I also believe that animals can get depressed as well. Animals that I have had (especially dogs) seem to know when you are feeling down or depressed and seem to sometimes share those emotions with you. I guess if your pet seems to be depressed then maybe you should look at yourself and see what kind of emotions you are emitting as well.
Animals definitely form relationships and can thus express emotions such as depression. There is a beautiful video from a news clip that elaborates on a very close relationship shared by a dog and an elephant. When the dog got injured, the elephant waited outside the house the entire time the dog was recovering. She only left when the dog was once more able to roam with her.
I think that the question is fairly solid. I would suggest that a slight rewording might be in order. For example, instead of "Do animals get depressed," why not try, "Do animals experience depression?" I think that it sounds a bit more clinical and less vernacular, or common speak, in the writing of the paper. I think that you will need to substantiate your findings with some evidence that suggests that there are conditions in animals where tendencies of depression behavior could be evident. The studies on animals' learned helplessness, especially with experiments done with canines, could definitely be useful for this particular paper.
There is absolutely no doubt that animals of higher intelligence become depressed in certain circumstances. Any pet owner who has had a number of animals will quickly attest to this, as will vets. For instance, one dog was attacked by several and suffered multiple wounds; when she became infected from these wounds, she was given antibiotics intravenously. However, after a few days, the veternarian became concerned because, although the infection was reduced and healing had begun, the dog would eat little and was listless. "She is depressed," he told the owner and we must do something about it. "Perhaps you can take her home and administer antibiotics orally, keeping her quiet." The owner concurred with this judgment, brought the dog home, and in a couple of days her spirits returned when she was able to again be outdoors for a time (she usually came in at night only). A very bright terrier, Pepper's morale was boosted by leaving the confines of the animal hospital!
Tales and tales have been told of dogs who have pined away when their masters have died. After all, it only stands to reason that these intelligent animals who show so much joy can equally feel "the other side of the coin." In another example, during a study of monkeys without their mothers, the babies soon died. If, however, they had a cloth or stuffed "surrogate" mother, they survived. Obviously, then, there is an intrinsic need to have someone to cling to, or depression sets in.
As always, we can learn much from our furry--and hairy, like horses--friends.
I definitely think that an argument can be made for the fact that animals get depressed. Having worked with horses all of my lofe, I have seen it first hand. Also, I have a number of close friends who work with the animals at parks and zoos who would definitely argue that sadness/depression is an emotion that animals feel. If you were going to prove this, I would look at studies that have been done about the behavior of animals when they lose their companions. For instance, a dog or a cat who has lived in a household with another pet will grieve when that pet dies or leaves. Horses do this as well. They have companions among their animal friends and they do mourn when this companions go away. Similarly, animals will go through a period of depression when their main human companion dies or when they are sold or given away for any reason. This is the reason animals have been known to travel extremely long distances to try to return to the family that they have known for a long time. I would also look at postpartum depression among animals. When a mother loses her baby, even in the animal world, she will mourn and become depressed, often not eating and sacrificing her own health in the process. There is a great deal of scientific precedence for this concept, and animal behaviorists (scientists who work with animals on a regular basis) are a good first place to start in terms of amassing reference material for an argument of this nature.
i think yes, animals do get depressed, especially when the mother dies or someone close dies to them.