What causes tear stains in dogs_

Tear stains in dogs are reddish-brown or rust-colored streaks that appear beneath the eyes, most often on dogs with light-colored coats. These stains are not just a cosmetic issue—they can indicate underlying health or environmental problems. Understanding what causes tear stains is essential for effectively preventing and treating them. Below are the most common causes:

1. Excessive Tear Production (Epiphora)

The most direct cause of tear stains is excessive tearing. Dogs naturally produce tears to keep their eyes lubricated and flush out irritants, but when they produce more than usual or cannot drain them properly, the overflow can lead to staining. Common reasons for epiphora include:

• Irritation from hair around the eyes

• Allergens or environmental irritants

• Eye infections

• Abnormal eyelid or eyelash growth (e.g., entropion or distichiasis)

• Blocked or underdeveloped tear ducts

2. Porphyrin Pigments

Tears contain compounds called porphyrins, which are iron-containing molecules produced when the body breaks down red blood cells. These are naturally excreted in tears, saliva, and urine. When tears sit on a dog’s fur, especially on light-colored coats, the porphyrins oxidize and cause reddish or brownish stains. The more tears produced or retained, the more pronounced the staining becomes.

3. Blocked Tear Ducts

Some dogs have narrowed or completely blocked nasolacrimal (tear) ducts, preventing proper drainage into the nasal cavity. This causes tears to spill over the eyelids and onto the face. The stagnant moisture on the skin promotes staining and may encourage bacterial or yeast overgrowth, worsening the discoloration and potentially causing infections.

4. Shallow Eye Sockets or Protruding Eyes

Certain breeds, especially brachycephalic (flat-faced) dogs like Pugs, Shih Tzus, and Bulldogs, are more prone to tear stains due to their facial structure. Their shallow eye sockets can make it difficult for tears to drain normally, and their prominent eyes are more prone to irritation.

5. Hair Irritation

Hair around the eyes, especially when long or inward-growing, can wick tears onto the face and irritate the eye itself, causing more tears to be produced. Trimming the fur around the eyes can help reduce this irritation and prevent staining.

6. Infections and Eye Conditions

Eye infections (bacterial or viral), conjunctivitis, corneal ulcers, or glaucoma can all cause increased tear production and staining. These conditions typically have other signs, such as redness, swelling, or discharge, and require veterinary care.

7. Teething in Puppies

In puppies, especially breeds like Maltese and Poodles, teething can stimulate the tear glands, resulting in increased tearing and staining. This usually resolves once adult teeth come in.

8. Allergies

Dogs can be allergic to food ingredients, pollen, dust, mold, or cleaning products. Allergies often cause eye irritation and watery discharge, contributing to tear stains. Identifying and eliminating the allergen can help control symptoms.

9. Diet and Water Quality

Poor-quality diets or water high in minerals and iron can worsen staining. Filtered or distilled water can reduce porphyrin buildup. Additionally, some commercial dog foods contain artificial ingredients that can cause allergic reactions or worsen tear staining.

10. Yeast and Bacterial Infections

Constant dampness under the eyes creates a breeding ground for bacteria and yeast, especially Malassezia, a common yeast that thrives in moist, warm environments. This not only worsens the staining but can cause unpleasant odors and skin irritation. If the stain area is smelly or itchy, this could be the cause.

11. Breed Predisposition

Tear staining is more common in some breeds than others. Dogs most susceptible include:

• Maltese

• Poodles

• Shih Tzus

• Lhasa Apsos

• Bichon Frises

• Cocker Spaniels

• Bulldogs These breeds often have light-colored coats and facial structures that make them prone to eye discharge.

12. Poor Grooming and Hygiene

Neglecting regular cleaning of the face can cause dried tear residue to accumulate, trapping moisture and bacteria. Regular wiping of the eyes and face, especially in high-risk breeds, is crucial to reduce staining.

13. Stress and Environmental Factors

Stress can cause excessive tearing in some dogs, as can exposure to wind, smoke, or harsh weather. Reducing environmental irritants and maintaining a calm, stable environment can help minimize symptoms.

---

Conclusion

Tear stains in dogs can result from a combination of anatomical, environmental, dietary, and health factors. While the stains themselves are usually not dangerous, they can indicate underlying issues that may require attention. Regular grooming, a high-quality diet, clean water, and veterinary checkups are essential for managing and preventing tear stains. If the staining is sudden, excessive, or accompanied by other symptoms like swelling, odor, or redness, a vet visit is necessary to rule out infections or other eye problems.