The key to understanding the skin is to understand that no matter what the actual cause of a given problem may be, the skin has only one way to react when it gets angry: it turns red, it loses its hair, it may be itchy or get infected and you may see a symmetrical or assymetrical pattern of specific lesions. The way the skin looks therefore, is a very ineffective way to judge the cause of a problem and an even less helpful way of deciding on a course of action.
There are a wide variety of medical problems that affect the skin. In many of these cases the skin looks, feels and smells abnormal, but those abnormal characteristics do not necessarily help make the diagnosis. Without a diagnosis there can be no logical treatment decision made. All efforts to treat are thus guesses and may be merely treating symptoms or secondary problems, like superficial infection, without ever getting to the actual underlying cause.
Broad categories of diseases affecting the skin include allergy (environmental, food), infection (bacteria, yeast), parasites (sarcoptic mange, demodectic mange, ticks, fleas, others), immune-mediated disease (several) and others.
A veterinarian's basic approach to skin disease is: a detailed history, a detailed physical examination, skin scrape, fungal culture, basic laboratory tests. Other tests or evaluations may be ordered based on those results. There is just no simple way to address "skin disease" without understanding the underlying cause.
I am sorry to hear that another dog you had lost its life to skin disease, but I will say this: if your doctor is unable to communicate to you what he/she is treating and why with respect to any disease including skin disease, or his/her treatments are ineffective as with your last dog, then by all means seek a second opinion. While it is true that some diseases can only be managed but not cured, it should not be necessary for a dog to lose its life without you having had a good understanding of what and why. That would be a real tragedy.
Please do go to your doctor with your dog, explain your financial limitations, and follow his or her recommendations. Its the only way to understand the cause and get the problem under control. In the long run, you will save money through reduction in the need for acute care visits for a future chronic unsolved skin problem.
Dr. Arnie Goldman
We have a dog that gets spots like that and she has responded to allergy medicine.