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Jacobaea vulgaris, syn. Senecio jacobaea, is a very common wild flower in the family Asteraceae that is native to northern Eurasia, usually in dry, open places, and has also been widely distributed as a weed elsewhere.
Rhaponticum repens, synonyms including Acroptilon repens and Leuzea repens, with the common name Russian knapweed, is a species of bushy rhizomatous perennial, up to 80 cm tall. Stems and leaves are finely arachnoid-tomentose becoming glabrous and green with age. The rosette leaves are oblanceolate, pinnately lobed to entire, 2–3 cm wide by 3–8 cm long. The lower cauline leaves are smaller, pinnately lobed; the upper leaves become much reduced, sessile, serrate to entire. The heads are numerous terminating the branches. Flowers are pink to purplish, the marginal ones not enlarged. The outer and middle involucral bracts are broad, striate, smooth with broadly rounded tips; the inner bracts are narrower with hairy tips. Pappus present with bristles 6–11 mm long. Fruit is a whitish, slightly ridged achene.
Abamectin (also called avermectin B1) is a widely used insecticide and anthelmintic. Abamectin, is a member of the avermectin family and is a natural fermentation product of soil dwelling actinomycete Streptomyces avermitilis. Abamectin differs from ivermectin, the popular member of the avermectin family, by a double bond between carbons 22 and 25. Fermentation of Streptomyces avermitilis yields eight closely related avermectin homologs, with the B1a and B1b forms comprising the majority of the fermentation. The non-proprietary name, abamectin, refers to a mixture of B1a (~80%) and B1b (~20%). Out of all the avermectins, abamectin is the only one that is used both in agriculture and pharmaceuticals.
Sesquiterpene lactones (SLs) are a class of sesquiterpenoids that contain a lactone ring. They are most often found in plants of the family Asteraceae. Other plant families with SLs are Umbelliferae and Magnoliaceae (magnolias). A collection of colorless, lipophilic solids, SLs are a rich source of drugs. They can be allergenic and toxic in grazing livestock causing severe neurological problems in horses. Some are also found in corals of the order Alcyonacea.
Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle, sheep and wombats. Moxidectin kills some of the most common internal and external parasites by selectively binding to a parasite's glutamate-gated chloride ion channels. These channels are vital to the function of invertebrate nerve and muscle cells; when moxidectin binds to the channels, it disrupts neurotransmission, resulting in paralysis and death of the parasite.
Equine protozoal myeloencephalitis (EPM) is a disease that affects the central nervous system of horses. It is caused by a protozoal infection that is brought about by the apicomplexan parasites Sarcocystis neurona or Neospora hughesi. Most cases are caused by S. neurona. The lifecycle and transmission of N. hughesi is not well understood. The parasites create lesions in both the brain and spinal cord of the affected horses leading to neurological issues. Most horses infected with S. neurona do not exhibit neurological symptoms consistent with EPM.
Cerebellar abiotrophy (CA), also called cerebellar cortical abiotrophy (CCA), is a genetic neurological disease in animals, best known to affect certain breeds of horses, dogs and cats. It can also develop in humans. It develops when the neurons known as Purkinje cells, located in the cerebellum of the brain, begin to die off. These cells affect balance and coordination. They have a critical role to play in the brain. The Purkinje layer allows communication between the granular and molecular cortical layers in the cerebellum. Put simply, without Purkinje cells, an animal loses its sense of space and distance, making balance and coordination difficult. People with damage to the cerebellum can experience symptoms like unsteady gait, poor muscle control, and trouble speaking or swallowing.
Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids. A recent study conducted in the Cosmics Leaving Outdoor Droplets large cloud chamber at CERN, has identified sesquiterpenes—gaseous hydrocarbons that are released by plants—as potentially playing a major role in cloud formation in relatively pristine regions of the atmosphere.
