Editor’s note: We have created a series of interviews about Stablelab‘s serum amyloid A (SAA) testing in horses with industry experts and partner Zoetis. Don’t miss our previous article Paving Her Own Path.
David Levine, DVM, DACVS-LA, DACVSMR, is an associate professor of Clinical Large Animal Surgery at one of the busiest large animal hospitals in the United States. He received his BS from Worcester Polytechnic Institute in 2000 and his veterinary medicine degree from Tufts University in 2004. Following his vet school graduation, he did two surgical internships and his residency at the University of Pennsylvania’s New Bolton Center.
Levine has spent more than 20 years as a veterinary surgeon. However, he believes that he’s “not just a carpenter; I have to think about the whole horse!”
His career hasn’t just been about high-profile athletes. His caseload ranges from the “backyard pet to Amish working horses to elite world-class athletes,” he said.
Levine expanded his focus to include sports medicine and rehabilitation of horses because, just like in human medicine, a huge part of a surgeon’s success is in how the horse is rehabbed, he said.
While Levine’s caseload includes all types of surgery, his primary focus is on orthopedic cases. And for his practice, he said he does a lot of Stablelab® serum amyloid A (SAA) tests. “All pre-ops are looked at for general health,” he said. “Generally, in post-op orthopedic cases we see a serum amyloid A spike after surgery; then it comes down. If it doesn’t come down or spikes again, it tells you you’d better start looking [for post-operative infection] and not bury your head in the sand.
“Serum amyloid A testing has revolutionized how we look at our post-operative patients in early detection of post-operative implant infections. Early detection is key to being successful in treating the infection!” Levine stated.
In fact, Levine said he thinks that most equine cases can benefit from SAA testing.
One example he mentioned is a horse with a medial condyle fracture, where he would implant a plate and screws. He expects the pre-op Stablelab serum amyloid A to be low (10 or 0). Two days after surgery the serum amyloid A will be fairly high, he said.
Then Levine will test at three, five and seven days after surgery. “By Day 5, if I’m not seeing serum amyloid A coming down, I’m concerned [about infection],” he stated. “Back in the day [before SAA testing] if the horse wasn’t showing clinical signs [of infection], then we got behind the 8-ball. Serum amyloid A gives us an early way to detect orthopedic infections. If serum amyloid A is dropping, I feel more comfortable.”
He said the previous gold standard for testing for infection was fibrinogen, “but the horse would often already be lame before we noticed an increase in that test,” he said.
Sports Medicine: Not Just Lameness
As more research has been done on sports medicine and on serum amyloid A use in horses, veterinarians are learning how to best use serum amyloid A in practice.
For example, a horse with lower airway issues could have asthma or an underlying infection. “They have different serum amyloid A results,” said Levine. Horses with asthma will not have an elevated serum amyloid A, but horses with underlying infections will have a spike in serum amyloid A.
“If a horse has a swollen lower limb and its serum amyloid A is up, then we often need an antibiotic,” he noted.
“In a cellulitis case, “We will check serum amyloid A every third day to make sure the treatment is working and decide if we need to make a change.”
With cellulitis cases and wounds, Levine runs serial Stablelab serum amyloid A tests to make sure he is on track with his treatments.
Veterinarians are used to doing pre-op screening bloodwork, but Levine said that adding serum amyloid A testing can really reveal whether something is wrong. “Most horses should not have an elevated serum amyloid A before surgery,” said Levine.
Levine cited a couple of research studies from his academic colleagues highlighting the usefulness of Stablelab serum amyloid A testing in equine colic cases. “Evaluation of serum amyloid A and haptoglobin concentrations as prognostic indicators for horses with colic” was authored by Trina L. Westerman, Crystal M. Foster, Susan J. Tornquist and Keith P Poulsen (PMID: 27031421; DOI:10.2460/javma.248.8.935), and “Serum amyloid A concentration in postoperative colic horses and its association with postoperative complications” was authored by Maia R. Aitken, Darko Stefanovski and Louise L. Southwood (Vet Surg 2019 Feb;48(2):143-151. doi: 10.1111/vsu.13133.) https://pubmed.ncbi.nlm.nih.gov/30499192/).
Levine said that for colic, while “the horse will tell you pain-wise that it needs surgery, if a horse’s serum amyloid A is high, it can be an indicator that it may need surgery.”
