The flu takes the clinic by storm, but Dr. Pol and his staff must fight through it. Dr. Brenda struggles to find out what is causing a dog to be so abnormally lethargic. She learns from his owner that it's possible he was exposed to marijuana. Dr. Brenda is relieved that the dog will be back to normal in a day. Then an entire herd of cows are too thin despite being well fed. Dr. Pol thinks it's a lack of minerals, and is surprised to find the entire herd has come down with pneumonia.