![]() All these contribute to hypercalcemia and the deposition of calcium in many organs and tissues.Ĭlinical signs of poisoning include weight loss, lameness and a humped-up appearance with choppy gait. This induces increased intestinal absorption of Ca with sustained secretion of calcitonin and decreased parathyroid activity. Similar to Solanum malacoxylon (the cause of enzootic calcification in South America), jasmine contains a steroidal glycoside of 1,25-(OH)2 cholecalciferol (a vitamin D analog). They form green berries that ripen black.Ĭestrum diurnum is found on disturbed soil in Florida, Texas, California, Mexico and Hawaii. Flowers are white and clustered on the axillary peduncles. The leaves are elliptic, with a dark-green, glossy upper surface. Photo 3: Cestrum diurnum (day-blooming jasmine or wild jasmine) is an introduced tropical plant commonly found in Florida, Texas, California and Hawaii. Treatment, though it may not be effective once clinical signs have developed, should include aggressive fluid therapy (diuresis).Ĭestrum diurnum (day-blooming jasmine or wild jasmine - Photo 3). Clinical chemistry changes begin as a hypocalcemia that progresses to azotemia and hypercreatinemia. Though poisoning in horses is infrequent and poorly described, clinical signs in sheep and cattle begin as depression, colic, weakness, irregular gait that can progress to lateral recumbency, coma and convulsions. The oxalates are oral irritants, so most horses avoid eating them. These plants all contain soluble oxalates that are metabolic toxins that also cause renal disease (nephrosis) and hypocalcemia. Rumex crispus (curly dock) and other dock species. Halogeton glomeratus (halogeton), invading and expanding desert weed. Sarcobatus vermiculatus (black greasewood), western-range plant, 10 percent to 20 percent oxalates. Oxalate-induced nephrosis and hypocalcemia: Treatment should include extensive fluid therapy to maintain kidney perfusion, electrolyte and acid-base balances (diuresis). Because tannic and gallic acid cause severe renal tubular nephrosis (kidney disease), clinical signs include dehydration, azotemia, hyperphosphatemia, hypocalcemia and hypoproteinemia. Not all tree parts contain enough tannins to be toxic, but animals have been poisoned from eating flowers, leaf buds or acorns.Ĭlinical signs begin as depression, acute colic, straining (constipation, frequent urination) followed by bloody diarrhea, hematuria, rapid heartbeat and rapid breathing. Oaks contain toxic tannins, such as gallotannin. In the West, Gambels or scrub oak (shown here) is a shrub that grows in dense clusters on foothills and mountain slopes. ![]() (Oak) varies from large trees to shrubs that have large, alternate, simple, lobed leaves. Because only large amounts of onion contain enough toxin, it rarely poisons horses. (onion): Onions contain an oxidant (N-propyl disulfide) similar to red maple in that it can cause acute hemolytic anemia. Other antioxidants such as ascorbic acid also may be helpful.Īllium spp. Because methemoglobinemia is limited, response to methylene blue is minimal. ![]() Treatment is symptomatic and includes blood transfusions, fluid replacement and oxygen therapy. Post-mortem findings include icterus, enlarged and swollen spleen, liver and kidneys and red urine. The clinical signs of poisoning usually develop within 24 hours of exposure and include anorexia, depression, weakness and methemoglobinemia.įatally poisoned horses develop intravascular and extravascular hemolysis, icterus, anemia, hemoglobinuria, respiratory distress, Heinz body anemia, colic, laminitis, coma and death. Red maple leaves contain an unidentified toxin that causes oxidative hemolysis. Most poisoning occurs in the fall, after storms cause branches to fall into paddocks or when trimmings are fed to animals.Īlthough only red maple has been associated with poisoning in horses, red-maple hybrids should be considered toxic until proven otherwise. The wilted and shed leaves are most toxic. Red maple is highly toxic for horses about 1.5 gm leaf/kg BW or 1 kg of wilted leaves will kill a 450-g horse. It grows to 30 m, bearing large leaves that have three to five lobes with a shiny green topside and silvery-gray underside. Photo 1: Acer rubrum (red maple) is a common ornamental shade tree. Hemolysis with hemoglobin-induced nephrosis: This final installment covers nephrotoxic and miscellaneous toxic plants, with descriptions of poisoning and plant-induced disease, along with recommended treatment and management practices to avoid poisoning. The three previous articles covered hepatoxic, neurotoxic and myotoxic plants. Because most horses are selective grazers, they are poisoned less frequently than other livestock, but some plants are palatable or they may be reluctantly accepted when feed selection is limited. This is the last of four articles about plants likely to poison horses in North America. ![]()
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