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The clinical pathology and pathophysiology of heartwater: a review
S R Van Amstel1, A J Guthrie, F Reyers
1Department of Medicine, Faculty of Veterinary Science, University of Pretoria, Onderstepoort.
Insights
This study investigates heartwater disease in calves, revealing that increased capillary permeability significantly impacts cardiac and lung function. Key findings include progressive anemia and altered white blood cell counts, with the underlying cause of permeability changes remaining unknown.
Area of Science:
- Veterinary Pathology
- Animal Physiology
Background:
- Heartwater is a significant tick-borne disease affecting livestock.
- Understanding its clinical pathology and pathophysiology is crucial for effective management.
Purpose of the Study:
- To review existing literature on heartwater's clinical pathology and pathophysiology.
- To compare published findings with results from experimentally induced heartwater in calves.
Main Methods:
- Literature review of heartwater clinical pathology and pathophysiology.
- Comparison with unpublished data from experimental heartwater induction in calves.
Main Results:
- Pathophysiological changes center on increased capillary permeability, affecting cardiac and lung function.
- Severe cases show decreased cardiac output and diastolic blood pressure.
- Lung function varies from respiratory alkalosis to acidosis.
- Clinical pathology reveals progressive anemia, fluctuating white blood cell counts (eosinopenia, lymphocytosis), elevated bilirubin, and decreased total serum proteins (albumin).
Conclusions:
- Increased capillary permeability is a central pathophysiological feature of heartwater, though its cause is undetermined.
- Significant clinical pathological alterations accompany the disease, impacting hematological and biochemical parameters.
Abstract:
This paper reviews the available literature on the clinical pathology and pathophysiology of heartwater and makes comparisons with unpublished results obtained from a recent study in experimentally-induced heartwater in calves. The pathophysiological changes seem to center on an increased capillary permeability the result of which is reflected most noticeably in cardiac and lung function. There is a marked drop in cardiac output in severe cases and some workers have recorded a severe drop in diastolic blood pressure in the advanced stage of the disease. Changes in lung function are variable, depending on the stage of the disease, and may change from a respiratory alkalosis in the early febrile stage to a respiratory acidosis in more advanced cases. The basic cause for the increased capillary permeability is not known. The main clinical pathological changes measured include a progressive anaemia, fluctuations in total and differential white cell count, of which an eosinopenia and a lymphocytosis are the most marked, increases in total bilirubin which coincide with darkening of plasma colour, and a drop in total serum proteins mostly shown in the albumin levels.