colour. The bot remains in the stomach till the following spring,
when it detaches itself, passes into the food and is discharged with
the faeces. When very numerous, bots may cause symptoms of
indigestion, though frequently their presence in the stomach is not
indicated by any sign of ill-health. They are difficult to dislodge
or kill. Green food, iodine, naphthalin, hydrochloric acid and
vegetable bitters have been recommended; but the most effective
remedy is a dose of carbon bisulphide given in a gelatin capsule,
repeated in twelve hours, and followed twelve hours later by an
aloetic ball.
Of the parasites which infest cattle and sheep mention will only be made of Distomum hepaticum, or common fluke, which causes In cattle and sheep. liver-rot or distomiasis, a very fatal disease of lambs and sheep under two years old. It occurs most frequently after a wet season on low-lying, marshy or undrained land, but it may be carried to other pastures by sheep which have been driven through a fluke-infested country, and sheep allowed to graze along ditches by the roadside may contract the parasite. For a full description of its anatomy and development see Trematodes. Preventive treatment comprises the destruction of flukes and snails; avoidance of low-lying, wet pastures draining infested land, and top-dressing with salt, gas-lime, lime water or soot; supplying sheep with pure drinking water; placing rock-salt in the fields, and providing extra food and a tonic lick consisting of salt, aniseed, ferrous sulphate, linseed and peas-meal.
Husk, hoose or verminous bronchitis of calves is caused by Strongylus micrurus, or pointed-tailed strongyle, a thread-worm 1 to 3 in. long, and S. pulmonaris, a similar but smaller nematode; and the corresponding disease of sheep is due to S. filaria and S. rufescens. The male S. filaria is l to 2 in., and the female 2 to 4 in. long. They are white in colour and of the thickness of ordinary sewing cotton. The S. rufescens is thinner and shorter than S. filaria and its colour is brownish red. The development of these strongyles is not accurately known. When expelled and deposited in water or moist earth, the embryos may live for many months. Hoose occurs in spring and continues until autumn, when it may be most severe. In sheep the symptoms are coughing, at first strong, with long intervals, then weak and frequent, leaving the sheep distressed and wheezing; discharge from the nose, salivation, occasional retching with expulsion of parasites in frothy mucus, advancing emaciation, anaemia and weakness. In calves the symptoms are similar but less acute. Various methods of cure have been tried. Remedies given by the mouth are seldom satisfactory. Good results have followed fumigations with chlorine, burning sulphur, tar, &c., and intra-tracheal injections of chloroform, iodine and ether, oil of turpentine, carbolic acid, and opium tincture, or chloroform, ether, creosote and olive oil. The system should be supported with as much good nourishing food as possible.
The principal parasites which infest the alimentary canal of cattle or sheep are strongyles and taeniae. The strongyles of the fourth stomach are S. contortus, or twisted wire-worm (male 10 to 20 mm., female 20 to 30 mm. long), S. convolutus (female 10 to 13 mm.), S. cervicornis (female 10 to 12 mm.), S. gracilis (female 3 to 4 mm.), and an unnamed species (female 9 mm. long) discovered by McFadyean in 1896. In the contents of the stomach the contortus may easily be recognized, but the other parasites, owing to their small size or situation in the mucous membrane, may be overlooked in an ordinary post-mortem examination. The contortus, which is best known, may serve as the type. It lives on the blood which it abstracts from the mucous membrane, and, according to the state of repletion, its body may be red or white. The ova of this worm are discharged in the faeces and spread over the pastures by infected sheep. The ova hatch in a few days, and, according to Ransom, within a fortnight embryos one-thirtieth of an inch long may be found encased in a chitinoid investment, which protects them from the effects of excessive cold, heat or moisture. When the ground is damp and the temperature not too low, the embryos creep up the leaves of grasses and other plants, but when the temperature is below 40° F. they are inactive (Ransom). Sheep feeding on infected pasture gather the young worms and convey them to the fourth stomach, where they, attain maturity in two or three weeks. In wet weather the embryos may be washed into ponds and ditches, and cattle and sheep may swallow them when drinking. Strongyles cause loss of appetite, irritation and inflammation of the stomach and bowel, diarrhoea, anaemia, progressive emaciation, and, if not destroyed or expelled, a lingering death from exhaustion. The success or failure of medicinal treatment depends on the degree of infestation. A change of pasture is always desirable, and as remedies a few doses of oil of turpentine in linseed oil, or a solution of lysol or cyllin, and a powder consisting of arsenic, ferrous sulphate, areca, nux vomica and common salt may be tried. The ox may be the bearer of three and the sheep of twelve species of taeniae, and of these the commonest is Moniezia (taenia) expansa, which is more frequently found in sheep than in cattle. It is the longest tapeworm, being from 6 to 30 ft. in sheep and from 40 to 100 ft. in cattle. Its maximum breadth is ¾ in.; it is found in the small intestine, and sometimes in sufficient numbers in lambs to obstruct the bowel. Infested animals are constantly spreading the ripe segments over the pastures, from which the ova or embryos are gathered by sheep. The symptoms are inappetence, dry harsh wool, weakness, anaemia and diarrhoea with segments of the worms in the faeces. Various drugs have been prescribed for the expulsion of tapeworms, but the most useful are male fern extract, turpentine, kamala, kousso, aloes and linseed oil. Very young animals should be supported by dry nourishing food and tonics, including salt and ferrous sulphate.
