Two words that are often confused are edema (or oedema in older or British books) and inflammation. What's the difference--and does it matter?
For most horse owners, the safest words are to use like "swollen", "weeping", "pus-filled" and "irritated" if you are describing a condition over the phone to a veterinarian. It is always best to use descriptive words that will give the vet (or the person taking the message for the vet) rather than to misuse technical or medical words and send an incorrect message.
Then again, there's that chilling moment when you read a report on your horse or hear a vet describing "edematous swelling" and you wonder, in a panic, what that word means.
In the most simple terms, "edema" means "fluid-filled" and a common description is edema of the limbs. When you see a horse with puffy legs, you can gently press the hide and feel the soft swelling beneath. Fluid is trapped under the skin, perhaps because of a toxic reaction or a lymph system problem; there are many causes of edema.
"Pulmonary edema" means fluid in the lungs.
Inflammation is a word used to describe the body's localized reaction to trauma. When that stifle hits the oxer or the bared wire slices a pastern, the body reacts with a set of "911" coded responses to get rid of infection: send white blood cells, swell up, turn red, get hot, etc. Inflammatory responses vary with the animal, the environment and the injury. Edema may be the result of one of these responses but for a simple cut or trauma, the edema is usually limited to the general area of the injury.
If you don't understand what a veterinarian tells you, or what is written on a report, ask for an explanation. It is very important for an owner to understand the horse's condition and symptoms and, especially, the treatment.
Have you updated the first aid and medical books on your shelf lately? It's important to have a couple of up-to-date reference books on hand. If you refer to books that are published in England, you may find that some terms are different from what your American vet uses. You need a book with the latest information on parasites, infectious diseases, and therapy for injuries. EPM, West Nile Virus, shock wave therapy, and Tildren are examples of new diseases and treatments that wouldn't be in a book older than 2005.
A book that I reach for all the time is The Horse's Health from A to Z by Peter Rossdale FRCVS, a leading British vet. It is a very, very thorough dictionary of equine veterinary words, with lengthy explanations of important concepts. It is really helpful to check spelling, too!