Mastocytaemia in cats: Prevalence, detection and quantification methods, haematological associations and potential implications in 30 cats with mast cell tumours

Abstract

The significance of mastocytaemia in cats is different from that in dogs because it appears exclusively associated with mast cell neoplasia. The prevalence of mastocytaemia was 0.05% of all feline submissions to a private laboratory and 43% in cats with mast cell neoplasia. None of 30 healthy cats had mastocytaemia. There was no sex bias or significant age difference between mastocytaemic and non-mastocytaemic cats with mast cell tumours (MCT). Buffy coat (BC) examination was the best screening method for detection of mastocytaemia but direct blood film examination was more accurate for quantifying degree of mastocytaemia. BC examination should be performed in all cases of suspected/known mast cell neoplasia as mastocytaemia was missed on nearly 30% of occasions when direct film examination only was used. Mastocytaemia was associated with decreased haematocrit (HCT) but not with other haematological parameters. Mastocytaemic cats can survive significant lengths of time (up to 27 months) even when splenectomy is not performed.

MASTOCYTEMIA ASSOCIATED WITH A VISCERAL MAST CELL TUMOR IN A SUMATRAN TIGER (PANTHERA TIGRIS)

“…3 Therefore, in cats, detection of mast cells in the blood is a useful diagnostic tool for mast cell neoplasia. 1,9 In the current case, peripheral blood smear analysis revealed a circulating atypical mastocytic population, strongly suggestive of mast cell neoplasia and explaining the moderate leukocytosis observed on the CBC. This finding emphasizes the importance of peripheral blood smear evaluation in hematologic evaluation in exotic species.…”

“…3,9,12 In one study, circulating mast cells were not identified in clinically normal cats or ill cats without mast cell tumor-related disease. 3 Therefore, in cats, detection of mast cells in the blood is a useful diagnostic tool for mast cell neoplasia.…”

Significance of mastocytemia in cats

“…An earlier study found no mast cells during evaluation of BC smears from 40 healthy and 40 ill cats without mast cell tumor (MCT), concluding that mastocytemia is a very rare finding in healthy cats and in cats with non‐MCT‐related diseases . In contrast, bone marrow or BC involvement is reported in up to 100% of cats with systemic MCT . These findings support the value of the practice of BC evaluation for MCT staging in cats.…”

“…Detection of circulating mast cells during blood smear (BS) or buffy coat (BC) evaluation is a rare finding in cats, with an overall reported incidence of 0.05% . An earlier study found no mast cells during evaluation of BC smears from 40 healthy and 40 ill cats without mast cell tumor (MCT), concluding that mastocytemia is a very rare finding in healthy cats and in cats with non‐MCT‐related diseases .…”

Lingual mast cell tumour in a cat

“…The staging approach to feline MCT has not been standardly defined as in dogs; staging for canine patients includes assessing regional lymph nodes with cytology, abdominal ultrasound ±liver and spleen cytology, and thoracic radiographs. While not useful in the dog, buffy coat screening may be more helpful in the cat as mastocytosis is caused almost entirely by mast cell neoplasia (Skeldon and others 2010). Its role in peripheral feline mast cell disease is undefined.…”