Locoweed

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Locoweed (also crazyweed and loco) is a common name in North America for any plant that produces swainsonine, an alkaloid harmful to livestock. Worldwide, swainsonine is produced by a small number of species, most of them in three genera of the flowering plant family Fabaceae: Oxytropis and Astragalus in North America, [1] and Swainsona in Australia. The term locoweed usually refers only to the North American species of Oxytropis and Astragalus, but this article includes the other species as well. Some references may incorrectly list Datura as locoweed. [2]

Contents

Locoweed is relatively palatable to livestock, and some individual animals will seek it out. Livestock poisoned by chronic ingestion of large amounts of swainsonine develop a medical condition known as locoism (swainsonine disease, swainsonine toxicosis in North America) and pea struck in Australia. [3] Locoism is reported most often in cattle, sheep, and horses, but has also been reported in elk and deer. It is the most widespread poisonous plant problem in the western United States. [1] [4]

Most of the 2,000 species of Astragalus, including many that are commonly known as locoweeds, do not produce swainsonine. Some species, including a few that produce swainsonine, accumulate selenium. This has led to confusion between swainsonine poisoning and selenium poisoning due to this genus.[ citation needed ]

History and etymology

The first technical account (in English) of locoism was published in 1873, in the United States. Linguists have documented locoism in use among English speakers by 1889, and both loco and locoweed in use by 1844. [5]

Loco, a loanword from Spanish, is understood by most English-speaking users in the sense of crazy, and this appears to have also been the sense understood by vaqueros. [5] In Spanish, however, loco has an older, different sense. In Spain, where the native Astragalus species are not known to cause locoism, for centuries loco has been applied to some of these species in the sense of rambling: common names include yerba loca (hierba loca; rambling herb) and chocho loco (rambling lupine).[ citation needed ]

The presence of a toxin in locoweed was demonstrated in 1909. Initially, the toxin was reported to be a barium compound, but that was soon disproved. Swainsonine, first isolated from Swainsona, was shown to be responsible for pea struck in 1979, and was reported in both Oxytropis and Astragalus in 1982. [6]

Since 1982, swainsonine has been isolated from still more plants, some of which also are reported to cause locoism or medical conditions similar to it. The first report of locoism in South America, involving Astragalus pehuenches, was published in 2000. [7]

Taxa producing swainsonine

Swainsonine is produced by a small number of species, including species in several genera of plants and two genera of fungi.

Oxytropis sericea in bloom Oxytropis sericea.jpg
Oxytropis sericea in bloom
Astragalus lentiginosus in fruit Astragalus lentiginosus 4.jpg
Astragalus lentiginosus in fruit
Swainsona galegifolia Curtis's botanical magazine (No. 792) (8469881299).jpg
Swainsona galegifolia

Oxytropis is distributed throughout western North America, particularly in the Great Plains and Rocky Mountains. However, most species of Oxytropis have narrow habitat requirements and within those habitats are abundant only in unusually wet years. [1] The species most frequently encountered by livestock are O. lambertii (Lambert locoweed, purple locoweed, woolly locoweed) and especially Oxytropis sericea (white locoweed, white point locoweed, white point loco). Swainsonine has also been found in O. campestris (in Canada). [8]

Some species of Astragalus (milkvetch) are also referred to as locoweed. Swainsonine has been found in: [8]

In Argentina, locoism (locoismo) was first reported in 2000. A flock of sheep grazing a pasture with Astragalus pehuenches was poisoned and 220 sheep (73%) died. [7] Although this was the first report of locoism in South America, [7] swainsonine had been isolated previously from A. pehuenches and several other species in Argentina and Peru. [7] [9]

In the Old World, native plants causing locoism have not been reported. Astragalus lusitanicus in Morocco was suspected, [10] but has been shown be neither a producer of swainsonine nor an accumulator of selenium. Its toxicity is suspected to be due to a novel alkaloid. [11]

In Australia, species of Swainsona (Darling pea) that cause pea struck include: [8] [12]

Astragalus and Oxytropis are two of 20 genera (and 78 names of genera) in the tribe Galegeae, subtribe Astragalinae. Some authorities include Swainsona in the subtribe. [13] Formerly, Swainsona was in another subtribe, Coluteinae, that has been combined into Astragalinae.

Swainsonine has also been isolated from Sida carpinifolia and Ipomoea carnea , and both species have been reported to cause locoism. [14]

Embellisia , a fungus isolated from Oxytropis lambertii, has also been shown to produce swainsonine and to cause locoism in rats. [15] Rhizoctonia leguminicola , a fungal plant pathogen that may occur on red clover ( Trifolium pratense ), also produces swainsonine. Although intoxication due to this fungus resembles locoism, it has additional signs and symptoms due to the production of other toxins. [16]

Pathology

Intoxication with swainsonine has several kinds of effect.

