The benefits of in-house cytology in small animal practice

Cytological and haematological analyses are an essential part of daily life as a small animal practitioner. Haematology samples are often run as part of routine profiles and in the majority of unwell patients. Cytological assessment of lumps and bumps and of any bodily fluid samples can provide diagnosis, enhancement of differentials and in some cases, the best treatment options for the patient.

Whilst there has never been a better array of external laboratories to submit these samples to, there are moments in any day when an in-house analysis can provide this information with a very short turn around and without the problems caused by sample storage and transport.

Aspirate or operate? A cytology case study

It's Saturday morning, and you’re just about to start a list of appointments. Mrs Brown is a new client to the practice. She is extremely worried about an ulcerated mass on her dog’s leg. The lump had been present for about 6 months but was small. The previous vet told her that it was fatty and nothing to worry about. When she got home from work it had exploded as you can see! She has small children in the house and doesn’t want the dog to be around them until a dressing has been applied.

You perform a quick clinical examination and find the mass is ulcerated and pendulous but it would be impossible to apply a dressing.

Should you just bite the bullet and remove the mass? The base is quite narrow and it would shell out easily. Or should you aspirate the mass first to find out what it is, even though it will still need removing? You're not very confident with cytology and the the Diff-Quik needs replacing, so you decide to shell it out this afternoon after the consults are done. Mrs Brown is delighted when you offer this option as she will be able to get Dusty home that evening and the mass will be gone.

Unfortunately this is a bad call. The mass comes out and it is easy enough to close the wound but Dusty has a challenging anaesthetic and the wound bleeds badly. At the post-operative check the wound is breaking down and continuing to ooze blood.

How can we improve our response to this mass call?

Aspirates of the mass at presentation would have confirmed that the mass is a mast cell tumour. This would have alerted you to the risk of anaesthetic complications, wound breakdown and bleeding problems (due to heparin released by the granules). You would have known that wide margins were required.

If the first vet had aspirated the mass 6 months ago, it might have been removed when it was a lot smaller and before it started to behave aggressively. Staging (with appropriate aspirates of internal organs) could have been performed before the removal to ensure that there was no internal spread.

Analysing haematology samples

Small animal practitioners are now routinely using in-house analysers to perform haematology samples on a regular basis. Our increasing reliance on the in-house machine means we are sometimes out of the habit of submitting blood smears and rarely consider the need for reviewing the results of smears in-house due to a lack of confidence in making accurate interpretations.

However, this dependence on an in-house analyser that can provide results in a few minutes means that we sometimes miss things. The in house analyser relies on a computer program to give its best assessment of the cell type and this can never beat the subtle nuanced view of a human brain.

By looking at haematology smears ourselves in combination with the in-house analyser we can really ensure that we are getting the most information from the patient’s sample. The classic example of this is the platelet count. Analysers will often get this wrong when there is any platelet aggregation, macrothrombocytes or when there are abnormal circulating cells (such as lymphoblasts).

Analysing cytology samples

There are many ways that a busy practitioner can utilise cytology in their daily patient care. All bodily fluid samples can be assessed for their cell contents and aspirating any lesions such as a skin lump or internal mass can provide a quick diagnostic tool. To get the best from your samples it is important to use the correct technique to obtain the cells and to ensure you are using the most useful staining techniques.

The challenge is then to interpret what you see in light of your clinical findings. By taking a straight forward and logical approach to interpretation the practitioner can get valuable and rapid information from the patient without the delay that external laboratory submission will entail. This is particularly useful at that Friday evening surgery or during holiday periods when the post can significantly delay sample submission.

Get the most from every sample you collect

Of course external laboratories will continue to provide a much needed source of expertise but what should the practitioner be expecting from them? Poor sample collection and a lack of clinical information will hinder the cytologist. Equally poor reporting and a lack of consideration of patient signalment and likely differentials will make the external interpretations less useful. By having a clear understanding of how to process samples and what to expect from sample analysis, both in-house and externally, the practitioner can ensure that their patients get the most out of each and every sample collected. This ensures that clients and the practices get value for money from the costs that these techniques entail.