Selenium Toxicosis Flashcards
You have a selenium deficiency under what level?
What can selenium deficiency cause in lambs, calves and foals?
White muscle disease or nutritional muscle dystrophy
What can selenium deficiency cause in young pigs?
Hepatosis dietetica
What can selenium deficiency cause in chicks?
Exudative diathesis
What can selenium deficiency cause in chickens?
Nutritional pancreatic atrophy
What can selenium deficiency cause in pigs?
Porcine stress syndrome
Where are 4 parts of the country that can have soil deficient in selenium?
- Northwest
- Northeast
- Southeast
- Great lakes
What are 9 states that have selenium rich soil?
- South Dakota
- North Dakota
- Wyoming
- Montana
- Nebraska
- Kansas
- Utah
- Colorado
- New Mexico
What are selenium requirements?
0.1 mg/kg depending on Vitamin E
Selenium can be given as a feed supplement for what 4 species?
- Cattle
- Sheep
- Swine
- Poultry
Can selenium be given as an injectable?
Yes with vitamin E
Selenium can be used in medicated shampoos for treatment of what?
Dermatitis
What are 3 species that may graze on seleniferous plants?
- Cattle
- Sheep
- Horses
What 2 species may eat grains grown on selenium-rich soil?
- Swine
- Poultry
Seleniferous plants can accumulate how much selenium?
Up to 15,000 ppm
What are 4 examples of seleniferous plants?
- Astragalus (locoweed, milk vetch)
- Stanleya (prince’s plume)
- Oonopsis (golden wood)
- Xylorrhiza (woody aster)
Facultative accumulators can accumulate how much selenium?
Up to 25-100 ppm
Do facultative accumulators require selenium?
No but they can accumulate it.
What are 3 examples of facultative selenium accumulators?
- Aster (aster)
- Atriplex (saltbrush)
- Castilleja (paint brush)
Passive accumulators can accumulate how much selenium?
Up to 1-25 ppm
Many plants including crop plants such as corn, wheat, oats, barley, grass and hay are what type of selenium accumulators?
Passive
Selenium contaminated water can cause what in waterfowl?
Teratogenic effects
Improper use of selenium-medicated shampoos may cause toxicosis in what species?
Small animals
Is selenium an essential trace element?
Yes
What are the 3 oxidative states of selenium?
- Selenate (+6)
- Selenite (+4)
- Selenide (-2)
Selenium has chemical and physical properties similar to what other 2 elements?
- Sulfur
- Arsenic
What does selenium combine with?
-SH group of glutathione
What is selenium a component of?
Glutathione peroxidase
Selenium acts as an antioxidant by preventing what?
Peroxide accumulation through reduction of glutathione.
What is synergistic with selenium?
Vitamin E
What does the combination of selenium and vitamin E prevent?
Cellular degeneration and cell membrane damage
What is selenium also found in?
5-deiodinase
What is selenium an irritant to?
Mucous membranes
List the various forms of selenium in order of increasing toxicity.
- Synthetic organoselenium compounds
- Selenide
- Selenate = selenite
- Organic selenium in plants
What is the acute toxic dose of oral selenium (selenite) in horses?
Cattle?
Swine?
- 3.3 mg/kg
- 10 mg/kg
- 17 mg/kg
What is the oral subacute toxic level of selenium for swine?
20-50 ppm for 3 days or more
What is the chronic toxic level of selenium for horses, cattle and swine?
Over what time period?
- 5-10 ppm
- Several weeks or months
What seen in the soil of the Great Plains promotes formation of selenate?
Arid alkaline
T/F: Elemental selenium is relatively non-toxic.
True
What are 2 ways selenium toxicity can be reduced?
- High protein diet
- Ingestion of other elements that bind selenium such as copper
What type of plants have a bad odor and are generally unpalatable, are only eaten when other forage is unavailable?
Seleniferous plants
Where is selenium readily absorbed from?
Small intestine
Which form of selenium is more rapidly absorbed?
Soluble organic selenium in plants
What form of selenium is not absorbed because it is insoluble in water?
Elemental selenium
Where are 3 areas of the body selenium is particularly distributed to?
- Liver
- Kidney
- Spleen
Chronic exposure to selenium results in what?
High concentration in hair and hoof.
Does selenium cross the placenta?
Yes, can be teratogenic
What is the main way selenium is excreted?
What are 2 other ways it can be excreted?
- Urine
- Milk and bile
What can increase the biliary excretion of selenium?
Arsenic
Where does selenium cause irritation?
