We all see those adverts that seem to be too good to be true. So why should you ask for evidence? Well, now and again something good does come along and if you dismiss everything you see then you and your horse could miss out. If the company is genuine then they will be able to provide evidence to support their claims. Remember that in the UK and many countries it’s a legal requirement to be able to support any claims that are made with data and that this has to be provided on request.
You can email the company or reach out via social media. You should give them a reasonable time to respond, such as 14 days. It’s best to approach along the lines of “Hi, I’m interested in your XYZ product as advertised in/on ABC. Could you please tell me a little more about what trials or studies you have done and the evidence to support the product and the claims?“ It is probably not helpful to mention 3rd parties such as, my vet said or Dr David Marlin said, etc. If you get a response you can share it on my page or share it with me privately and I can post it anonymously.
If a company doesn’t provide the evidence you ask for then that should make you very suspicious and should put you off buying from them. You might also want to help other consumers by reporting them to the Advertising Standards Association (ASA). It’s a simple, quick and anonymous process and you will get feedback on your complaint and whether action was taken against the company. https://www.asa.org.uk/make-a-complaint.html