Vet on call: Do cows really die of heart failure?

Last month, I was driving past Shamakhokho in Vihiga County when I received a call from Kimani in Naivasha. He said one of his prized dairy cows had shown signs of dullness and reduced appetite that morning.

An animal health service provider who attended to the cow had said all the other parameters looked normal.

The cow then suddenly collapsed and died without receiving any treatment. Kimani feared the animal could have died of anthrax since there was an outbreak in Nakuru.

Since I was far, I advised him to check out veterinary doctors near his farm because the carcass could not wait until the following day, when I expected to pass through Naivasha on my way back to Nairobi.

Three days later, he called and said he was surprised at the diagnosis he had been given. “Could my cow really have died of heart failure?” he mused.

He sent me the post-mortem report and requested I review it and share my opinion. I received full cooperation from the attending doctor and proceeded to review the report. I also called Kimani’s farm manager for a detailed history of the case before death.

Apparently, the cow had not shown any other signs of illness before the day it died. It was a seven-month pregnant heifer in good body condition.

It was in the maternity pen with 10 other pregnant animals. None of the other cows had shown any signs of illness to that date.

Post-mortem examination had confirmed the carcass was in good body condition. No exterior signs of illness were observed.

There were bleeding spots under the skin and on the surfaces of internal organs. The rumen and other stomachs were full of feed material.

The heart contained a large blood clot. The lungs were enlarged, bleeding and hepatised, meaning that they looked like the liver.

Medically, this means the lungs were inflamed, swollen and contained a lot of blood which makes them look like the liver. It is also called lung consolidation.

INFECTIOUS AGENT

The report further said there was a lot of fat around the heart and the intestines. The author deduced the fat was narrowing the intestinal passage. The doctor concluded the cow died of heart failure due to obesity.

The presence of feed material in the stomachs and intestines confirmed that the animal had died suddenly and not that the intestines were blocked by fat.

It is normal for the heart to have a large blood clot after death and therefore that did not signify heart failure.

The presence of fat around the intestines and the heart is normal as fat forms a good protective cushion to safeguard these organs from external physical forces that may go past the body wall.

That is why animals, including humans, will fight hitting each other with brute force and the internal organs still remain intact.

The real cause of death lay in the disease changes seen in the lungs, under the skin and the surfaces of the body organs.

The extensive consolidation of the lungs was not due to inability of the heart to pump blood but the inflammation caused by an infectious agent.

This resulted in fluid oozing through the lung tissue and caused inability of the lungs to oxygenate the blood.

In addition, the bleeding seen on the surface of body organs and under the skin indicated there was a disease agent that created holes in the blood vessels and allowed blood cells to pass out into the tissues. This will normally occur when the infectious agent also produces toxins.

From the doctor’s post-mortem findings, I diagnosed very sudden pneumonia medically known as per acute pneumonia.

The first doctor agreed that heart failure was not the correct post-mortem diagnosis since the lung hepatisation and bleeding under the skin and on the surfaces of internal organs had not been explained. I suspected the cow had died of per acute pneumonia caused by the bacteria Mannheimia haemolytica.

LABORATORY ANALYSIS

The following day, another cow in the same maternity group died suddenly at 4am. She had calved the previous day. At about midnight, the cow started breathing heavily and was staggering. She collapsed and died four hours later.

I carried out a post-mortem examination and got the same findings as the first doctor. This cow had bluing of the skin of the udder and the mucous membranes of the eyes and mouth.

This must also have been there in the first cow since it emanates from inability of the lungs to load the blood with sufficient oxygen.

Examination of the voice box area and the tonsils revealed a lot of bleeding and swelling of the tonsils. This confirmed my earlier diagnosis. I took samples for laboratory analysis.

I advised that all the cows in the maternity pen be treated with antibiotic injections for three days. The manager informed me the following day that the nasal discharge initially observed had stopped and all the animals were eating normally.

The veterinary research laboratories at Kabete confirmed the presence of the suspect bacteria and rested the case. The farm has not had other similar cases since the last one.

Heart failure does occur in cattle but it is very rare. One should be very careful to diagnose the disease because it is usually a result of other disease processes.

These include genetic defects, bacterial infections, high altitude and physical trauma such as nails and wires piercing the heart through the cow’s stomach.

The bacterium Mannheimia haemolytica, formerly called Pasteurella haemolytica, lives innocently in the tonsils of many cattle without causing disease.

When the animal is stressed by weather, calving or pregnancy, the bacteria sometimes rapidly multiply and cause sudden pneumonia. Death of the animal is due to toxins produced by the germ and inability of the lungs to function.