Okay, so now, for a little taste of the wonderful world of pathology. Vet students, as you know, need to spend a lot of time learning about normal structure and function, and Gura has given me a good insight into that aspect this week. Once students have done that, it's then really important that they start to understand how diseases develop and how disease processes develop. So, I'm going to give you a little insight into that, and I'm going to do so by using two cases of heart pathology. Now Gura has spent some time showing you the structure of normal heart valves and how thin and delicate these structures should be in a normal animal. The first case that I have is a case called endocardiosis in a dog. This condition results in the heart valves, as the dog's age, becoming slowly taken over by little pear-like white lesions, and a lesion is just an abnormality of tissue. So, you get these little rounded areas on the edges of the heart valves, and what I've got is an example of that here. These little pear-like lesions and what happens in these cases is that instead of the heart valves meeting nicely together like this and performing their function, because of the nodular developments on these heart valves, the valves start to do this, and they start to become what we call incompetent, and this just means that they can't perform their function properly. So, that is an example of an age-related degenerative disease of the heart valves of dogs. It's particularly common in small breed dogs and in those breeds, one of the best recognized breeds to have this condition would be the Cavalier King Charles Spaniel. The other case that I have is another disease that affects heart valves, but it's a very different type of process this time. This heart that I have here is a heart from a sheep. And what we have here is a condition called endocarditis, and in endocarditis, what happens usually is that the animal has a preexisting bacterial infection. In a sheep, it might, for example, be an infected joint, or infected tooth, or some other process elsewhere that causes bacteria to get into the bloodstream, and this can cause damage to the heart valves, and as we can see in this case here, instead, again, of having nice, delicate, thin heart valves, these valves are covered in large lesions composed of inflammatory cells and debris, and there's just no way that these heart valves will be able to function properly. These animals will be lethargic, they will tire very easily, and their hearts will probably have dramatic heart murmurs, which you can hear with a stethoscope, and a heart murmur is just an abnormality in the blood flow across the lesions that we would see in these hearts. So, two very different cases of heart valve disease. One, an age-related change in a dog, and one, a change related to infection and damage along those lines in a sheep, but I hope that gives you a little bit of a taste into the world of pathology.