A Seminar on Taurine Deficiency in Cats Group 10 March 3, 2014 1

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A Seminar onTaurine Deficiency in

Cats

Group 10

March 3, 2014

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Biochemistry of Taurine

Figure 1. Chemical structure of taurine

IUPAC name : 2-aminoethanesulfonic acid

Taurine is an sulfonic acid containing an amino group, yet it is not an amino acid as it is often called one, because it lacks a carboxyl group.

Biosynthesis of Taurine

A dietary deficiency of vitamin B6 shows a depressing effect on taurine biosynthesis.

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Methionine

Cystein

Cysteine sulfunic

acid

Cysteic acid

Hypotaurine

Cysteamine

Taurine

Phosphopantothenate

TransulfurationVit

Cysteine sulfinate decarboxylase

Hypotaurinedecarboxylase

Cysteamine dioxygenaseCysteine

dioxygenase (CDO)

Cysteine sulfinic acid dehydrogenase

Cysteine sulfinate decarboxylase

Cysteine sulfinic acid

pathway

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Taurine Transport in the Body

Taurine transport across cell membrane

• Na+ - dependent taurine transporter

Taurine release from the cell via three mechanisms

- Exocytosis occurs at basal membrane

- Energy-dependent transporter

- Ca2+ - dependent transport

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Taurine

syste

m

Visual

systemImmu

ne syste

m

Renal syste

m

Cardiovascular

Physiological Function of Taurine

Bile acidconjugation

Nervous system

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Roles of Taurine in Nervous System

• Taurine acts as a neurotransmitter.

- Its ability to elicit neuronal hyperpolarization.

- The presence of specific taurine synthesizing enzymes (CSAD), taurine-specific receptor, and a taurine transporter system.

CSAD = Cysteine sulfinic acid decarboxylase

Taurine as a neuroprotective agent.

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Roles of Taurine in Cardiovascular System

Taurine acts as positive inotropes by promoting calcium-ion release from sarcoplasmic reticulum in cardiac myocytes by modulates calcium transportation during the excitation-contraction coupling.

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Roles of Taurine in Cardiovascular System

Excitation-contraction coupling

of cardiac myocyte.

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Roles of Taurine in Visual System

• Taurine is found in high concentration at the retina, particularly in photoreceptor cell bodies of outer nuclear layer.

• Kittens are more prone to taurine depletion in photoreceptor cells compared to adult cats.

Photoreceptor cell

Phototransductionsystem

oute

r seg

men

tIn

ner s

egm

ent

Synaptic terminal

CNG channel

Na+/Ca2+

exchangerdisks

Ca2+

Na+

Ca2+

Na+

taurinedepolarization

Intracellular Ca2+

reopening

Ca2+Na+

Outer segment

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Roles of Taurine in Immune System

Myeloperoxidase

Taurine can eradicate free radicals generated from specific myeloperoxidase reaction, i.e. hypochlorous acid (HOCl) and hypobromous acid (HOBr), thus it can reduce oxidative stress.

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Roles of Taurine in Renal SystemRenal vascular

resistance

• Taurine aids in renal blood flow regulation.

Glomerulus

• Elimination of reactive oxygen species (ROS)

Proximal tubule

•Taurine affects sodium transportation.•Regulation of taurine body pool size.

Medullary collecting duct

• Taurine acts as osmoregulator, thus it can control the cell volume.

Taurine may prevent glomerulonephritis, diabetic nephopathy, chronic renal failure, and acute kidney injury (AKI)

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Roles of Taurine in Renal System

Taurine transport in renal tubular cell

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Taurine Deficiency in Cats

Why are cats more likely to develop taurine deficiency?

-CSAD-Bile conjugation

How does taurine deficiency affects cats health?

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Bile acid conjugationCholestero

l7αHydroxyCholest

erol

Cholic acid(primary bile

acid)

Chenodeoxy(primary bile

acid)

Glyconolic acid

Taurocholic acid

Taurochenodeoxycholic acid

Linthocolic acid(secondary bile

acid)

7αHydroxylase

Taurine TaurineGlycine

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Cardiac

Function

Visual

System

Immune

System

Reproductive

System & Developm

ent

Taurine Deficiency on Cats Health

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Cardiac FunctionDecreas

e Ca2+ influx

Impaired sensitivity of contractile

protein to Ca2+

CellApoptosis

Impaired systole and diastole

Feline Dilated Cardiomyopathy (DCM)

Heart failure

Feline central retinal

degeneration(FCRD)

Tapetum Lucidum

Lateral geniculate body

Superior colliculus

Lens

Retina

Visual system

Feline central retinal degeneration (FCRD)

Tapetum lucidumNORMAL

TAURINE DEFICIENCY

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Immune system

1. Leucopenia

2. Decrease respiratory burst of neutrophils

3. Decrease phagocytic activity of phagocytes

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Reproductive System & Development

Taurine-deficient pregnant queen

1. More incidences of fetal death (resorption), abortion, or stillbirth.

2. Reduction of taurine concentration in feline maternal milk.

Kittens born from taurine-deficient

female cats

1. Low survival rate

2. Low birth weight

3. Growth retardation

4. Bone malformation

5. Impaired nervous and visual system development.

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Kittens born from taurine-deficient female cats.

a. A premature kitten with congenital hydrocephalus.

b. A stillbirth kitten with anencephaly.

c. Severe congenital hydrocephalus, a brain from 1-year old kitten.

a b c

Nutritional Aspects

Commercial diets

Dry dietCanned diet

Recommended amount

Bioavailability

Ingredients

Effects on digestive

physiology

Processing

Taurine Requirement for Cats

Growth and Reproduction

Adult Maintenance

Nutrient Minimum Minimum Maximum

Taurine (extrude,%)

0.10 0.10

Taurine (canned,%)

0.20 0.20

The Association of American Feed Control Officials (AAFCO) 

How to prevent taurine deficiency

in cats?

Nutritional Aspects

Commercial diets

Homemade meal

Taurine amount labelled on Hill’s commercial cats

diets

Canned diets (Fed)

Canned diets (DM)

Dry diets (Fed)

Dry diets (DM)

0 0.1 0.2 0.3 0.4 0.5

Dry diet

Canned diet

Recommended taurine

amount

Beef Lamb Pork ChickenCod fish Oyster Clam0

500

1000

1500

2000

2500

3000

Raw Baked

Boiled

Taurine amount in food (mg/kg, wet weight)

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Case studyFeline Dilated Cardiomyopathy

History taking

Domestic male cat, 4 years old, 3.8 kg. body weight

• Signs of depression, poor appetite, cough, and dyspnea since 3 weeks ago.

• The cat has muffled cardiac sound.

• The owner had fed the cat with commercial dog food for 1 year and 6 months.

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Examination

• Thoracic radiograph shows severe fluid accumulation in pleural space.

• Electrocardiography shows decrease in 'R' wave amplitude

• Echocardiography shows incress in EDV = End diastolic volume or LVIDd  ↓ , ESV = End systolic volume or LVIDs  ↓ and shortening fraction ↑

• Hematology and Serum biochemical parameter are normal

• Direct opthalmoscopic is normal

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Shortening fraction

Measurement Normal

LVIDd (cm) 2.45 1.59 ± 0.19

LVISd (cm) 2.27 0.80 ± 0.14

∆ D (%) 8.5 49.8 ± 5.3

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Thank you for your attention