A Conversation with Dr. Keith Latson, DVM, DACVS, Board-Certified Equine Surgeon and Co-Formulator of 6666 Equine Supplements
Key Takeaways
- There is a critical difference between a finding and a risk. Knowing which is which determines whether you walk away or negotiate
- Post-sale drop is real and predictable. Every horse has been running on adrenaline for weeks and every system is under stress when they load on the trailer
- Feed changes, dehydration, and cortisol suppression of the immune system are the three biggest post-sale threats
- Slow and steady applies to how a horse is prepped for a sale and right on through the four weeks after you buy one
- The gut supplement is the most important one to start first, before anything else
- Establishing a baseline through post-purchase bloodwork and radiographs gives you and your veterinarian something to compare against for the rest of that horse's career
Quick Answer
Sale season is one of the highest-stress periods in a horse's life. The prep, the environment, the travel, the new home, the new feed, the new routine. Every one of those things stacks on top of the last. We sat down with Dr. Keith Latson, board-certified equine surgeon and co-formulator of 6666 Equine Supplements, to talk through what buyers need to know on both sides of the transaction. With the Return to Remuda Sale at the Four Sixes Ranch coming up, it was the right time to bring together the perspective of someone who has spent decades representing buyers at the highest levels of the industry and the team that has been preparing these horses all year.
Who Is Dr. Keith Latson?
Dr. Keith Latson went to the racetrack for the first time in 1992 at Louisiana Downs and knew immediately that was where he was headed. He completed an equine surgery residency at UC Davis, earned his specialty certification in equine surgery, and spent about ten years on the Southern California racetrack circuit at Santa Anita, Del Mar, and Hollywood Park. He then transitioned to representing buyers at thoroughbred sales across the country, from Saratoga and Ocala to Lexington and California, going through horses with a fine-tooth comb so buyers knew exactly what they were purchasing.
He also served for seven years as the AAEP On Call veterinarian for NBC's Triple Crown coverage, working with media to communicate what was happening with horses during the sport's biggest moments.
"I worked the buyer side. My job was to go through those horses with a fine-tooth comb so a buyer knew exactly what they were getting. Everybody knew from the bloodlines and the catalogs what the breedings were and what the hot studs are. My job was really moving past just what those horses look like and taking a look at all of their joints, their throats, how they walk, what their conformation is, and putting all of those things together to be able to say, what are the risks of longevity for this horse?"
He is also one of the veterinarians behind the 6666 Equine Supplements formulas, which is why his perspective on sale season matters far beyond the thoroughbred world.
At the Sale, You Are Seeing a Snapshot Not a Baseline
Dr. Keith was direct about what buyers are actually looking at when they walk through a sale barn.
"They are shiny. They are beautiful. They are full of themselves and muscled up, and they have got a bloom on them."
That is not a criticism. Good consignors work all year to present a horse well, and the ranches that people keep coming back to are the ones that bring horses along intentionally instead of pushing them hard for three weeks. But the picture in front of you at the sale is a snapshot, not a baseline.
"My job was always to move past what the horse looked like standing there. Every joint, on film and by hand. The throat, at rest, on endoscopy. How the horse walks away and back, flexed and extended. Palpation of the flexor tendons, the suspensory branches, all the way down to the heel bulbs. Conformation, topline, balance, and how the pieces fit together. Then we put all of that into one summary and gave it to the buyer so they could decide if the horse fit what they were trying to do."
In a thoroughbred sale, every horse has 42 standardized radiographic views taken before the sale, plus endoscopy video of the airway at rest. The scope of a two-week sale like Keeneland September is significant.
"It is sort of like tax season for accountants, once a month. It is not unreasonable to think that I would look at 40,000 to 50,000 x-ray views during the course of that sale."
At performance horse and ranch sales, the repository may be less standardized and the pre-purchase exam may be left to the buyer. Dr. Keith is direct: do not skip it.
Findings Are Not the Same Thing As Risks
The distinction Dr. Keith wishes more buyers understood is the difference between a finding and a risk.
"We are trying to identify every risk we can and then prioritize those risks. Some findings tell us this horse is not going to go the distance we want it to go. Many others are just findings. The critical thing is differentiating a trauma-based finding, like a chip in a joint, from an adaptive finding."
Yearlings and two-year-olds in sale prep are experiencing stresses on their musculoskeletal system that they have never experienced before in such intensity and in such a concentrated timeframe. The body has to adapt. Bones remodel. Tendons and ligaments adjust to new loads.
"We expect the body to adapt. We expect bone to remodel according to those stresses. That is physiology, not damage. So the questions become: is this mild, moderate, or severe? What does this finding mean for the time after the sale? How quickly can we move with this horse, or does it need some time to just be a horse and move in every direction instead of straight ahead?"
The Hot-Button Finding: Sesamoiditis
One finding that gets horses scratched off lists more than almost anything else is sesamoiditis.
"The sesamoid bones sit at the back of the fetlock. They are the attachment point for the tendons and ligaments that run on either side of that joint and let them change direction. Think of them as the hammock the fetlock sinks into when it bears weight. When a horse goes from pasture turnout to repetitive, concentrated work, those sesamoid bones have to remodel. And so do the suspensory branches that attach to them."
