1. Ben Green
Poisonous Plant Research Laboratory
Logan, Utah

2. The Larkspur Problem
 Cattle losses typically
around 5% and can
reach 15%.
 Producers move cattle off
of the larkspur
containing pastures
resulting in wasted high
quality forage.
 Loss of a cow leaves an
early-weaned, poor
performing calf.

3. Clinical signs of larkspur poisoning
•Staggering gait.
•Muscle trembles.
•Collapse to sternal and then
lateral recumbency (this can lead
to death for various reasons).
•Difficulty breathing (rapid and
shallow).
•Death occurs from
neuromuscular paralysis and/or
bloat.

4. Methods of Avoiding Death Losses
 Drug treatment.
 Neostigmine (0.02 mg/kg body
weight) (Green et al., 2009. Am J Vet Res. 70:539-46).
 Current management -(T0xic
Window) (Pfister et al., 1999. J Nat Toxins. 8:81-94).
 Future Management - select
animals with decreased
susceptibility to poisonous
plants (Green et al., 2014. Rangelands. Accepted 10-20-2013).

5. Grazing Management!
1) Graze early before
the larkspur flowers.
2) Remove cattle
during the “toxic
window”.
3) Graze late in the
season when the seed
pods begin to shatter.

6. Toxic Window
Pfister et al., 1999. J Nat Toxins. 8:81-94

7. Quantitative Measures of Larkspur
Toxicity in Cattle
 Clinical signs of
larkspur toxicity are
difficult to measure in
cattle.
 Staggering gait.
 Respiratory
depression.
 Collapse.

8. Muscle Weakness
 The most obvious clinical sign in
poisoned cattle.
 Designed a protocol to measure it.

9. Responses of cattle dosed with two
different populations of tall larkspur
D. occidentale
Dose (mg/kg BW) Exercise to Collapse
(City, State)
Animals (#) Total Alkaloid
Y/N (#) Time (min)
Victor, ID (toxic)
8
37.6 (8.8 MSAL)
Y (12)
17 ±9.9
Logan, UT (less-toxic)
8
37.6 (0 MSAL)
N (12)
N.A.
Cook et al., 2011. Am J Vet Res. 72:706-14.

10. Larkspur Breed Study
 Developed two quantitative
measures of larkspur
intoxication.
 Heart rate.
 Time to collapse (muscle
weakness).
 Evaluating cattle breeds for
susceptibility to larkspur
intoxication.

11. Cattle responses to 8 mg/kg
MSAL-type alkaloids.
Green et al., 2014. Rangelands. Accepted 10-20-2013

12. Average time (minutes) to exercise-induced
clinical signs of poisoning.
Breed, (number of
Time to muscle fatigue,
animals)
(minutes)
Angus, 21
15.3 ± 3.4
Brahman, 13
9.4 ± 3.3
Line 1, Hereford, 36
8.8 ± 1.8
Holstein, 15
26.8 ± 3.4
Jersey, 14
29.3 ± 2.9
Green et al., 2014. Rangelands. Accepted 10-20-2013

13. Genomic Analysis
 Illumina BovineHD
genotyping array.
 777,962 polymorphisms
across the entire
bovine genome.
 We are genotyping
selected Angus and
Hereford individuals.
http://www.cancer.gov/cancertopics/understandingcanc
er/geneticvariation/page13

14. Conclusions
 Neostigmine reverses larkspur poisoning in
cattle.
 There are more susceptible and less susceptible
cattle in every breed.
 May be possible to select for less susceptible
animals.
 Goal of this research is to identify a genetic
marker(s) to be used for herd management.

15. Acknowledgements
 Dale Gardner, Steve Lee- Chemistry
 Isabella McCollum- Cell-Based Assays, Cattle.
 Kevin Welch, Zane Davis, Rex Probst, Danny
Hansen- Cattle Experiments
 Jessie Roper- Larkspur Analysis
 Daniel Cook – Larkspur populations