Total fatty acids
Fatty acids and glucose are the most important cellular energy sources. Fatty acids serve also in many other important roles, such as constituents of cell membranes. Different fatty acids differ by the length and amount of double bonds in their carbon chains. Different fatty acids have different biological properties.
The percentage and molar concentrations of fatty acids have different metabolic properties. Because fatty acids are mainly carried in the circulation bound to bigger lipids such as cholesterol and triglycerides, cholesterol and triglyceride concentrations strongly affect the molar concentration of all fatty acids in the bloodstream. Thus, in hyperlipidemic states, the molar concentrations of all measured fatty acid types in the bloodstream typically increase. The molar concentration can be used to estimate e.g. the amount of fatty acid available for the tissues. However, the percentage concentrations of fatty acids are perceived to reflect dietary effects more accurately. Disease effects of fatty acids have been studied mainly by evaluating the percentages of fatty acids.
It should be noted that the reference values represent the fatty acid levels of normal, healthy dogs. The ideal concentration may differ from this depending on the condition being treated, the state of health, or the physiological state.
Polyunsaturated fatty acids (PUFA)
The carbon chains of polyunsaturated fatty acids have more than one double bond. They are divided into omega-3 and omega-6 fatty acids according to the location of the double bonds. Polyunsaturated fatty acids contain fewer calories than saturated fatty acids and are needed e.g. maintenance of cell membrane fluidity. Diet affects the blood concentration of polyunsaturated fatty acids. Polyunsaturated fatty acids have long been used as dietary supplements, but their blood concentrations in different disease states have not yet been extensively studied.
Saturated fatty acids (SFA)
The carbon chains of saturated fatty acids don’t contain any double bonds. These fatty acids are so-called non-essential fatty acids, since the dog’s body is able of forming them sufficiently from other molecules. The diet affects the amount of saturated fatty acids, and obese dogs typically have higher saturated fatty acid blood levels. However, disease effects on saturated and unsaturated fatty acid blood levels have not yet been extensively studied.
Omega-3 fatty acids (Omega-3)
Omega-3 fatty acids are polyunsaturated fatty acids. The omega-3 fatty acids EPA, DHA and ALA are so-called dietary essential fatty acids in dogs, which means that they must be adequately supplied in the diet. Omega-3 fatty acid supplements are used to treat inflammatory skin diseases, osteoarthritis, cardiac disease, gastrointestinal diseases, cancer and kidney failure. However, excessive use of omega-3 fatty acids can also have side effects such as gastrointestinal symptoms and impaired wound healing. Although omega-3 fatty acids are commonly used in the treatment of diseases, the effects of diseases on blood levels of omega-3 fatty acids have not yet been extensively studied.
Omega-6 fatty acids (Omega-6)
Omega-6 fatty acids are polyunsaturated fatty acids. The omega-6 fatty acid linoleic acid (LA) is a so-called essential fatty acid in dogs. This means that the dog’s body will not be able to form it sufficiently from other molecules and will need to be given a sufficient amount of food. The diet affects the omega-6 fatty acid blood concentration. Insufficient intake of Omega-6 fatty acids can cause weight loss, poor skin and coat quality and reproductive problems. Although omega-6 fatty acids are commonly used as dietary supplements, the effects of diseases on the blood levels of omega-6 fatty acids have not yet been extensively studied.
Several health effects have been associated with the dietary ratio of omega-6 to omega-3 fatty acids. The blood omega-6/omega-3 ratio can be affected by diet. A diet rich in fish or fish oil will reduce this ratio. The ratio of omega-6 fatty acids to omega-3 fatty acids in the diet is currently recommended to be 5: 1 or 10: 1, so 5-10 times more omega-6 fatty acids than omega-3 fatty acids. The high blood omega-6/omega-3 ratio has been linked, among other things, to obesity and behavioral disorders such as aggression. However, large proportion of the health effects of the blood omega-6/omega-3 ratio are still undetermined in dogs.
Arachidonic acid (AA)
Arachidonic acid is an omega-6 fatty acid which is a non-essential fatty acid in normal conditions, as the body is able of forming it from linoleic acid. However, if there is a deficiency of linoleic acid, arachidonic acid becomes an essential fatty acid. Arachidonic acid increases muscle growth and muscle regeneration after exercise. Arachidonic acid has been studied in dogs mainly in terms of dietary supplementation, and the changes in blood arachidonic acid concentration in different diseases have not yet been extensively studied.
Linoleic Acid (LA)
Linoleic acid is an omega-6 fatty acid, that is classified as an essential fatty acid in dogs. This means that the dog’s body is not able of forming it sufficiently from other molecules and needs to be adequately supplied in the diet. Linoleic acid is present in plants. For example, poppy seed, sunflower, corn and soy beans contain a lot of linoleic acid. Linoleic acid has many positive effects, such as increasing muscle growth after exercise and controlling hypertriglyceridemia. Linoleic acid is considered a proinflammatory fatty acid as it can form eicosanoids. Linoleic acid has been studied mainly as a supplement, and the relationship between blood linoleic acid concentration and diseases have not yet been extensively studied in dogs.