Red tear staining is a common complaint for specific breeds of dogs. The red tear stains are primarily caused by porphyrins, iron-containing molecules produced when the body breaks down red blood cells. These molecules are excreted through tears, saliva, and urine and can cause staining when they come into contact with fur. Minimal studies have been conducted on the causes and prevention of staining, but a species-appropriate diet has been shown to reduce the production of excessive tears.

Causes of Excessive Tear Staining in Dogs

Red tear stains in dogs primarily stem from porphyrins, natural by-products of red blood cell breakdown. These iron-containing molecules can stain light-colored fur when expelled through tears, saliva, and urine. Several factors contribute to the development of these stains.

Excessive tear production, or epiphora, which can be triggered by eye infections, allergies, or irritants, leads to more pronounced staining. The overflow of tears onto the face creates an environment conducive for porphyrins to stain the fur. Abnormalities in tear drainage can cause tears to spill onto the face rather than drain appropriately through the nasal lacrimal system. This chronic wetness around the eyes is a primary cause of staining.

Dogs with brachycephalic features, such as Bulldogs or Shih Tzus, often exhibit more noticeable tear staining due to their facial structure, which can contribute to tear duct problems or create folds around the eyes that trap moisture. 

The diet and water a dog consumes can influence tear staining. A high mineral content in drinking water or specific dietary components might increase tear production or alter its composition, leading to more prominent staining.

Various health conditions also play a role. For instance, teething in puppies or chronic conditions like keratoconjunctivitis sicca (dry eye) can change tear quality and increase production, further contributing to the problem.

Prescription drugs that can impact tear production and fur staining include sulfonamide, oral prednisone, and ear medications like terbinafine and florfenicol. Sulfonamides are used to combat urinary tract infections or treat ulcerative colitis. Oral prednisone is used for a variety of medical conditions, including skin infections, cancer, arthritis, and allergies. These medications can cause neurogenic keratoconjunctivitis sicca (nKCS), which reduces tear production, making the porphyrins in tears more concentrated and the staining more pronounced. However, once the drugs are discontinued, the side effects should be resolved.

Certain dog breeds are more prone to excessive tears and tear staining, particularly those with brachycephalic (short-nosed) facial structures and lighter-colored fur. Breeds commonly affected include:

Shih Tzu: This breed often has issues with tear drainage due to their short nose and large, round eyes, which can lead to tear spillage onto the face.

Maltese: Known for their beautiful white coats, Maltese dogs are also known for tear staining. Their fine hair and light color make the stains particularly noticeable.

Lhasa Apso: Similar to the Shih Tzu, the Lhasa Apso has a facial structure that can contribute to tear staining problems.

Poodles: Poodles, especially the toy and miniature varieties, can have significant issues with tear staining.

Bulldog: English and French Bulldogs may experience tear staining due to their wrinkled face and flat facial structure.

Cocker Spaniel: Known for their beautiful, droopy eyes, Cocker Spaniels can have blocked tear ducts and excessive tearing.

Pekingese: This breed often struggles with tear staining due to their flat face and prominent eyes.

Boxer: Boxers are prone to various eye issues due to their facial structure, including excessive tearing.

Cavalier King Charles Spaniel: Their prominent eyes and distinctive facial structure can lead to tear duct problems and staining.

These breeds often require regular eye cleaning to manage tear staining and prevent associated issues like skin irritation or infection.

Poor Oral Health Can Affect Tear Staining

Oral health significantly influences tear production and staining in dogs due to the close anatomical and physiological relationships between the oral cavity and the eyes. Good oral health ensures that the overall bacterial load in the body is controlled, which is crucial because dental diseases can lead to an overgrowth of bacteria. These bacteria can produce by-products, including porphyrins, the compounds containing iron responsible for the reddish-brown color seen in tear stains.

When dogs have periodontal disease or other oral health issues, the amount of bacteria in the mouth increases. These bacteria can enter the circulatory system and potentially affect different body parts, including the tear ducts and glands. Increased bacterial content in the tears can lead to more pronounced staining as the bacteria might alter the composition of the tears, increasing the concentration of staining compounds.

Additionally, inflammation from poor dental health can have systemic effects, potentially causing or exacerbating conditions that affect tear production, such as dry eye. Chronic inflammation can lead to changes in the tear film's stability, impacting eye health and contributing to issues with excessive tearing. When tears overflow onto the fur regularly, they provide a medium for bacteria to thrive, which, coupled with iron-containing compounds, leads to visible tear staining.

Dietary Changes To Help With Tear Staining

Dietary interventions can be crucial in managing the occurrence and severity of red tear stains in dogs. Research suggests several specific dietary approaches that could mitigate these stains. Feeding species-appropriate diets that include foods that have anti-inflammatory and antioxidant properties can alter tear composition and thus reduce tear staining. 

