There are many -
Although these may narrow down the possibilities as to what may be wrong with your cat, there is nothing that can take the place of a one-on-one visit with a vet. There are many conditions that cannot be properly diagnoses until the animal is seen and examined. Should medication be necessary, the vet will have had to examine the cat before medication can be dispensed. It is just in everyone's best interest if you take your cat to a vet as soon as you notice there is something wrong.
The vet should do a total work-over on the horse. Temperature, capillary re-fill, feces test, blood tests, shots (may need booster in 3 weeks).
Basically just tell him you would like a FULL health check.
PS Don;t forget his hoofs! Get a farrier too, the vet can hook you up with a good one. :-) Have fun with him (The horse not the vet) LOL :-)