has to an individual dog may vary greatly. In a report, describing dog allergen extracts of dog hair, belonging to patients' dogs or from dogs of the same breed, with low molecular mass that are absent in extracts of commercial allergen test kits, it has been found that "[f]actors related to individual dogs seem to influence the allergenicity more than breed or gender." Show coats The nature and quality of a purebred dog's coat is important to the dog fancy in the judging of the dog at conformation shows. The exact requirements are detailed in each breed's breed standard and do not generalise in any way, and the terminology may be very different even when referring to similar features. See individual breed articles for specific information. Nutritional impacts on coat A dog's coat is an outward indicator of internal well-being. For this reason, coat health is an important aspect of pet care to many dog owners. Dog coats can be impacted by nutritional components from the diet. Below is a table that summarizes the effects of several nutrients (minerals, vitamins) on the domestic canine coat, based on current evidence: Trace minerals Zinc Zinc contributes to hair growth and can prevent hair from becoming dry and brittle. In addition to, zinc when supplemented in combination with linoleic acids has been found to improve the coat of canines by reducing water loss in the trans-epidermal layer of the skin. Dogs can obtain zinc in their diet, through the addition of various ingredients, including; red meats, whole grains, poultry by-product meals, and fish meals. Copper Copper is a trace mineral that is required in the diet of canines at 7.3 mg/kg. Copper is involved in multiple enzymatic pathways. In dogs, a lack of copper in the diet, leading to a copper deficiency, results in incomplete keratinization. This leads to a dry coat, hypo-pigmentation, and discoloration of the coat. Selenium Selenium is another one of the many trace minerals essential for a dog's diet. Selenium is typically required in lower levels in comparison to other minerals. It is involved in the prevention of oxidative damage as well as the production of anti-oxidants. Selenium aids in the promotion of coat growth. Lack of selenium in the diet of a dog can contribute to the occurrence of sparse coat growth. Dogs can obtain selenium in their diet through the addition of various ingredients including; tuna fish,