Helenalin, or (-)-4-Hydroxy-4a,8-dimethyl-3,3a,4a,7a,8,9,9a-octahydroazuleno[6,5-b]furan-2,5-dione, is a toxic sesquiterpene lactone which can be found in several plants such as Arnica montana and Arnica chamissonis Helenalin is responsible for the toxicity of the Arnica spp. Although toxic, helenalin possesses some in vitro anti-inflammatory and anti-neoplastic effects. Helenalin can inhibit certain enzymes, such as 5-lipoxygenase and leukotriene C4 synthase. For this reason the compound or its derivatives may have potential medical applications.
Equine polysaccharide storage myopathy is a hereditary glycogen storage disease of horses that causes exertional rhabdomyolysis. It is currently known to affect the following breeds American Quarter Horses, American Paint Horses, Warmbloods, Cobs, Dales Ponies, Thoroughbreds, Arabians, New Forest ponies, and a large number of Heavy horse breeds. While incurable, PSSM can be managed with appropriate diet and exercise. There are currently 2 subtypes, known as Type 1 PSSM and Type 2 PSSM.
Hereditary equine regional dermal asthenia (HERDA), also known as hyperelastosis cutis (HC), is an inherited autosomal recessive connective tissue disorder. It develops from a homozygous recessive mutation that weakens collagen fibers that allow the skin of the animal to stay connected to the rest of the animal. Affected horses have extremely fragile skin that tears easily and exhibits impaired healing. In horses with HC, the skin separates between the deep and superficial dermis. There is no cure. Most affected individuals receive an injury they cannot heal, and are euthanized. Managed breeding strategy is currently the only option for reducing the incidence of the disease.
Lameness is an abnormal gait or stance of an animal that is the result of dysfunction of the locomotor system. In the horse, it is most commonly caused by pain, but can be due to neurologic or mechanical dysfunction. Lameness is a common veterinary problem in racehorses, sport horses, and pleasure horses. It is one of the most costly health problems for the equine industry, both monetarily for the cost of diagnosis and treatment, and for the cost of time off resulting in loss-of-use.
Actinobacillosis is a zoonotic disease caused by Actinobacillus. It is more commonly associated with animals than with humans.
Merrilactone A is one of the four sesquiterpenes that were newly discovered from the fruit of Illicium merrillianum in 2000. Members of the genus Illicium include Chinese star anise, widely used as a spice for flavouring food and beverages, and also poisonous plants such as Japanese star anise. Chemical studies of Illicium have developed rapidly over the last 20 years, and merrilactone A has been shown to have neurotrophic activity in fetal rat cortical neuron cultures. This has led researchers to believe that Merrilactone A may hold therapeutic potential in the treatment of neuro-degenerative diseases such as Alzheimer's disease and Parkinson's disease.
Colitis X, equine colitis X or peracute toxemic colitis is a catchall term for various fatal forms of acute or peracute colitis found in horses, but particularly a fulminant colitis where clinical signs include sudden onset of severe diarrhea, abdominal pain, shock, and dehydration. Death is common, with 90–100% mortality, usually in less than 24 hours. The causative factor may be Clostridium difficile, but it also may be caused by other intestinal pathogens. Horses under stress appear to be more susceptible to developing colitis X, and like the condition pseudomembranous colitis in humans, an association with prior antibiotic use also exists. Immediate and aggressive treatment can sometimes save the horse, but even in such cases, 75% mortality is considered a best-case scenario.
Nutritional Muscular Dystrophy is a disease caused by a deficiency of selenium and vitamin E in dietary intake. Soils that contains low levels of selenium produce forages and grains that are deficient in selenium. Similarly, if the forage is of low quality or is not stored properly it may be deficient in vitamin E. If an animal consumes this type of diet without additional supplementation they become susceptible to this disease. This condition often affects young ruminants, such as calves and lambs.
