Winter can be tough on all of us, human and canine.

It's no wonder that the flu season for us is usually over the winter months. Although our dogs don't tend to have a flu season as we do, diseases such as the canine flu, various respiratory diseases and other issues are often seen in the winter. A healthy immune system is your dog's first line of defense against diseases such as these, as well as bacterial, viral and fungal infections. Although a strong immune system is no guarantee your dog won't get sick, it increases his odds that he won't; or, if he does, his body is better prepared to fight against the illness. The immune system is a complicated thing. Many of the body's parts are involved, including the tonsils, bone marrow, spleen, lymphatic system and more. Therefore, the idea of boosting that system and increasing it's effectiveness, is also complicated and because of this, there is a lot of controversy. Let's take a look at what is known.

Make Good Habits

Healthy living habits are the immune system's first line of support and good nutrition tops the list. Feed your dog an excellent, balanced diet of quality ingredients. Although there are few studies directly linking good nutrition or a specific diet to good immune health, we do know that all of the body's systems need good nutrition to function well so it's reasonable to believe that includes the immune system too.

Habit: Regular Exercise

Second on the list of healthy living practices is exercise. Your dog's body was made to move, walk, run, dig and jump. The body must move regularly to keep everything working as it should. The circulatory system and digestive system are both known to work better with daily exercise compared to when the body is at rest for long periods of time. How much exercise is needed depends on your dog's age, state of health and physical abilities, so if you have any questions, talk to your dog's veterinarian.

Habit: Average Body Weight

Your dog also needs to be at a good weight for his size, breed and age. Ideally, he is neither too fat nor too thin. One of the things I've found fascinating about dogs is the many variations in body size, shape and weight there is depending on breed. A Greyhound, for example, and a Basset Hound who both weight 70 pounds will look completely different. If you have any questions about your dog's weight, talk to your veterinarian.

Habit: Frequent Sleep

You probably pay attention to your own sleep habits, but have you paid any attention to how much sleep your dog gets? Just because your dog seems to nap often doesn't mean he's getting good, deep, restful sleep. Instead, he's dozing in a light sleep from which he can awake at the slightest sound. At night, many dogs assign themselves the job of night watchman and patrol the house. Others will stay in the bedroom with you, maybe even on the bed, but again are alert. A lack of sleep can be just as damaging for your dog as it is for you. Convincing your dog to sleep when he'd prefer to patrol the house might be difficult though. Perhaps he can sleep for several hours during the day or night in a crate.

Habit: Cleanliness

Cleanliness is also important for good health and a good immune system. This doesn't mean your dog needs a bath every week; in fact, too many baths can damage his skin. However, you should clean his teeth, watch his eyes for matter that should be washed off and clean his ears when needed. Check your pup for cleanliness around the genitalia and after he's moved his bowels. Make sure his area to relieve himself in the back yard is picked up and washed down regularly.

Vitamins, Minerals, Supplements

Ideally, your dog should be getting all the nutrients he needs from his dog food. However, dog foods are made for the average dog and what exactly is an 'average' dog? Each dog is an individual with unique needs and his own digestive system. Sometimes supplements can fill in the nutritional gaps that a dog food might not be providing. Along that same vein, if your dog is working hard, exercising more than normal, is in a training program or is otherwise stressed, some supplements may be warranted. However, don't supplement indiscriminately. If your dog food is balanced and you supplement incorrectly, your dog could potentially be affected negatively. Vitamins A, D, and E are fat soluble vitamins and excess will be stored in the body's fat cells. Over supplementation can create toxic levels in your dog's body which are quite dangerous. If you'd like to supplement your dog's food with a vitamin and mineral supplement, talk to your veterinarian before doing so. Shelves in health food stores, grocery stores and even pet stores all showcase herbal supplements that are supposed to cure (or help) all ills, including boosting the immune system. Some studies have been done on some of these supplements and some have lived up to their promotions. Milk thistle, for example, has been shown to aid liver function in both dogs and people. Many of the other studies on herbs don't live up to scientific scrutiny even when anecdotal reports show benefits. Other herbal remedies haven't been studied at all or the studies have been funded (or done) only by the maker of the supplement. Due to the lack of information, giving herbal remedies to your dog to boost immune system strength should be done only after researching the herb carefully and discussing this with your veterinarian. Probiotic supplements, however, are generally regarded as safe. This is particularly true when given as food; yogurt with live, active cultures, for example, is both a good food itself and supplies beneficial probiotics. Researchers at Harvard Medical School have found a relationship between the beneficial bacteria in the digestive system and a strong immune system. How this happens isn't completely understood yet, however, but research is continuing. Therefore, supplementing your dog's diet with a food containing probiotics can be beneficial.

Work with Your Veterinarian

I've long considered my dogs' veterinarian my partner in my dogs continued good health and I suggest you do too. My dogs' veterinarian keeps up on studies, research, new techniques and medications. In addition, if I ask her a question she isn't comfortable answering, she will tell me she needs to do more research herself and she'll get back to me. I admire that. Since research on how the immune system functions is ongoing, talk to your veterinarian regularly and especially before giving your dog any supplements or herbal remedies.