Range  Beef  Cow  Symposium,  Dec.  3-‐5,  2013   12/5/13  

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Russ Daly, DVM, MS, DACVPM

Extension Veterinarian South Dakota State University

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Animal Health Effects of the October South Dakota Blizzard: Observations

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Late Fall 2013 n Warmer than normal

n Good moisture

n Implications: n Fall forage green-up

n High moisture n High protein n Lower energy

n No need to wean early – calves nursing on pasture n Cows still on summer pasture n No winter coats yet

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Thursday night, Oct.3: Rain

n Rain totals before turning to snow Friday PM: n Union Center – 1.26” n Cottonwood – 1.64”

n ~ 10% of annual precipitation

n Implication: Cattle are literally “soaked to the skin”

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Observation: Thermoregulation

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n Wind chills during storm = as low as 12 – 16 F

n Cows needed to ↑ energy intake by 47 – 94% just to maintain

n Energy deficits + energy expended = hypothermia

n Lower Critical Temperature: Effective temperature below which an animal expends energy to maintain body heat and metabolism

n For each 1° below LCT, energy requirements ↑ by 1-2%

Ref: Ames, DR; 1978

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Friday afternoon, Oct. 4: Blizzard

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Friday afternoon, Oct. 4: Blizzard

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n @ Union Center: n Hourly average sustained winds = as high as 49 mph n Peak wind gust = 62 mph n 12” of snow - 3-4’ snowdrifts

n Elsewhere: n Many areas 20-30” snow (58” in Black Hills) – 6-7’ drifts n 71 mph peak wind gust @ Ellsworth AFB

n Cattle bunched and drifted with wind n Fences breached

Range  Beef  Cow  Symposium,  Dec.  3-‐5,  2013   12/5/13  

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Observation: Causes of Death

n Hypothermia

n Entrapment in fences à exhaustion

n Entrapment in mud (creeks and stock dams) à exhaustion

n Drowning in creeks and stock dams

n Exhaustion on dry land

n Pulmonary edema secondary to exertion

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Observation: Pulmonary Edema

n Common observation: “gallons of fluid” pouring from nose and mouth of carcasses when moved n “Drowned standing up”

n Cold temperatures + exertion + physiologic stress à sympathetic nervous system response

n Renin – Angiotensin – Aldosterone System activated n Blood vessels constrict n  Increased resistance in systemic

arteries n Heart has to work harder to pump

against resistance

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Observation: Pulmonary Edema

n Aldosterone stimulates kidneys to hold on to sodium and water n Increased blood volume and blood pressure

n When left heart can no longer pump blood against this resistance, pulmonary edema occurs n Fluid enters airways and

accumulates n Increased difficulty for

blood/O2 exchange

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“Dryland Drowning”?

n When freshwater taken into lungs: n Water pulled from airways into lung

blood vessels by osmosis

n Contrast with saltwater drowning n Osmosis pulls water from

bloodstream into lungs

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Observations: Following the Storm

n “Transport tetany” n Signs = Hyperexcitable à tremors à

recumbency n Long-term feed & water deprivation n Rapid resumption of feed and water n Exacerbated by hypomagnesemia (grass tetany)

n Fall green-up of pastures

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Obervations: Following the Storm n Bloating in calves

n Disruptions in feeding n Rapid resumption afterwards à rumen

acidosis?

n Exertional rhabdomyolysis (“tying up”) in horses n Prolonged muscular exertion n Muscle cell damage à myoglobin release into

bloodstream n Potential for kidney failure in extreme cases

n Behavioral changes – aggression in cows

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Weeks Following the Storm

n Any long-term stress event: n Increased blood cortisol levels n Shift immune system towards Th-2 response

(antibodies) & away from Th-1 response (CMI) n 2 weeks after storm

n Increased susceptibility to BRDC – especially native viruses

n Diminished response to vaccines

n Pinkeye

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Weeks Following the Storm

n Changes in management n Weaning calves – starting on feed

n Reproduction n Fetal losses in very stressed animals n No evidence to suggest fetal losses will be

widespread n Sublethal effects on fetus = ??

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Lessons n Be prepared for sequelae

n Tetany conditions n Bloat

n Pinkeye

n Manage feed resumption?

n Adjust management to allow for stress levels in cattle n Vaccines

n Animal ID

n Good management and proper animal care may not always be enough

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Acknowledgements n  SDSU Extension

n  Ken Olson n  Dave Ollila n  Warren Rusche n  Dennis Todey n  George Perry n  Adele Harty

n  SDSU Vet & Biomed Sciences n  Dale Miskimins n  Regg Neiger

n  Colorado State University n  Joe Neary

n  SD Animal Industry Board

n  Dustin Oedekoven

n  Todd Tedrow

n  Mendel Miller

n  South Dakota veterinarians

n  John Allan, Hermosa

n  Ethan Andress, Lodgepole

n  Scott Cammack, Sturgis

n  Vicki Cook, Rapid City

n  Erica Koller-Ross, Edgemont

n  Stephanie Stevens, Edgemont

n  West River ranchers

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