Daniel H. Gould, DVM, PhDDaniel H. Gould, DVM, PhDColorado State Veterinary Colorado State Veterinary

Diagnostic LaboratoryDiagnostic LaboratoryCollege Vet Med & Biomed SciencesCollege Vet Med & Biomed Sciences

Colorado State UniversityColorado State University

SulfurSulfur--related related Polioencephalomalacia in Polioencephalomalacia in

CattleCattle

Polioencephalomalacia:Polioencephalomalacia:Polio = gray matterPolio = gray matter

Malacia = softening or tissue deathMalacia = softening or tissue deathEncephalo = brainEncephalo = brain

Clinical signsClinical signsSubacute; blindness and staggeringSubacute; blindness and staggering

Features of PEMFeatures of PEM

Acute; blindness, recumbence, seizuresAcute; blindness, recumbence, seizures(Se (Se ““blind staggersblind staggers”” and related myths,and related myths,OO’’Toole, Vet Path 1996) Toole, Vet Path 1996)

Polioencephalomalacia:Polioencephalomalacia:Polio = gray matterPolio = gray matter

Malacia = softening or tissue deathMalacia = softening or tissue deathEncephalo = brainEncephalo = brain

ItIt’’s a nons a non--specific lesion specific lesion ––causes causes include:include:

Lead toxicityLead toxicity

PEM TerminologyPEM Terminology

Salt toxicosis/water deprivationSalt toxicosis/water deprivationThiamine deficiencyThiamine deficiencyExcessive sulfur intakeExcessive sulfur intake

AutofluorescenceAutofluorescence

PEM UV IlluminationPEM UV Illumination

PEM microscopic lesionPEM microscopic lesion

Dead nerve cellDead nerve cell

Normal nerve cellNormal nerve cell

Chronic PEM taken at slaughterChronic PEM taken at slaughter

AbnormalAbnormal

NormalNormal

Potential Sulfur SourcesPotential Sulfur Sources•• WaterWater

•• Mismixed feeds (mineral sulfates), Mismixed feeds (mineral sulfates), sulfate additives as feed intake limiters sulfate additives as feed intake limiters or sorting of pelleted supplementsor sorting of pelleted supplements

•• Sulfate accumulation by grasses and Sulfate accumulation by grasses and weedsweeds•• Cruciferous plants Cruciferous plants –– turnips, rape, kale turnips, rape, kale and oil seed crops / mealsand oil seed crops / meals

•• ByBy--products of corn and sugar products of corn and sugar processing processing –– sulfur added in processsulfur added in process

•• Low fiber, high sulfate (Low fiber, high sulfate (≈≈0.3% S), high 0.3% S), high CHO diet consistently induces PEMCHO diet consistently induces PEM

•• Thiamine status is unaltered during Thiamine status is unaltered during development and expression of PEMdevelopment and expression of PEM

•• Odor ofOdor of HH22S in eructated gas when S in eructated gas when clinical signs beginclinical signs begin

Experimental Studies at CSUExperimental Studies at CSU

Gas Cap SamplingGas Cap Sampling

Gas Cap SamplingGas Cap Sampling

HH22S Detector TubesS Detector Tubes

Exper Investigations Exper Investigations –– HH22S in Gas S in Gas CapCap

••Elemental Sulfur Elemental Sulfur -- little toxicitylittle toxicity••Sulfate Sulfate -- little toxicitylittle toxicity

••Sulfide (HSulfide (H22S) S) -- high toxicity high toxicity ((similar to cyanide)similar to cyanide)

butbut -- with ruminal microbial with ruminal microbial metabolism, sulfur is reduced tometabolism, sulfur is reduced to

Total S should not exceed 0.3Total S should not exceed 0.3--.5% DM.5% DM

Types of SulfurTypes of Sulfur

PEM risk periodPEM risk period

Days post arrivalDays post arrival

0

5

10

15

20

25

30

1 8 15 22 29 36 43 50 57 64 71 78 85N

umbe

r of H

ead

Dia

gnos

ed

McAllister: JAVMA McAllister: JAVMA 1997, 211:12751997, 211:1275

Ruminal Gas Cap HRuminal Gas Cap H22S Production in Feedlot SteersS Production in Feedlot Steers

Loneragan: Bov Pract Loneragan: Bov Pract 2005, 39:162005, 39:16

PEM Risk Period and Ruminal HPEM Risk Period and Ruminal H22SS

Loneragan: Bov Pract Loneragan: Bov Pract 2005, 39:162005, 39:16

Dietary [S] incl. HDietary [S] incl. H22O plus O plus risky behavior; risky behavior; (gluttony, sorting, (gluttony, sorting, and mixing)and mixing)

Metals?Metals?

CHOCHO

pHpH

SulfateSulfate--reducing reducing microbesmicrobes

Risk FactorsRisk Factors

ThiamineThiaminePrevention?Prevention?

[H2S]

[H2S][HS-]

What about thiamine treatment of What about thiamine treatment of clinical case of PEM?clinical case of PEM?

•• Positive response to thiamine Positive response to thiamine therapy does not prove thiamine therapy does not prove thiamine deficiency is the causedeficiency is the cause•• ThiamineThiamine administration can have a administration can have a nonnon--specific beneficial effect on an energy specific beneficial effect on an energy deficient braindeficient brain

Ex. Thiamine provides mitigates nervous Ex. Thiamine provides mitigates nervous signs in calves with lead poisoningsigns in calves with lead poisoning