Soluble oxalate (FINAL) Flashcards
What are some of the plants that contain large amounts of soluble oxalates?
- Halogeton (Halogeton glomeratus)
- Greasewood (Sarcobatus vermiculatus)
- Pigweed (Amaranthus spp)
- Lamb’s quarters (Chenopodium album)
- Sorrel, sour sob (Oxalis spp)
- Sorrel, dock (Rumex spp)
- Rhubarb (Rheum rhaponticum)
- Beet, mangold (Beta vulgaris)
What are other sources of soluble oxalate toxicity (besides all the plants)?
- Potassium and sodium oxalates are found in household and industrial products such as rust removers, bleaches, and tanning compounds
- Fungi (Aspergillus, Penicillium)
- Ethylene glycol in small animals and poultry
What is this?
Halogeton (Halogeton glomeratus)
What plant is this?
Greasewood (Sarcobatus vermiclatus)
What plants are these?
Curly dock, Dock (Rumex spp)
What is this?
Rhubarb (Rheum rhaponticum)
What plant is this?
Beet (Beta vulgaris)
Toxic doses in sheep?
- Sheep may be poisoned by 0.55% of body weight
- Starved or water-deprived sheep can be killed by only 0.1% body weight
What is the nonfatal toxic dose for adult horses?
200 g/day for 8 days
Which species are most susceptible to toxicosis?
Cattle and sheep are most susceptible (although the rumen microflora can detoxify oxalates to carbonates and bicarbonates)
How does rumen microflora accomodate to soluble oxalates?
Ruminants allowed to graze small amounts of oxalate containing plants gradually results in detoxification of up to 70% soluble oxalates than normal
Which part of the plant contains the highest concentration of oxalates?
Oxalate is highest in the leaves, followed by the seeds, then the stem
T/F: A large amount of oxalate over a short period is more toxic
TRUE
T/F: Presence of food in the rumen reduces the rate of oxalate absorption
TRUE
Does calcium affect oxalate toxicity?
Yes–Ca or Ca-rich diets decreases toxicity by forming insoluble calcium oxalate which is not absorbed
T/F: Oxalate-producing fungi may increase the oxalate content of some moldy forages
TRUE
Where/what are soluble oxalates metabolized to?
Where are they absorbed to?
- Can be metabolized to a certain extent in the rumen to carbonate and bicarbonate
- Absorbed to the blood and may affect serum and tissue calcium
What happens to soluble oxalates after absorption? What does this lead to?
- After absorption, soluble oxalates combine w/ Ca ion to form insoluble Ca oxalate
- This leads to hypocalcemia and tetany in acute cases or affects bone and milk production in lower levels
Where does precipitation of Ca oxalate crystals take place and what is the result?
In the kidney tubules –> kidney damage and necrosis
Fatal renal tubular toxicosis and signs of oliguria, depression, hyperkalemia, and cardiac failure
When do clinical signs appear?
Onset of clinical signs is in a few hours from ingestion of a toxic dose
Clinical signs?
- Colic, dullness, depression, muscle twitching and weakness, head and neck pulled to one side in sheep (as in milk fever in cattle) then prostration, coma, and death
- Rapid breathing and blood-tinged froth around the mouth
- Convulsions in some cases
What might animals develop if they don’t die from acute toxicosis?
Chronic tubular nephrosis and polyuria
5 lesions that can be seen from soluble oxalate toxicosis?
- Plant in the rumen
- Excess fluid in abdominal and thoracic cavities, petechial hemorrhages in GI mucosa
- Emphysema in the lungs which may contain inspired ingesta
- Mouth and esophagus may be filled w/ blood-tinged froth
- Kidneys show dark red cortex and medulla separated by a gray line from accumulation of oxalate crystals in the renal tubules
Laboratory diagnosis (3)?
- Presence of Ca oxalate crystals (polarizing rosette-shaped) in the kidney tubules
- Hypocalcemia
- High BUN
Diagnosis?
History, clinical signs, lesions, and presence of Ca oxalate crystals in kidneys and blood vessels
DDx and how to differentiate?
- Rumen acidosis (carbohydrate engorgement)
- pH is rumen in oxalate toxicity is alkaline
- Milk fever
- Doesn’t have such prominent lesions like oxalate toxicosis
- Hypocalcemia
T/F: Treatment is usually of little value once clinical signs appear
TRUE
Treatment?
- Activated charcoal or limewater to prevent absorption
- Calcium gluconate IV slowly may cause transient improvement, but is not curative
- Saline-glucose to treat alkalosis and cause diuresis
Prevention?
- Supplementation of Ca salts (dicalcium phosphate) or Ca-rich diet is protective
- Supportive therapy for nephrosis
