Vet traces recent mystery of pig deaths to rare cause

Combining two otherwise appropriate medications in a feed ration had lethal results on a hog farm.


By Dr. Blaine Tully, The Western Producer (Canada)†

November 18, 2021


Tully is a veterinarian and owner of Swine Health Professionals Ltd. in Steinbach, Man.


Hoofbeats on the Prairies arenít always horses. Sometimes they are zebras.


Diagnosing toxicities in modern swine production is rare. Housing pigs in confinement reduces accidental exposure to a lot of toxic substances that may be found in farmyards.


Pigs, by their nature, are also somewhat resistant to noxious compounds and chemicals that can be toxic to other farm animals. For example, lead poisoning in cattle is not uncommon but is rare in pigs.


I recently diagnosed a case of ionophore toxicity in a pig farm that was due to a feed milling error, which put a second medication, tiamulin, in feed at the same time as an ionophore. More on that later.


Ionophores are a class of antimicrobial used to safely aid intestinal health and improve feed efficiency in many finisher-pig flows.


Feed makes up approximately 70 percent of the cost of production of a finished pig. The recent increase in grain prices across Western Canada has prompted many farms to explore strategies to improve feed conversion.


Common feed-to-gain ratios on modern pig farms are around 2.7:1. In other words, a one-kilogram increase in weight gain requires 2.7 kg of feed. With the strategic use of ionophores, producers can improve their ratio by nearly three percent and increase average daily gain by eight grams per day.


While these changes may seem small, they are consistent, repeatable and in todayís economics, result in savings of approximately $3 per finished pig.


In contrast, antimicrobials like tiamulin are used therapeutically to control or prevent intestinal pathogens like Brachyspira species. These organisms can cause diarrhea in growing pigs for many years.


The farm in question...