Omega-3 fatty acids are recommended due to their anti-inflammatory properties. The Real Ancestral 6X DietTM includes small fatty fish as 10% of the total diet. Omega-3 fatty acids are often deficient in dogs, especially kibble-fed dogs. 

Because the primary functions of omega-3 (reduce inflammation) and omega-6 (increase inflammation) are essentially the opposite, the dog diet must supply them in the correct ratio. Many commercial kibble products are high in omega-6, even those labeled as 'complete and balanced.’'Adding raw fish to a kibble diet can aid in balancing omega-6 to omega-3 fatty acids. 

Fatty fish make up 10%  of the diet. Choosing smaller fatty fish near the bottom of the food chain lowers the risk of mercury contamination. Larger fish species that have the potential to contain higher mercury level should be avoided. Examples of fish to add to the diet include herring, sardines, mackerel, capelin, salmon, and smelt. Canned fish preserved in water only, with no spices or oils, can be fed to dogs. 

Another component of the Real Ancestral 6X Diet that may offer help with tearing and staining is the raw meaty bones (RMBs). Although feeding RMBs primarily provides a source of calcium, phosphorus, and other trace minerals, they are also essential for oral health. The RMBs will influence tear and saliva production and reduce plaque and calculus buildup, modifying the environmental conditions that lead to tear staining. 

Edible bones to be added to the diet are soft and malleable. Birds and small animals have hollow, non-weight-bearing bones that are digestible. Weight-bearing bones from large animals should be avoided to prevent damage to the teeth. 

Choosing the right bone is crucial. Small-breed dogs often do best with rabbit, Cornish hens, chicken or duck feet, chicken wings, or chicken necks. The best bones for a medium-sized dog include poultry necks, poultry feet, rabbit, and duck wings. Larger dogs can be fed pork or lamb trotters, poultry necks, turkey wings, beef short ribs, and poultry necks.

Air-dried chews such as bull pizzles, bison scapula, tracheas, and beef backstraps require dogs to chew with all parts of their mouth, naturally cleaning all tooth surfaces. All chew sessions should be supervised.

In dogs, oxidative stress can contribute to inflammatory conditions that affect the eyes, such as keratoconjunctivitis sicca. Mitigating oxidative damage with antioxidant supplementation can reduce these inflammatory responses, as well as more stable tear production and reduced tear staining.

Antioxidants can directly affect the quality of tears. Improved systemic antioxidant status can lead to healthier tear composition, which might reduce the concentration of substances like porphyrins that cause visible staining on the fur around the eyes. Maintaining a good balance of antioxidants in a diet might help manage or reduce issues with excessive tearing and tear staining, alongside other health benefits.

Fresh foods that contain antioxidants are readily found in nature in many fresh raw vegetables and fruits. The colored fruits and vegetables, such as blueberries, goji berries, carrots, and dark leafy greens, tend to have the highest concentrations. 

Not all dogs will eat fruits and vegetables. Other good sources of AOs are mushrooms, pine bark extract, milk thistle, phytoestrogens such as soybeans, and spices including rosemary, thyme, marjoram, oregano, sage, basil, pepper, clove, cinnamon, and nutmeg. All of these AOs can be added to a dog's meal.

High mineral content, especially hard water, may contribute to tear staining. Minerals like iron and magnesium found in hard water can interact with tear compounds, possibly leading to staining when tears contact the fur around the eyes. 

Chemicals or contaminants in poor-quality water could lead to health issues or irritations that might affect the eyes indirectly. For example, chemicals like chlorine or pollutants found in some water sources could irritate the eyes, possibly leading to increased tear production or changes in tear composition that might exacerbate staining.

The pH level of water can also affect eye health. Too alkaline or acidic water might irritate the eyes and the skin, potentially affecting tear quality and staining.

If a dog shows signs of excessive tearing, examining physical health factors like allergies, blocked tear ducts, eye infections, and environmental stressors that affect the dog's overall well-being could be beneficial.

Addressing these underlying causes, such as treating eye infections or adjusting the diet, can help mitigate the appearance of red tear stains. Concerning the role of dietary minerals, although specific minerals do not directly cause excessive tearing, they may contribute to conditions that exacerbate it. Imbalances in essential minerals like calcium and phosphorus, high sodium intake, and deficiencies in zinc and copper can indirectly affect tear production due to their broader health impacts. Similarly, water quality, particularly the hardness of the water, might irritate the eyes or alter the pH balance, potentially leading to increased tear production. Feeding a species-appropriate diet and providing high-quality filtered water are the first steps to control the tear staining.

Red tear stains in dogs are primarily due to porphyrins, iron-containing molecules produced from the breakdown of red blood cells. 

