What is Taurine?
Taurine is an amino acid. Amino acids are the basic building blocks of protein. There are 22 amino acids that are needed for proper functioning of the body. It is found in high quantities in the brain, retina, heart, and in platelets. It functions in tissues by stabilizing cell membranes and aiding the transport of potassium, sodium, calcium, and magnesium in and out of cells. Taurine helps to generate and regulate nerve impulses and supports the maintenance of normal fluid balance; it is also used by the body in visual pathways, as well as in the brain and nervous system, where it works together with glycine and GABA as a neurotransmitter.
In dogs, 12 amino acids are “nonessential,” meaning the body can make them on its own. The other 10 amino acids are “essential,” meaning they must be supplied by the diet. Taurine is considered nonessential for dogs, but it is essential for cats, meaning cats have 11 essential amino acids.
Most dogs make taurine from other amino acids called cysteine and methionine via the cysteine sulfinic pathway using vitamin B-6, zinc and manganese as cofactors. (Today's chemistry lesson!) More accurately, in the presence of vitamin B6, the methionine is transformed into cysteine and then the cysteine is needed for producing taurine.
Which Pets Are Most at Risk for Taurine Deficiency?
While taurine is known to be an "essential" amino acid for cats, recent studies show it may be required in the diet for some dog breeds as well. These breeds have either a metabolic abnormality that impairs the taurine synthesis and utilization or they have naturally occurring higher taurine requirements. Those breeds include American Cocker Spaniels, Golden Retrievers, Labrador Retrievers, English Setters, Newfoundlands, Saint Bernards, Portuguese Water Dogs, Great Danes, Boxers, Irish Wolfhounds, and Doberman Pinschers.
Big dogs are at higher risk of developing taurine deficiency; when compared to small dogs, they have a much slower taurine production rate. Even when fed the same diet, large and giant breeds produce less taurine than small and toy breeds.
What Foods Contain the Most Taurine?
Taurine is found in fish, meat, and milk. It is completely absent in cereal grains. Heart muscle contains the most taurine. Lamb, beef, venison, rabbit, and chicken breast meat are much lower in taurine than dark meat from poultry.
A published study listed the following concentrations: The highest concentration of taurine was found in clams and octopus (41.4 micromoles/g and 31.2 micromoles/g), followed by shrimp and fish (12.4 micromoles/g and 9.1 micromoles/g). Beef, pork and lamb meat contain taurine in concentrations ranging 3.5-4.0 micromoles/g. Taurine concentration in chicken leg was 6.6 micromoles/g and in chicken breast was 1.4 micromoles/g. Taurine was undetectable in fruits and vegetables. From the seeds, cereals and grains examined, rice, corn, oatmeal, rye, wheat, barley, and sesame seed contained no taurine.
However, dogs can utilize foods high in cysteine and methionine to make taurine. (Cats cannot.) Cysteine is found in highest levels in eggs, soy, cheese, poultry, oats, broccoli, red pepper, and garlic. Methionine is found in highest levels in eggs, fish, sesame seeds, soy, cheese, beef, and poultry.
While companies that produce grain-filled pet food insist that grains provide enough methionine and cysteine for dogs to make enough taurine, it is clear that the amino acids needed to produce optimal health exist mainly in animal products, not grains. The vast majority of dry pet foods contain little or no real meat, but instead use cheaper substitutes like grain proteins (corn gluten, wheat gluten, pea protein, soy protein), and by-product meals. Many pet food companies now add taurine to their products, however there are no stated requirements for supplementing dog food with taurine. Cat food almost always includes supplemental taurine.
Roles of Taurine in the Body
- It acts as an antioxidant; it helps prevent retinal degeneration and other serious eye diseases.
- It acts as an anti-inflammatory agent and may help decrease allergic inflammation.
- It reduces blood pressure and cholesterol level.
- It lowers triglycerides.
- It improves detoxification function of the liver.
- It helps to strengthen the heart muscle.
- It immediately restores and protects corneal cells in the eye from harmful ultraviolet rays.
- Taurine may help control the nervous system. It has been used to treat anxiety and seizure issues in people. Levels of taurine increase in the brain when under stress, suggesting a potential neuroprotective role.
