Specific Nutritional Imbalances
Hair consists of 95 % protein, and is rich in sulphur amino acids such as methionine and cystine. The growth of hair and renewal of the skin will absorb 30 % of dietary protein (Scott et al., 2001). Any situation where protein requirements are not fulfilled will lead to poor coat and skin with generalized scaling, loss of pigment, poor hair growth, easy shedding, thin, dull and brittle hair.
Protein deficiency can either be due to a lack of supply i.e., poor quality diet, unbalanced home prepared food, low protein diet or to protein loss related to a systemic illness such as protein losing gastro-enteropathy, nephropathy, hepatopathy, or chronic bleeding. The reason for the nutritional imbalance needs to be identified and corrected.
Essential Fatty Acid Deficiencies
Essential fatty acids are not synthesized by the organism, thus their supplementation in the diet is «essential». They are primarily the precursors of two families of polyunsaturated fatty acids (PUFA), omega-6 fatty acids and omega-3 fatty acids.
PUFA fulfill five main functions:
- Incorporation in the structure of the cell membrane, which gives it its flexibility and permeability
- Production of eicosanoids (leukotrienes, prostaglandins, etc.)
- Maintenance of the skin barrier permeability (especially omega-6 fatty acids)
- Cholesterol metabolism and transport
- Immunomodulation through an influence on antigen presenting cells and T lymphocytes
PUFA deficiencies are observed in animals suffering from malassimilation or animals fed with poor-quality diets or diets that have been overheated for a lengthy period. The cutaneous signs are xerosis, dull hair and a keratoseborrheic disorder. The response to PUFA supplementation is rapid.
– Linoleic acid, a precursor of omega-6 fatty acids, is abundant in most vegetable oils. It represents more than 70% of the fatty acids in evening primrose oil and more than 50% in sunflower oil, corn and soy oils.
Cats are deficient in Δ-6 desaturase which is the enzyme needed for the first step of the transformation of linoleic acid into arachidonic acid. Thus linoleic acid and arachidonic acid are both essential nutrients for the cat (Figure 3).
– Alpha linolenic acid, a member of the omega-3 fatty acids, is found in green vegetables, fruits, grasses and plankton, and in concentrated form in the oil of plants like soy, flax, or linseed. The oils of fish from cold waters contain very high levels of two long-chain fatty acids derived from alpha linolenic acid: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Figure 3). These two fatty acids participate in the fluidity of the cell membranes.
Figure 3. Hepatic synthesis of long-chain omega-6 and omega-3 fatty acids from their respective precursors. To view click on figure
In addition to their anti-inflammatory, anti-neoplastic, immuno-stimulant, and cardio-protective properties, omega-3 fatty acids are also often used as anti-pruritic agents. Even in situations of an open wound or post-surgery, the benefit of supplementation still outclasses the mild reduction of perfusion which could potentially impede the healing process (Scardino et al., 1999).