Organic Arsenical Toxicosis in Turkeys: Incoordination and Hind-Limb Paralysis

Organic arsenical toxicosis is a poisoning problem caused by too much organic arsenic compound in the diet. In poultry, the compounds historically associated with this problem include roxarsone, arsanilic acid, and nitarsone. These additives were once used in feed, but they are no longer approved for use in US animal feeds. Even so, your vet may still consider this diagnosis if there is possible exposure to old feed, mislabeled feed, imported products, or a feed-mixing error.

In turkeys, the classic concern is neurologic injury. Birds may first look wobbly or weak, then progress to poor coordination and hind-limb paralysis. Merck Veterinary Manual notes that roxarsone can produce toxicosis in turkeys at only about twice the former recommended concentration of 50 ppm, which helps explain why turkeys are a species of special concern.

This condition is an emergency because a turkey that cannot stand is at risk for dehydration, trampling, and drowning if water access is not managed carefully. Early recognition matters. If exposure is stopped while signs are still mild, some birds may recover. If paralysis is already established, the damage may be irreversible.

Because several other poultry problems can also cause weakness or paralysis, your vet will usually look at the whole picture: feed history, flock pattern, timing, physical exam findings, and sometimes necropsy or feed analysis.

The direct cause is excess intake of an organic arsenical compound, most often through feed. Merck Veterinary Manual describes this toxicosis as resulting from too much arsenic-containing additive in pig or poultry diets, with severity depending on dose and duration. Clinical signs may appear after days with a major overdose or after weeks with more moderate overexposure.

In practical terms, your vet may investigate several exposure routes. These include old medicated feed still in storage, feed mill or on-farm mixing errors, accidental access to the wrong ration, imported feed ingredients, or mislabeled products. Turkeys are notably sensitive to roxarsone, so even a smaller formulation error can matter.

Although these compounds are no longer legal feed additives in the United States, that does not fully eliminate risk. Old inventory can persist on farms, and contamination or formulation mistakes can still happen. If multiple birds become weak after a new feed delivery, that timing is an important clue to share with your vet.

Other toxic and non-toxic conditions can mimic this syndrome. In turkeys, your vet may also consider ionophore toxicosis, botulism, insecticide exposure, trauma, severe nutritional imbalance, and infectious causes of weakness or paralysis.

Diagnosis usually starts with history and pattern recognition. Your vet will ask when signs began, whether there was a recent feed change, how many birds are affected, and whether the problem is getting worse. Sudden incoordination and hind-limb paralysis after a ration change can strongly raise suspicion for a feed-related toxicosis.

A physical exam helps your vet assess hydration, body condition, ability to stand, and whether the problem looks neurologic, muscular, or systemic. Because several poultry diseases and toxicities can cause similar signs, diagnosis is often about ruling out other causes while investigating the feed source.

In flock cases, your vet may recommend feed analysis and necropsy of a freshly deceased or humanely euthanized affected bird. Merck notes that analysis of feed samples for high levels of phenylarsonic compounds helps confirm the diagnosis, and Cornell's Avian Health program offers poultry diagnostic support, necropsy services, and advanced testing for turkeys and other poultry.

There is no simple in-clinic screening test that confirms this syndrome in a live turkey. That is why sample quality and timing matter. If you suspect a feed problem, save the original bag, lot number, label, and a clean feed sample for your vet or diagnostic lab.

Prevention starts with feed control. Buy feed from reputable suppliers, keep original labels and lot numbers, and avoid using old or unidentified feed. If you mix feed on-farm, double-check formulas, ingredient bins, and medication lines before each batch. Never assume an older product is still appropriate because it was used years ago.

Store turkey feed separately from other species' rations and clearly label every container. Cross-contamination and feed swaps are common ways toxic exposures happen in poultry systems. If a new bag or batch looks different, smells unusual, or is linked to sudden neurologic signs, stop using it and contact your vet right away.

For flock health programs, it helps to keep a simple log of feed deliveries, ration changes, illness dates, and deaths. That record can make a major difference if your vet needs to trace a toxicosis pattern. In larger or mixed-species operations, periodic review of feed handling protocols with your vet or nutrition consultant can reduce preventable mistakes.

Because organic arsenical feed additives have been withdrawn from US use, any suspected exposure deserves careful investigation. Quick action protects the rest of the flock and may improve the outlook for birds that are only mildly affected.