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Although heart conditions in cows aren’t all that common, we do see cases occasionally. Last Friday was one of those days when vet Tommy Heffernan saw two cows, both with heart conditions.
The first was an early morning call to a cow that staggered in from the field for morning milking. She had milked the night before and was bright up to this point. The farmer – correctly because of the time of year – made a presumption of perhaps grass tetany.
When I arrived on farm the cow was down in the sick pen. We got her up and began an examination; we ruled out grass tetany but unfortunately discovered an equally sinister condition.
On exam, we quickly pinpointed some sort of cardiac disease. We noted the veins in her neck where turgid as the flow of blood back into the heart was being inhibited. I could barely hear a very faint and fast heartbeat.
As the exam continued, the cow collapsed and died within about two minutes. She had suffered cardiac arrest. We decided that a post-mortem would be carried out to identify the problem.
Discovering the problem
In the post-mortem we discovered a condition called pericarditis. This is an infection between the pericardium (membrane covering the heart) and the heart muscle. It was like a basketball of pus around the heart, this is why I could barely hear the heart beat when I listened earlier. It was amazing this cow was so well right up to when she died. The wall of pus surrounding the heart will suffocate the heart eventually.
The causes of this pericarditis is usually a wire penetrating from the stomach through the diaphragm into the heart wall. This can commonly occur at calving time with forcing or contractions of labour. In this case there was no wire, so the likely source of the infection was through the blood.
Both myself and the farmer were glad to get a diagnosis and we both realised there was little we could do. These cases, even when spotted early, can respond poorly to treatment. One thing that is worthwhile is a post-mortem to identify the cause, especially where there is a sudden death.
Another case of heart problems
I saw the second cow later that evening on another farm. I had treated the same cow five weeks earlier for pneumonia. She had responded well to the first treatment but now was in a lot of distress.
On exam I noticed again that the jugular veins in her neck were very congested. There was also a very obvious jugular pulse (a wave of movement up along the vein towards the head). Veins, unlike arteries, should not have a pulse and this is due to the fact that blood wasn’t flowing freely through the heart and was backing up the veins in the neck.
Unfortunately success tends to be on the low side
When I listened to her heart I could hear a very distinct murmur. This murmur is usually associated with a heart that is not pumping blood through efficiently. This sound is classic for cows with lesions on the valves of the heart called endocarditis.
What happens these cases if there is bacteria in the blood stream is that they can lodge on valves and accumulate over time. The nice smooth surface of the valves changes into mushroom-like growths which severely affect blood flow through the heart. I occasionally do see these cases after pneumonia where bacteria enter the blood stream from the lungs and cause the signs I described.
These cases of endocarditis have very variable prognosis. This lady has gone on a long course of antibiotics and we will reassess her this week.
So, thankfully, heart cases are rare, but we do see them. Unfortunately, when we do see them, they are quite far gone and treatment success tends to be on the low side.
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