Severe sesamoiditis is a hard conversation, but not automatically a pass. Barrel horse people see sesamoid issues too. The principle carries across disciplines.
"We would qualify it. If it was a desirable mating out of an accomplished stallion and an accomplished mare, we would ask a better question: is there a chance that with four or six months out of the sale, these sesamoids remodel and strengthen into what we need for a long career?"
Get Your Own Baseline, Even When the Repository Is Good
Whether the sale has a full repository or not, Dr. Keith recommends establishing your own baseline immediately after purchase.
"A lot of my clients depended on the repository films to make the purchase decision, and then immediately after they bought the horse, they would pull bloodwork and take a full set of radiographs of their own. I would read those against the presale films. That was not about looking for nefarious behavior. It was about establishing a baseline. In three weeks, three months, or three years, when something comes up, you have something to compare back to. That is worth a great deal."
At the Return to Remuda Sale, that standard is built in from the seller side. Dr. Nathan Canaday, the head veterinarian and Horse Division Manager at the Four Sixes Ranch, describes how they approach it:
"Every yearling and two-year-old in the Return to Remuda Sale has a full repository that we do here at the ranch. We also work with buyers on vet checks. The two weeks before the sale we will be performing a lot of vet checks at buyers' request. We work with buyers and provide all the information we can. We stand behind our horses."
That baseline travels with the horse wherever it goes next. For buyers purchasing at other sales this fall where the repository is less complete, Dr. Keith's advice is to ask for the same level of transparency and to build your own record from day one.
"This industry runs on relationships. Clear, thorough, honest communication between the seller's vet, the buyer, and the new vet at home is worth more than any single finding on a film. It also pays off later. If a horse gets shipping fever out of a sale, which happens, everybody already has the information they need to act instead of guess."
The Post-Sale Drop Is Real, and It Is Physiology
Here is the part nobody puts on a hip number.
That horse has been running on adrenaline for the last month. It traveled. It is in a new environment with new horses on either side of it. It has been shown ten, twenty, thirty times a day, halter on, halter off. Then it gets sold, shipped again, and handed to new caretakers on a new routine.
"Cortisol goes up with all that stress, and cortisol suppresses the immune system. IgA drops. Immunoglobulin A is the protective layer in the mucous membranes of the lungs, trachea, and gut, and it is directly suppressed by cortisol. Your respiratory tract and your GI tract both depend on it. A dehydrated horse is at risk of respiratory disease and at risk of impaction colic. And the microbiome shifts when feed changes, and these horses are often coming off high-grain diets that helped build that bloom."
Stack those on top of each other and a letdown is a natural response. Some letdown is appropriate.
"We just do not want to see them let way down. That is where support comes in."
Slow and Steady Is the Whole Program
If there is one motto for sale season on both sides of the transaction, it is slow and steady.
On feed transitions:
"Transition feed over about two weeks. That gives the horse time to adjust to new feed and a new routine. During those same two weeks, get the horse out to move and stay mentally healthy. Just do not push straight into training."
On water:
"Water is the first priority. I love an electrolyte paste before and during travel, and electrolyte powder after. Horses lose a huge amount of electrolytes in sweat, and electrolytes are what let the cellular machinery work: electrical impulses, gastrointestinal motility, energy. When electrolyte levels drop, we start seeing changes in gut motility, changes in energy, and changes in how much they drink."
One rule: electrolyte water should never be the only water offered. Always have plain water available alongside it. 6666 Electrolyte Paste for the road. 6666 Electrolyte Recover Powder after arrival, into the feed or the water bucket.
On supplements:
"Start at a quarter or a half dose of whatever you are adding and stagger the start of each one so you know what the horse is accepting and what it is rejecting. The last thing we want is a horse backing out of its feed tub at a new place because there is something in there it does not recognize. We are not dumping full-intensity training on them all at once, and we should not dump the kitchen sink into the feed tub either. I think that is respectful to the horse."
If you are buying from a ranch that already has the horse on a program and you can take the product home with it, that is the easiest transition there is. The 6666 Ranch has a sound management routine for everything from the yearlings to the two-year olds to the ranch horses so if you’re buying from the ranch, you can ask Dr. Canaday about that horse's specific supplement routine.
On which supplement to start first:
"For a horse coming out of a sale, the probiotic and gut health supplement is the most important one. The GI tract is at such high risk of microbiome shift with all of that stress. That is the one I want on early and kept on through the integration phase at the new place and into the training program."
6666 Complete Gut Protection covers both gastric and hindgut, which is exactly what is under pressure in these horses. Prebiotics, probiotics, and postbiotics to stabilize the microbial community during transition. L-glutamine and oat beta glucan to protect the stomach lining and support barrier integrity through the period when cortisol suppression leaves the gut most vulnerable.
Three Red Flags in the First Two Weeks
Dr. Keith gave three specific signals that tell you a horse needs more than time and monitoring.
1. Any cough.
"Not a bad cough. Any cough. You have a horse that traveled, breathed dust, and probably did not drink as much as it should have. That is a horse with low-level dehydration at risk of a respiratory infection. Any cough gets my full attention."
