Hearsay is that which was heard from others and is unsubstantiated. In this case it is the reporting of another person’s words which quote the words of others. Without substantiation at this point it is hearsay. Granted however there are certain exceptions. The definition is not ‘black and white’ hearsay can be called second-hand evidence or rumour.
During the OJ Simpson Trial, though his wife’s diaries contained statements about physical abuse they were inadmissible as evidence.
The Federal Rules of Evidence are given here where the parties may well argue before the Judge whether evidence of this sort can be admitted or not.
http://legal-dictionary.thefreedictionary.com/Federal+Rules+of+Evidence
In the instance I quoted it was about the publicist who reported one person speaking to another. That is unlikely to be admissible.
As for the dogs, there would be film evidence and first hand reports of the Scientists to can identify the piss or saw the dog doing it (and also identify it forensically). There would be more pieces to fit together.
One person reporting what one person said to another and there is nothing else there is little to go on.
There are of course various circumstances where a court or an investigative committee could accept or reject hearsay.