Why Has My Dog’s Coat Changed Colour? Causes & Prevention

1. Understanding What Does Not Cause Coat Colour Change

Many dog owners wonder why their pet’s coat has changed colour, but first it’s helpful to clear up some common misconceptions. For example, beet pulp, sometimes mistaken for beetroot, is white and does not cause red discoloration. Similarly, dietary copper, despite being metallic orange, is found in very small amounts in dog food and does not influence coat colour. Understanding what does not cause pigment changes helps focus on the real factors involved.

2. The Role of Pigments in Coat Colour

Hair colour in dogs is primarily determined by pigments produced by specialised cells called melanocytes within the hair follicles. These cells produce two main types of pigment: yellow-red pheomelanin and black-brown eumelanin. Genetics dictate the amount and distribution of these pigments, which gives rise to the wide variety of coat colours and patterns seen across dog breeds.

3. Common Causes of Coat Colour Changes

Beyond genetics, many environmental and physiological factors can cause a dog’s coat to change colour. These include medications, shampoos, sun exposure, heat sources like hair driers, and ageing. For example, black hairs may turn reddish as they reach the end of their resting phase. Sunlight can bleach hair, causing lighter patches especially on the outer coat, while the hair closer to the skin remains unchanged.

4. How Coat Physiology Affects Colour Changes

When systemic factors influence pigment-producing cells, hair growing during that time reflects the change. Such changes may appear as bands of colour on individual hairs, depending on how long the factor was active. Because hairs grow at different times, these colour variations appear scattered rather than uniform. Importantly, hairs in a resting phase during the change are unaffected.

5. Beta Carotene and Its Effects on Coat Colour

Beta carotene, a vitamin A precursor and antioxidant, can cause a yellow-orange skin tone if consumed in excessive amounts, though this is uncommon in dogs fed typical diets. Unlike flamingos, which are fed carotene-rich foods for their pink colour, normal beta carotene levels in commercial dog foods should not alter coat or skin colour. Always avoid excessive supplementation beyond recommended levels.

6. Porphyrin Staining: A Common Cause of Red Stains

Pink or reddish stains on white or light-coated dogs often result from porphyrin staining. Porphyrins are chemicals in saliva and tears that oxidise and stain the hair upon drying. Excessive licking due to allergies, irritations, or infections can increase staining, especially around eyes, muzzles, beards, and paws. Wiping these areas clean daily helps reduce visible stains.

7. Amino Acids Tyrosine and Phenylalanine in Pigmentation

Studies have shown that higher levels of the amino acid tyrosine, synthesised from phenylalanine, can intensify pigment production. Tyrosine supports melanin synthesis and plays roles in hormone regulation and neurotransmitter production. Some pet food manufacturers add tyrosine to sustain vibrant coat colours in dark breeds. However, care should be taken with dietary allergens and with avoiding human foods containing artificial sweeteners like aspartame, which contains phenylalanine.

8. Practical Prevention of Red Coat Stains

• Avoid carotene-rich supplements unless advised by a vet.
• Wipe beards and muzzles clean after meals to remove saliva.
• Clean eyes daily with saline or pet-specific wipes to prevent tear staining.
• If excessive licking occurs, consider dietary allergens and consult your vet about diet adjustments.
• Feed omega-3 rich diets to support coat health and reduce allergy sensitivity.
• Avoid dairy products like cheese, which are common allergens and rich in tyrosine.
• Steer clear of human foods containing artificial sweeteners such as aspartame.

If you observe sudden or patchy coat colour changes, especially if accompanied by hair loss or skin irritation, it’s important to seek veterinary advice promptly to rule out health conditions. Maintaining regular grooming, a balanced diet, and attentive care ensures your dog’s coat remains healthy and beautiful.

Responsible ownership includes recognising normal changes such as those associated with ageing or sun exposure, and distinguishing them from changes that merit professional veterinary evaluation.

For those interested in welcoming a new dog with vibrant coat colours, consider choosing from puppies available from reputable breeders who prioritise health and ethical breeding practices.