2. A creeping temperature.
"I like seeing a temperature between 100 and 101 in an adult horse. When it starts creeping up and staying there, I am checking multiple times a day. The call-your-vet cutoff is 101.5."
3. Changes in manure consistency.
"If I see a soft pile instead of well-formed apples, I am watching closely, and I am immediately looking at how much that horse is eating. Have they backed out of the feed tub? Respiratory and gastrointestinal are the two big ones, and manure is the report card you can read every morning without touching the horse."
These are the small things that feel skippable when the horse looks fine. Taking temperature twice a day. Measuring water intake. They feel skippable and they are the ones that matter most.
The Excitement Is the Risk
Most experienced horse people know all of this. What Dr. Keith has watched happen over and over is not ignorance. It is excitement.
"You bought a horse, maybe several. You are running on adrenaline too. The gradual steps get compressed in the logistics and the thrill of getting them home. So put some intention on the boring parts."
Slow and steady applies to how a horse is prepped for a sale and right on through the four weeks after you buy one.
"These are powerful, strong animals, and they are also sensitive animals. They are sensitive to change."
Good luck to everybody out there buying horses this fall.
Actionable Checklist: Post-Sale Management
- ✓ Pull bloodwork and a new set of radiographs after purchase to establish your baseline
- ✓ Run a SAA (Serum Amyloid A) test when the horse arrives to catch infection before symptoms appear
- ✓ Take temperature twice daily. 99 to 101 is normal, above 101.5 call your vet
- ✓ Watch manure consistency every single day
- ✓ Monitor water intake and ensure constant access to plain, fresh water at all times
- ✓ Use Electrolyte Paste before and during travel, Electrolyte Powder after arrival
- ✓ Make all feed changes over a minimum of two weeks
- ✓ Do not push the horse into training immediately. Movement yes, work no
- ✓ Support the gut daily
- ✓ Start all supplements at a half dose and stagger introduction one at a time
- ✓ Transfer all pre-sale records to your ongoing veterinarian for continuity of care
Frequently Asked Questions
Do I need a pre-purchase exam if the sale has a repository?
The repository is a starting point, not a complete picture. Pull your own bloodwork and radiographs immediately after purchase regardless. Not to look for problems that were missed, but to establish your baseline. Three months or three years from now, that baseline is what tells you whether something has changed and what it looked like before it did.
What is the difference between a finding and a risk?
A finding is something present in the radiographs or physical exam. A risk is a finding that has a meaningful probability of affecting the horse's ability to do its job over time. Not every finding is a risk. Context, bloodlines, severity, and the horse's intended use all factor into the assessment. This is why having an experienced vet on your side matters.
What is sesamoiditis and should I walk away if a horse has it?
Sesamoiditis refers to remodeling of the sesamoid bones at the back of the fetlock. It is extremely common in sale prep horses because those bones are adapting to new levels of stress. Mild sesamoiditis is very different from severe sesamoiditis. Severe cases warrant further ultrasound of the suspensory branches and a careful assessment of whether time and appropriate management could allow proper remodeling. It is not automatically a pass.
What causes the post-sale drop?
The post-sale drop is primarily a cortisol and immune suppression event. The horse has been running on adrenaline through weeks of intensive prep and the sale itself. When that adrenaline drops, elevated cortisol suppresses immunoglobulin A in both the lungs and the gut, making the horse vulnerable to respiratory illness and GI disruption at the same time. Feed changes, travel dehydration, and a new environment compound that vulnerability.
Why is the gut supplement the most important one to start first?
Because the gastrointestinal system is at the highest risk during the transition period. The microbiome has been under stress from high-grain sale prep diets, elevated cortisol, travel, and feed changes. Getting a prebiotic, probiotic, and postbiotic formula in place early stabilizes that microbial environment before it can shift into a state that causes loose manure, weight loss, or colic.
How long should feed transitions take?
A minimum of two weeks. That applies to hay changes, grain changes, and forage source changes. The hindgut microbiome needs time to adjust to new feed. Rushing that transition is one of the most consistent triggers for GI disruption in horses coming out of a sale.
How do I use electrolytes around a sale?
Paste before and during travel. Powder after arrival. Always offer plain water alongside electrolyte water. Horses that are not drinking enough are at risk of both impaction colic and respiratory illness.
When should I call the vet after a sale purchase?
Immediately if you see any cough, if temperature rises above 101.5 and stays there, or if manure consistency changes and the horse backs away from its feed. Do not wait for multiple symptoms to stack up. Each of those three signals on its own warrants a call.
When to Call Your Veterinarian
Contact your veterinarian immediately after purchase to arrange a post-purchase baseline exam. During the transition period, call if you observe any cough, a temperature consistently above 101.5 degrees Fahrenheit, changes in manure consistency paired with reduced feed intake, rapid weight loss, or signs of colic. Early intervention consistently produces better outcomes than waiting.
We focus on the whole horse. The science. What works and stands the test of time, not chasing trends or quick fixes.
Formulated by veterinarians. Trusted on the ranch and in the arena. Built for horses that work.
The 6666 Equine Supplements Team
