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Transport Tetany in Ruminants:

Introduction

(Railroad disease, Railroad sickness, Staggers)

Transport tetany occurs after the stress of prolonged transport, typically in cows and ewes

in late pregnancy, although it is also seen in lambs transported to feedlots and in cattle

and in sheep transported to slaughter. Crowded, hot, poorly ventilated transport vehicles

(railroad cars or trailers) with minimal or no access to feed or water appear to predispose

animals to the condition; however, prolonged travel by foot is also a risk factor. The

disease is characterized by recumbency, GI stasis, and coma, and is generally fatal.

Although cows in late gestation are most commonly affected, the disease is also seen in

cows that have recently calved, as well as in bulls, steers, and dry cows. Risk factors

include heavy feeding prior to shipment, deprivation of feed and water for >24 hr during

transit, and unrestricted access to water and exercise immediately after arrival. Exposure

to hot environmental conditions is also associated with an increased incidence. While the

specific cause of tetany is unknown, the condition may be a form of acute hypocalcemia

precipitated by late pregnancy and early lactation, or by fasting before or during transit.

Physical stress is undoubtedly related. Hypomagnesemia may be a precipitating factor in

cattle and a contributing factor in sheep.

Clinical signs in cattle may occur while in transit or up to 48 hr after arrival. Early clinical

signs include restlessness and excitement, trismus, and grinding of teeth. A staggering

gait may be observed and later, if recumbent, cattle often demonstrate paddling of the

hindlegs. Rumen motility and GI stasis is observed and animals become completely

anorectic. Tachycardia and rapid, labored respiration may be observed. Abortion may be a

complication. Cattle that do not recover gradually become more obtunded to the point of

coma and die within 3-4 days. Moderate hypocalcemia and hypophosphatemia may be

observed in cattle. Some sheep are hypocalcemic and hypomagnesemic or hypoglycemic;

however, some show no measurable biochemical abnormalities. No specific lesions are

observed at necropsy aside from lesions associated with prolonged recumbency. Ischemic

muscle necrosis is the most common of these. In lambs, early signs include restlessness,

staggering, and partial hindlimb paralysis followed by lateral recumbency. Death can occur

rapidly or after 2-3 days of recumbency. In lambs, mild hypocalcemia may be noted.

Recovery rates are fair even with treatment. The relationship of clinical signs with

transport or forced, prolonged exercise is diagnostic.

Some animals respond to treatment with combinations of parenteral calcium, magnesium,

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and glucose. IV injections of calcium borogluconate (25% solution at 400-800 mL/cow or

100 mL/ewe) or calcium borogluconate with magnesium sulfate (5% solution, same

volumes) can be administered slowly. A dose of 50 mL can be given SC, SID, to affected

lambs in feedlots. Repeated injections may be warranted, but failure to respond is common

(50%) and most likely due to concurrent muscle necrosis. Additional treatment

considerations include IV administration of large volumes of polyionic fluids such as

lactated Ringers solution. Animals should be offered good quality feeds (eg, alfalfa hay),

fresh water, and soft bedding with good footing underneath. Sedation may be necessary if

animals are hyperexcitable or convulsing.

If prolonged transport times of cows or ewes in advanced pregnancy is unavoidable,

animals should be fed a restricted diet several days prior to shipment, then provided

adequate feed, water, and rest periods during transport. Administration of ataractic agents

(unless transport is to slaughter) such as promazine hydrochloride before loading is

recommended, especially for nervous animals. Upon unloading at the destination, animals

should be allowed limited access to water for the first 24 hr and minimal exercise for 2-3

days.