GI mucosa
Selenium can cause a dramatic depletion of what?
Tissue glutathione (GSH)
Selenium can replace what in amino acids, causing abnormal proteins?
Sulfur
What can be decreased in chronic selenium toxicosis?
What else can be decreased?
- ATP
- Tissue ascorbic acid
Death in acute and subacute toxicosis is mainly due to what?
This results from what?
- Respiratory insufficiency
- Pulmonary edema and hemorrhage
Death in chronic selenium toxicosis may be due to what?
Resulting from what?
- Starvation and thirst
- Weakness, lameness, blindness
Onset of acute oral selenium toxicosis can be seen in what time frame?
A few hours to a few days
GI signs such as colic, bloat, and dark watery diarrhea can be seen with which selenium toxicosis?
Acute oral toxicosis
Respiratory signs such as labored respiration with fluid sounds in the lungs, bloody froth from the nares and cyanosis can be seen with which form of selenium toxicosis?
Acute oral toxicosis
What are 4 other clinical signs that can be seen with acute selenium toxicosis?
- Fever
- Polyuria
- Mydriasis
- Uncertain gait
Neurologic signs including mydriasis and incoordination can be seen with which form of selenium toxicosis?
Acute parenteral selenium toxicosis
What is another term for subacute selenium toxicosis in cattle?
“Blind staggers”
Poor appetite, aimless wandering, circling, walking through objects, normal respiration and temperature is seen with what stage for subacute selenium toxicosis?
Stage 1
Depression, incoordination, foreleg weakness and walking on knees and complete anorexia can be seen with which stage of selenium toxicosis?
Stage 2
Colic, hypothermia, emaciation, clouded corneas near blindness, paresis, coma and death in hours can be seen with which stage of selenium toxicosis?
Stage 3
Signs of subacute selenium toxicosis are similar to cattle but the stages are not as well define in what species?
Sheep
Subacute selenium toxicosis in swine is also know as what?
What type of condition is this?
- “Porcine focal symmetrical poliomyelomalacia”
- Neuroparalytic
What are 3 neurological signs that can be seen with subacute selenium toxicosis in swine?
- Incoordination
- Lameness
- Paralysis
What are 3 other signs of subacute selenium toxicosis seen in swine?
- Alopecia
- Hoof abnormalities
- Separation of the hoof
Rough hair coat, loss of hair from mane and tail, hoof deformities and sloughing, stiffness of joints, lameness, partial blindness, anemia, lethargy, emaciation, infertility and death defects are clinical signs that can be seen with which form of selenium toxicosis?
Chronic selenium toxicosis
What is chronic selenium toxicosis also known as?
Alkali disease
Hemorrhagic gastroenteritis, congestion of organs, hemorrhages, pulmonary edema, hydrothorax and gut contents smelling like rotten garlic or rotten horseradish are signs of which type of selenium toxicosis?
Acute
Focal symmetrical poliomyelomalacia can be seen in subacute selenium toxicosis in what species?
Swine
Abnormal hooves, cardiac damage and hepatic necrosis can be seen with which type of selenium toxicosis?
Chronic
Selenium levels are elevated above what level with acute toxicosis?
Chronic?
- > 2 ppm
- > 5 ppm
What are 3 sources for specimens in acute selenium toxicosis?
- Blood
- Kidney
- Liver
What are 2 sources of specimens for chronic selenium toxicosis?
- Hair
- Hoof
Blood or plasma glutathione peroxidase activity correlates well with blood selenium concentrations in what 3 species?
But not in what species?
- Cattle, sheep, swine
- Not in horses
Pneumonia, infectious hepatitis, enterotoxemia and pasteurellosis are differentials for which two types of selenium toxicosis?
Acute or subacute
Molybdenum toxicosis, fluoride toxicosis, freezing, ergotism and laminitis are differentials for which type of selenium toxicosis?
Chronic
What are 2 things that can be used in the treatment of acute selenium toxicosis?
- Saline cathartics
- Acetylcysteine
What type of symptomatic therapy can be used for the treatment of pulmonary edema, circulatory shock and gasteroenteritis seen with acute selenium toxicosis?
Oxygen therapy
What are 3 dietary changes that can be made to try and prevent subacute and chronic selenium toxicity?
- Add copper to diet
- Diet high in protein
- Increase sulfur-containing proteins
Addition of what to the diet increases biliary excretion of selenium?
Organic arsenicals
What is the prognosis for selenium toxicosis?
Poor in acute toxicosis because animals die quickly