The heart is an important muscle when it comes to pumping blood around the body, so heart diseases like congestive heart failure (CHF), hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and heartworms reduce blood flow to the skin and other organs.

Hypotension (reduced blood pressure) causes reduced blood flow to the skin and other organs. Although hypertension (elevated blood pressure) increases blood flow around the body, it stresses detoxifying organs like the kidneys and liver and negatively affects their function.

The body needs fat to function, but high lipids (fats) like cholesterol thicken the blood and reduce its ability to reach the skin and penetrate other important organs.

If an animal is obese, that means they have grown too large for their heart and vessels to transport blood to the skin effectively. Pets struggling with obesity will also suffer from skin problems as a result of elevated blood lipid levels, infection and inflammation of skin folds, and increased abrasion (rubbing) by collars, harnesses, and environmental surfaces.

The adrenal glands produce anti-inflammatory steroids and water-balancing hormones. Cushing's disease (hyperadrenocorticism) involves an excessive production of steroids from the adrenal glands and causes thin skin, sparse hair coat, and chronic bacterial, yeast, or other infections. 

Addison’s disease (hypoadrenocorticism) involves reduced production of steroid and water-balancing hormones, causes less blood flow to the skin, and unnecessarily stresses all organ systems.

The thyroid glands are responsible for producing hormones that maintain blood flow, blood lipid levels, and metabolism. Hypothyroidism is the under-production of thyroid hormones which leads to reduced blood flow, elevated blood lipid levels, and weight gain. 

Hyperthyroidism is the overproduction of thyroid hormones, which increases blood flow around the body but negatively impacts whole-body health by elevating blood pressure and stressing all organ systems.

The kidneys function as one of the body’s filtration systems to cleanse the blood of toxins, maintain electrolyte and water balance, and prevent glucose and protein loss in urine. Kidney disease causes nitrogen (from the breakdown of protein) and other toxins to build up in the blood and, by extension, negatively impacts the skin and coat.

The liver also functions as the blood’s filter and is responsible for regulating immune function and blood protein and fat levels. Diseases of the liver weaken immune-system function, cause increased levels of blood lipids and toxins, and reduce blood protein levels.

The digestive tract has a major connection to internal organs and skin health. During the first phase of digestion, a dog's stomach uses a strong acid to store and break down food. The small intestine moves that food from the stomach to the large intestine, using digestive enzymes from the pancreas to absorb nutrients. Finally, the large intestine (colon) forms and stores feces and maintains hydration. 

Problems in any or all of these areas lead to reduced nutrient absorption, hydration imbalances, and immune system malfunction. Talk to your veterinarian about regularly performing diagnostic testing with blood, urine, and fecal samples to assess your pet’s internal organ health and monitor for infection with bacteria, parasites, and viruses.

If keeping your dog’s skin and coat soft and glossy is important to you, that’s just another reason to help keep your pet’s internal health in top shape!

“Nutritional deficiencies can contribute to skin and coat abnormalities,” Dr. Mahaney advises “So your pet’s primary meals must be nutritionally-complete and balanced.” 

Eating foods that aren’t nutritionally-complete and balanced (i.e., supplemental foods) on a short-term basis shouldn’t lead to nutritional deficiencies or subsequent skin and coat problems. However, beware that long-term feeding of nutritionally-lacking meals can negatively impact the skin, coat, and other body systems.

Dr. Mahaney advises that whole-food diets can benefit a pet’s skin and coat more so than long-term feeding of meals exclusively composed of kibble and other processed foods. 

 “Whole-food nutrients contain enzymes and co-factors essential to digestion and are often better absorbed by the digestive tract than processed foods. Additionally, the inherent moisture of whole foods also promotes better hydration and blood flow than foods and treats that have had their moisture removed.”

“Most pet foods and treats are made with feed-grade ingredients that have been deemed unfit for human consumption,” Dr. Mahaney reveals. “Feed-grade ingredients are permitted to have a higher level of toxins–such as mold-based aflatoxin and vomitoxin–which only needs to be ingested in small quantities to damage the gastrointestinal tract (stomach, small and large intestine), kidneys, liver, pancreas, and immune system. Such toxins are even carcinogenic (cancer-causing).”

Damage to the GI tract and liver from these ingredients might have a negative effect on skin and coat health, leading to dog shedding, skin flaking, and more.

Many processed pet food and dog treats contain artificial colors, artificial flavors, and chemical preservatives. Some of the artificial colors in pet foods and dog treats––Blue 2, Red 40, Yellow 5 and 6––can contribute to hypersensitivity (allergic-type) reactions, behavior problems, and cancer in humans. 

You’ve probably heard of caramel color before; it’s a common ingredient in processes people food. Pet companies also use caramel color to make foods and treats appear more like real meat. Beware, pet parents: this artificial color contains 4-methylimidazole (4-MIE), a known animal carcinogen.

For these reasons, Dr. Mahaney suggest that pet parents should “take steps to eliminate artificial colors from pet meals and treats. Generally, artificial flavors aren’t inherently harmful but can cause digestive tract responses like food aversion, vomiting, or stool problems and shouldn’t enter our pets’ bodies.”

Pets that eat an appropriate amount of calories each day to maintain an ideal body weight have better long-term overall health. Dr. Mahaney's suggests partnering with your veterinarian to “assess your pet’s weight and body condition score (BCS) and determine if weight loss is needed.” 

If you're looking to boost your dog's diet, "consider the addition of daily dietary supplements to promote skin and coat health," says Dr. Mahaney. The best dog supplements for skin and coat will include skin-beneficial ingredients like: 

Omega Fatty Acids

Omega fatty acids are important in promoting the health of skin, hair, joints, nerves, and other body tissues. Omegas 3 and 9 have natural anti-inflammatory effects, while Omega 6 provides the basic building blocks of nerve tissue. Seek dog allergy supplements that contain multiple types of vegetarian and animal-based omega-fatty acids like flaxseed, krill, safflower oil, and salmon oil for dogs’ skin health. 

Minerals

Zinc Gluconate is a mineral crucial to skin health. Zinc promotes protein synthesis for more supple and resilient skin, and has anti-inflammatory and antioxidant effects for overall skin barrier health.

Vitamins 

Vitamins like B7 (Biotin) contain proteins, carbohydrates, and fat metabolism that provide the basic building blocks of skin and hair. B9 (Folic Acid) promotes hydration by enhancing the skin’s barrier function to protect against environmental irritants and infectious organisms. 

If you’re looking for a skin and coat supplement for dogs with dry skin, Vitamin E is a moisturizing ingredient that also boasts antioxidant and anti-inflammatory effects to shield the skin from UV damage.