Taurine

Overview

Taurine is an amino acid nutritional supplement used primarily in dogs and cats for the treatment of taurine deficiency–associated cardiomyopathies, particularly dilated cardiomyopathy (DCM). In cats, taurine supplementation has proven beneficial for the prevention of retinal degeneration and the prevention and adjunctive treatment of DCM caused by taurine deficiency.

Taurine supplementation is also used as an adjunctive treatment for DCM in dogs, especially in breeds reported to be predisposed, which include American cocker spaniels, golden retrievers, Newfoundlands, English setters, St. Bernards and Irish wolfhounds. Studies have shown that taurine may be beneficial in animals with DCM even when taurine deficiency is not documented, although in dogs the role of taurine in the absence of documented deficiency is regarded as uncertain and remains controversial. Because taurine has a low potential for toxicity, it has also been suggested for other conditions such as seizures and hepatic disorders, although supporting scientific evidence is limited.

Mechanism of Action (MOA): Taurine is an important amino acid involved in bile acid conjugation, modulation of calcium flux, stabilization of neuronal membranes, and normal cardiac function; its effect on calcium flux also reduces platelet aggregation. It exerts positive inotropic effects on the heart without affecting resting membrane potential and helps regulate ionic currents across cell membranes. Taurine is also important for normal central nervous system development and has GABA-like activity that may contribute to its potential anticonvulsant effects.

Indications

Taurine is primarily used in dogs and cats to treat or prevent conditions associated with taurine deficiency, particularly those affecting cardiac function.

• Dilated cardiomyopathy (DCM): Treatment and adjunctive management of taurine deficiency–associated DCM in dogs and cats.
• Retinal degeneration (cats): Prevention of retinal degeneration associated with taurine deficiency, and, once degeneration has begun, taurine can halt its progression at any stage.
• Adjunctive cardiac support: May be used as an adjunctive treatment in dogs and cats with DCM even when taurine deficiency has not been documented.
• Seizure disorders: Sometimes used as an adjunctive therapy, although supporting evidence is limited.
• Hepatic disorders: Occasionally used as an adjunctive supplement in hepatic conditions, but clinical evidence remains limited.
• Cats on long-term ursodiol: Supplementation should be considered in a cat with a poor appetite that is receiving long-term ursodeoxycholic acid, because feline bile acid conjugation obligatorily consumes taurine.

Dosage (Reference)

Dog

In dogs, taurine is most commonly used as an adjunctive treatment for dilated cardiomyopathy (DCM). It may also be used as an adjunctive supplement in seizure management.

Cat

In cats, taurine is primarily used as adjunctive therapy for taurine deficiency–associated dilated cardiomyopathy (DCM). It has also been used as an adjunctive supplement in seizure disorders and hepatopathies.

Warnings & Precautions

Taurine is generally considered a safe nutritional supplement in dogs and cats. However, supplementation should not replace appropriate diagnostic evaluation when taurine deficiency or underlying disease is suspected.

• Not a substitute for diagnosis: Taurine supplementation should not be used in place of proper diagnostic investigation and management of the underlying condition.
• Assessment of taurine status: When taurine deficiency is suspected, whole blood taurine concentrations are preferred over plasma concentrations for evaluating body taurine status.
• Sample collection considerations: Hemolysis or contamination with the buffy coat may interfere with taurine measurements and affect test accuracy; blood for taurine measurement should be drawn into lithium heparin tubes and frozen immediately.
• Interpretation of laboratory results: Whole blood taurine assays may yield false-positive results in prolonged fasting or anorectic animals and false-negative results after recent feeding, dietary changes, or thromboembolic events.
• A breed-specific interval was proposed: The whole blood reference range normally quoted for dogs has been questioned in golden retrievers, where a higher interval of 213 to 377 nmol/mL has been proposed, so a result near the lower limit may mean different things in different breeds; the study behind that proposal was later the subject of a published correction in which some study-design concerns remained unresolved.
• Not a stand-alone cardiac treatment: Even the dogs reported to respond well to taurine and L-carnitine still require additional cardiac medication.

Drug Interactions

No clinically significant interactions have been reported with taurine itself in dogs and cats, but two drugs are recorded as lowering taurine status in the cat.

• No known interactions: Taurine itself has no reported interactions in animals.
• Colestyramine (cholestyramine): May cause taurine depletion in cats, and may also reduce absorption of macronutrients and fat-soluble vitamins.
• Ursodeoxycholic acid (ursodiol): Long-term use in cats has raised concern about taurine deficiency, and one reference advises against relying on it in hepatic lipidosis for that reason.

Side Effects & Overdose

Side Effects

Taurine is generally well tolerated in dogs and cats, and adverse effects appear to be uncommon.

