Collection from the nasal cavity can be used to diagnose chronic or acute rhinitis or sinusitis in cats.
Samples are collected from the nasal cavity rather than just from the secretions in the nasal cavity, and the samples obtained in this way are more likely to represent true etiologic significance. In this article, both methods are described separately. An x-ray of the skull should be performed to determine the appropriate sample collection site before determining whether to use nasal sampling. General anesthesia is necessary for proper localization and imaging analysis of the nasal cavity.
The most common method of examination is an open ventral dorsal X-ray. Increased opacity of the nasal bone indicates the need for puncture. If nasal bone puncture is chosen, it should be performed at the level indicated by the arrow approximately 2 mm off the midline. If nasal irrigation is chosen to be performed, the left nasal irrigation may be chosen.
Nasal puncture
Nasal aspiration (nasal puncture) is performed by sampling small needles to puncture the nasal cavity to obtain disease material. The method described below is a transpalatine approach to sampling.
Method
Once the puncture site has been determined and the need for puncture has been established, the sick cat should lie prone and it is important to place an endotracheal tube with an air bag. A 22-gauge disposable needle and a 6mL or 12mL syringe are used to determine the point of needle penetration based on the X-ray findings. It is correctly positioned according to the dentition and the distance from the septum (median septum). The hard palate is punctured using a drill. Once the needle is able to enter the nasal cavity, the sample is obtained by several firm aspirations with the syringe. After the sample is taken, the needle is removed and if bleeding occurs, some pressure is applied to the biopsy site to stop the bleeding. Occasionally several drops of blood may be seen in the vicinity. After sampling, the sample is pushed onto a clean slide to prepare a smear, stained to observe the cellular composition, and then sent to the veterinary pathology laboratory for examination.
If only blood is present, puncture sampling should be repeated. Some samples should also be saved for bacterial culture and drug sensitivity testing. Another portion of the sample should be placed on a sterile polyester slant applicator (sterile dacron-tippedapplicator) and sent for PCR testing of viral respiratory pathogens.
Precautions
Forceful puncture results in a better quality sample and is unlikely to cause nasal damage. Unlike dogs, cats are rarely subject to problems caused by the occurrence of bleeding.
If there is osteolytic disease of the nasal cavity, the hard palate can be easily punctured with a needle, and the likelihood of a tumor is extremely high when this occurs.
Some cats have a thick and dense hard palate, so a 22-gauge disposable needle cannot be passed through. If this occurs, a 20-gauge disposable needle can be used. Alternatively, a 22-gauge or 20-gauge spinal anesthesia needle and probe can be used, but this is rarely necessary.
The same equipment and technique can be used to puncture from the back toward the abdomen from the nasal bone, but it is difficult to determine the marker for the chosen site.
