Alternative Hydatids Diagnosis Discounted

Press, Volume CIII, Issue 30396, 21 March 1964, Page 16

Alternative Hydatids Diagnosis Discounted

There are three important factors which discount diagnosis of hydatids from the inspection of dog faeces, says the chief veterinary officer for the National Hydatids Council (Mr G. A. Thomson) in reply to a letter to the editor of “The Press" signed “Microscope." The correspondent says all dog owners should be grateful to Mr Skinner for pressing for an alternative method of testing for tapeworm, and seek the advice of a veterinary expert. He writes: — Alternative Sought “All dog-owners who value their dogs should be grate ful to, and fully support, Mr Skinner for pressing for an alternative method of testing for tapeworm In place of the painful, dangerous method used at present. All dog manuals warn of the dangers of the unnecessary use of vermifuges. The published records show the small percentage ot dogs which require dosing. Would some veterinary expert please advise what method a practising veterinary surgeon would use to establish the presence of tapeworm? I am sure the dog would not be dosed as at present. Needless suffering to animals is to be avoided.” Similar Suggestions

Mr Thomson replies:— “Your correspondent refers to a statement by Mr H. D. Skinner, of Christchurch, who claimed that the proper way to test dogs for hydatids was by inspecting their faeces. “Similar suggestions have been made in the past by persons filled with enthusiasm rather than with knowledge of the subject. “There are three important factors which render such a system of diagnosis impossible. “The first factor is the irregular release of worm segments containing eggs, which may result in the passage of completely egg-free faeces from dogs which are in fact carrying tapeworms. “The second factor concerns the technique of examination and the time and equipment required for such examination.

“Looking for the tapeworm eggs of such small size in a quantity of faecal material under a microscope could be compared with hunting for a pea on an area the size of a rootball ground. Accurate diagnosis would be possible only by the use of complicated techniques for flotation and concentration of eggs present in the sample. Identification Difficult “Thirdly, if eggs were found to be present, their identification would be extremely difficult, if not impossible because of the similarity in appearance, shape, and size, of the eggs of the different species of tapeworms which can infect a dog. “For example the eggs of Echinococcuj granulosus, the true hydatid worm, and those of Taenia pisiformis a worm which has a life-cycle involving the dog and rabbit, and which has no relationship to human health, are similar in appearance and shape, and may be of the same size. “Authoritative textbooks of parasitology state that the eggs of E. granulosus may vary from 0.032 to 0.036 mm in length and from 0.250 to 3.30 mm in width, while those

of T. pisiformis are 0.034 mm in length and vary from 0.024 to 0.028 mm in width. “The eggs of other tapeworms present in the dog have similar variations within the same general dimensions. “Mr Skinner and ‘Microscope’ would perhaps be wiser to regard the periodic dosing and testing of their dogs as a relatively simple method by which they can be assured that their dogs are not a danger to human health,” Mr Thomson says.