White Muscle Disease of Lambs and Hoggets

New Zealand Journal of Agriculture, Volume 89, Issue 4, 15 October 1954, Page 369

White Muscle Disease of Lambs and Hoggets

XA/HITE muscle disease is a condition ; ’ which affects lambs (stiff lamb disease), hoggets, and calves, and which is characterised by a stiff gait and occasionally sudden death in animals in which the heart muscle is affected. Though there is no record of the disease in calves in New Zealand, this is the only country in which it has been recorded in hoggets; no cases have yet been reported in the North Island. In this article D. C. Dodd, Veterinary Research Officer, Department of Agriculture Animal Research Station, Wallaceville, describes the symptoms and causes of the disease and treatment and prevention methods. WHITE muscle disease has been recorded in the South Island since 1950, but it came into prominence because of its wide distribution and increased incidence during the latter part of 1953. Conditions of Occurrence In both lambs and hoggets increased muscular activity is usually necessary

before the clinical signs of the disease are . evident, but it is by no means always essential. Muscular activity is thus only a precipitating factor which causes muscles already damaged to show outward signs of the changes which have taken place in them. This increased muscular activity occurs in hoggets when they are driven to pasture after wintering on turnips and in lambs when they are driven or rounded up for marking; thus most cases occur in lambs at 3 weeks of age. The disease has occurred in lambs in the Nelson and Canterbury . districts and in hoggets in South Canterbury, Otago, and Southland, the incidence in any one flock can be up to 10 per cent, or higher on occasions. ■ There seems little doubt that the cause of white muscle disease is a deficiency of vitamin E (a-tocopherol) either absolute or induced by one or more anti-vitamin E factors. Experimental work will have to be done to prove that this is true in New Zealand, but both the clinical and post-mortem findings are identical with those found in England and the United States and in _ artificially induced vitamin E deficiency in lambs. Clinical Signs . Clinical signs of the disease are as follows: , lambs the age incidence is from the first week to at least 12 weeks after , birth, with the majority of cases occurring at about 3 weeks. Obviously affected lambs have a stiff, stilted gait and arched back and tend to walk on the front of the hooves (see illustration on this page). They are disinclined to move about and spend much time lying down. All degrees of severity occur, so that in mild cases the lamb differs only slightly from normal whereas severely affected lambs are unable to rise and if not attended to invariably die from either starvation or pneumonia. Sudden deaths may occur in apparently normal lambs,

but in these the heart muscle is affected. Muscular stiffness. may be very difficult to detect in mild. cases, though often they do not do as well as the unaffected lambs in the flock. Wasting of the muscles, especially of the limbs, is prominent in lambs in which the muscle changes are progressive.

In hoggets the clinical signs are essentially the same as for lambs, but a number of affected hoggets may pass red-brown urine. This coloration of the urine is probably a direct result of muscle damage.

One may confuse white muscle disease with a number of the common diseases of lambs, but it is most likely to be confused with arthritis or tetanus. Arthritis differs in that affected lambs walk with a limp and and it may be possible to detect swollen joints. Mild cases of tetanus may appear to be similar. to white muscle disease because of the general stiffness of the body, but the typical spasms of tetanus, in which the limbs are held rigidly outstretched and the head thrown back, should serve to differentiate them. • When older lambs in good condition are found dead it is likely that they will be regarded as cases of pulpy kidney, unless a careful examination of the body muscles and heart is made. Post-mortem Findings When a post-mortem examination is made by simply opening the carcass along the midline indications of white muscle disease may be and often have been overlooked. All the muscles of the body, but particularly those of the hind limbs and back, should be incised and the heart examined externally and internally. The muscle changes take the form of either yellow-white streaks in the muscle or a generalised paleness similar to the appearance of fish flesh. The muscle changes are

usually equal on both sides of the body. If the heart is affected, similar changes will be found (see the lower illustration on the previous page). Treatment and Prevention

No work has yet been done in New Zealand on treatment and prevention of the disease, but it has been shown overseas that vitamin E both prevented and cured naturally occurring stiff lamb disease. The disease was prevented in lambs by dosing them soon after birth with vitamin E. Even though severely affected lambs were cured, treatment was not considered satisfactory, since they failed to thrive. It may yet prove to be economical to treat mildly affected lambs and hoggets, but this will depend on the results of treatment trials. No work has yet been done on the prevention of the disease in hoggets. The dose rate and period of treatment of lambs or hoggets depend on the severity of the case. Based on results reported from overseas and the small numbers of animals treated in New Zealand, the suggested dose rates are as follows: —

Lambs, 100 to 500 mg. a-tocopherol.

Hoggets, 500 to 1000 mg. a-tocopherol. One treatment may be sufficient in early cases,, whereas it is necessary to continue daily dosing for 4 or 5 days or longer in advanced cases. However, since the economics of sheep raising make doubtful the value of treating the worst cases, it may be more profitable to carry out preventive dosing of the unaffected animals in a flock when there is evidence that a large number may be affected. For such preventive dosing 50 to 100 mg. is recommended for lambs and 200 to 300 mg. for hoggets. Since driving is an important factor, the incidence can be lowered by not driving lambs and hoggets at the critical period; if driving the flock is essential, it should be done very quietly and in easy stages. Summary White muscle disease of lambs and hoggets is a comparatively new disease in New Zealand and farmers and veterinary surgeons should be on the alert for its appearance. It is recommended that if a farmer suspects that this condition is present in his flock, he should consult a veterinary surgeon to confirm the diagnosis and advise treatment and preventive measures. The disease occurs in young lambs from birth onward and in hoggets while wintering on turnips or within 24 hours of being driven off. Increased muscular activity can precipitate an outbreak with heavy losses. A deficiency of vitamin E is considered to be the cause and treatment of mild cases with this vitamin is recommended. Measures suggested for prevention include taking particular care to drive lambs or hoggets as little as possible at the critical times and dosing unaffected animals with vitamin E. Experimental work on prevention and treatment of the disease is now in progress and it is hoped that more precise recommendations regarding these aspects will be possible as a result of this work.

REGISTRATION OF DAIRY FACTORY MANAGERS Intending applicants are hereby notified that applications for registration under the Dairy Factory Managers Regulations should reach the Registrar, Dairy Factory Managers Registration Board, c/o Department of Agriculture, P.O. Box 2298, Wellington, on or before 1 December 1954. Forms are available from the Registrar. Attention is drawn to the fact that any application which is received by the Board after 1 December 1954, shall not, except in special circumstances, be considered by the Board until after 1 December 1955. E. M. EDGECOMBE, Registrar. N.B. — This notice refers to persons who are NOT AT PRESENT HOLDERS OF CERTIFICATES. Notice of renewal and renewal form will be posted to every registered manager by the Registrar.