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This article was published in 1960
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.

Non-Contagious Ovine Posthitis

"SHEATH ROT"

E. R. TUOHY, B.V.Sc., Veterinary Inspector, Wagga

A condition which occurs each year in the Wagga District is non-contagious Posthitis (Sheath Rot) of sheep. This disease appears to have increased with the spread of improved pastures and each year the extent of its occurrence has increased in keeping with the introduction of more improved pastures.

The disease, which mainly affects wethers, commences with an external ulceration of the prepuce; which often progresses to internal ulceration. Watson and Murnane (1958) found with their trial sheep, in the western district of Victoria, that the establishment of an external lesion occurred before internal involvement in at least 89 per cent. of cases; while in the remainder an external lesion was already present when the internal lesions were first observed. These external lesions range from small isolated ulcers to large scabs which may completely cover and occlude the preputial orifice. Distension of the sheath with urine and odious discharges occurs and this together with staining of the wool, may be the first indication to the owner that the sheep are affected. When the orifice is completely blocked the animal loses condition, walks stiffly with an arched back, is seen to lie down frequently and may die suddenly. Morbidity ranges from about 5 per cent. to 75 per cent.; with an average incidence of about 25 per cent, in affected flocks in the Wagga district.

Whereas external ulceration is relatively harmless and may resolve of itself, internal ulceration is more serious; and most troublesome in areas where pastures are improved. Southcott and Hewetson (1959) found on the Northern Tablelands of N.S.W. that the external, but not the internal form of non-contagious Posthitis was common in wethers grazing on non-leguminous native pastures. There is some contention as to whether the external and internal conditions are stages of the same disease and practically all cases of internal ulceration seen by the writer appeared to have been preceded by, or accompanied with external ulceration. Whether or not they progressed from the external to the internal form depended upon the nature of the subsequent grazing; which is borne out by Pemberton's (1959) trial in which 8 out of 11 sheep recovered within one week of being transferred on to a Capeweed dominant pasture, which weed is particularly prolific in the Wagga district.

The disease appears to have a seasonal and breed incidence. External ulceration, which occurs in the Wagga district all year round, increases during the autumn, winter and spring and declines in the summer. The highest incidence of internal ulceration is seen in the spring; declining in the summer coincident with the "lush" and "dry" periods of pasture growth, but maintaining a level of incidence during the winter months. Although the disease has been seen in two-tooth sheep in the Wagga district it is most common in sheep over three years of age. It is uncommon in rams; with no counterpart in the ewe.

It is considered generally that Merinos and their crosses are much more prone to sheath rot than British breeds; as instanced by a report of Beveridge and Johnstone (1963a) that on one of the properties visited by them 75 per cent. of Merino wethers had internal ulcers, whilst no Romney Marsh wethers, run with them, were infected. No such spectacular difference in breed incidence has been seen personally, but a breed difference in incidence definitely exists.

Beveridge and Johnstone (1953b) have concluded, and it is generally accepted, that sheath rot is not a contagious disease; the primary cause being other than an infectious agent. However, many laymen have been met with who will not accept this view. Attempts by those research workers to induce sheath rot by mechanical means, such as covering the prepuce with long wool, occlusion of the orifice with grass seedsetc., also failed. The removal of wool from the vicinity of the prepuce, or "ringing". had no curative effect on internal or external forms of the disease according to experiments conducted in Melbourne and Armidale, N.S.W.

The seasonal variations, the geographical distribution and the non-infectious nature of the disease all suggested that diet might be of importance. Watson and Murnane (1958) proved that lesions were capable of disappearing entirely, within three weeks, from almost all sheep transferred from pastures consisting predominantly of rye grass, or rye grass and subterranean clover, to a pasture consisting predominantly of Capeweed, or to a diet of chaffed oaten hay. The removal of affected sheep from clover dominant pastures to poorer Cape or Skelton weed pastures is popular as a cure for the condition in the Wagga District and appears to have been practised long before the nature of the disease was understood. It was thought by Beveridge and Johnstone (1953b) that the effect of diet on the prepuce was exerted through the urine. They experimented by operating on a sheep with sheath rot and providing an opening for the urine from the posterior part of the prepuce. The anterior, affected portion was kept free from urine by sutures placed just in front of the artificial opening. The internal and external forms of the disease healed within six days. They found that the reaction of the urine was largely determined by the quality and quantity of the diet. Leguminous diets always gave an alkaline urine and a high protein diet containing peanut meal or linseed meal usually rave an alkaline urine. A diet inadequate in amount gave an acid urine and fasting was found sometimes to cure "Sheath rot" spontaneously. Webster (1948) was of the opinion that the acid reaction of the urine in sheep from which food was withheld was the primary feature leading to resolution of the lesions. Beveridge and Johnston (1954) found that resolution of both external and internal lesions occurred when sheep were semi-starved for several weeks. They were encouraged to find in one of their trials that 69 of 87 diseased wethers (80 per cent. of which had internal lesions) completely recovered after 19 days semi-starvation. However, with neither their observations nor those later of Watson and Murnane (1958) was there found to be any consistent relationship between urine pH and the development or regression of lesions. Later investigations carried out by Southcott and Hewetson (1959) showed that fasting cured external ulceration, and less severe internal ulceration but caused loss of condition, deaths and a break in the wool; the sheep, cured by fasting, soon relapsing when returned to clover pastures.