Neorickettsia risticii, formerly Ehrlichia risticii, is an obligate intracellular gram negative bacteria that typically lives as an endosymbiont in parasitic flatworms, specifically flukes. N. risticii is the known causative agent of equine neorickettsiosis, which gets its name from its discovery near the Potomac River in Maryland and Virginia. N. risticii was first recovered from horses in this region in 1984 but was not recognized as the causative agent of PHF until 1979. Potomac horse fever is currently endemic in the United States but has also been reported with lower frequency in other regions, including Canada, Brazil, Uruguay, and Europe. PHF is a condition that is clinically important for horses since it can cause serious signs such as fever, diarrhea, colic, and laminitis. PHF has a fatality rate of approximately 30%, making this condition one of the concerns for horse owners in endemic regions N. risticii is typically acquired in the middle to late summer near freshwater streams or rivers, as well as on irrigated pastures. This is a seasonal infection because it relies on the ingestion of an arthropod vector, which is more commonly found on pasture in the summer months. Although N. risticii is a well known causative agent for PHF in horses, it may act as a potential pathogen in cats and dogs as well. Not only has N. risticii been successfully cultured from monocytes of dogs and cats, but cats have become clinically ill after experimental infection with the bacteria. In addition, N. risticii has been isolated and cultured from human histiocytic lymphoma cells.
Shivers, or equine shivering, is a rare, progressive neuromuscular disorder of horses. It is characterized by muscle tremors, difficulty holding up the hind limbs, and an unusual gait when the horse is asked to move backwards. Shivers is poorly understood and no effective treatment is available at this time.
Ann Trommershausen Bowling was an American scientist who was one of the world's leading geneticists in the study of horses, conducting research in the areas of molecular genetics and cytogenetics. She was a major figure in the development of testing to determine animal parentage, first with blood typing in the 1980s and then DNA testing in the 1990s. She later became known for her studies of hereditary diseases in horses and equine coat color genetics, as well as research on horse evolution and the development of horse breeds. She studied the population genetics of feral horses, did considerable work to help preserve the Przewalski's horse, and was one of the founding members of the international project to map the horse genome. She was an adjunct professor at the University of California, Davis (UCD), and at the time of her death in 2000 was the executive associate director of the Veterinary Genetics Laboratory (VGL) there. Her unexpected death on December 8, 2000, at age 57 was attributed to a massive stroke.
The horse tongue, like that of most mammals, is pink in color and plays an important role in taste perception. With its long, narrow shape typical of herbivorous animals, it enables the horse to grasp its vegetable food, with the help of its lips and teeth. This tongue is sensitive to pressure and temperature, and is involved in licking and chewing. Although the mare licks its foal for a long time immediately after birth, there is little research into the gustatory sensitivity of horses and the social use these animals make of their tongues.
References
- 1 2 3 4 5 H. T. Chang; W. K. Rumbeiha; J. S. Patterson; B. Puschner; A. P. Knight (28 April 2011). "Toxic Equine Parkinsonism: An Immunohistochemical Study of 10 Horses With Nigropallidal Encephalomalacia". Veterinary Pathology. 49 (2): 398–402. doi:10.1177/0300985811406885. PMID 21527781. S2CID 7343822 . Retrieved 8 July 2020.
- ↑ Elliott, Crb; McCowan, Ci (April 2012). "Nigropallidal encephalomalacia in horses grazing Rhaponticum repens (creeping knapweed): EQUINE". Australian Veterinary Journal. 90 (4): 151–154. doi: 10.1111/j.1751-0813.2011.00879.x . PMID 22443332.
- ↑ "Yellow Starthistle". ASPCA. Retrieved 8 July 2020.
- ↑ Robles, M.; Wang, N.; Kim, R.; Choi, B.H. (1997). "Cytotoxic effects of repin, a principal sesquiterpene lactone of russian knapweed". Journal of Neuroscience Research. 47 (1): 90–7. doi:10.1002/(SICI)1097-4547(19970101)47:1<90::AID-JNR10>3.0.CO;2-E. PMID 8981242. S2CID 23156210.
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