In Summary
  • While diarrhoea was present, it was mild and was unlikely to be the cause of the general weakness and difficulties in standing for some of the pigs.
  • Some pigs showed weakness of the legs but did not have diarrhoea.
  • Red root pig weed contains nitrates and an unidentified toxin that poisons the kidney.
  • There is no specific treatment for amaranthus poisoning in pigs, sheep, goats or cows but many affected animals recover over a period of time from mild poisoning when access to the weed is removed.

Peter keeps pigs in Ruiru, on the outskirts of Nairobi, and always he feeds them on commercial foods.

Having done pig farming for about five years, he has mastered the science and art of growing the swine from birth to finishing for the slaughter market.

Peter even sometimes calls me to report a sick pig and goes ahead to suggest what could be wrong with the animal.

I was, therefore, concerned when about a month ago, Peter called me and reported he had a case of weak pigs, some looked confused and others appeared to have difficulties in standing. Some of the animals had diarrhoea.

“And what is the temperature of the sick pigs?” I asked Peter as he always has the temperature of ailing pigs when he reports. It ranged between 38.8 and 39.5 degrees Centigrade.

That was within the normal range of 38.8 to 40 degrees Centigrade.

I arrived at Peter’s farm in 40 minutes and found eight sick pigs in two adjacent pens. The signs of illness were just as he had described.

While diarrhoea was present, it was mild and was unlikely to be the cause of the general weakness and difficulties in standing for some of the pigs.

One clear pattern was that the young pigs weighing about 20kg were the most affected.

Peter’s farm worker, in-charge of the pigs, informed me the animals had started showing the signs the previous evening.

I examined all the sick pigs and their temperature agreed with Peter’s report. Some of the pigs had slightly elevated breathing rate but everything else looked normal.

Some pigs showed weakness of the legs but did not have diarrhoea.

I ran through my mental disease checklist and returned a blank.

CHANGE IN FEEDING

I told him I needed full history of the pigs for the last one month because the disease appeared unusual. I wanted to know what the animals had been fed on and whether there was any change in feeding.

I also wanted to know whether there was a change in the drinking water supply.

Peter said about three weeks earlier, a friend had visited the farm and noticed the leafy greenish red plants growing abundantly at the pig manure dump pit.

He said he used to rear pigs and they really liked to eat the plant. He picked some of the plants and fed the pigs in the two pens. The pigs happily ate the plants.

“That is the only change that I know has occurred with these pigs in the last one month,” Peter concluded. He said he did not object to his friend’s action because the pigs seemed to like the plant and the plant had been collected from his farm.

I prompted George, the worker, to add onto the testimony his boss had given. “We have continued giving the pigs in these two pens those leaves because they appeared to like them but stopped about five days ago when the plants got finished,” he volunteered.

I visited the manure dump pit and confirmed the presence of cut stumps of the Amaranthus reflexus plant. There were also many small plants with only a few leaves growing in the area.

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