Last month, after speaking with a groomer who tried to convince me that Papillons have double coats, I wrote a bit about how to tell if your dog has a single or double coat. I happen to have one dog with each coat type. Kitsune, my Papillon, has an amazingly soft single coat which, yes, I do trim often. Fenrir, my Alaskan Klee Kai, has a thick, warm double coat. He sheds a lot more than Kitsune does, and when I brush him I can clearly see that he has two different types of fur. While it's generally thought to be ok to trim a single coated dog, unless it was medically necessary, I wouldn't ever shave Fen's double coat.
Why shouldn't you shave the fur of a double coated dog?
Their fur is naturally designed to protect them from the elements. Most people can easily understand how a plush double coat could keep a dog like a husky warm in the winter. But, like the insulation in your house, a double coat can help protect your pet from the heat of the summer too! It protects their skin from sunburn, which is not only painful but, like in humans, can lead to more serious complications such as skin cancer.
In addition, double coat regrowth doesn't always go smoothly.
When you trim the fur of a single coated dog, the process of the fur growing back is, in healthy dogs, fairly simple. It's very similar to how your own hair grows long again after a haircut. Cut the fur of a double coated animal and the regrowth process is a bit more complicated.
Double coated dogs have two types of fur, and they don't follow the same regrowth pattern. If you go back and look at my post about how to tell if a dog has a single or double coat (link above) you can see that Fenrir, my double coated Alaskan Klee Kai, sheds only a small amount of guard hairs at a time, compared to quite a bit of his undercoat.
The undercoat is designed to be shed and regrown more often than the guard hairs, or top coat. That means that, when shaved, a double coated dog's undercoat will grown back much faster than their topcoat. This can, at best, leave double coated dogs looking a bit silly for quite awhile after they are shaved. With the top of their guard hairs removed, they can be a different color entirely. If their undercoat grows back before their topcoat, as is common, the texture of their fur will be different than what you're used to. It can appear more coarse/frizzy until the sleek guard hairs have a chance to grow back.
At worst, the different regrowth patterns can cause tangles and matting. The exact reason is unknown, but some dogs even suffer from post clipping alopecia. Patches of fur may take a very long time to grow back, or may never grow back at all. Of course dogs can still lead happy lives with funky looking coats, but extra care may have to be taken to ensure they don't develop mats and/or sunburns.
I'm not an expert when it comes to grooming, but I've had no such issues when it comes to trimming the hair of my single coated Papillon. His fur always grows back beautifully. Keep in mind though, that all dogs can become susceptible to sunburn if their fur is cut too short. While, generally, trimming the hair of a long, single coated dog shouldn't present any major problems, make sure you always leave enough fur to protect the dog's skin from the sun's rays.
If you have a double coated dog that seems to be suffering because of the heat, follow basic heat safety advice. Pay special attention to your dog's grooming. A clean, well groomed coat will help to dissipate heat much better than dirty or matted fur. Especially if your pet is shedding heavily, brushing to remove excess undercoat will go a long way towards keeping your pet cooler. If you don't want to do this yourself, many groomers offer de-shedding treatments. No clippers involved, just the already loose/shedding undercoat is removed.
It's important to note that some very long haired double coated breeds (powder puff Chinese Cresteds and Shih Tzus come to mind for me) are commonly trimmed. If you're unsure if a trim would be appropriate for your individual dog talk to your dog's breeder, a breed mentor, and/or a well respected local groomer. They should be able to advise what would be appropriate for your dog based on breed and your dog's individual lifestyle/coat type.
Comment below! What type of dog do you have? What is his/her coat type and do you ever trim your dog's fur?