Red Rim Elk Die-Off:

An investigation into a Wyoming outbreak

Red Rim Wildlife Habitat Management Area

• Old Daley Ranch owned by WGFD

• Approx. 50 sections 

  • 1 section is a square mile (640 acres)

• 10 miles southwest of Rawlins, WY

• Important pronghorn winter range 

• Not typically used by elk, but 800 elk on the area in winter 2004

• 5th year of drought

Daley Ranch (Red Rim) Wildlife Habitat Area

• Short, dry summers  

• Long, variable winters 

• Drought common in Wyoming  

• Much of Wyoming is high desert

8 Feb 2004

• Coyote hunters find 2 down elk alive, report to WGFD

  • Elk had been partially depredated by coyotes

• Elk euthanized and taken to WSVL

  • State diagnostic lab

• At necropsy:

  • Subcutaneous hemorrhages (bruises)

    • Animals were getting up and falling down

  • Degenerative myopathy

So what?

• Differential diagnoses? 

  • Capture myopathy/exertional rhabdomyolysis/exertional myopathy: muscles overworked, degenerate, lactic acid builds up, causes neurological problems further down

    • Snowstorm around this time, hard for animals to run in snow… can cause capture myopathy

  • Hypocalcemia 

  • Trauma to the back/spinal cord

• Is it important? 

  • No, only 2 animals affected

14 Feb 2004

• 7 additional down elk found

• WSVL and WGFD vets go to field:

  • Elk down, unable to rise, but alert and responsive 

  • Normal TPR (temp., pulse, respiration)

  • Seemed to progress to depression and death

  • Necropsies- like that at lab

• Blood & urine samples collected

Pic

• Not normal behavior, wild elk won’t let you pet them

• Had the ability to move their head, weren't particularly strong 

  • Easy to restrain them and get a blood sample 

• Sternal recumbency (lying on their sternum)

• Unable to rise, but they are alert and active 

• Found 52 elk entangled in barbed-wired fences 

  • Tried to jump fence, but couldn't do it

Red Urine seen in snow:

• Exertional rhabdomyolysis causes the muscle fibers to break down

• Myoglobin in the muscles breaking down getting released, passes through the urine 

• Tested the urine for myoglobinuria, which would be very consistent with capture myopathy

  • It was negative 

• Red urine was not due to myoglobin, does not have any excess protein

What might cause Red Urine?

• Could any of these causes relate to clinical signs?

• Any new ideas?

  • Capture myopathy

  • Kidney trauma 

  • Hemolysis 

    • Red blood cells bursting 

  • Certain drugs 

    • Meth labs?

20 Feb 2004

• 63 elk confirmed down or dead 

• WGFD, WSVL pathologist & toxicologist & students return to field 

• Clinical and pathologic picture remained the same 

• Toxicologist and Game Warden notice lichen

What would YOU test for?

Capture myopathy: no myoglobin in the urine

WSVL ruled out:

• Parasites, viruses, bacteria

• Salt poisoning 

  • Can cause brain damage, paralysis 

• OP/Carbomates

• Nitrates 

• Sulfates

• Heavy metals

• Selenium 

• CWD, meningeal worm, carotid artery worm

• Algal and plant toxins (Halogeton, locoweed etc)

R/Os cont.

• Drilling surfactants 

• H2S

• Sorghum

• Zing phosphide 

• Corticosteroids, Gossypol

• Halothane, succinylcholine 

• Venom 

• Aminoglycosides 

• Herbicides

• Coniine 

• Illicit drugs 

• Ethylene glycol

• Grass tetany, milk fever

• Botulism

• Compound 1080

• Strynchnine 

• Carbon disulfide 

• **ALL NEGATIVE

29 Feb & Mar 2004

• Over 280 confirmed cases

• 4 live elk brought to WSVL for Treatment 

  • Seemed like they were in the early phases

Reason for treating elk

• Assurance for biologists/warden

• Diagnostics

• Political pressure

Treatments Attempted:

• Vitamins (A, B, D, E)

• Minerals (Se, Ca, Mg, P, K)

• Fluids (LR, Dextrose)

• Penicillin 

• Dexamethasone, Flunixin, Meglumine 

• No response to any treatments

ABADRL ruled out Tick Paralysis

• Ticks in wintertime kind of unusual 

• Tick paralysis: enough ticks, toxins ticks release can cause paralysis 

• Took ticks off elk, put on sheep 

  • Sheep were fine 

  • Ticks were not carrying tick paralysis 

• Conclusion: high ticks because elk weren’t able to groom

WSVL toxicologist: lichen hypothesis

• Literature from 30s in cattle and sheep

• Had strong reservations 

  • Not documented since, clinical picture, mouse trials 

• Then came results of rumen analysis:

  • Found that over 50% of it was made up of Xanthoparmelia chlorochroa (tumbleweed shield lichen)

