CONTROL OF HYDATIDS

New Zealand Journal of Agriculture, Volume 63, Issue 5, 15 November 1941, Page 413

CONTROL OF HYDATIDS

Country Dog Owners Must Assist In Checking the Disease

By

SIR LOUIS BARNETT,

Emeritus Professor of Surgery, University of

Otago, and Chairman of the Hydatids Committee.

ZN the following article Sir Louis Barnett emphasises the need for something more than persuasive measures if the spread of hydatids in this country is to be checked. He points out that years of intensive and systematic propaganda designed to educate people have yielded discouraging results, and he has something to say to some country dog owners for their lack of co-operation. “A considerable number of more intelligent dog owners,” he states, “do try to keep their dogs free of the parasite worms . . . but unfortunately there is a considerable number—perhaps, indeed, the majority whose attitude is apathetic, neglectful, or even scornful.”

IN a recent statement Mr. R. A. Nicol, S.P.C.A. Inspector for the Wellington Province, points out the harmful effect of allowing hungry dogs to wander about the farms and countryside seeking what they might devour. Not only do they seize upon discarded offal when an animal is slaughtered at the homestead, but they nose around in distant pastures, and if they find a dead sheep they tear into its inside for the food they lack. Mr. Nicol deserves the thanks of the community for his plain speaking, and no doubt many dog owners will profit by his helpful advice. Many will read it and heed it, but, alas, many will do neither. That conclusion has been arrived at by the Hydatid Committee — Drs. Hercus. and D’Ath, of Dunedin, Dr.' Ritchie, of Wellington, and Dr. Hopkirk, of Wellington, with myself as chairman after years of intensive and expensive efforts on educational and persuasive propaganda. We have concentrated mainly on an attempt to drive home the importance of the two outstanding lines of prevention, namely, .. 1. N,ot allowing dogs to feed on raw offal, such as the liver and lungs of sheep. 2. Dosing dogs regularly with a safe and efficient worm-expelling medicine, such as arecoline.

Risks to Children

The other precautions advised for example, that deal with the evils of food, water, and hand pollution by dogs, and with the special risks to children from caressing country dogs—are of importance, too, but not to be compared in preventive value with the two first mentioned.

Over and over again these recommendations and the reasons for them have been brought under the notice oi dog owners in the hope that the knowledge imparted, plus a little commonsense, would lead to their widespread adoption, and now, after years of this educational and persuasive campaign, what is the result? A considerable number of the more ' intelligent, dog owners do try to keep their dogs free of parasitic worms. They do feed them properly and dose them regularly. On their farms and in their districts it has been noted that the prevalence of hydatid disease has "been reduced. But, unfortunately, there is also a considerable number of dog owners — perhaps, indeed, the majority—whose attitude is apathetic, or neglectful, or scornful. Their dogs continue to harbour and spread the hydatid parasite, and New Zealand remains a country notorious for its prevalence.

Persuasive Methods

The New Zealand Government 'has so far favoured persuasive methods only. It is true that last year legislation was passed making it illegal to feed dogs on raw offal, but no steps have been taken so far to enforce this measure. The practical difficulties associated with enforcement have no doubt led to this hesitation. The. Government also distributes annually worm-expelling medicine in the form of arecoline tablets, with full instructions for use, to every dog owner at the time of dog registration. By law, the dog owners have to pay an extra registration fee of one shilling to cover the cost of the tablets, but there is no law compelling them to

dose , their dogs, and a very large number neglect or refuse to do so. 1

There are about 200,000 dogs in New Zealand (1 in 8 of the population), most of them country dogs, and of these about one-third are carriers of the hydatid tapeworm. The dog, be it remembered, is the only animal in this country that harbours the parasite in the worm stage, and the dog, therefore, is the sole distributor of the hydatid eggs, which, if swallowed by other farm animals or by human beings, grow into cysts.

Every year a hundred or more new cases of hydatid disease are admitted into our hospitals. About 14 per cent, of these cases end fatally, and the others may suffer years of . disability.

