 therapy

3 Months Post-treatment

GC376 + GS-441524 Treatment

21 Weeks

GS-441524 Treatment

10 Months Post-treatment

GC376 + GS-441524 Treatment

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