Use of liquid magnesium in rabbits

with chronic sludge



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Rabbit urine always contains a certain amount of sediments. This is absolutely normal, rabbits' systems work in this way to excrete the excess of calcium in their bodies.



The presence of some sediment in the urine of rabbit is normal (left). A thick paste that becomes a solid millimeter thick “cake” when drying is called sludge (right). The presence of sludge in the bladder is irritating and painful.

Up to now, sludge in rabbits has been treated by flushing the bladder at regular intervals, e.g. every 6 months. The rabbit is anesthetized and a catheter is introduced into the bladder before flushing. Since the procedure is accompanied by pain, the rabbit needs to be given pain relief medication for a few days. Rabbits with chronic sludge and repeated flushing show longer recovery times after each new attempt to clear the bladder.

Sludge can be treated via a non-invasive procedure. An effective way is the administration of subcutaneous fluids, followed by a diuretic drug like furosemide. One time is usually enough, although it can be repeated in the next 24 hours.

Recently, it was discovered that liquid magnesium may clear sludge over a longer period of time.

Scotchie is a 6 year old house rabbit. He has been battling bladder sludge for a while, at least 5 years, and needed bladder flushes regularly. These radiographs were taken before liquid magnesium was administrated and show that his bladder is full of sludge.

Barbara Schmeitz

BEFORE: Radiographs of Scotchie, 6 years old, before giving liquid magnesium. The bladder is full of sludge.


After the last bladder flushing in January (first 2 radiographs), we started giving him 1cc of liquid magnesium daily in his water. This was recommended by Megan Mather, a rabbit owner who sprinkles liquid magnesium over fresh vegetables before feeding them to her rabbits

Amount: About 1 to 1.5 ml/cc are added to 500 ml of fresh water (20oz) every morning.

At his next vet checkup in October (10 months later), there was no sludge at all.

Barbara Schmeitz

AFTER: Radiographs of Scotchie, 6 years old, after giving liquid magnesium during 10 months on a daily basis. New radiographs taken a few months after starting daily liquid magnesium. The bladder is clear, the sludge has disappeared.

If liquid magnesium does not help, several other products can be tried to treat sludge. Since they decrease the pH of the urine, they should not be used over longer periods of time. These products include:

•      Feeding fresh or dried cranberries daily or non-sweetened cranberry juice. The properties of cranberry may, furthermore, prevent the onset of cystitis (bladder infection).

•      Vitamin C. For smaller animals, the intake of Vit C is up to 100 mg, probably best between 25-50 mg/kg rabbit once a day. Part of the Vit C will be converted in oxalates, which may start a stone, but studies showed that high intake of Vit C did not contribute to the formation of stones. The use of Vit C in rabbits remains controversial among professionals.

•      Use of citrate based products (e.g. Polycitra®) in order to change the pH of the urine, in rabbits that suffer from chronic urinary tract infection or uroliths (bladder stones). The daily dosage in dogs is: 150 mg/kg per day. It has been used in rabbits and seems to have delayed the formation of new stones. Long-term use of this urine acidifier may be harmful to the rabbit.

•      Use of acidifiers like ammonium chloride (200 mg/kg/day, PO, TID) and DL-methionine (1,000-1,500 mg/cat/day, PO) may help acidify the urine. Long-term use of this urine acidifier may be harmful to the rabbit.



My gratitude goes to Barbara Schmeitz (USA), Rachel Ihlenfeldt (USA), Megan Mather (USA) and Ros Lamb (UK) for the information on liquid magnesium, their suggestions, and for sharing the x-rays of Scotchie.