Millions of Carriers

There are approximately 32 million sheep in this country, and nearly half of them harbour hydatid cysts, in liver and lungs. The lives of these animals are short compared with human existence, and the cysts they carry have not, as a rule, had time to cause notable impairment in the quality of wool or meat.

The farmer reckons on getting the same , price for his sheep whether they have cysts or not, and unless one of his own family falls a victim to hydatid infection he is apt to think preventive measures are not worth bothering about.

If he thought hydatid prevalence would hit him economically he would probably take more notice, and, as a matter of fact, he does unwittingly share in a considerable economic loss. All animals killed, in abattoirs and freezing works are inspected by veterinary officials, and every liver that harbours visible hydatid cysts is con-

demned as unfit for sale and is sent to the destructor. Now, livers have high nutritive and medicinal value. They are worth from 6d to 9d or more each. Last year the Government actually received £400,000 for exported livers, and that sum was earned on the clean livers only, which represent only about half the total inspected. It is easy, therefore, to see that the prevalence of hydatid cysts in sheep and cattle, for cattle are as badly infected as sheep, is entailing an annual loss to the farming community of hundreds of thousands of pounds. Payment for Livers A suggestion, made originally, I think, by Mr. W. C. Barry, Director of the Livestock Division of the Department of Agriculture, and recently revised, is that carcasses with clean livers should be regarded as worth

more than those showing hydatid infection, and that payment should be regulated accordingly. If this suggestion, despite certain practical difficulties, were adopted, it would undoubtedly strongly reinforce preventive propaganda. The fact remains that a very large number of dog owners, perhaps the majority, are doing little or nothing to help in the hydatid campaign. This does not matter much in the towns, because town dogs do not, as a rule, get the infected kind of food, namely, raw livers or lungs and livers of sheep, which country dogs so habitually feed upon whenever they get the chance. Town dogs, therefore, do not constitute a serious hydatid danger, but country dogs do, and so it is in the country districts that preventive precautions should be universally and thoroughly carried out, and why not?

Reasons for Laxity.

Here, in conclusion, are the reasons for this regrettable laxity or opposition on the part of country dog owners in carrying out the recommendations of the Hydatid Committee:— (1) In Regard to the Feeding of — Dogs enjoy and thrive on raw offal, and- the farmers say it is too much bother or it is impracticable or wasteful to sterilise it by boiling, or, to prevent it being consumed, burning it, burying it, or in other ways keeping it out of the way of the dogs. They say, too, that dogs, even if not fed by their masters on raw offal, find this food for themselves in dead sheep about, the countryside. As a matter of fact, however, it is not so very much trouble to make a practice of boiling sliced up offal for a quarter of an hour before giving it. to the dogs, and the alternative should be disposal of this offal by burning or burying and the feeding of the dogs on some other part of the sheep’s carcass. The offal of sheep found recently dead might be cut out and dealt with similarly, and it is worth noting that pronounced putrefaction in the carcass itself kills hydatid infection. (2) In Regard to the Dosing of Dogs. —The most effective drug for the eradication of worms in dogs is arecoline, and that is what the tablets issued by the Government contain. Alleged illeffects, even the death of good dogs after arecoline dosing, have been reported in the papers, and unwarranted rumours and talk and gross exaggeration have combined to create a scare against the use of the drug. Careful research work in the field and in the laboratory on thousands of dogs has shown that these tablets, when properly administered according to instructions, are safe and effective in the vast majority of cases. Only in a minute proportion have there been any serious • ill-effects. It is admitted that there are rare cases of abnormal sensitiveness to the drug, particularly in dogs of delicate or impaired constitution. Animals, like people, sometimes show peculiarities in this way. Some folks, for instance, are badly, upset by even a small dose of ■ aspirin or quinine, and honey, strawberries, and shellfish sometimes cause distressing reactions. One has to remember that there are about 200,000 dogs in New Zealand and that thousands of them are dying every year in the ordinary course of events. Even if arecoline is responsible for three or four extra deaths, that fact should not weigh against the great benefits accruing to the welfare of the community by its administration.