    • Description matched

  • Lichen was major part of diet

WGFD fed lichen to 3 elk from NER

• Confirm or deny this finding 

• Lichen is an adaptable, unique species

Red urine noted in expt. Elk at 4 days

At 7 days 1st elk down

Signs and lesions identical to Red Rim cases

At day 10 second elk down

• Cases looked virtually identical to Red Rim habitat area

  • These elk came from the National Elk Refuge, were nowhere near Red Rim

  • No previous exposure 

• 3rd elk stayed healthy, lost a lot of weight

At same time:

• Elk migrated out of Red Rim Area

  • Things warmed up

• Down elk and losses stopped

Elk Population

• Hunt Areas 15, 21 in SE WY

• Reduced hunting licenses for 2 years 

• Population recovered

• Today is quite robust

What is Lichen?

• Commensal between algae and fungus 

• Many different species of lichen

• Some are important parts of certain wildlife diets

• Elk documented to eat some other spp. Of lichen

Tumbleweed shield lichen

• Xanthoparmelia chlorochroa 

• Very common ground lichen in WY

• Early literature: Parmelia molluscula 

  • Diff. species

• Toxic year round

What is the toxic compound?

• Usnic Acid? Hypothesis in 50s

• Usnic Acid associated with liver damage in humans, not with muscle or nerve damage 

• The lichen contains high levels of Usnic Acid

• But there may be another compound responsible for the paresis

Occurrences since 2004

• Tough to predict 

• Elk occasionally winter in Red Rim

  • Outbreak in 2008

  • Bait line to lead them out of the Red Rim

• Does the lichen contain variable amounts of toxin in different seasons or years?

Rebecca Dailey PhD

• Sheep are affected by Xanthoparmelia chlorochroa 

  • Clinical picture similar to elk 

• Toxicity of X. chlorochroa varies 

  • Season and location

  • Toxic year round not true

• Red urine occurs in all sheep fed lichen

  • Regardless of severity of paresis 

• Usnic Acid can be toxic to sheep 

  • Produces a myodegenerative disorder similar to lichen toxicity 

• Very high dose required 

  • More than they could possibly eat!

• No hepatotoxicity even at very high doses

• Concentrations of Usnic and Salazinic acids vary in X. chlorochroa 

Some mice respond to X.chlorochroa similar to elk and livestock

Livestock Implications

• Original documentation in sheep & cattle 

• No documented cases since the 30s until elk die-off 

• Seven documented outbreaks since 

  • Most had red urine 

• This lichen is very common 

• Quite possibly more occasional cases

Red Urine

• Unrelated to myopathy/myoglobinuric nephrosis 

• No kidney lesions 

• Urinalysis “normal”

• Navajos used Tumbleweed shield lichen for dye 

  • Soak it in water, water would turn red

  • Causes the urine to become red, does not cause any kidney damage

• Remains a diagnostic indicator for potential Lichen Toxicosis 

  • Bright red urine

Where do we (want to) go from here?

• Identify wildlife species susceptibility 

• Identify additional toxin compound(s)

• Identify “toxicity test” of lichen 

• Develop true diagnostic assay

• Current management is working, so little interest in funding above 

  • Management: when you see syndrome, get the animals out of there, move them someplace else, problem goes away

Human Implications

• Scientists: interesting, intriguing, exciting!

• Wildlife Managers: saddening, disheartening, stressful

Summary

• 326 confirmed cases

• Estimate of 400-500 cases

• Limited to elk

• Feb to early March 2004

• Diagnosis: Tumbleweed shield lichen toxicity 

• 84% of losses were adult female elk 

  • Cow-calf herd

Special Thanks to WSVL!

• Merle Raisbeck: toxicologist who came up with the hypothesis that it was lichen

• Todd Cornish: wildlife pathologist

• Beth Williams

• Brian Perry: necropsy technician

Take Home Message/Discussions

• When large numbers of animals are dying in a short time frame: think toxins!

  • Why?

    • When conditions are right, toxic component seems to build up

      • 5 years of drought, heavy snow on the ground, not much forage for elk to eat

    • Everybody can be exposed at the same time 

      • Unique to toxins 

    • A lot of toxins can take effect immediately or soon after exposure 

• Why is it unlikely to be infectious?

  • Some exceptions?

    • Time it takes for replication, not all going to get infected at the same time

    • Infectious outbreak much more gradual

    • Transmission time, incubation period, how much time it takes to multiply

    • Anthrax 

      • More like a toxin

      • Animals don't transmit to each other, in the soil 

      • Short incubation period 

• What are the wildlife population-level impacts of toxins?

  • More than population can compensate for

  • Limit hunting 

  • Don't see populations going extinct due to toxins, unless toxins persist

• Does it matter if it is a natural or mad-made toxin? 

  • No, they behave the same way