BRONCHITIS IN STOCK

Te Awamutu Courier, Volume 60, Issue 4235, 24 January 1940, Page 12

BRONCHITIS IN STOCK

LUNGWORM IN CALVES AND LAMBS. VERMINOUS PNEUMONIA. In a chat yesterday with the dis-, trict inspector of stock, Mr G. d. Melrose, that gentleman mentioned that seevral farmers in this district have lately been experiencing a good deal of trouble and worry on account of unidentified illness among their calves and lambs. Mr Melrose said the trouble had been diagnosed as lungworm, verminous pneumonia and bronchitis, and with the incidence of these ailments, caused by parasitic infection, he said the history of the parasite and its prevention rather than treatment of infected animals — may be accepted as of some value by farmers. Mr Melrose said that if the farmer could only realise what he is up against in regard to parasitic infection of young stock, the attention to this aspect of animal husbandry would be more strict, and, incidentally, the results would be apparent in the good health of young stock. The name of the parasite in the sheep was dictyocaulus filaria, and in calves dictyocaulus vivaparus.

All domestic animals are liable to invasion of the air-tubes and lungs by animal parasites, which sometimes excite symptoms of bronchitis and pneumonia. Young cattle and sheep are especially prone to such attacks, and his remarks would be confined to these subjects. Invasion of the air-tubes and lungs by worms set up a local irritation and provoked symptoms of persistent coughing known as “hoose” or “husk.” The disease is usually more prevalent in the summer months, but may appear at any season of the year. Animals in poor condition, from any cause, and those affected with intestinal worms, are more subject to attacks. Wet, low-lying badly drained pastures, devoid of proper shelter, also favour infection; also calf paddocks that have been in use for a number of years, without any treatment with liming and harrowing. It should be realised that parasites and larvae detest sunlight. The life history of the parasite is as follows:—The eggs are embrymotic when laid in the air passages, and are coughed up into the pharynx. There they are normally swallowed and so reach the intestine, though a few may be coughed out in mucous on to the pasture. The eggs hatch in the intestine and the first stage of the larvae pass out with the faeces (dung). After one or two days the larvae undergo the first moult, in a further three or four days more the second moult is undergone. As a rule, however, the first stage skin is soon cast, and the infective larvae as usual is unsheathed in that of the second stage. The infected larvae show little tendency to .migrate upward on to grass, and under experimental conditions may survive for nine months in shallow water, so that young stock frequently swallow them in drinking water or while grazing over damp depressions in paddocks or marshy areas. The larvae will develop at temperatures as low as 41 degrees Fahr., and appear to remain healthier and more active at such temperatures than higher ones. In mild winters, therefore, development is likely to continue throughout, though the optimum deevlopment will coincide with wet conditions in the spring.

After being swallowed by young stock the larvae worm into the small intestine wall and pass by lympth vessels into the lungs. They are found in large numbers in the misenteric glands from two to five days after infection. Here the third moult is undergone and the fourth stage larvae then leave the glands and pass in the lymph stream to the heart, and are then carried in the blood to the lungs. They pass through the wall of the alreoti in to the larger air pasages and the fourth stage larvae, about 1/50-inch, may be found in the bronchia tubes after eight days. Adult male and female worms are developed in the lungs eighteen days after infection, and eggs may be produced in a minimum period of twenty-six days, but normally in about five weeks. The effect of the adult worms, especially when they are numerous, appear to be due largely to mechanical effects, the masses of worms and eggs completely blocking the air passages thus causing collapse of the lung supplied by them, the principal cause of death being suffocation from mechanical blocking of the air passages. In the collapsed area of lung tissue, also, secondary infection with bacteria may lead to extensive areas of pneumonia. Symptoms: The first symptom of coughing is usually exhibited about 30 days after infection, and coincides with the development of the adult worm and the passage of larvae in the droppings. In light infection the cough is usually strong and harsh, whereas in heavy infection it may be absent or very soft. Respiration becomes more rapid and shallow in proportion to the degree of obstructions of air passages. Heavily infected animals become weak and listless and death may occur two months after infection. In light to moderate infections, unless pneumonia develops, animals may show little abnormality other than coughing, this being particularly at night or when yarded or disturbed. The diarrhoea often attributed to lungworm infection is frequently due to the concurrent infection with small intestinal worms (which will be the subject of a later article). Diagnosis: In the majority of instances symptoms of coughing, particularly of an epidemic nature among young stock may be regarded as an indication of lungworm infection. Postmortem The dark red areas of collapsed lung tissue of solid consistency are more or less extensive, and on opening the bronchi and finer air passages, a bloody froth and thread-like worms are easily detected. In evaluating the importance of the worms found, regard should be had to the extent of the collapsed or pneu"monic area, these being extensive when lungworm is the primary cause of disease. In the same way infection with les sthan 50 adult worms may be usually disregarded, since such numbers are frequently present in apparently healthy stock. In the latter instance look for pleurisy or

pneumonia from other causes such as starvation and exposure. Treatment: The practibility of effectively treating lungworm infection is still a matter of controversy, taking into consideration the accessibility of any mechanical or medicinal treatment to the worms in the finer air passages. There seems to be a considerable body of evidence which suggests that beneficial results follow from certain lines of treatment. There is little doubt, however, that in many instances the supposed beneficial effects of treatment are due to the tendency where young stock are not heavily infected, and where nutrition has been adopted and maintained, for them to throw off infection very rapidly, while treatment to remove stomach parasites may also play a large part in any improvement seen. The principal methods of treatment advocated are:— 1. Strict attention to nutritional measures and removal of other parasites.

2. Intratracheal injections. 3. Inhalation of volatile substances. 4. Administration of drugs by mouth. The above in their order: No. 1 should be plus. There is no doubt that, except in the case of massive infection, young stock when adequately fed and kept under otherwise favourable conditions, may rapidly throw off infection completely without any medicinal treatment—therefore, improvement of nutrition should be considered the first line of treatment and if carried out will be the only treatment necessary. Affected stock should receive supplementary feeding such as bran, crushed linseed, crushed oats, etc. at a time, prior to usual time the young stock get affected or when pastures fail to be palatable, or to be run on the best of pastures or lucerne. Animals should be removed from lowlying, wet areas to Well-drained country, always provided nutritional conditions can be satisfactorily maintained. 2. Intratracheal injections: The

merits of this treatment in the hands of other than a qualified practitioner are doubtful, and comment for the purpose of this article are not desirable. 3. Inhalation of volatile substances. Chloroform-saturated piece of towelling in a 71b treacle tin or other such receptacle over nose of calf, until showing signs of unsteadiness on feet. On no account should calf be backed into a corner, but should be held by the operator’s assistant in a standing position. Two minutes should be sufficient inhalation. Starve calves for six hours.

4. Administration of volatile dijigs by mouth have been suggested as’effective if these are absorbed and excreted through the lungs. Carbon tetrachloride, which has been recommended for this purpose, is completely ineffective and there is no conclusive proof that any other drugs are of value when administered in this way. Finally, at the best, the adoption of any of the treatments Other than No. 1 can only remove a proportion of the worms, thus relieving the respiratory distress and enable the animal subsequently to throw off the infection completely. Summarised: Little can be done in regard to treatment beyond the allowance of extra food of a nourishing character to improve the condition and bodily resistance of the animals. Tonics such as salt bricks (cobaltised) and change of pastures are indicated. Due regard must be given to stomach and intestinal parasites by regular dosing with approved drenches, particularly bluestone 2oz, nicotine sulphate 2oz, water 1 gallon. Dose for calves, three fluid ounces (6 tablespoons) at three-weekly intervals during the summer and autumn months.