All Creatures Great and Small - Season 3 Episode 12 Matters of Life and Death

James treats Paul Cotterell's dog Theo, who has been losing weight and is diagnosed with Hodgkin's disease. James recommends that Theo be put down and Paul agrees. James doesn't realize the impact this has on Paul and the tragic results that ensue. James meets Lord Hulton, a hard working farm owner despite his aristocratic background. Hulton takes a liking to a horse that has wandered onto his property from the nearby military depot. At the Billings farm, James finds young calves who are wasting away. He thinks they have ingested an irritant of some kind, but the vets simply can't isolate it.