Red tinge to the dog’s coat - causes and remedy

If a dog’s coat changes colour, the dog food is the first suspect. But what is the actual reason for this phenomenon? Continue reading to find out more!

Many dog owners will be familiar with the phenomenon:

The coat suddenly has a reddish tinge, while pale-coloured dogs display discoloured areas on the flews (upper lips) and paws. The finger of suspicion immediately points to the ingredients of the food, however this is not sustainable from a scientific perspective.

Discolouration around the flews and paws

Dog saliva contains what are called porphyrins. These are one of the components of haemoglobin and occur in all canine bodily fluids, but especially in saliva and lacrimal fluid. When dogs lick their paws, flews or other parts of the body, these proteins are deposited on the coat and react with oxygen in the air to form a reddish stain. Up to a certain degree, these discolourations are entirely natural and unavoidable. However, if they occur to an excessive extent, you should check with your vet to determine the cause of the dog's elevated saliva production or of excessive licking of specific parts of the body.

Coloured tinges to the coat

Carotinoids and copper are frequently suspected of being deposited on the coat and giving it a reddish tinge. However, this is simply not possible from a chemistry and physics perspective as the fat-soluble carotene cannot be deposited in the protein structure of the hair. The lack of copper actually has the opposite effect: Copper, along with tyrosine, is essential for the development of healthy hair. If one of these two substances is missing, the hair will grow incorrectly pigmented (Zentek & Meyer, 1991).


What causes the reddish tinge?

In the vast majority of cases, abnormal pigmentation cannot be attributed to a nutrient deficiency. Take another close look at your dog’s coat. If it grows out from the skin in the regular colour and the coloured tinge is only visible at the tips of the hair, it cannot be due to a lack of nutrition. In these cases, the reddish tinge can be attributed to different environmental factors. A study carried out by Katrin Busch-Kschiewan and her colleagues (2004) demonstrated that UV light, elevated temperatures and humidity have a measurable effect on the colouration of the coat. Ultraviolet light primarily causes the coat to become lighter in colour as it breaks down the pigment melanin, which results in a reddish tinge on dark-haired dogs. It has also been proven that particular wavelengths of sunlight bring about a yellow tinge on wool. Since wool has the same biochemical structure, it is entirely plausible that this scenario could apply to the yellow colouration of a white dog coat. Furthermore, the above-mentioned study demonstrated that an increase in temperature and humidity leads to a short-term darkening of the coat lasting for around 24 hours.

The discolouration can also be the result of a mechanical stress on the coat. The dog rubs its coat on different surfaces, the hair becomes brittle and the light is now refracted differently so that the coat now appears to have a reddish tinge. After the next moulting period, the hair grows back again intact and appears once again in its original colour.

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