The Pet Integumentary System
Skin, Coat, Nails, and the Biology of Protection & Aging
Written by Dr. Sarah Calvin, DVM
Dr. Sarah Calvin, DVM is a small-animal veterinarian with interests in dermatology and internal medicine. She supports La Petite Labs by helping ensure our skin, coat, and nail education remains biologically accurate, conservative, and easy for pet parents to understand.
The Building Blocks
Image Credit: Martin Högborn / The Royal Swedish Academy of Sciences
Proteins
Proteins like collagen, elastin, and keratin provide structure and flexibility to skin, hair, and nails. Diets need to contain sufficient and balanced amounts of protein for dogs and cats to synthesize these molecules.
Image Credit: University of Rochester image / Zhihuan Li
Lipids
Lipids are foundational to a healthy integumentary system. They are an important component of the skin barrier: maintaining hydration, regulating the immune system, and preventing damage. Medically, fatty acids have been used to treat a variety of skin conditions.
Image Credit: Dr. Robert Berdan, Canadian Nature Photographer
Vitamins
Vitamins like biotin, vitamin A, and vitamin D support immune regulation, hair structure, and cell regeneration. Deficient animals can have severe consequences to their integumentary system.
Image Credit: Tina Carvalho, University of Hawai'i
Signaling molecules
The integumentary system interprets the world for the rest of the body. It is rich with neurotransmitters, hormones, and cytokines, all using distinct mechanisms to communicate with other organ systems.
Image Credit: Canva Image Library
Water
Dehydrated skin decreases the barrier capacity of the integumentary system. It can be cracked and brittle, leading to discomfort and opportunistic infections. All previous building blocks need proper hydration to form an effective integumentary system.
“In the United States today, dysfunction of the integumentary system is the top complaint at a veterinary visit.”
Protection
The integumentary system is the body’s first line of defense. It acts as a physical barrier, covering sensitive underlying tissues like nerves, vessels, and bones. It is a powerful immunological barrier, preventing infection from various diseases. Your pet’s skin is covered in receptors that screen everything they encounter. If something is perceived as a threat, these receptors will send signals to the immune system to bring in defenders like white blood cells to kill any incoming pathogens.
This is why the outermost layer of skin is called the “skin barrier”. A breakdown in the skin barrier can cause chronic, localized inflammation. Evidence from human medicine correlates chronic inflammation with conditions like diabetes, dementia, and heart disease, and similar pathways are suspected in pets. Furthermore, a damaged skin barrier can be itchy, painful, and prone to infection. We now know that some breeds have a genetically worse skin barrier than others, showing that we need to be proactive in promoting a strong skin barrier. These breeds include bulldog breeds, German Shepherds, Retrievers, West Highland White Terriers, and Staffordshire Terriers.
Sensation
The integumentary system is rich in nerves that allow your pet to feel sensations like hot, cold, and pain. Unlike people, dogs and cats have unique tactile hairs located on their face and head. These are highly sensitive hairs that detect pressure (even as light as a change in air flow), allowing animals to navigate with low visibility.
Image Credit: Digital CGI rendering of DNA. Artist unknown.
Thermoregulation
Your pet’s coat can be either fur, hair, or both (called a double coat), and is essential for regulating body temperature. Fur tends to be shorter and dense, as it has one specific length it will grow to. On the contrary, hair will grow continuously. The coat is a natural insulation, keeping your pet warm when it’s cold and naturally cooling when it’s hot.
Moisture regulation
The coat can also prevent moisture from evaporating from the skin. This protects your pet from dehydration.
Can dogs and cats sweat? Yes! However, their sweat glands are mainly in their paw pads. This doesn’t have the same cooling effect as humans, which is why they primarily use other methods like panting (dogs) and grooming (cats) to cool their bodies.
Comfort
A good integumentary system will keep your pet comfortable. Strong nails protect sensitive underlying quicks. Healthy skin is free of itch and pain. A well-maintained coat won’t snag as your pet moves. Perhaps our favorite of all – a healthy integumentary system allows our pets to feel all the pleasure of a good belly rub, chin scratch, or a loving touch.
Common Causes of Integumentary System Dysfunction
Allergies
Allergies occur when the body perceives a non-pathogen (like foods, shampoos, or pollens) as a potential threat, causing an immune response. The skin is one of the main locations allergies will present in a dog or cat. Common symptoms include: itching, hives, rashes, overgrooming, excessive shedding, and/or chronic ear infections.
The three most common allergies seen in dogs and cats are 1) flea allergy, 2) food allergy, and 3) environmental allergies.
Image Credit: CDC.Gov
Flea allergies are seen most often in pets with access to the outdoors and lack of a flea preventative. A dog or cat can have a widespread flea allergic reaction without being infested with fleas. Pets with this allergy overreact to the flea saliva, meaning a flea can jump on your pet, bite them, leave, and still cause an allergic reaction. Symptoms of a flea allergy are usually seen with intense itching around the base of the tail and hind legs. Animals will scoot, bite, and scratch to relieve this itch, which can lead to hair loss and skin trauma.
