Align-ju STUDENT
PCV is a measure of the amount of red blood cells ( RBCs ) in the blood and the reading is recorded as a percentage . PCV is very important and gives an indication of hydration levels . The reading would be high if the patient is dehydrated and low in cases such as haemorrhage or anaemia [ 5 ] .
PCV is read using a micro haematocrit reader . However , if this is not available , a ruler can be used , with the following calculation :
PCV (%) = height of red blood cells ( cm ) ÷ total column height of RBCs and plasma in tube × 100
Using the Hawksley haematocrit reader
• Place the capillary tube in the reader slot with the seal facing downwards and align the bottom of the red cells to the 0 mark on the reader .
• Move the tube reader across until the top of the plasma is lined up with 100 % on the reader .
• With the movable PCV reading line , move horizontally to the point where the red blood cell layer intersects with the buffy coat .
• Record the PCV reading .
The normal PCV for a dog is 37 – 55 % and for a cat it is 24 – 45 % [ 5 ] . Figure 3 shows a PCV reading using a micro haematocrit reader , which reads 32 – 33 %.
Calculating total protein using the plasma layer
• Put on gloves before handling the capillary tube .
• Using distilled water , calibrate the refractometer so it reads 1.000 .
• Wipe away the distilled water from the refractometer and snap the capillary tube so one part is solely plasma and the other part is red blood cells .
• Tap the unbroken end of the capillary tube on to the refractometer and add 2 – 3 drops of plasma .
• Hold the refractometer to a light source and look down the eyepiece to read the total protein from the scale labelled TP , SP or TS .
The normal total protein for a dog is 5.4 – 7.5 g / dl and for a cat it is 6.0 – 7.9 g / dl [ 6 ] . Usually , the normal reference ranges for total protein are given in g / l , so if the result is in g / dl , multiply the result by 10 to convert g / dl to g / l ( a decilitre is 100 ml so it is 1 / 10th of a litre , 1000 ml [ 7 ] . High plasma protein , known as hyperproteinaemia , can be due to dehydration or chronic inflammation [ 8 ] . Low plasma protein ( hypoproteinaemia ) can be due to malnutrition , starvation , overhydration , congestive heart failure with oedema , severe liver or kidney disease , blood loss or burns [ 8 ] .
Urinalysis
Urine testing is carried out daily in practice . Once the urine sample has been collected , its colour , odour and turbidity should be noted .
Colour
Urochrome is a pigment responsible for the pale yellow colour of urine in dogs and cats [ 2 ] . Very pale or colourless urine indicates that the patient is drinking a lot , which may be due to a medical condition such as kidney disease . Dark yellow urine indicates that the patient is not drinking enough water or is in a degree of dehydration . Urine of any other colour , such as red , brown or black , may be indicative of injury or an underlying condition [ 9 ] .
Odour
Figure 3 . A micro haematocrit reader .
The blood sample shown in Figure 3 was from a cat , which is important to note because this reading is considered normal for a cat . If this sample had been taken from a dog , it would be considered a low reading .
Using the spun-down capillary tube , the total protein can also be calculated using the plasma layer .
Urine usually has a slight odour , but any pungent odour should be noted and investigated because it may be a sign of infection . The urine of entire cats may have a strong smell due to scent marking .
Turbidity
Turbidity is the cloudiness of the urine . The urine of cats and dogs should be clear . However , if the urine is left to stand for a long period of time , precipitation of phosphate can occur and cause turbidity [ 2 ] .
Volume 38 ( 6 ) • December 2023
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