- Taurine has been studied for its glucose-lowering effects and insulin-like action. Its hypoglycemic effects occur through enhanced insulin sensitivity, reduced inflammation, stimulation of insulin secretion, and reduced oxidative stress. This may be beneficial for diabetics.
- Taurine has been used topically as an antioxidant in gingivitis.
- In mice with induced T-cell lymphoma, the addition of taurine to chemotherapy exerted an antitumor effect.
- Taurine has been shown to facilitate musculotendinous wound healing in animal studies. It is likely to modulate this through enhanced antioxidant activity and collagen synthesis. This may be helpful for animals with cruciate ligament injuries.
One good thing about taurine is that it is not destroyed by heating or freezing. However, because it dissolves easily in water, you should not throw out the broth when cooking. Be sure to include the juice in your pet's diet if you are making your own pet food.
Diseases Associated with Low Taurine Levels
- Dilated cardiomyopathy - Cat breeds that appear to be more predisposed to developing dilated cardiomyopathy include Burmese, Abyssinian, and Siamese. The average age of a cat that suffers from DCM is around ten. Dog breeds predisposed to DCM include the Doberman Pinscher, Great Dane, Boxer, and Cocker Spaniel. Dogs can be affected as early as age four.
- Retinal degeneration and blindness, especially in cats.
- Cysteine stones or crystals in the urine may indicate malabsorption issues which may cause taurine deficiency.
Which Pets Would Benefit from Supplemental Taurine?
If you are concerned and want to know whether supplementation is needed, it is best advised to have your dog’s whole blood and plasma tested to measure the levels of methionine, cysteine and taurine.
A whole blood taurine level can cost $100 to $200 at Wisconsin Veterinary Diagnostic Lab or University of California Davis Veterinary Diagnostic Lab. Test results usually take about 5-7 days to return. The reference range for whole blood normal taurine levels in dogs at these labs is 200-350 nmol/mL, with a critical level of <150 nmol/mL.
Once the results are ready, the veterinarian should be objectively able to determine whether supplementation is needed. Pets with dilated cardiomyopathy, retinal degeneration, cystinuria, seizures, or hepatitis (inflammation of the liver) may benefit from taurine supplementation.
Risk factors for low taurine may include:
- Aging may decrease taurine synthesis
- Decreased absorption in the bowel secondary to diseases such as lymphangiectasia, IBD, lymphoma, and SIBO.
- Genetics - American Cocker Spaniels, Golden Retrievers, Labrador Retrievers, English Setters, Newfoundlands, Saint Bernards, Portuguese Water Dogs, Great Danes, Boxers, Irish Wolfhounds, and Doberman Pinschers may have decreased ability to synthesize and utilize taurine.
- Cystinuria - This has been reported in cats and more than 70 dog breeds, most frequently in Dachshunds, Basset Hounds, Irish Terriers, and English Bulldogs.
- Poor diet that contains little meat protein with no added taurine.
- Foods containing MSG (flavoring) will degrade taurine.
- Zinc deficiency, as zinc is required for taurine synthesis.
- Vitamin B6 deficiency (food sources of vitamin B6 include poultry, fish, chickpeas, and bananas) as vitamin B6 is required for taurine metabolism.
- Low taurine levels are common in people who suffer from anxiety, hypothyroidism, high blood pressure, gout, obesity, kidney failure, and depression. More testing needs to be performed on dogs and cats with similar diseases.
- In humans, an infection with Candida (a fungal infection caused by yeast) will produce an amino acid called beta-alanine. This competes with taurine for reabsorption in the kidney and can result in taurine loss through the urine. Studies need to be performed in pets suffering with yeast overgrowth.
Can Taurine Supplementation Be Given Without Testing First?
The good news is that there are no known side effects of excess taurine in dogs and cats. The only bad thing about taurine is its deficiency. If you don't feed your dog or cat a diet that can supply enough taurine, your pet is likely to suffer from a taurine deficiency.
Pets that are at risk from taurine deficiency may benefit from taurine supplementation. Suitable daily doses would be 500 mg for small dogs, 1,000 mg for medium sized dogs, and 2,000 mg for large breed dogs, given once daily. Cats can be dosed the same as small dogs.