Shave Science: The Facts About Shaving

All Things Paw

By Michelle Knowles

There is an ongoing battle raging. Shaving down dogs and cats is probably one of the most controversial topics there is in the grooming industry so I wanted to shed some light on the scientific side of the debate.

This is not a judgement of those who shave nor a vindication of those who choose not to shave, but a presentation of the mechanisms of the hair and function of the skin so that we, as groomers, may make an educated decision when presented with a pet whose owner would like a shave. Here are some researched facts about the hair and skin of pets.

First things first, let’s define what “shaving” means. This term actually means something different depending on what type of coat you are dealing with. For short coats like Dalmatians, Pugs, Labrador Retrievers and Rottweilers, shaving means any clipper work that takes the natural lay of the hair off of the body. Partial shaving of the throat, sanitary, ears and pads (with a #7 or shorter) are minimally damaging to the skin.

For double coated animals such as Pomeranians, Chow Chows, Golden Retrievers, etc., shaving means any length taken off that makes the primary hair the same length as the secondary hair as this then defeats the protective layering of the double coat. Long coats should be left with enough hair to cover the skin completely.

The hair or fur of any animal is an extension of the skin and is an integral part of the pets’ mechanism of protection from the outside world. The hair is a natural wind and sun barrier and is essential in the movement of oils across the skin. Each hair follicle is attached to a muscle called the Erector Pili that raises and lowers the hair in a complex ventilation system to keep the pet cool in summer and warm in winter.

Dogs are seven times more absorbent than humans and cats are 30 times more absorbent. This means that when the hair is removed, there is a greater chance of toxins, chemicals and other environmental pollutants to be absorbed into the body because there is no barrier to prevent it. Cat hair is so dense because their skin is very thin and needs the thickest layer of protection possible. When a substance is put directly on cat skin, it goes into the bloodstream and the cat can taste it, this is why many dog products cannot be used on cats.

Melanin, or the pigment in human skin that gets darker as we tan, protects us from UV rays but does not function the same way in dogs and cats. K9 and Feline melanin resides in the cortex of the hair shaft so the skin has no UV protection when the hair is removed. In dogs and cats, Pheomelanin (redheads) and Eumelanin (everyone else) lives in the cortex of the primary hair shaft not the skin. This can be seen on a double coat the best by parting the hair and seeing the richly colored hairs as opposed to the “diluted” secondary hairs.

There are 2 major shedding times of the year that happen during the Solstices, June 21 and December 21. Off season shedding should be minimal in a hydrated, healthy coat. Large amounts of off season shedding can happen when the coat is too dry and it breaks off or there is an underlying issue causing Alopecia or hair loss. The first issue can be alleviated with extra hydration treatments while the second needs to be explored by a veterinarian.

“Bad skin” is a sign of imbalance and needs a hair covering to protect the skin and keep it properly oiled. A shorter length of hair will not reduce contact allergies. Regular and proper cleansing of the skin is the only thing that will reduce the irritant that is sticking to your pet. Shaving causes the hair to fall out in small sharp pieces that aggravate itching and allergies.

Comedones and clogged follicles can actually be caused by shaving wire coats without carding and stripping out the dead hairs before clipping takes place. Wire coats have hair follicles that grow very deeply in the skin. The new hair growth does not push the old hairs out, instead, they grow beside the old hairs until they are pulled out by the groomer. When old hairs aren’t stripped out or carded and the breed pattern is clippered, the skin can actually grow over the follicles, trapping the hair and creating the “bumps” that we see on the skin of these types of coats. Enthusiasts of wire coated dogs know that clipping the hair instead of stripping it will result in a loss of color and texture in the coat as the primary hairs are damaged over a long period of time of being shaved.

Drop coats like Shih Tzu and Maltese, for example, do not experience the same issues that double, short and wire coats have. These coats should not be clipped so short that skin is showing as to give them enough of a hair layer to block UV rays.

Shaving backwards on a short, wire or double coat with a stiffly held primary hair, results in a possible breakage of the erector pili, the muscle that is responsible for movement of the hair in the follicle. And working these types of coats backwards pulls the “back” of the follicle open and may allow bacteria or fungus to slip inside. Drop and curly coats that are fluff dried normally have a very weak muscle, which means that the hair can be worked in any direction without damaging the growing part of the follicle.

There are some very good reasons to shave. If the pet is very matted then it may be wise to get rid of the coat and start over so that the skin can breathe and brush burn does not occur by long periods of dematting. If the pet you are working with is a Doodle of some sort and swims every day then a nice short clip will make everyone’s life so much easier. Extremely elderly pets can benefit from a shorter clip as it takes less time and keeps them from having to stand for longer periods. Sometimes, the owner truly means well but does not maintain the coat of their pet properly and every groom becomes a struggle. In these cases, a good compromise of length can be achieved for the well–being of the pet and your peace of mind.

In conclusion, there are many fact–based arguments to make a groomer rethink their position on the shaving issue. The best way to help you help your client in the decision-making process about shaving is to know the facts and be able to communicate these facts to your client without making them feel as if they are doing something wrong.

