Natural light has role in shedding

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By Dr. John Koch

Question: I have two dogs. One is strictly an outdoor dog that we adopted a few years ago when he showed up half-starved on our doorstep. He is a mixed breed with maybe some collie and black lab in his background. His hair is semi-long. I have noticed that he sheds every spring and every fall. Our second dog is also a mixed breed that we adopted from the Humane Society as a puppy. She is a small dog and only goes outside to use the bathroom. She is probably rat terrier crossed with something, and has relatively short hair. She sheds constantly. We have put up with it, but it has been a little aggravating. We have tried several medications that are supposed to help, and they do a little; however, it is still a problem. Why does the dog outside only shed twice per year while the house dog is always shedding?

Answer: Hair is important to help protect the pet from dirt, environmental extremes, infection and other stresses. Shedding is the normal process of replacing aging hair with healthy new growth. All dogs shed. Genetics play a large role in how much a dog sheds.

Another factor frequently overlooked in shedding is the amount of natural light that the pet receives. It is normal that pets receiving natural light shed twice a year. Outdoor dogs typically are exposed only to the natural light from the sun and fit this pattern.

Indoor dogs, on the other hand, receive artificial light, and shedding with artificial light tends to be more constant. There is a complex interaction of light with the pituitary gland that controls these patterns.

Other factors that may be involved in shedding are parasites, infection, quality of diet, allergies and stress. It is also possible that an outdoor dog may shed a lot more than people realize. Daily contact with outdoor pets is not as close as it would be with an indoor pet. Shedding outside is not going to be noticed nearly as much as shedding inside. There are a number of things that can be done to minimize shedding, but it cannot be stopped.

Dr. Koch is a Cape Girardeau-area veterinarian.