Acute Heartwater most often begins with a sudden fever, anorexia and listlessness, some may also develop diarrhoea. These symptoms are most often followed by neurological signs that may include chewing movements, protrusion of the tongue, twitching of the eyelids, and circling, often with a high stepping gait. Affected animals sometimes stand rigidly with muscle tremors and may become aggressive or anxious. As the disease progresses, the neurologic signs become more severe, and the animal goes into convulsions.
In the terminal stages, lateral recumbency with paddling or galloping movements, opisthotonos, hyperesthesia, nystagmus and frothing at the mouth are common.
Animals with the acute form of Heartwater will usually die within a week of infection.
On rare occasions, Heartwater occurs as a subacute disease (a condition which falls between acute and chronic) with symptoms such as a prolonged fever, coughing and mild incoordination: these animals will either recover or die within 1 to 2 weeks.
Where fatalities have occurred and post mortems have been carried out: Common lesions include Pulmonary and Mediastinal Oedema, Intestinal Congestion, Hydrothorax, Ascites, and Oedema of the Mediastinal and Bronchial Lymph Nodes. Petechial Haemorrhages are often found on the Epicardium and Endocardium Congestion and Meningeal Oedema have also been found in the brain.
Morbidity and Mortality of Heartwater
The mortality rate in susceptible animals ranges from 6% to 90%. Breeds of domesticated ruminants vary in their susceptibility, with higher morbidity and mortality rates in non-native than indigenous breeds.
Most infections in wild ruminants appear to be subclinical or mild.
Control of Heartwater
Because of the fragility of the Heartwater organism and its inability to survive outside of a host for more than a few hours, it is possible to reduce the presence and possibly eradicate the presence of Heartwater in a certain geographic area, cattle or game breeding farm.
The Springbok | Heartwater Coffee Springbok at Purple Rain Game Breeding are proven Heartwater resistant, with zero mortalities from this disease in the past eighteen months. We have been able to control Heartwater by ensuring that our animals were initially blocked and have now built up a natural resistance (immunity) to this disease.
We continue controlled dipping and monitoring of our game for ticks and/or symptoms to ensure that our animals remain 100% Heartwater resistant.