The principal round-worms of the intestine of ruminants are Ascaris vitulorum, or calf ascarid, Strongylus filicollis, S. ventricosus, Sclerostomum hypostomum, Anchylostomum cernuum and Trichocephalus affinis, or common whip-worm, which sometimes causes severe symptoms in sheep. For a full account of the development of Cysticercus bovis, or beef measle, the larval form of Taenia saginata of the human subject, see Tapeworms. Another bladder-worm, found in the peritoneum of sheep and cattle, is Cysticercus tenuicollis, or slender-necked hydatid, the larval form of Taenia marginata of the dog. It seldom produces serious lesions. An important hydatid of ruminants in Coenurus cerebralis, which produces in sheep, cattle, goats and deer gid or sturdy, a peculiar affection of the central nervous system characterized by congestion, compression of the brain, vertigo, inco-ordination, and other symptoms of cerebrospinal paralysis. This bladder-worm is the cystic form of Taenia coenurus of the dog. It is found in the cranial cavity, resting on the brain, within its substance or at its base, and sometimes in the spinal canal. The symptoms vary with the position and number of the vesicles. In an ordinary case the animal feeds intermittently or not at all, appears unaccountably nervous or very dull, more or less blind and deaf, with glazed eye, dilated pupil, the head twisted or inclined always to one side—that occupied by the cyst—and when moving the sheep constantly tends to turn in the same direction. When the vesicle is deep-seated or within the cerebral lobe, the sheep carries the head low, brings the feet together and turns round and round like a dog preparing to lie down. When the developing cyst exerts pressure at the base of the cerebellum, the sheep repeatedly falls and rolls over. In other cases the chief symptoms may be frequent falling, always on the same side, high trotting action with varying length of step, advancing by rearing and leaping, complete motor paralysis, and in spinal cases posterior paralysis with dragging of the hind limbs. Medicinal treatment is of no avail, but in some cases the hydatid can be removed by trephining the skull. Gid may be prevented by attending to the treatment of dogs infested with the tapeworm.
The helminthes of the pig, although not very detrimental to the animal itself, are nevertheless of great importance as regards the In the pig. entozoa of man. Allusion must be made to Trichinella spiralis, which causes trichinosis. The male is 118th, the female 18th in. long, and the embryos 130th to 127th in. The ova measure 11270th in. in their long diameter; they are hatched within the body of the female worm. When scraps of trichinous flesh or infested rats have been ingested by the pig, the cysts enclosing the larval trichinae are dissolved by the gastric juice in about eighteen hours, and the worms are found free in the intestine. In twenty-four to forty-eight hours later these larvae, having undergone certain transformations, become sexually mature; then they copulate, and after an interval the embryos leave the body of the female worm and immediately begin to penetrate the intestinal wall in order to pass into various voluntary muscles, where they become encysted. About twelve days elapse from the time they begin their wandering. Usually each larva is enveloped in a capsule, but two or even three larvae have been found in one investment. They have been known to live in their capsules for eighteen months to two years.
Cysticercus cellulosae is the larval form of Taenia solium of man (see Tapeworms). “Measly pork” is caused by the presence in the flesh of the pig of this entozoon, which is bladder-like in form. It has also been discovered in the dog. Other important parasites of the pig are Stephanurus dentatus, or crown-tailed strongyle, Echinorhynchus gigas, or thorn-headed worm, Ascaris suis, or pig ascarid, and Strongyloides suis. For these the most useful remedies are castor oil seeds, given with the food, and oil of turpentine in milk, followed by a dose of Epsom salts.
Of all the domesticated animals the dog is by far the most frequently infested with worms. A very common round-worm is In the dog. Ascaris marginata (3 to 8 in. long), a variety of the ascarid (A. mystax) of the cat. It occurs in the intestine or stomach of young dogs. The symptoms are emaciation, drooping belly, irritable skin, irregular appetite, vomiting the worms in mucus, colic and diarrhoea. The treatment comprises the administration of areca or santonin in milk, followed by a dose of purgative medicine. A nematode, Filaria immitis, inhabits the heart of the dog, and its larvae may be found in the blood, causing endocarditis, obstruction of the vessels, and fits, which often end in death. Spiroptera sanguinolenta may be found in the dog encysted in the wall of the stomach. Other nematodes of the dog are Anchylostomum trigonocephalum, which causes frequent bleeding from the nose and pernicious anaemia, and Trichocephalus depressiusculus, or whip-worm, which is found in the caecum. The dog harbours eight species of taeniae and five species of Bothriocephalus. Taenia serrata, about 3 ft. in length, is found in about 10% of