He questions whether a colicky horse with high serum amyloid A results could have enteritis. “Pre-op serum amyloid A testing can give you more information on systemic inflammation,” he said.
He noted that Stablelab serum amyloid A testing post-surgery will help veterinarians catch surgical site infections earlier.
“A high serum amyloid A [in a colicky horse] doesn’t mean euthanasia,” he stressed. “With a high post-op serum amyloid A, you should look for incision or vein infection [from the catheter].”
In the Field
When asked about uses for Stablelab serum amyloid A testing in the field, Levine said that he would recommend running a serum amyloid A test to show inflammatory status. “It’s less expensive and takes less time and is more accurate than fibrinogen or just a CBC,” he said.
If you are going to castrate a horse, for example, Levine said, “you can pull blood and a serum amyloid A test, and by the time you are ready to sedate the horse, you can see the numbers. If he has a high serum amyloid A, maybe you shouldn’t castrate today.
“It’s 10 minutes, and it’s easy to carry in the field,” he added.
“People always ask me, ‘Oh, I have a horse with a foot abscess that’s draining pus, but it doesn’t have a high serum amyloid A.’ I say that’s great; it probably doesn’t have a systemic reaction, it has a local reaction. But when you have that more swollen lower limb with a draining foot abscess and its serum amyloid A is up, then that horse probably needs antimicrobials.”
Levine said cellulitis cases are another great use of Stablelab serum amyloid A testing to decide when to start or stop antibiotics or change your regimen. “If your fibrinogen is still climbing three days later but your serum amyloid A hasn’t budged, it tells me that your antibiotic might not be the one [to use in this case]. Get a base serum amyloid A and fibrinogen—run them in tandem,” he advised. He predicted that “in 10 years, we’ll be running serum amyloid A and not fibrinogen.”
He also said he advises referring veterinarians to run Stablelab serum amyloid A tests on patients once they are discharged from the hospital. “In the discharge instructions, I put a check for a serum amyloid A test in three to five days,” said Levine. “The majority of referring vets in our area use serum amyloid A.”
If it was a leg surgery and the leg looks better and the serum amyloid A is coming down, “Then I can change the bandage on the farm and stop antibiotics,” said Levine.
He said it is up to all veterinarians to practice antimicrobial stewardship and not give antibiotics to everything.
Levine also said veterinarians can use Stablelab serum amyloid A tests serially on respiratory cases to see how they are responding to treatment.
He also advised that with any horse going to a big competition or with a new horse coming into a barn for quarantine, “run a serum amyloid A test to see general health and look at inflammation. I feel better if the result is zero.”
If a horse gets to an event and doesn’t look right, “you can test it in the truck or trailer in 10 minutes” and know if there is something going on.
About David Levine, DVM, DACVS-LA, DACVSMR
When Levine was about 10 years old, he and his brother went to collect mail for a neighbor, and they were attacked by a pack of dogs. That traumatic incident left Levine so scared of animals that he didn’t even want to leave the house.
He said his mother “decided she was going to help me get over my fear by taking me to a barn and getting me to ride horses.” After the first day at the stables in Connecticut, where he locked himself in the bathroom for a while, he “got into it” and started riding.
“There’s something about the outside of a horse that’s good for the inside of a person,” he quipped. “I became a lover of all animals … horses especially,” said Levine. “I spent my youth and high school days riding horses, competitively show jumping. When I went to college, I knew I wanted to get into veterinary medicine.
“I wasn’t sure I wanted to do just horses, and I wasn’t sure I wanted to be a surgeon, but as I went through vet school … when you love horses you love horses,” he said, laughing. “Turns out I could do surgery. So, I focused on that, and that’s where I am today.”
Levine said that when the sports medicine and rehabilitation college came out, a lot of the surgeons jumped in and got on board.
“In horses and dogs, they didn’t focus as much on looking scientifically at what is good and bad [for rehab after surgery],” he added. “Rest for 30 says and walk for 30 days …
Any surgeon worth their weight should be interested in improving their outcomes,” stressed Levine. “And rehab is the way to go.”
“I do a lot of lameness work, as most vets do, so sports medicine rehabilitation fits in with the nuts and bolts of surgery,” he said. “A lot of what happens when they come in is sports medicine.”
Levine has in-surgery days and days where he looks at lame horses. He takes phone calls and handles “what comes in the door.”
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