Nasal Bot in Sheep: Grub in the Head.

Woodville Examiner, Volume XIII, Issue 2384, 26 June 1895, Page 4

Nasal Bot in Sheep: Grub in the Head.

( (Estrus ovit.-) (By John A. Gilbuth, M.8.0.V.5.) Sheep of all descriptions, but especially lambs, may suffer at this time of the year (March) from the presence of the (Estrus ovti, or sheep gad-fly, in the nasal cavities and sinuses of the head. From the j margin of the nostrils, where the fly deposits them (or the eggs) the young larva? make their way through the nasal passages into the sinuses i or air-cavities of the head, where they may often be seen on splitting open a sheep's head in winter. During the winter and spring they mature, after which they become detached, and are expelled on to the ground, where, in about forty-eight hours, if circumstances are suitable, the larvte becomes a chrysalis or pupa. They remain in this state for a period of-from six to eight weeks, when, development having taken place, one end of the pupa case breaks off, and the complete fly or imago escapes and seeks ita mate.^ The (Estrus may be found during the summer months on walls and fences in the neighbourhood of sheep, especially near plantations and bush. "It is a dull-coloured insect, with head or thorax together about as long as the five-ringed abdomen; its back is brown, with small points and patches of a darker tint, its under-surface dark-brown, with a spot at the centre of each abdominal segment. The wings are two in number, almost as long as the entire body, ana nearly completely enveloping it, variegated with spots and stripes, and having small horny internal portions which envelop the poisers or balancers ; small chitinous organs • representing the posterior pair of wings of all Diptera. . . . The head is large, yellow, and spongy in appearance."— Steele. In older countries, during the attack of the fly, sheep become very excited, even though only one fly be in their vicinity. They stamp with their feet, snort, shake the head, rush about, and hold the nose to the ground, burying it amongst any sof i. soil or dust that may be near; at other times the sheep may be found packed together, stamping and snorting fiercely. Flocks, however, in New Zealand become affected with the larvte without any previous agitation of the animals having been noticed. Both old and young sheep may be affected, but lambs as a rule experience more inconvenience. When animals are exhibiting the symptoms of irritation it is highly necessary that some treatment should be resorted to. The inhalation of tobacco smoke and of the fumes of burning sulphur are said to be beneficial; but my experience as to these remedies is that they are far from being efficient. These larva) are difficult to kill, for they have great powers of resistence. If the larvae are still in the nostrils—which should be determined by killing and examining an affected animal—the surest method is to sj ringe the nostrils with some fluid which, if it does not completely kill the parasite, will cause it to lose hold and be expelled. For this purpose I have found the following mixture to be of benefit: Carbolic acid, 1 part; oil of turpentine, 8 parts; glycerine, 80 parts; and water to make 60 parts. The operation should be performed by means of a small vulcanite syringe holding about two drachms. This is filled with the mixture, and half of the quantity injected gently into each nostril, i The animal should be held by an assistant between his knees, his left hand firmly grasping the head. After having syringed the nostrils the animal should be allowed to sneeze freely. In cases where disturbance is caused by the presence of larvtß in the sinuses of the head the only remedy is a surgical operation, which it is not desirable that any one but a qualified veterinarian should perform. In this, as in all other parasitic diseases, however, prevention is the best measure to adopt. This can be accomplished partly by destroying all larvte found on opening animals, and partly by taking precautions to prevent the fly depositing eggs on the sheep. For this purpose furrows in in the pasture are useful, so that the sheep may bury his nose amongst the soft earth during the attack of the fly; sprinkling the sheep's salt over tar; and application of fish-oil, tar, &c, over the region of the nostrils, which is best accomplished automatically by placing the salt in a long box covered by a lid perforated with round holes about 2in. in diameter, the margins and upper surface of which should be smeared with the substance to be used : thus every time the sheep lick the salt they will receive a dressing. By such means as these the fly may be prevented from depositing eggs.