• Hypocalcaemia phase: -soon after intake, 2-6 hours
- Paresis to paralysis, semi-comatose, “milk fever” signs.
- Head thrown back onto shoulder
Treatment of these symptoms with Ca-borogluconate gives good results and animals may recover.
• Kidney failure phase: Following day to few days later due to blockage and damage of tubuli by Ca-oxalate crystals resulting in:
- Uraemia: BUN and creatinine increase
- Oliguria or anuria
Treatment of very little value - irreversible condition.
• Acute poisoning happens where:
- unadapted animals suddenly eat a relatively large amount of oxalate containing plants and the oxalates are absorbed into the circulation
- excessive large amounts of oxalates are absorbed in adapted animals which are not able to detoxify all the oxalates in the rumen (e.g. large amounts during droughts)
• Chronic effect characterized by:
Calcium deficiency resulting in:
- bone abnormality,
- poor milk production and
- poor growth.
N.B. Kidney- and bladder stones where oxalates can play a role amongst other things.
- Nothing significant,
• Nephrosis and Uraemia:
- Ascites, hydrothorax, perirenal and subcutaneous oedema.
- Kidneys pale, oedematous, swollen - nephrosis.
- Ammonia and urea odour (uraemia).
- Haemorrhages in different organs.
- Oedema and haemorrhages in rumen.
Typical oxalate crystals in kidney tubules (seen under polarized light) with signs of kidney damage.
• Avoid sudden exposure to oxalate containing plants or intake of large quantities
• Avoid oxalate containing plants as the only food.
• Feed Ca2+ in the form of dicalcium phosphate as a lick (25% or more with salt) or mixed in the supplementary feed.
Colour photos. Final web-ready size: JPEG, 72 ppi. Photo 1: 25.3 kb; Photo 2: 20.4 kb; Photo 3: 17.3 kb; Photo 4: 20.8 kb; Photo 5: 9.12 kb; Photo 6: 54.6 kb. Original TIFF file housed at the Dept. of Paraclinical Sciences, Section Pharmacology and Toxicology, University of Pretoria.