[MUSIC] [MUSIC] I'm Dr. Brian Aldridge and I am here in the imaging unit at the large animal hospital at the College of Veterinary Medicine at the University of Illinois. I'm standing here to illustrate some of the more sensitive detection mechanisms that we have. How do we detect disease? How do we look inside of the animal and know the disease is taking place? We see about 1,000 food animals that come to the hospital each year. And you might wonder why on Earth do we see that many animals. Why do animals come to the hospital? Well, we think of them as iceberg indicators, that's what we call them, iceberg indicators. Because they're often the tip of the iceberg. What you can see when you can see obvious disease, they're really the most severely affected animal in the whole spectrum of disease. You see disease comes in many different forms, many different severities. So it can affect different body systems. It can be caused by different agents, but also be in different degrees of severity. So when we have an animal that comes to the hospital, the owners notice that something is wrong with that animal. It might be that it has a cough, has a nasal discharge, has some problem with intestinal function, has diarrhea, it might be losing weight, or it might be, or it might be lame. We often then embark on a set of investigations to work at what's going on with the animal so we can direct therapeutics and treatment and give the owner an outlook as to whether that animal will recover and what will the cost be in treatment of that animal. But we also take care to point out to the owners that this animal is often an indicator of something that's taking place back in the herd, in the population, in the flock. Every animal that you see sick, for every animal that you see sick ihere's usually three to seven or eight more animals that have the same disease but to lesser degrees. That's not true, obviously, if you have an animal that has a fracture or something that's traumatic. But that's particularly true with infectious disease. Why would one animal become ill and none of the others be infected? If that animal is the index case, if that animal is the first one, then it's possible that the other animals in the herd have contracted that disease. Or maybe there's something about that animal's immune system, or genetic makeup so it's more susceptible, and the others are not exhibiting the same signs. So the process of unraveling that disease is really important in showing you, and showing the producer, what else is taking place in the herd because infectious disease impairs productivity. Think about respiratory disease, for instance, when you have an outbreak of respiratory disease in a population, the ones that are most susceptible will present with fevers and they might go off their feed. But some of those will recover spontaneously, and show no other signs, some of them will continue in that phase of the infection. But some will progress to a certain type of disease, in which the the infection becomes established within the lungs. And, therefore, the outward signs might not be very evident. So that's when we can use other diagnostics, other signs that the disease has been taking place inside of the animal. And very often what the clinical signs to the producer would be is, a change in productivity, a change in weight gain, a change in milk production, a change in growth characteristics. So very often it might not be a cough or it might not be diarrhea, it might not be an overt weight loss, it might be a subtle change. But unless we're measuring those things we won't be able to detect it. An animal with intestinal disease as well, the intestine needs to be fully functioning to absorb all of the nutrients. And if there's any impediment for that then essentially all the nutrients that are taken in and all the costs that are being put into that animal, they're going into the disease process itself. Some of those nutrients might not be absorbed and are being passed just out in the feces. So, essentially, the owner's wasting money. It's an area of inefficiency. It's also an area of inefficiency because those nutrients aren't being used to growth. So if in the production system the owner has certain targets, and if the target is a kilo or two kilos of growth, and let's say the animal is growing at half a kilo because it can't absorb all of those nutrients. Then that disease is causing an inefficiency, even their might not be any overt clinical disease. An animal with lameness, the energy that go into the pain response for that animal, pain invokes a whole set of physiological responses that takes energy and takes protein and takes nutrients away from the growth process or away from the production process. So we know, too, with the immune system that a low grade infection, a chronic infection, one that's been there a long period of time but doesn't show overt clinical signs, can redirect nutrients away from growth and productivity to the immune system so that growth becomes inefficient. The food conversion efficiency is reduced. Every kilo or pound of food isn't being converted into the amount of growth that it should do, because those nutrients are being diverted away. That's why disease can affect production efficiency, and we need to have good monitoring systems by which that low level of disease can be detected. Disease detection isn't just picking up the sick animals. The ones that have those overt clinical signs. It's also monitoring productivity. So we can do that by looking at production records. We can make sure that animals are identified early in the process of the disease. Because the longer a disease Is present in a host body, the harder it is to treat, and the harder it is to reverse. So the acute short-term diseases are much less severe in production reduction than are the low grade, long-standing chronic infections. So in your management systems think about ways in which your monitoring for disease. Certainly we need to pick up those animals that serve a source of infection. Certainly we need to pick up those animals that are suffering. But you need monitoring systems by which you can pick up disease that's low grade and hidden from the visible eye. And pick them up early so that you can intervene and treat those disease, or put in place preventative strategies so that it doesn't spread and effect the rest of the herd. [MUSIC]