Livestock that graze for several weeks on locoweed (and little else) develop a lysosomal storage disease similar to genetic mannosidosis. [17] Swainsonine inhibits a lysosomal enzyme, alpha-mannosidase. [18] This results in abnormal accumulation of the molecules normally processed by the enzyme, and this accumulation leads to vacuolation of most tissues. Vacuolation is most obvious in neurons and epithelial cells. The vacuolation resolves shortly after poisoning is discontinued, but if the vacuolation is so severe that it destroys cells, it may result in some neurologic damage that is irreversible and permanent. [17] The damage is highly varied. In cattle at high altitude, complications of locoism can include congestive heart failure. [19]

Diagnosis

Diagnosis of clinical poisoning is generally made by documenting exposure, identifying the neurologic signs, and analyzing blood serum for alpha-mannosidase activity and swainsonine. [17]

In mule deer, clinical signs of locoism are similar to chronic wasting disease. Histological signs of vacuolation provide a differential diagnosis. [20]

Sub-clinical intoxication has been investigated in cattle grazing on Astragalus mollissimus. As the estimated intake of swainsonine increased, blood serum alpha-mannosidase activity and albumin decreased, and alkaline phosphatase and thyroid hormone increased. [21]

Prevention

Because O. sericea is both frequently encountered and relatively palatable to livestock, it is an important cause of economic losses in livestock production. Keeping livestock away from locoweed-infested pasture in spring and fall when grass and other forbs are not actively growing is recommended. Another suggested remedy is to provide palatable supplemental nutrients if animals are to be kept in infested pasture. These remedies take into account livestock preference for locoweed during seasons when grass is dry and not very nutritious. [22] Conditioned food aversion has been used experimentally to discourage livestock from eating it. [23] [24] In horses, a small study has shown promising results using lithium chloride as the aversive agent. [24]

See also

Related Research Articles

<i>Astragalus</i> (plant) Genus of legumes

Astragalus is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to temperate regions of the Northern Hemisphere. Common names include milkvetch, locoweed and goat's-thorn. Some pale-flowered vetches are similar in appearance, but they are more vine-like than Astragalus.

<span class="mw-page-title-main">Alpha-mannosidosis</span> Medical condition

Alpha-mannosidosis is a lysosomal storage disorder, first described by Swedish physician Okerman in 1967. In humans it is known to be caused by an autosomal recessive genetic mutation in the gene MAN2B1, located on chromosome 19, affecting the production of the enzyme alpha-D-mannosidase, resulting in its deficiency. Consequently, if both parents are carriers, there will be a 25% chance with each pregnancy that the defective gene from both parents will be inherited, and the child will develop the disease. There is a two in three chance that unaffected siblings will be carriers. In livestock alpha-mannosidosis is caused by chronic poisoning with swainsonine from locoweed.

<i>Swainsona</i> Genus of legumes

Swainsona is a genus of about 85 species of flowering plants in the family Fabaceae, and is endemic to Australia. Plants in this genus are herbs or subshrubs with imparipinnate leaves and usually purple flowers similar to others in the family.

<span class="mw-page-title-main">Swainsonine</span> Chemical compound

Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed it also is a significant cause of economic losses in livestock industries, particularly in North America. It was first isolated from Swainsona canescens.

Persin is a fungicidal toxin present in the avocado. Persin is an oil-soluble compound structurally similar to a fatty acid, a colourless oil, and it leaches into the body of the fruit from the seeds.

<i>Astragalus mongholicus</i> Species of plant

Astragalus mongholicus, synonyms including Astragalus propinquus and Astragalus membranaceus, commonly known as Mongolian milkvetch in English; 'Хунчир' in Mongolian; huáng qí, běi qí or huáng huā huáng qí, in Mongolia, is a flowering plant in the family Fabaceae. It is one of the 50 fundamental herbs used in traditional Mongolian medicine. It is a perennial plant and it is not listed as being threatened.

<i>Astragalus bisulcatus</i> Species of plant

Astragalus bisulcatus, commonly called two-grooved milkvetch or silver-leafed milkvetch, is a leafy perennial with pea-like flowers. It is native to central and western North America, and typically grows on selenium-rich soils. It accumulates selenium within its tissues, and when livestock consume it, the selenium can be toxic.

