Talking OCD with Joe Pagan
Dr Joe Pagan from the Kentucky Equine Research is one of those amazing people who combines awesome knowledge and an equally awesome ability to express themselves. Talking to Joe is a treat anytime, and when he talks about the ‘hot’ topic of OCD – that’s news.
But first some very good news, the famous KER Conference is headed for Australia next year…
"We’ve had a conference in the States for the last twelve years. Every year we’ve held an equine nutrition conference focussed primarily at feed manufacturers, people in academia, and veterinarians. All the previous conferences have been in Lexington and we are planning to bring it to Australia in 2003 and probably Europe in 2004."
"The theme of this conference will be skeletal development and soundness. It seems that unsoundness is the number one problem, OCD but also bone strength in general."
What is OCD?
"It is where the articular cartilage which covers the end of the bone, gets a lesion where it is supposed to be smooth and provide a frictionless surface for the joint to go back and forth. And if there is a lesion there, it causes a lot of pain and lameness."
"The big deal in the Southern Hemisphere right now is that no one ever x-rayed for it before the Thoroughbred Yearling Sales. There’s a lot of OCD that is only evident radiographically - without any clinical symptoms. There is a push now to make radiographs (x-rays) pre-sale, not mandatory but allowable. That has happened in the States for a long time. There is a repository of radiographs, and prospective buyers can come in and have a good idea of the incidence of this problem."
"In the Southern Hemisphere, everyone was saying ‘oh we don’t need to do that’, then the Hong Kong Jockey Club came in and said, ‘we’re not buying until we see radiographs’. So now it is happening.
What has happened in the States is that we are now looking at the careers of the horses that were radiographed to see just how relevant a lot of those lesions were to subsequent performance. It has got to the point where any lesion is a reason to knock a horse way down – and the reality is that a lot of the lesions aren’t clinically relevant and will never be clinically relevant. I think the buyers are becoming more sophisticated now, they are saying ‘the horse has a lesion, fine, but does it have a high probability of compromising his career?"
"The folks in Australia are very interested in that sort of information. If they have to radiograph, they want to be able to say ‘the probability of that lesion becoming a problem is…’. The problem with racehorses is that you can rate the severity of a lesion but it is the location which is also very telling. If the OCD is in the hock, it rarely causes any problems, even though they may have a lesion that is fairly large it is not on a weight-bearing surface. Now they have got tens of thousands of these radiographs, and the race records, so there have been some big studies. Colorado State was in charge of one big study to sort out which ones we should be worried about and which ones we shouldn’t. I don’t have confirmation yet but we are trying to get Wayne McIlwraith, who heads the orthopaedic research centre at Colorado State to be our head speaker at this conference. He is one of the world’s leading authorities on these problems."
But won’t the breeders just go in and surgically remove the lesions in the foals and then they won’t show up on the radiographs?
"This is a bit of a grey area whether you have to declare if the horse has had surgery. I’m not 100% clear if you have to have a letter in the repository saying this foal has been operated on…"
When we visited one of the big Kentucky Thoroughbred Stud Farms, I’ve never seen so many surgical bandages on foals in all my life?
"Those weren’t for osteochondrosis, that was for periosteal elevation, and that surgery isn’t declared. That’s like marrying a girl and asking her if she wore braces when she was younger to straighten her teeth?"
Do you think OCD is heritable?
"Absolutely. No doubt."
And it is a simple recessive gene?
"It is not clear cut, and it is probably not a simple gene. It’s more complicated than that, but I’ll say with certainty, it is heritable. In Warmbloods it is a very big problem. There are more and more problems with Thoroughbreds because the gene pool is getting narrower and narrower. A study was published in Standardbreds which established a positive correlation between OCD and performance. Foals that had OCD were better racehorses on the harness track. It may be as we select for certain traits we get some of these other traits along for the ride. If you look at Thoroughbred horses, the way the gene pool has become so narrow, it seems likely that very thing will happen, you get traits you hadn’t bred for."
Isn’t that controlled by the fact that if the mare is unsound, she doesn’t get to race and if she doesn’t get to race she doesn’t get to have foals?
