I have no idea where to look for the answer, so here I am 
Police are summoned to what appears to be a bloody crime scene, no body. How long would it take them to determine that the blood was, in fact, pig’s blood?
Thanks!
RSID (short for “rapid stain identification”) is a registered trademark of a company called Independent Forensics. They offer separate tests to detect human blood, saliva, urine, and semen. The blood test can be done in the field and takes about ten minutes to process. Here’s a page from the company with some technical details: https://www.ifi-test.com/documents/BLOOD-Dual-Buffer-with-SpinEZE-042016.pdf
Among the details is the claim that
“No cross reactivity with animal blood has been
observed. Species tested: ferret, skunk, opossum, dog, cat,
cow, pig, chicken, owl, horse, goat, turtle, elk, deer, tiger,
alpaca, orangutan, gorilla, spider monkey, bonobo, and
baboon.”
Thanks! Unfortunately the story is set late 50s early 60s. Guess I shoulda specified
This might be cheating, but the cops probably would have heard, earlier in the day, about a theft of a lot of pigs blood, or maybe a dead pig turned up somewhere. Cops being cops, that might be the first thing that crosses their mind when encountering a massive amount of blood at a crime scene.
The plan was the have the protagonist use dried pig’s blood from the garden store in a water balloon. I honestly don’t know if reconstituted pig’s blood would pass for fresh blood.
Big city or rural police dept. would make a difference. Probably need state police services to help with a small police dept. Back in the 50s-60s could easily take at least a day. If the blood was the only way to identify a victim probably be done as quickly as possible. If there’s a dead body there and the blood assumed to come from that it could take days before the blood was analyzed back then.
Detectives being detective would consider the area and whether pig blood was obtainable and the decide whether to rush it to the old fashioned lab. Where horned rimmed glasses wearing lab guys would test it fast, because of the hierarchy in the police department. Lab guys being just a smidge higher than foot print followers, ya know.
And, pig blood to the gritty, determined, cynical detective might appear differently to his experienced eye.
Or he has a hunch.
It’s amazing how Detective Jones’ (known as Jonesy by the boys in the squad room) hunches are often correct.
Sorry, I got carried away. 
I think 24 hours would be a reasonable amount of time to get the analysis done.
Animal blood of whatever sort is probably more available in rural areas, and rural police would be more familiar with what an animal accident or slaughter looks like. And even more so in the e.g. 1950s than today. Heck, maybe fresh pig, cow, & human blood smell different enough to identify for somebody who deals with all 3 regularly.
A problem with any bloody scene that might be a crime is how much blood distributed how. A murderer with no experience murdering might well spread waaay too much decoy pig blood around in an unrealistic way and thereby arouse suspicion that the scene is artificial.
It’s been done.
Agatha Christie: A Holiday for Murder