There are several publications that are made for groomers to give to their clients, as well as charts and research papers that can be used as teaching tools. One of the easiest ways to help your client understand the science behind your reasoning is to give them a brochure with a gentle suggestion to read it in their spare time. 

Many owners just want what they want and they will go elsewhere if you don’t give them their desired trim. I would rather treat the skin gently and re-oil the pet after shaving than have them go somewhere else and perhaps get a less desirable trim and skin issues on top of that. Hopefully this knowledge will give you the information you need to make educated decisions about when and how you shave in your salon. ✂


  1. Mary Oquendo says:

    I love this article!

  2. Malissa Conti-Diener says:

    BRILLIANT! Very well said.

  3. Jennifer Schilling says:


  4. Veronica says:

    Very informative! Thanks!

  5. Ann Carter says:

    Very well written article thank you

  6. Sarah says:

    Really good article

  7. Jackie Larocque says:

    Great article, and in a perfect world where all owners diligently combed their dog and cat, fed them awesome food and wanted all the dogs in show coat there would be no argument. However, we don’t live in a perfect world.

  8. Auriel Bow says:

    Excellent article to say the least.
    I really enjoyed reading it.

  9. Nancy Bynes NCMG says:

    Excellent article! I especially appreciate the discussion about wire-coats!

  10. Kathleen says:


  11. Barbara says:

    Very well done. Excellent writing. I only question the matter of “absorbency”. Cat skin is thin, but it is not a sieve. I need to see the science. Wish you had references.

  12. gayle says:

    So is it ok to shave a doodle with a 7 if they are not matted

  13. Carolyn Park says:

    Can you point us in the direction of the articles which we can use to show the data to clients, or so that I can write a Brochure to give them.

  14. linda says:

    What scientific studies and data do you have to support the theories you are calling fact. I sincerely doubt there have been too many studies that have proven the theories you write about. Most of what you call fact is merely observation and speculation of how and why certian things happen when a coat is shaved. While some of those may be true they have not been scientifically proven

  15. Cindy muit says:

    Great article. Thanks

  16. Rene says:

    References for the science please??? I cannot find any scientific evidence. Everything I find says “there is no real research, only opinion “..even from dermatology specialists. If you have the references we would love to see it

  17. RFC says:

    I have yet to find any article that cites any scientific study on the effect of shaving vs not on core temperature during hot weather. Many claims are made no data seems to exist. I even scoured the scientific literature. It seems that real research has not been done and all of this on both sides is simply opinion.

    I would like to see a large study of dogs of different breeds (many dogs from each breed/coat type) including measurements of core temp, outward signs of heat stress, amount of water consumed, all the things that can be measured that can perhaps answer the question about shaving with data, not opinion and cartoon of hair structure. But real measurements.

  18. Dog's day out says:

    I tell my clients on the consequences of shaving them but it’s their pet’s and I need to provide a service. I don’t do so short

  19. Lara says:

    Really enjoyed the article. I’m so glad I own my salon and can flat out refuse to shave dogs such as Labs or Golden’s. Client education is key!

  20. Hfields says:

    Very informative, Thank You
    What are Yorkies and Pekinese dogs considered in hair type?

  21. Christina says:

    I agree with most comments on here. I like the article because it backs what I’ve been taught and how I like to groom and what I think is best for the animals….but having the references for the science is really what would make this article legitimate.

  22. RCF says:

    As far as I can tell, the science does not exist. I searched the literature for it. As a scientist in an animal science department at a research university, I am lucky to have access to almost all scientific publications without being blocked by a paywall. I searched quite a bit on this topic. Seems that no study has been done and no results published. There is no data out there.

  23. Smash says:

    I live in a climate of hot summers and cold winters. When the weather turned warm I took my golden in and had her shaved. She went from a pooped pooch who was panting constantly to a puppy who would bounce around the park. One story doesn’t make science, but don’t try to tell me that coat kept her cool. Maybe it offered sun protection, but it made her hot!

  24. Gayle F says:

    I would like to know what you mean or what you use when you talk about re-oiling the skin

  25. Garth Engwall says:

    For those looking for scientific literature on the topic, there is plenty out there. I am not sure how you are doing your searches.

    But the first question is: “do you doubt the science of dog and cat hair and skin that is presented here?” A statement in the article like “Each hair follicle is attached to a muscle called the Erector Pili” or “Dogs are seven times more absorbent than humans and cats are 30 times more absorbent.” are not “observations” or “opinion” as some have claimed in their comments, they are statements of biological fact. What proof do you have that they are false? I would love to also have citations for some of this in scientific journals, but lack of citation doesn’t make the statements false or unscientific.

    Here is a peer reviewed study showing how body surface temperature in direct sunlight is lower in long and double-coated dogs compared to short haired dogs, just as the author of this article claims. If not for the scientific reasons stated here, what reasons do you have for this phenomenon? Magic?

    Kwon, Claire J. and Brundage, Cord M. (2019) Quantifying body surface temperature differences in canine coat types using infrared thermography. Journal of Thermal Biology, 82, 18-22

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