In fact, one was published just this year. http://www.medwelljournals.com/abstract/?doi=javaa.2013.181.185
From the study:
Here's an in vitro study from 2003: http://www.ncbi.nlm.nih.gov/pubmed/12950656
I've been giving Billy various doses of L-lysine to get him to stop sneezing. We got his runny eyes under control with lysine, but he remained very sneezey.
When I found the information on Lactoferrin in regards to herpes (I didn't have the 2013 study at the time, but human study papers), I added Bovine Lactoferrin to his supplement regimen.
I didn't track how long it took to take effect. I just noticed one day that he rarely sneezes any longer. I asked Gary if he'd heard Bill sneezing much, and upon reflection, he said "I can't remember the last time I heard him sneeze."
I confirmed with Jarrow that their lactoferrin is Bovine Lactoferrin. This is important, because lactoferrin is also made from transgenically modified rice that produce human lactoferrin.
I am giving my cats 250mg daily, split into two doses, 125mg in the morning and 125mg in the evening. The Jarrow lactoferrin comes in 250mg capsules: easy to open and sprinkle on half a capsule and mix into food. I did not buy the 2013 paper to see the doses used for either lysine or lactoferrin.
It is palatable to all of my cats, some of whom are very picky (it has so many benefits, I give it to all of them now).