Evidence supports that a species-appropriate diet with raw meaty bones, seafood, and foods rich in antioxidants can reduce excessive tear production and staining.

Excessive tearing and staining can be caused by a combination of issues, making finding the root cause imperative to managing it.

Immunopathogenesis of keratoconjunctivitis sicca in the dog 

Clinical evaluation of a nutraceutical diet as an adjuvant to pharmacological treatment in dogs affected by Keratoconjunctivitis sicca   

Sulfonamide-associated keratoconjunctivitis sicca and corneal ulceration in a dysuric dog  

Tear Fluid Pharmacokinetics Following Oral Prednisone Administration in Dogs With and Without Conjunctivitis - PMC 

Long-lasting otic medications may be a rare cause of neurogenic keratoconjunctivitis sicca in dogs. 

Ocular surface Rose Bengal staining in normal dogs and dogs with Keratoconjunctivitis Sicca: Preliminary findings    

Role of dietary antioxidants to protect against DNA damage in adult dogs 

Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs   

Excessive tear production, or epiphora, can be triggered by eye infections, allergies, or irritants and leads to more pronounced staining. The overflow of tears onto the face creates an environment conducive for porphyrins to stain the fur. Abnormalities in tear drainage can cause tears to spill onto the face rather than drain appropriately through the nasal lacrimal system. This chronic wetness around the eyes is a primary cause of staining.

<a href="https://www.feedreal.com/articles/why-are-my-dogs-teeth-so-disgusting">Oral health</a> significantly influences tear production and staining in dogs due to the close anatomical and physiological relationships between the oral cavity and the eyes. Good oral health ensures that the overall bacterial load in the body is controlled, which is crucial because dental diseases can lead to an overgrowth of bacteria. These bacteria can produce by-products, including porphyrins, the compounds containing iron responsible for the reddish-brown color seen in tear stains.

When dogs have periodontal disease or other oral health issues, the amount of bacteria in their mouths increases. These bacteria can enter the circulatory system and potentially affect different body parts, including the tear ducts and glands. Increased bacterial content in the tears can lead to more pronounced staining, as the bacteria might alter the composition of the tears, increasing the concentration of staining compounds.

Omega-3 fatty acids are recommended due to their anti-inflammatory properties. The <a href="https://www.feedreal.com/articles/introduction-to-real-ancestral-6x-diet">Real Ancestral 6X DietTM</a> includes small fatty fish as 10% of the total diet. However, dogs, especially kibble-fed dogs, are often deficient in omega-3 fatty acids. 

Because the primary functions of omega-3 (reduce inflammation) and omega-6 (increase inflammation) are essentially the opposite, the dog diet must supply them in the correct ratio. Many commercial kibble products are high in omega-6, even those labeled as 'complete and balanced.’'Adding raw fish to a kibble diet can aid in <a href="https://www.feedreal.com/articles/balancing-omega3-and-omega6">balancing omega-6 to omega-3 fatty acids</a>. 

Fatty fish make up 10%  of the diet. Choosing smaller fatty fish near the bottom of the food chain lowers the risk of mercury contamination. Larger fish species that potentially contain higher mercury levels should be avoided. Examples of fish to add to the diet include herring, sardines, mackerel, capelin, salmon, and smelt. Canned fish preserved in water only, with no spices or oils, can be fed to dogs. 

<a href="https://www.feedreal.com/articles/raw-meaty-bones-safety-and-how-to-add">Choosing the right bone is crucial</a>. Small-breed dogs often do best with rabbit, Cornish hens, chicken or duck feet, chicken wings, or chicken necks. The best bones for a medium-sized dog include poultry necks, poultry feet, rabbit, and duck wings. Larger dogs can be fed pork or lamb trotters, poultry necks, turkey wings, beef short ribs, and poultry necks.

<a href="https://www.feedreal.com/articles/free-radicals-and-natural-antioxidants">Antioxidants</a> can directly affect the quality of tears. Improved systemic antioxidant status can lead to healthier tear composition, which might reduce the concentration of substances like porphyrins that cause visible staining on the fur around the eyes. Maintaining a good balance of antioxidants in a diet might help manage or reduce issues with excessive tearing and tear staining, alongside other health benefits.

Not all dogs will eat fruits and vegetables. Other good sources of AOs are mushrooms, pine bark extract, milk thistle, phytoestrogens such as soybeans, and spices including rosemary, thyme, marjoram, oregano, sage, basil, pepper, clove, and cinnamon. All of these AOs can be added to a dog's meal.

Chemicals or contaminants in poor-quality water could lead to health issues or irritations that might indirectly affect the eyes. For example, chemicals like chlorine or pollutants found in some water sources could irritate the eyes, possibly leading to increased tear production or changes in tear composition that might exacerbate staining.

Dietary Considerations For Excessive Tears and Staining in Dogs

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