Fine needle aspiration
Fine needle aspiration (FNA) is used to obtain a sample for cytology from soft tissue masses or abdominal viscera. If a FNA is taken from an abdominal organ it is prudent to perform a blood profile to assess clotting before the sample is taken.
Unless the tiger is a cub it will need to be sedated for a FNA.
FNA of a soft tissue mass:
The fur over the mass is clipped and the skin aseptically prepared. The mass should be immobilised using one hand and a 21G 5/8” needle inserted into the lesion with the other hand. The needle should be moved gently to and fro within the lesion and then removed. The aspirate should then be expelled from the needle onto the centre of a microscope slide using a syringe containing air. A second spreader slide should then be gently placed horizontally and at right angles over the slide with the sample. The slide should be drawn quickly and smoothly over the bottom slide. The smear should be examined on the underside of the spreader slide.
FNA of an abdominal organ:
This should be performed using ultrasound guidance. The preparation and technique is as above but a longer 21G needle will be required.
For vets with experience in cytology the smear can be prepared in house with a stain such as Diff Quick. However, it is preferable to send the smear for interpretation to a cytologist at an external laboratory if possible.