<i>Oxytropis</i> Genus of flowering plants in the pea and bean family Fabaceae

Oxytropis is a genus of plants in the legume family. It includes over 600 species native to subarctic to temperate regions of North America and Eurasia. It is one of three genera of plants known as locoweeds, and are notorious for being toxic to grazing animals. The other locoweed genus is the closely related Astragalus. Most oxtropis species are native to Eurasia and North America, but several species are native to the Arctic. These are hairy perennial plants which produce raceme inflorescences of pink, purple, white, or yellow flowers which are generally pea-like but have distinctive sharply beaked keels. The stems are leafless, the leaves being all basal. The plant produces legume pods containing the seeds.

<i>Astragalus lentiginosus</i> Species of plant

Astragalus lentiginosus is a species of legume native to western North America where it grows in a range of habitats. Common names include spotted locoweed and freckled milkvetch. There are a great number of wild varieties. The flower and the fruit of an individual plant are generally needed to identify the specific variety.

Locoweed may refer to:

<i>Swainsona greyana</i> Species of plant

Swainsona greyana, commonly known as the Darling pea or hairy-Darling pea, is a species of flowering plant in the family Fabaceae and is endemic to south-eastern continental Australia. It is an erect perennial subshrub with imparipinnate leaves with 17 to 21 egg-shaped leaflets, and racemes of 12 to 20 or more white, pink or purple flowers.

<i>Oxytropis lambertii</i> Species of plant

Oxytropis lambertii commonly known as purple locoweed, Colorado locoweed, Lambert's crazy weed, or Lambert’s Locoweed is a species of flowering plant in the legume family.

<i>Astragalus osterhoutii</i> Species of astragalus

Astragalus osterhoutii, or the Osterhout milkvetch or Kremmling milkvetch, is an endangered species of milkvetch, discovered and collected in 1905 at Sulfur Spring in Grand County Colorado by Colorado botanist George Everett Osterhout for which the plant was named. It is found in the U.S. state of Colorado, in a 13 kilometres (8.1 mi) radius near the town of Kremmling.

<i>Oxytropis sericea</i> Species of flowering plant

Oxytropis sericea is a species of flowering plant in the legume family known by the common names white locoweed, white point-vetch, whitepoint crazyweed, and silky crazyweed. It is native to western North America from Yukon and British Columbia south through the Pacific Northwest, the Rocky Mountains, and the Great Plains.

Woolly locoweed is a common name for several plants and may refer to:

<i>Astragalus mollissimus</i> Species of legume

Astragalus mollissimus is a perennial plant in the legume family (Fabaceae) found in the Colorado Plateau and Canyonlands region of the southwestern United States.

<span class="mw-page-title-main">Zygacine</span> Chemical compound

Zygacine is a steroidal alkaloid of the genera Toxicoscordion, Zigadenus, Stenanthium and Anticlea of the family Melanthiaceae. These plants are commonly known and generally referred to as death camas. Death camas is prevalent throughout North America and is frequently the source of poisoning for outdoor enthusiasts and livestock due to its resemblance to other edible plants such as the wild onion. Despite this resemblance, the death camas plant lacks the distinct onion odor and is bitter to taste.

<i>Astragalus racemosus</i> Species of plant in the family Fabaceae

Astragalus racemosus, the cream milkvetch, is a species of flowering plant in the family Fabaceae. It is native to central North America. A selenium hyperaccumulator, it is considered capable of poisoning livestock as one of the locoweeds.

