FVR Research and Development

Timeline and benchmarks

Feline viral rhinotracheitis (FVR), a common and ubiquitous upper respiratory infection (URI), was the target of Sass & Sass, Inc. initial research and development. The disease is caused by a herpesvirus known as feline rhinotracheitis virus (FRV). The virus is easily transmitted between the cats, and and the disease is ubiquitous, especially in multi-cat environments.

Polyprenyl Immunostimulant™ Research and Development timeline & benchmarks (FRV.)

• 2006 through 2013

Sass & Sass, Inc. conducted three clinical double-blinded, randomized, placebo-controlled clinical trials of the efficacy of Polyprenyl Immunostimulant (PI, PPI) in FVR in collaboration with Dr. A.M. Legendre of the University of Tennessee-Knoxville (UTK) as Principal Investigator. The studies were performed in specific pathogen-free cats by the team of UTK College of Veterinary Medicine at the Veterinary Research Facility.

• 2009 - 2010

Sass & Sass, Inc. carried out a field safety study in compliance with Title 9 CFR and approved by State Veterinarians of the states where the study was conducted. This study included 390 owned cats of various breeds, sex, and age. The cats were seen by their veterinarians who provided their assessment of the safety.

Results of the studies were published in 2017 by A.M. Legendre et al. You may download the paper from the publisher's website: Polyprenyl Immunostimulant in Feline Rhinotracheitis: Randomized Placebo-Controled Experimental and Field Safety Studies.(1)

• 2010 - Ongoing

Since 2009, Sass and Sass, Inc. have been collecting case reports on treating chronic rhinotracheitis in cats.

• 2012

Based on the results of several USDA-compliant studies, Sass & Sass, Inc. the US Department of Agriculture (USDA) issued a conditional license to Sass & Sass, Inc. and Polyprenyl Immunostimulant. The licensing followed a rigorous, extensive review of all data supporting the product safety and efficacy Following the USDA acceptance, Sass & Sass, Inc. continues research on the product en route to the full license.

• 2017

Dr. M.R. Geist summarized his trials in a patient with a chronic disease. The manuscript is in progress.

Dr. Diane Hendrix of UTK completed a clinical safety study on the ocular topical application of Polyprenyl Immunostimulant. The results were presented at the meeting of the American College of Veterinary Ophthalmologists in Baltimore, MD in October 2017.

• 2019

Sass and Sass, Inc. conducted and completed a field study in collaboration with the Planned Pethood facility in VA.

• 2018 - 2020 and beyond

Since 2018, Sass and Sass have been planning a field study of Polyprenyl Immunostimulant to treat ocular herpetic disease. We hoped to complete the trials in 2020, but COVID-19 intervened with the plans.

(1) Results of research published in peer-reviewed journals cannot be used to substantiate health claims and do not substitute government regulated trials.

(2) Please note that under their ethics in clinical trials guidelines, Sass & Sass, Inc. believes that study animals should not be euthanized but should be provided a chance through adoption and be treated like any owned pet. Sass & Sass, Inc. does not purposely infect animals with fatal diseases and does not support any research that does.


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