Congenital Tremors in Piglets: Causes of Shaking and Weakness

Congenital tremors are abnormal, rhythmic shaking movements seen in newborn piglets. You may also hear this condition called shaker pigs, dancing pigs, or myoclonia congenita. The tremors are usually most obvious when a piglet tries to stand, walk, nurse, or becomes excited. They often lessen during rest or sleep.

This condition is present at or very soon after birth. In many piglets, the shaking comes from abnormal development or injury in the nervous system, especially changes linked to poor myelin formation in the brain and spinal cord. Myelin helps nerves send signals smoothly, so when it is reduced or disrupted, piglets can appear shaky and weak.

Severity varies. Some piglets have mild tremors and still nurse with help. Others cannot coordinate well enough to latch, compete with littermates, or stay warm. That is why early veterinary guidance matters. The main goals are to identify the likely cause, support nursing and body temperature, and watch for complications such as dehydration, poor growth, or accidental crushing.

Atypical porcine pestivirus, or APPV, is now considered one of the most important causes of congenital tremor type A-II in piglets. Research has linked congenital infection with APPV to piglets born with tremors, and affected piglets may have changes in myelin within the brainstem, cerebellum, and spinal pathways. In practical terms, that means the nervous system wiring is not working smoothly at birth.

Your vet may still consider other causes because congenital tremors are a syndrome, not one single disease. Historically, congenital tremors in pigs have been grouped into different types, including forms linked to viral infection, inherited defects, and cases with no clear cause. Differential diagnoses can include other neurologic disease, toxic exposure during pregnancy, and developmental problems that affect movement.

Problems in the sow can matter too. Merck notes that vitamin A deficiency in sows can cause congenital neurologic abnormalities in piglets, including incoordination and other nervous system signs. That does not mean every shaky piglet has a vitamin deficiency, but it is one reason your vet may ask about feed quality, storage, supplementation, and the sow's health during gestation.

Because several conditions can look similar in a newborn piglet, the cause usually cannot be confirmed by appearance alone. Litter history, sow history, farm pattern, and diagnostic testing all help narrow the answer.

Diagnosis starts with a hands-on exam and a careful history. Your vet will want to know when the tremors started, how many piglets are affected, whether the shaking improves during sleep, and whether the piglets can nurse and gain weight. They may also ask about gilt versus sow status, recent herd introductions, vaccination plans, feed changes, and any reproductive or neurologic problems in previous litters.

If congenital tremors are suspected, your vet may recommend testing for APPV through a veterinary diagnostic laboratory. Current U.S. lab catalogs show APPV real-time PCR is available on porcine samples such as tissues, brain, spinal cord, oral fluids, serum, or whole blood, depending on the lab and case setup. In herd investigations, PCR helps support whether APPV is involved, especially when several piglets in a litter or farrowing group are affected.

In some cases, diagnosis also includes necropsy of a deceased piglet and tissue submission. This can help rule out other infectious, toxic, or developmental causes and may show changes consistent with hypomyelination or myelin injury. Your vet may also assess hydration, body temperature, nursing success, and whether tube feeding or split-suckling support is needed right away.

A practical diagnosis often combines three pieces: the piglet's clinical signs, the litter or herd pattern, and lab results. That approach helps your vet guide both immediate care for the piglets and prevention steps for future litters.

Prevention starts before farrowing. Work with your vet to review sow and gilt health, incoming animal biosecurity, and the history of any previous affected litters. Because APPV has been linked to congenital tremors and there is no commercially available vaccine, prevention focuses on herd management rather than a single shot or medication.

Good gestation nutrition matters. Make sure pregnant sows receive a balanced ration formulated for swine and stored correctly so vitamin content is preserved. Merck notes that vitamin A deficiency in sows can lead to congenital neurologic abnormalities in piglets, so feed quality and supplementation plans are worth reviewing if congenital problems appear.

If congenital tremors occur, ask your vet whether diagnostic testing should be done on affected piglets or deceased neonates. Confirming APPV or ruling out other causes can shape future breeding and biosecurity decisions. In herd settings, your vet may recommend tracking which litters are affected, limiting unnecessary animal movement, and tightening sanitation and introduction protocols.

For pet parents and small-scale keepers, the practical goal is early recognition and planning. Keep farrowing areas warm, dry, and well supervised, and have a feeding support plan ready for weak newborns. Even when the tremors themselves improve with time, the first few days are when piglets are most vulnerable.