Quick answer:   Check your horse's pulses, now, today so that you know what is right in health for him, then you will be alerted if laminitis makes them rise.  Learn how to do it.  https://www.youtube.com/shorts/pRZ4QXIsIZQ

The next sign is likely to be a hesitation in their steps, being careful and perhaps reluctant to walk.  This can develop very quickly into the typical stance of a laminitic horse.  Weight in standing taken right back with the front feet pushed out in front, trying to take the weight off.  THIS IS A VET EMERGENCY, CALL NOW AND SAY 'I THINK IT IS LAMINITIS.'

Other signs include a full hard crest and full orbital sockets above the eye.

It is your job to keep your horse as safe as you can, don't let him get fat, act before that gets past the point of no return. Consider a muzzle.  Strip graze or use a dry lot.

Once a horse has had laminitis he will always be vulnerable to another attack, believe me it is horrible so protect your horse, stay vigilant.