Food allergies are a common cause of chronic itching in dogs and cats. They tend to present in multiple areas of the body with year-around symptoms. Beef, dairy, chicken, and wheat are the most common food allergens in dogs, while beef, fish, and chicken were the most common in cats. Food allergies are best diagnosed through an elimination diet performed under the supervision of a veterinarian.
Environmental allergies have a wide variety of presentations because they have a wide variety of causes. A pet may present with itching and rashes on the paws and underbelly if they are allergic to grass. Seasonal allergies may occur when pets are allergen to pollen. Indoor only animals can have year-around allergies to laundry detergents, dust mites, or even other pets. The gold standard for diagnosing environmental allergies in dogs and cats is Intradermal Skin Testing (similar to a skin prick test in people) through a veterinary dermatologist.
Excess moisture
When it comes to hydration, there can be too much of a good thing. Excess moisture on the skin can break down the barrier function of the skin and create an environment where bacteria and yeast can overpopulate. This occurs most often in ears, paws, and skin folds. Be sure to completely dry your pet, especially in these problem areas.
Underlying health conditions
Diseases affecting the liver, intestines, hormones, joints, and immune system can all cause changes to the integumentary system. It is especially important to discuss changes you see with a veterinarian in case they could be highlighting a deeper issue.
How to Care for your Pet’s Integumentary System
Remove the insulting cause
When possible, find what is causing damage to the skin barrier. Many pets will have multiple causes that need addressed. It can be helpful to keep a diary of the products and environments your pet is exposed to and track their symptoms.
A veterinarian should check your pet for external parasites like fleas and mites. To minimize the risk of flea bites, treat all pets in the home year around with an appropriate flea preventative.
Address any food allergies with a hypoallergenic or limited ingredient diet trial. Many pets with flea or environmental allergies also have a food allergy. Note: it takes up to 8 weeks of a strict diet trial to see results.
If you suspect an outdoor environmental allergy in your pet, try wiping their paws and underbelly each time they return from time outside. These pets respond well to frequent bathing as well.
Treat infections
Yeast and bacteria are the main causes of infection in pets. The most common places infections hide are inside the ears, between the legs, in skin folds, nail beds, and between paw pads. Until the infection is addressed, your pet will remain uncomfortable. Signs of infection include redness, itchiness, abnormal discharge, and abnormal smells (frequently like corn chips).
A veterinarian will tailor a treatment plan to your pet’s specific needs. Common treatments include medicated shampoos, wipes, ointments, and antibiotics.
Provide the right building blocks
This step can and should be started at the same time as steps 1 and 2. A healthy integumentary system is a balanced network of countless molecules, many that are discussed above.
This all starts with a balanced diet. Appropriate ratios of bioavailable proteins, fats, vitamins, and minerals all significantly impact the health of the integumentary system. A lot goes into picking a good food for your pet.
Some key factors to look for include:
- Products formulated by a Board-Certified Veterinary Nutritionist or equivalent PhD
- Products tested through AAFCO feeding trials
- Companies that respond to the Pet Food Manufacturer Evaluation Report
- Companies with quality control testing
Supplements can be given to in addition to a high-quality food. Fatty acids, like those found in La Petite Lab’s Pet Gala™, have been shown to improve the skin barrier and decrease skin inflammatory response. Zinc and biotin are also commonly supplemented, as deficiencies can have profound negative impacts on skin health.
Maintaining a healthy integumentary system will look different based on each pet’s needs. Much of maintenance will be continuing tools learned from steps 1-3. In addition, it is important to find a hygiene regimen that keeps your pet comfortable. This includes regular brushing, nail clipping, bathing, and trims for pets with hair.
Brushing should be done weekly at minimum, with some breeds requiring daily brushing.
Nails should be clipped or filed before they become brittle, frayed, or ingrown. Nails should never touch the ground. For many pets, this means a trim every 2-4 weeks.
Bath frequency varies greatly for dogs. Most cats do not need bathed. Signs of overbathing: dry skin, brittle hair, and itchiness after baths. Signs of under bathing: odor, waxy debris on skin, and allergy flare-ups.
If your pet has experienced skin issues in the past, it is not uncommon to see a flare up every year or so. Establish a “flare up” plan with your veterinarian.
References
- AVMA. Pet Ownership and Demographics Sourcebook. (2018). ebusiness.avma.org/Files/ProductDownloads/2019 ECO-PetDemoUpdateErrataFINAL-20190501.pdf
- Henein M, Vancheri S, Longo G, Vancheri F. The Role of Inflammation in Cardiovascular Disease. International Journal of Molecular Sciences. 23(21):12906 (2022). doi.org/10.3390/ijms232112906
- Tengvall K, Sundström E, Wang C, et al. Bayesian model and selection signature analyses reveal risk factors for canine atopic dermatitis. Communications Biology. 5:1348 (2022). doi.org/10.1038/s42003-022-04279-8
- Wootton F, Hoey C, Woods G, et al. An undernutrition screening score for dogs with protein-losing enteropathy: A prospective multicenter study. Journal of Veterinary Internal Medicine. 37:1821 (2023). doi.org/10.1111/jvim.16794
