I tore my ACL this year. Last year, my dog tore his.
One thing I learned when talking to (UK) doctors about my ACL is that there has been a lot of recent evidence-based medicine about surgical interventions. As a result, surgeons are less gung-ho: it turns out, quite often, surgery just doesn't do much good compared to physio.
By contrast, when I looked at the literature for animal cruciate ligament treatment, it's... oh gosh. I went into depth on this. In 2003 there was an article pointing out that there was almost no scientific evidence for most of the existing treatments. Ten years later, there was a review article which essentially said "oh, now the evidence is much better, we can rest easy". It categorized the research into four categories, the best one being credible randomized controlled trials. So I looked at the top category. The only RCT I found had about 40 animals, with substantial dropout (very likely non-random). There's a lot of natural improvement, and tiny effects from treatment, with significant results for some (out of many!) measured dependent variables.
After reading the top category, I didn't bother with the rest. What a disaster!
Cruciate ligament treatment for dogs is a $1bn industry. But there's just no decent science being done. It's all tests of 8 dogs without a control group, done by some guy pushing his new methodology. Honestly, it's shameful.
By contrast, one of the strengths of the NHS is maybe that it can knock heads together , get large-scale RCTs going, and learn something.