Every few years a new buzzword begins circulating in the horse health industry. And recently, a biomarker called SAA has become such a word, garnering attention from the equine veterinary community for its ability to indicate inflammation. So just what is SAA and why are so many veterinarians and researchers starting to analyze it?
TheHorse.com caught up with two veterinarians well-versed on the topic—Luis Castro, DVM, a racehorse practitioner with Teigland, Franklin & Brokken in Boynton Beach, Florida, Saratoga Springs, New York; and David Levine, DVM, Dipl. ACVS, staff surgeon at New Bolton Center, the large-animal hospital of the University of Pennsylvania School of Veterinary Medicine, in Kennett Square, Pennsylvania—to find out more about this important biomarker.
TheHorse.com: First, the burning question: What is SAA?
Dr. Luis Castro:Serum amyloid A. It’s a biomarker protein produced in the liver in the face of inflammation caused by infection.
Dr. David Levine:SAA has several roles in inflammatory processes, but most importantly for us it serves as a marker for inflammation that increases and decreases quickly so it can give us real-time information using a blood test.
TH.com: Is SAA found in healthy horses’ blood?
Levine:SAA is found in very low quantities in normal horses. It is not secreted until inflammation occurs.
TH.com: When does the horse’s body produce excess SAA, and what would elevated SAA levels indicate to a veterinarian?
Castro:In the face of infection SAA levels begin to rise almost immediately. The response is faster than (other abnormal values we’d look for on) most complete blood counts1and fibrinogen (a biomarker we have been using for decades) levels. It is extremely sensitive to onset, duration, and the end of the disease process.
Levine: There is still much to be learned about SAA, but we do know that it increases in response to inflammation and veterinarians can test for this increase using a simple blood test. It can be followed to see response to treatment, as SAA changes rapidly in the bloodstream and can indicate whether a particular treatment is effective.
TH.com: Why should veterinarians, horse owners, and trainers be familiar with SAA?
Castro:It is extremely useful in determining the presence of infection at a very early stage. It would allow not only earlier treatment but can monitor whether the treatment is working and when the proper time to end treatment would be. All this can be determined immediately, and stall-side.
Levine:SAA is more timely compared to fibrinogen, which is our current gold standard test for inflammation. When you look at fibrinogen you are often looking at the inflammatory picture with a 3-day lag period. That is less helpful when trying to determine if you treatment is effective and whether your horse is responding appropriately.
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