Diet then appeared to be the main cause of the condition and Watson and Murnane (1958) set out to prove what Beveridge and Johnstone (1953b) believed, but had been unable to prove that this was so. They found that when wethers were taken off mixed pasture and put on to Capeweed dominant stands or on to a diet of oaten chaft, the incidence of internal and external ulceration fell; but increased once the oaten chaff group was replaced on the mixed improved pasture and when the Capeweed group was transierred to a ryegrass — sub. clover pasture. These alterations in the incidence of sheath rot were due to changes in diet and not to any effects of fasting, since there was no restriction of food intake. Similar experiences to these have been noted in the Wagga District and this rule apparently holds also in the Northern Tablelands of the State; where Southcott and Hewetson (1959) found a significant increase in the incidence of both external and internal ulceration when wethers were transferred from non-leguminous native pastures to improved pastures containing legumes. Despite the fact that some artesian waters may increase the alkalinity of the urine it is considered unlikely that bore water predisposes to sheath rot. Johnstone in (1948) concluded from his experiments that the undeveloped state of the prepuce and penis in wethers as a sequel to castration, bore no direct relationship to the occurrence of the condition.

The field of treatment of sheath rot has developed over the last few years. The surgical slitting of the sheath extended in a straight line, and not as a "V", to the limit of the prepuce, has proved effective in chronic cases of internal ulceration and is still recommended as a means of treatment on its own or in conjunction with other measures. Other traditional treatments are the application of a 10 per cent. Copper sulphate ointment as suggested by Filmer (1938) and Beveridge and Johnstone (1954); who reported 62 per cent recovery with a 5 per cent. solution of Copper sulphate which they favoured in preference to Zinc sulphate and Potassium permanganate. Southcott and Hewetson (1959) discredited Penicillin, injected intramuscularly or applied topically; finding it no more successful in the treatment of external and internal ulceration than Copper sulphate. The fact that sheath rot is much less common in rams than in wethers caused Watson and Murnane (1958) to implant 100 mgs. of Testosterone propionate in wethers in the autumn; which led to a sharp decrease in the incidence of external ulceration.

Lesions appeared again in many animals within a few months, but with an incidence persistently slightly lower than that in untreated sheep. None of the animals in this trial showed evidence of internal ulceration; which may be of significance in evaluating this approach to treatment. The most encouraging treatment encountered in the field by the writer is that using the quaternary ammonium, cationic, detergent and antiseptic; Cetrimide. The earliest known reference to the use of this drug is that by Roche (1958); who used a 20 per cent. alcoholic solution of Cetrimide (commercially known as "Cetafoot" (L.C.I.) and originally intended as a specific for Footrot in sheep). Pemberton (1959), who conducted trials on behalf of the manufacturers found that a 20 per cent. Cetrimide in alcohol or water. 10 per cent. Copper sulphate, and 90 per cent. ethyl alcohol all cured from 75 per cent. to 100 per cent. of external ulcers in one or two treatments, but only 20% Cetrimide in alcohol cured up to 42.5% of cases of internal involvement after two treatments; this figure being boosted to 80% when combined with the intramuscular injection of half a million units of an aqueous solution of Procaine Penicillin.

The treatment procedure recommended in the Wagga District has been to irrigate out the prepuce; using a small amount of the "Cetafoot" in warm water. The prepuce is then filled with ahout 4 ml. of neat "Cetafoot"; using a standard syringe and a bovine teat syphon, or a large bore needle the end of which has been cut and rounded off. Grazing on lush pastures is withheld and relapses looked for over the following 4 to 12 weeks. Additional treatments were found to be necessary when rain stimulated pasture regrowth and best results were obtained when a dry period followed treatment. "Cetafoot" treatment, along the lines outlined above, was found to cost about two pence per sheep, where one application sufficed. However, this treatment, combined with penicillin injection, proved prohibitive; costing in excess of two shillings per sheep. The approach of slitting the chronic cases after first douching with "Cetafoot", and injecting the neat "Cetafoot" into the prepuce of milder cases was found to give good results at much less cost than the "Cetafoot" - Penicillin therapy abovementioned.

Despite these advances in the chemo-therapy of the disease the so-called "fasting" treatment is still popular. With it a preliminary period of complete starvation is desirable, the sheep being given free access to water; the urine changing from an alkaline to an acid reaction. It has been found that the more complete the starvation, and the longer the period, the more rapidly cases will respond. Under stringent fasting conditions a high percentage of cases of sheath rot will recover within 14 days. After starvation for 4-6 days the sheep can be fed a limited amount of oaten or wheaten hay for 7-10 days. Under less stringent conditions the sheep can be enclosed on an area with little available feed and shepherded out for an hour's grazing each day. This should be continued for up to three weeks, depending on results. In some circumstances it has been found suficient to draft off the affected sheep and run them on the poorest country on the property. Cases stubborn to these procedures should be slit and treated with "Cetafoot" and, if still unresponsive, should be sent for slaughter.

References

Beveridge W. I. B. and Johnstone I. L. (1953a)—Aust. vet. J., 29:10
Beveridge W. I. B., and Johnstone I. L. (1953b)—Aust. vet. J., 29:12
Beveridge W. I. B. and Johnstone I. L. (1954)—Aust. vet. J., 30:1
Filmer, JF. (1938)—Aust. vet. J., 14:47
Johnstone, I. L (1948)—Aust. vet. J., 24:4
Pemberton, P. L. (1959)—Aust. vet. J., 35:8
Roche, D. (1958)—Aust. vet. J., 34:9
Southcott W. H., and Hewetson R. W. (1959)—Aust. vet. J., 35:3
Watson R. W., and Murnane D. (1958)—Aust, vet. J., 34:5
Webster, W. (1948)-Massey Agricultural College. Annual, 1948