Treatment with subcutaneous GS-441524 in ferrets affected by ferret systemic coronavirus-associated disease: seven cases (2021-2024).

Objectives: Ferret systemic coronavirus-associated disease is usually fatal in ferrets, and no specific treatments have been available to date. This disease shares similarities with feline infectious peritonitis, which has been successfully treated with antivirals in recent years. This report describes the effects of GS-441524 in ferrets with naturally acquired ferret systemic coronavirus-associated disease.

Materials and methods: Seven ferrets with ferret systemic coronavirus-associated disease confirmed by immunohistochemistry on biopsy samples were treated with subcutaneous GS-441524. Clinical signs and blood analysis including protein electrophoresis were periodically evaluated. Comorbidities and adverse effects during treatment were also recorded. Post-mortem examination with histopathological evaluation was conducted on the deceased ferrets.

Results: Clinical signs included respiratory, gastrointestinal, ocular and neurological disturbances, weight loss, lethargy and organomegaly. Initial hypergammaglobulinaemia and low albumin-to-globulin ratio were present in all ferrets. The dose range was 2 to 15 mg/kg/sc SID, two or three times per week. Total treatment duration ranged from 24 to 103 weeks. The clinical condition of all ferrets rapidly improved with increasing body weight after treatment initiation. Haematocrit, albumin and thrombocyte count normalised during the course of antiviral therapy, and plasmatic gamma globulin concentrations returned to normal in six of the seven ferrets. Survival time from the initiation of therapy ranged from 36 to 175 weeks. Three ferrets died; no pyogranulomatous inflammatory lesions compatible with ferret systemic coronavirus-associated disease were noted, and immunohistochemistry for coronavirus antigens was negative in all three.

Clinical significance: This study suggests injectable GS-441524 could be an effective treatment to improve the clinical status, haematological parameters and survival times of ferrets affected with ferret systemic coronavirus-associated disease.