CLINICAL NOTE AN ALTERNATE METHOD FOR PREPARING BLOOD SMEARS

K. B. HATm* Procedures for making blood smears have been described (1, 2). These techniques, however, require exposing the sample to the air or drawing duplicate samples - one for making smears and one for determining the hematological parameters. Exposure of a sample to the air has two disadvantages. Firstly, there is a possibility of contamination and subsequent bacterial growth while the sample is in transit to a laboratory. Secondly, the loss of vacuum when the stopper is removed prevents proper seating when it is replaced and there is a possibility of spillage during transit. The purpose of this paper is to describe a method whereby one unclotted sample can be used for making smears and for hematological analysis without encountering the disadvantages described above. The blood sample is inverted gently several times to allow thorough mixing. In the inverted position, a 20-gauge Vacutainer1 needle is inserted through the rubber stopper of the blood vial leaving approximately %" (3-4 mm) between the threaded portion of the hub and the stopper. Pressing the hub against the stopper causes the blood to flow down the needle and a small drop to form at the tip. The droplet is released by touching it to a prepared glass slide. The smear is then made in the usual manner (Figure 1). The advantages of this method are many. Only one blood sample need be collected for both smear preparation and for determination of hematological parameters, thus saving a little in time and the cost of a second vial. Fic. 1 Because the stopper remains on the vial, spillage does not occur. Loss of vacuum and further contact with the air are eliminated. and it is not necessary to have a tube rack (If the needle is inserted with the vial in the available in which to stand an unstoppered upright position, air may enter the vial in vial. order to equalize the pressure, in which case On occasion, the blood smear cannot be the stopper may "pop" off and cause spillage made at the time of sampling. The residual in transit.) Applicator sticks are not required, blood in the needle clots and a new one is required. The cost of each needle could be 'Health of Animals Branch, Agriculture considered a disadvantage to this technique Canada, c/o Veterinary Microbiology and Im- compared to the cost of applicator sticks or munology, Ontario Veterinary College, University microhematocrit tubes for transferring a droplet to the slide; however, the advantages in this of Guelph, Guelph, Ontario NlG 2W1. lBecton, Dickinson & Co. Ltd., Mississauga, method outweigh the cost factor. Ontario. It is the author's opinion that the distribu.11

CAN. VET. JOUR., vol. 18, no. 4, April, 1977

CANADIAN VETERINARY JOURNAL

tion of cells in the smear using this technique is not altered from conventional methods.

des gouttes de sang sur des lames de verre et faciliter la preparation de frottis sanguins.

Summary A method of preparing blood smears using Vacutainer needles for dispensing drops of blood to a glass slide is described.

References 1. SCHALM, 0. W., N. C. JAIN and E. J. CARROLL. Veterinary Hematology. Third Edition. pp. 25-27. Philadelphia: Lea and Febiger. 1975. 2. WINTROBE, M. M., G. R. LEE, D. R. BOGGS, T. C. BETHELL, J. W. ATHENS and J.

Re'sume

FOERSTER. Clinical Hematology. Sixth Edition. pp. 444-446. Philadelphia: Lea and Febiger. 1972.

L'auteur decrit une methode utilisant des aiguilles a vacutainer pour etaler facilement

LETTER TO THE EDITOR DISEASE PROBLEMS RELATED TO TYPE OF FOOD DEAR SIR:

I was very interested in the article in the November journal entitled "Hypocalcemic Paresis in Beef Cows in Northeastern Alberta" by E. Janzen. I was engaged in a similar project myself in postwar Britain, when rations for all, including dairy cattle, left much to be desired. My observations were reported in the British Veterinary Journal, Vol. 8, No. 7, July 1952. I was in practice at the time, and because all farmers were compelled to use homegrown foods as substitutes for those imported in more normal years, I had a unique opportunity to relate disease problems to the type of food used. My first note was that oats seemed to be responsible for more than their share of problems, and I eventually came to the conclusion that whatever minerals were present in this cereal were bonded in such a way that the digestive juices were unable to leach them out. I was not able to obtain any laboratory confirmation of this thought, but it tied in with an obscure fact discovered during my university days at Glasgow, that inhabitants of the relatively impoverished central lowlands of Scotland suffered more from rickets than any other population group in the British Isles, due to their addiction to porridge oats for breakfast.

A second noteworthy discovery, and a trap for the unwary, was that certain blends of minerals were unstable, and that magnesium was very suspect in this connection. After that I made a point of examining the makers analysis of all minerals used by my clients, and was surprised to discover how much out of balance some of them were and how few contained magnesium. Ultimately I prepared a list of all "approved" blends to recommend to my clients, but even then discovered that if a blend was required containing magnesium it had to be specially ordered. Things may have improved since then, I have been out of touch too long to know, but I would certainly not be surprised to find that a cow, whose body needs were for both magnesium and calcium, refused to touch a mineral mix which contained only calcium, and which her taste buds would tell her was not quite what she wanted. W. J. TARVER Veterinarian I/ C Health of Animals Branch Macey Foods Ltd. P.O. Box 635 Brandon, Manitoba R7A 5Z7

112

An alternate method for preparing blood smears.

CLINICAL NOTE AN ALTERNATE METHOD FOR PREPARING BLOOD SMEARS K. B. HATm* Procedures for making blood smears have been described (1, 2). These techniq...
405KB Sizes 0 Downloads 0 Views