References

  1. 1 2 3 Ralphs MH, James LF (February 1999). "Locoweed grazing". Journal of Natural Toxins. 8 (1): 47–51. PMID   10091127.
  2. ↑ "Sacred Datura (Locoweed) on North Kaibab Trail Grand Canyon - don't even think about smokin' this s**t uff". October 19, 2006.
  3. ↑ Pritchard DH, Huxtable CR, Dorling PR (March 1990). "Swainsonine toxicosis suppresses appetite and retards growth in weanling rats". Research in Veterinary Science. 48 (2): 228–30. doi:10.1016/S0034-5288(18)30995-0. PMID   2110378.
  4. ↑ "ARS and New Mexico Scientists Take a Long Look at Livestock and Locoweed : USDA ARS".
  5. 1 2 Robert N. Smead, Richard W. Slatta (2004). Vocabulario Vaquero/cowboy Talk: A Dictionary Of Spanish Terms From The American West. University of Oklahoma Press. p. 197. ISBN   978-0-8061-3631-8. page 115
  6. ↑ Keeler and Tu (1983), page 454.
  7. 1 2 3 4 C.A. Robles, C. Saber, M. Jefrey (2000). "Intoxicación por Astragalus pehuenches (locoismo) en ovinos Merino de la Patagonia Argentina" [Astragalus pehuenches (locoweed) poisoning in a Merino sheep flock in Patagonia Region, Argentina]. Revista de Medicina Veterinaria. 81 (5): 380–384.
  8. 1 2 3 Jones et al. (1997), page 752.
  9. ↑ Michael JP (December 1997). "Indolizidine and quinolizidine alkaloids". Natural Product Reports. 14 (6): 619–36. doi:10.1039/NP9971400619. PMID   9418297.
  10. ↑ Abdennebi EH, el Ouazzani N, Lamnaouer D (December 1998). "Clinical and analytical studies of sheep dosed with various preparations of Astragalus lusitanicus". Veterinary and Human Toxicology. 40 (6): 327–31. PMID   9830691.
  11. ↑ Ouazzani N, Lamnaouer D, Abdennebi EH (1999). "Toxicology of Astragalus lusitanicus Lam". Thérapie. 54 (6): 707–10. PMID   10709444.
  12. ↑ Les Tanner (August 2003). "Poisonous plant: Darling pea (Swainsona spp.)" (PDF). Northern Inland Weeds Advisory Committee. Archived from the original (PDF) on June 15, 2005. Retrieved May 11, 2009.
  13. ↑ "GRIN Genera of Fabaceae subtribe Astragalinae". Germplasm Resources Information Network. 2003. Archived from the original on October 15, 2008. Retrieved May 12, 2009.
  14. ↑ Carod-Artal FJ (2003). "[Neurological syndromes linked with the intake of plants and fungi containing a toxic component (I). Neurotoxic syndromes caused by the ingestion of plants, seeds and fruits]". Revista de Neurología (in Spanish). 36 (9): 860–71. PMID   12717675 . Retrieved May 13, 2009.
  15. ↑ McLain-Romero J, Creamer R, Zepeda H, Strickland J, Bell G (July 2004). "The toxicosis of Embellisia fungi from locoweed (Oxytropis lambertii) is similar to locoweed toxicosis in rats". Journal of Animal Science. 82 (7): 2169–74. doi:10.2527/2004.8272169x. PMID   15309966.
  16. ↑ Croom WJ, Hagler WM, Froetschel MA, Johnson AD (May 1995). "The involvement of slaframine and swainsonine in slobbers syndrome: a review". Journal of Animal Science. 73 (5): 1499–1508. doi:10.2527/1995.7351499x. PMID   7665382.
  17. 1 2 3 Stegelmeier BL, James LF, Panter KE, Ralphs MH, Gardner DR, Molyneux RJ, Pfister JA (February 1999). "The pathogenesis and toxicokinetics of locoweed (Astragalus and Oxytropis spp.) poisoning in livestock". Journal of Natural Toxins. 8 (1): 35–45. PMID   10091126.
  18. ↑ Jones et al. (1997), page 31.
  19. ↑ "High-mountain Disease: Introduction". The Merck Veterinary Manual. 2008. Retrieved May 11, 2009.
  20. ↑ Stegelmeier BL, James LF, Gardner DR, Panter KE, Lee ST, Ralphs MH, Pfister JA, Spraker TR (September 2005). "Locoweed (Oxytropis sericea)-induced lesions in mule deer (Odocoileius hemionus)". Veterinary Pathology. 42 (5): 566–78. doi:10.1354/vp.42-5-566. PMID   16145203. S2CID   2219085.
  21. ↑ Stegelmeier BL, Ralphs MH, Gardner DR, Molyneux RJ, James LF (October 1994). "Serum alpha-mannosidase activity and the clinicopathologic alterations of locoweed (Astragalus mollissimus) intoxication in range cattle". Journal of Veterinary Diagnostic Investigation. 6 (4): 473–9. doi:10.1177/104063879400600412. PMID   7858027. S2CID   32914209.
  22. ↑ "ARS and New Mexico Scientists Take a Long Look at Livestock and Locoweed" by Ann Perry, June 21, 2010, Agricultural Research Service, accessed September 29, 2010
  23. ↑ Ralphs MH, Provenza FD (November 1999). "Conditioned food aversions: principles and practices, with special reference to social facilitation". Proceedings of the Nutrition Society. 58 (4): 813–20. doi: 10.1017/S002966519900110X . PMID   10817148.
  24. 1 2 Pfister JA, Stegelmeier BL, Cheney CD, Ralphs MH, Gardner DR (January 2002). "Conditioning taste aversions to locoweed (Oxytropis sericea) in horses". Journal of Animal Science. 80 (1): 79–83. doi:10.2527/2002.80179x. ISSN   0021-8812. PMID   11831531 . Retrieved January 28, 2018.

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