• Gastrointestinal upset: Mild gastrointestinal distress may occur following oral administration, and vomiting has been reported; if a dose on an empty stomach is not tolerated, giving the next one with food or a small treat may help.

Overdose

Specific information regarding taurine overdose in dogs and cats is not available. However, taurine appears to have a low toxic potential.

• Low toxicity risk: Available information suggests a low likelihood of significant toxicity following excessive exposure.
• Management: In suspected overdose cases, appropriate veterinary evaluation and supportive care should be provided as needed, and a 24-hour poison control center that provides veterinary-specific information can be consulted.

Key Notes

Practical clinical points that may help optimize the use of taurine in dogs and cats:

• Cats have higher taurine requirements: Cats are particularly susceptible to taurine deficiency because low cysteinesulfinic acid decarboxylase activity limits how much they can make, and because they use taurine almost exclusively for bile acid conjugation; taurine is therefore an essential amino acid in the feline diet, and plant protein contains none.
• Cardiac response may take time: Clinical improvement in taurine-responsive cardiomyopathy is usually seen within about two weeks, while echocardiographic improvement takes longer, reported as four weeks or more and elsewhere as two to three months.
• Often combined with carnitine: Taurine is frequently used together with carnitine in dogs with dilated cardiomyopathy, particularly in breeds considered predisposed to taurine-responsive disease; in American cocker spaniels the published combination is taurine 500 mg with L-carnitine 1 g, two to three times daily, and 30 to 100 mg/kg daily has improved some echocardiographic measurements in English cocker spaniels.
• Nutritional history is important: Evaluation of diet can be valuable when investigating suspected taurine deficiency or taurine-responsive cardiomyopathy; grain-free, high-legume, lamb and rice, high-fiber and vegetarian or home-prepared diets have all been associated with taurine deficiency, and there is no official minimum taurine content for dog food.
• Wide clinical use despite limited evidence: Taurine is sometimes used for conditions beyond cardiomyopathy because of its favorable safety profile, although supporting scientific evidence for many of these applications remains limited.
• Blood and plasma concentrations: Reported normal values are about 200 to 350 nmol/mL in whole blood and 60 to 120 nmol/mL in plasma.
• No single cut-off is agreed: In dogs, plasma taurine concentrations <60 nmol/mL or whole-blood concentrations <200 nmol/mL are considered low; concentrations <40 nmol/mL in plasma or <150 nmol/mL in whole blood indicate more marked taurine deficiency. Interpretation should consider the laboratory reference interval and breed. In Golden Retrievers, proposed reference intervals are 63–194 nmol/mL for plasma and 213–377 nmol/mL for whole blood, and concentrations ≤60 nmol/mL in plasma or ≤250 nmol/mL in whole blood have been used clinically to identify low taurine status in dogs evaluated for diet-associated DCM.
• Do not wait for the assay: Because taurine costs little, is very unlikely to do harm, and is hard to measure reliably, supplementation is advised in all cats with dilated cardiomyopathy without waiting for a taurine result, and continued until the cat is shown not to be deficient or not to respond.
• Dogs make their own taurine: Unlike cats, a healthy dog on a balanced diet makes its own taurine from cysteine and methionine and is generally not considered to require it in the diet, which is why canine deficiency is treated as a breed or diet problem rather than an expected finding.
• Eyes are not only a feline concern: Retinal degeneration from taurine deficiency is best documented in cats, where it begins as a spot in the area centralis, then forms a horizontal band above the optic nerve, and finally becomes diffuse, but retinal abnormalities were also found in 9% of taurine-deficient English cocker spaniels in a prospective study. A cat found to have taurine-deficient retinopathy should also have thoracic radiographs and a cardiac ultrasound.
• How the treated dogs did: In a published outcome series, 23 of 24 golden retrievers with taurine-deficient dilated cardiomyopathy improved echocardiographically after a diet change together with supplementation at a median of 3000 mg a day, divided into two or three doses.
• Reproduction: Taurine deficiency in cats has also been associated with reproductive failure.
• Renal excretion: Excess taurine is excreted rapidly by the kidneys, and urinary excretion falls when a deficiency exists.
• Formulations and storage: Two products are labeled for animals, a 250 mg tablet for cats and a 375 mg per 4 mL liquid for dogs and cats; the rest are human nutrient products, including powders, sold over the counter, often from health food stores, and all should be stored at room temperature away from light and moisture.
• Administration in food: A powder form can be mixed into the animal’s food.
• The food matters as much as the tablet: In diet-associated disease a change to a well-studied, grain-based food is regarded as critical to recovery, and a cat should be eating a high-protein diet with sufficient taurine and no vegetarian food.