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960 Taurine Deficiency

Taurine Deficiency Client Education
Sheet
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systolic murmur, gallop sound, lethargy,
BASIC INFORMATION
dehydration, and hypothermia may decrease with prolonged fasting (2-3+
days), low values in such patients should be
Definition • Cats only: initially, increased granularity interpreted with caution.
Deficient blood taurine concentrations result in the area centralis, which progresses to ○ Plasma: immediately centrifuge blood,
from inadequate intake, synthesis, or availability hyperreflectivity that can eventually extend separate plasma from cells, and immedi-
of dietary taurine and can cause clinical disease. across to the nasal retina and finally result ately freeze plasma. Avoid contaminating
in diffuse retinal atrophy plasma with cells from buffy coat. If
Epidemiology sample is hemolyzed, draw new sample.
SPECIES, AGE, SEX Etiology and Pathophysiology ○ Whole blood: freeze whole blood sample
• Cats: taurine is an essential amino acid in the • Taurine is a sulfur-containing amino acid. immediately in appropriate plastic tube
diet of cats because they lack the ability to Unlike most other amino acids, it is not (to lyse red blood cells).
synthesize adequate amounts from the pre- incorporated into proteins but rather remains ○ Plasma and whole blood taurine refer-
cursor amino acids cysteine and methionine. one of the most abundant free amino acids ence ranges (reference intervals may vary,
• Dogs: taurine is not an essential amino acid in in the body. depending on the laboratory)
dogs as they can normally synthesize taurine • Taurine, synthesized from methionine and • Dogs: plasma: normal = 60-120 nmol/mL;
from precursor amino acids. However, taurine cysteine, is required for a variety of cellular deficient: < 40 nmol/mL; whole blood:
can become a conditionally essential amino homeostatic functions. In cats, synthesis is normal = 200-350 nmol/mL; deficient:
acid in some dogs and under some conditions. very limited and cannot maintain taurine < 150 nmol/mL
balance in the absence of adequate intake. • Cats: plasma: normal = 60-120 nmol/mL;
GENETICS, BREED PREDISPOSITION Dogs have a greater ability to synthesize deficient: < 40 nmol/mL; whole blood:
In dogs, taurine-deficient dilated cardiomyopa- taurine than do cats, but occasionally, they normal = 300-600 nmol/mL; deficient:
thy (DCM) has been identified in a variety of develop taurine deficiency. Obligatory loss < 200 nmol/mL
breeds, including American cocker spaniels, occurs in both species because only taurine
golden retrievers, Newfoundlands, and dogs can be used for conjugation of bile acids; TREATMENT
with cystine and urate urolithiasis consuming most other species can substitute glycine for
protein-restricted diets. taurine. Treatment Overview
• In cats and likely in dogs, excessive taurine- The goals of treatment are to restore taurine
RISK FACTORS conjugated bile salt loss in feces may occur homeostasis and improve cardiac function.
• Cats: inadequately supplemented commercial secondary to type of diet processing, protein DCM due to taurine deficiency may be revers-
or home-prepared diets source, fiber type and concentration, changes ible in some patients.
• Dogs: low-protein diets; vegetarian diets in location and/or numbers of intestinal
(plant protein sources are devoid of taurine); microflora, and/or increased secretion of Acute General Treatment
lamb meal and rice diets; grain-free diets bile salts due to changes in the release of • Supportive care for CHF and DCM (pp.
with legumes such as chickpeas, peas, and cholecystokinin. 263 and 409)
lentils; and diets supplemented with beet • Taurine supplementation while waiting
pulp, presumably due to inadequate or DIAGNOSIS confirmation of blood analysis
unavailable dietary sulfur amino acids. Large
breeds and dogs with lower than predicted Diagnostic Overview Chronic Treatment
energy requirements may be at higher risk. Taurine deficiency should be considered with • Ongoing treatment as needed for CHF
a compatible diet history and signs of cardiac • Cats: taurine supplementation with 250-
Clinical Presentation dysfunction (DCM in dogs, cats) or blindness 500 mg/CAT PO q 12h
DISEASE FORMS/SUBTYPES or reproductive failure (cats). • Dogs: taurine supplementation with 500-
• Cats: central retinal degeneration (CRD), 1000 mg/DOG PO q 8-12h for dogs < 25 kg
reproductive failure, growth retardation, and Differential Diagnosis or 1-2 g/DOG PO q 8-12h for dogs > 25 kg
DCM • Idiopathic DCM ○ Concurrent carnitine supplementation
• Dogs: DCM in susceptible breeds or • Other causes of myocardial failure 50-100 mg/kg PO q 8h is recommended
individuals • Retinal detachment or degeneration (cats) for American cocker spaniels and dogs
consuming protein-restricted diets.
HISTORY, CHIEF COMPLAINT Initial Database • Echocardiogenic improvement in cardiac
• Cats: blindness, signs of congestive heart • Thoracic radiography to determine presence function can take 3-4 months. Do not stop
failure (CHF) such as dyspnea, respiratory of CHF supplementation prematurely.
distress, lethargy, and anorexia (pp. 408 and • Fundic exam (cats [p. 1137])
409), or reproductive failure. Compatible Nutrition/Diet
diet history (poorly formulated commercial Advanced or Confirmatory Testing Ensure a nutritionally balanced diet with
or home-prepared diet) is suggestive. • Echocardiography for diagnosis of DCM: adequate sulfur amino acid content.
• Dogs: signs of CHF; possible history of dyskinesis (reduced systolic motion) of the
restricted diet (very-low-protein diets; left ventricular walls, increased end-diastolic Possible Complications
vegetarian diets; dry dog food with lamb diameter, and reduced shortening fraction. Taurine is an extremely safe substance, even
meal, rice, or both as the primary ingredient; • Assessment of both plasma and whole blood when given at pharmacologic doses.
grain-free and boutique diets) taurine concentrations (lithium heparin
[green top] tubes [p. 1384]) provides the Recommended Monitoring
PHYSICAL EXAM FINDINGS most accurate estimate of taurine status • Clinical condition, including daily resting
• Cats and dogs: if in CHF, variable combina- provided samples are collected and processed respiratory rate to predict CHF (until resolu-
tions of tachypnea, dyspnea, tachycardia, properly. Since plasma taurine concentrations tion of DCM)
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