"In November at Lexington, they sold a full sister to Fusaichi Pegasus in foal to Storm Cat, she was unraced, and she sold for four million dollars. They said she was injured in a paddock accident as yearling so they said she never raced, but the reality was, although she never raced she sold for $4,000,000. If you’ve got a fashionable stallion, you are going to breed to it, even if it does have OCD."
"They are managing OCD, they’ll x-ray the horses in January/February, operate on them so they don’t have the lesion when they go to the Sale – and I’m not sure what the regulation is about declaring that or not."
"What it has done is change the ratio of home bred to commercial racehorses, because a lot of the horses that race as ‘homebred’ do so because they had OCD and their market value was diminished to the extent that breeders decided to take the risk and race them themselves."
"The other thing is has done is caused a huge discrepancy in the price. At the upper end of the market, where you are seeing $4,000,000 yearlings, those are the perfect ones. They’ve got the pedigree, they’ve got clean throats, they’ve got clean x-rays, and there are a very small number of them, so the prices go crazy."
How much can nutritional factors affect whether OCD remains a lesion without it showing as lameness?
"We think that nutrition can affect whether it is even going to be detectable by radiograph, The management of nutrition can be extremely important in terms of there ever being a phenotypic expression of the problem."
What can you do nutritionally?
"One of the things you can do is slow them down. We’ve also done recent research that shows when you feed young horses high sugar and starch diets, that can lead to a greater incidence of OCD. If you feed a low starch diet – which is what they would have eaten in nature, feeding on grass all the time – you can help a lot."
"The problem is when you have a commercial pressure to have a foal that is 80% of his mature body weight, and 90% of his height at 18 months. You can’t grow a foal like that on just grass. So what we are trying to do is balance the commercial reality of that precocious development with moderating the problem. I think we could eliminate a lot of the problem if we didn’t race them as two year olds, allowed them to grow slowly, had them pot bellied and scruffy looking in the winter - but you’ll get knocked at the Sales so that that is not an option. So we’re trying to force the foals to grow faster than is best for them, while trying to give them the nutrition that will minimise incidence of OCD."
So what does this feed mix look like?
"A balance of minerals and vitamins number one, but then using sources of calories that don’t come from starch – such as fat and fibre. Fibre is what the foal would normally eat, but there are fibre sources that we call super fibres because they are very energy dense, twice as energy dense as grass. The problem seems to be with sugar and starch that when you get high glucose in the blood you get high insulin, and high insulin changes a lot of hormones that are necessary for cartilage maturation. You are trying to give them the calories without them ever seeing the high levels of glucose in the blood."
Are you marketing that type of feed in Australia?
"We are. It is a low glycemic feed. Many of the studs in the Hunter are using that kind of feed. We are custom making the feed for some of the larger Australian studs and they seem to be having a lot of success, and we are doing the same in Kentucky."
But I imagine that some of the Warmblood breeders in Australia who are worried about OCD but not big enough to rate a custom made feed, would also like to use such a feed…
"I’m sure that will happen. The first ones we wanted to do were the big farms that considered it a serious enough problem that they wanted a custom feed made, the next step will be a commercial feed on the market."
What I don’t understand is that we don’t race our Warmbloods as two-year-olds, and we don’t have Yearling Sales, so why do we have a problem with Warmbloods and OCD?
"I think that people are feeding young Warmbloods the same way your would feed a young Thoroughbred. We’ve got some new software where we can very nicely track growth rate. I think what it is going to take is for Warmblood breeder to follow a different curve, to say we don’t want to make them look like Thoroughbreds or Quarter horses early, we want them to be below this curve. But they are not going to be appealing to us – they are not going to look good. The trouble is people want a foal to look like the miniature version of the horse it is going to be, and that is probably not a good thing for horses at that age. For those young Warmbloods, any grain may be detrimental; you are better off with a real high forage diet and then using a balanced supplement. You’ve got to obviously have the correct balance of protein, vitamins and minerals, say a kilo a day of a balanced pellet – then if you do need extra calories, something like rice bran but don’t give them any grain at all. As we look at the problems that occur with horses, cereal grain is the culprit in a lot of those instances, for example, tying up in Thoroughbreds has been linked to excessive starch intake. With these Warmbloods, I think they’ve got delicate systems that have to be treated differently. But until we can get breeders to say ‘okay it looks like I’m starving my horse but it’s good for it – I know I’ll have a sounder horse at five years of age’ then we can help a lot."
What about mature horses, is there anything the owner can do to stop OCD cutting short the horse’s performance career?
"OCD doesn’t happen then, maybe the clinical expression occurs. OCD stops when the bone stops growing. I think some of the oral joint supplements – condroiton sulphates, glucosamines – those sorts of things may have a beneficial effect in reducing the clinical effect of those problems. Feeding probably won’t help in preventing or reversing the problem. When you get a six year old horse that suddenly has an OCD lesion, it had that lesion since it was six months old, and finally, he just pounded on it enough to show up clinically."
What about the suggestion that breeders should operate on foals that show lesions?
"They did a great study in Utrecht in Holland, and they followed these babies since birth – x-rayed them all the way through, and what they found was that you don’t want to start x-raying them early because in these Warmbloods, there is a lot of radiographic evidence that lesions that occur in weanlings go away naturally. If you started operating then you would unnecessarily perform a lot of surgery. Their recommendation was don’t even bother to x-ray for OCD until after they are 12 months old because a radiographic lesion before that time is probably going to go away on its own."
"We ran into that problem with one of our big Thoroughbred farms. They x-rayed their weanlings in October when they were 6-8 months old, and 40% of them had OCD. They withdrew them all from the Sale and they thought they had a crisis on their hands, and when they re-x-rayed them in February none of them had OCD!"
"When the cartilage has extremely high metabolism, it has great healing power also, they can heal those lesions themselves. Typically the further the joint is from the body, the earlier it matures and the earlier it is active. In that early activity if you keep x-raying and x-raying, you see these blemishes come up and you would say ‘that’s an OCD and it is going to be a problem’ and they go away on their own."
Is the likelihood of the problem resolving itself affected by the feed they are getting?
"Probably it helps if they are getting the nutrients for the proper maturation of that cartilage, even though that hasn’t been studied properly. When we do field surveys of OCD and factors that affect it, we tend to only look at OCD that has become clinically relevant enough to become surgical, because when we try to evaluate radiographic evidence it is all over the place, it is very difficult to pin down that this is a significant lesion."
"When you hear people discuss the incidence of the problem you hear a huge variation in terms of numbers, it depends so much on when they examined the horses, and how."
Paul Schockemöhle runs the line that OCD is not so bad for horses but very good for vets….
"That’s probably right, again the clinical relevance is the issue – whether it is going to make the horse lame. And not all OCD makes horses lame. If you try to sell a horse where they allow radiographs, it makes a horse cheap…"
Can you affect the development of OCD in utero?
"Sure, there was a great study in New Zealand where they took 24 Thoroughbred mares. Half the mares they fed a supplement that contained all the minerals that were required, including copper. The other group, they left copper out of the mix. When the foals were born they divided them into two groups and the ones that were out of mares that had copper, they gave copper to half of the foals, and half they didn’t. They did the same thing with the other group of foals. After 30/50 days they euthanased the foals and did an extensive necropsy to look for skeletal lesions, and what they found was that if a mare had received copper, the incidence of lesions in her foal was half the incidence of the mares who didn’t receive copper – regardless of what happened with the foals’ nutrition after they were born. It didn’t matter what you fed the foal, it depended on how the mare was fed in late pregnancy."
The problem is that in Australia we have some people with pretty weird ideas about feeding lots of copper – copper can be dangerous?
"Exactly, the thing you’ve got to realise that the amount of copper required for a late pregnant mare, is 150 milligrams a day. That .15 grams of copper – how could you supplement that yourself? You can’t do it without giving way too much. The idea of trying to add it yourself is dangerous. What you need to do is feed a feed that is formulated so your mare gets the right amount of copper."
"The problem is – particularly if you’ve had rain and the grass is good – the late pregnant mare looks good, and you think, why should we feed it? But then you can have copper deficiencies. We’ve formulated some feeds in Kentucky where we have nice pasture where you feed half a kilo a day, and it provides the trace minerals and a bit of calcium and phosphorous because they are getting plenty of protein and energy from the grass. The only thing they really need is those trace elements."
Here at The Horse Magazine, we are all looking forward to the KER Conference next year…