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Vet on call: Telling difference between black quarter and anthrax

Friday February 28 2020
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Patrick Mwangi feeds his dairy cattle in a farm in Kuresoi, Nakuru County. Farmers should always be wary of black quarter disease since it kills fast by producing very potent toxins and does not give room for treatment. However the good news is that the disease is effectively prevented through annual vaccination of cattle, sheep and goats. PHOTO | JOHN NJOROGE | NATION MEDIA GROUP

By DR JOSEPH MUGACHIA

The carcass of the high-producing young Friesian cow lay in the maternity pen with blood oozing from the nose and the vulva. I noticed the diagnostic war going on in the minds of my two intern doctors, Joyce and Eddy.

As we got closer to the carcass, Eddy lost patience and asked me if we were not going too close. The early practice life of a recently graduated doctor appears to be full of contradictions.

The last time we saw a carcass oozing like this at Kahawa Sukari, Joyce had quickly told me without prompting that she thought it was anthrax.

In the present case, I had appointed Joyce to be the team leader as we drove to the farm in Naivasha. Kevin, the farm manager, had called and said the cow had died suddenly.

The owner wanted to know what could have killed the animal on the farm that has 200 cows and whether others were in danger.

When Joyce finally saw that I was still advancing towards the animal, she lost her patience. “Doctor, don’t you think we could be dealing with anthrax?” she asked. I told her as the team leader, she should have guided us on what to do rather than ask questions.

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In my style of training, I always try to inculcate in my trainees the attitude that once appointed a leader, one must lead from the front and give unambiguous guidance.

Most trainees find it a difficult concept to execute but that is the way it should be. Joyce got the cue and ordered all of us to stop further approach to first get a detailed history of the case from Kevin. She tasked Eddy with taking notes as she interviewed Kevin.

The two interns then analysed the history and the observations from our standpoint and concluded the case was not anthrax. I agreed with their assessment.

Like an anthrax patient, Daisy had died suddenly and was in good body condition. However, the whole body had stiffened in a process called rigour mortis.

The legs, neck and tail could not be folded but, in the case of anthrax, they fold easily as rigour mortis is inhibited.

MORE ACCURATE DIAGNOSIS

Further, even from our distance, we could see there was no blood coming from the anus and the organ was also not protruding outward as is the case with anthrax. The blood was also red and diluted as opposed to dark and oily for anthrax.

When we did a post-mortem exam on the carcass, we noticed that the blood looked as if it was boiling out of the nose with lots of air bubbles.

The animal appeared to be breathing. Eddy commented that he had never come across a disease with such signs in his training. I reminded him that not all disease signs or post-mortem findings have been documented. Honestly, I had not seen something similar either.

We additionally observed that the carcass was abnormally rounded, especially on the sides and back. Palpating the skin produced crackling sounds under the skin, giving the feeling of an unfolding plastic sheet. The interns correctly diagnosed the occurrence as subcutaneous emphysema or gas accumulation under the skin.

Carrying out post-mortem examination in a maternity pen with 20 cattle presents a serious challenge of animal welfare.

The other animals should be shielded from seeing the carcass being opened up. I did not want to drag the carcass out of the pen to avoid contamination of other areas with whichever organism had caused the sudden death.

We drove out the other cows and screened off the pen with tarpaulin sheets. Before opening the carcass, I explained to my perplexed interns that we were dealing with highly infectious bacteria that produced lots of gas and toxins even after the death of the animal.

That was why the animal appeared to be breathing even in death. Opening up the carcass would lead us to a more accurate diagnosis.

At this point, Joyce requested me to take over the team’s leadership because she felt the case was beyond her experience. I congratulated her for internalising the “Peter principle”; that everyone is promoted to their level of incompetence.

ANNUAL VACCINATION

As I cut through the skin on top of the right shoulder, the carcass released a smelly gas. The tissues below the skin were full of dark blood and kept on getting darker as I cut deeper. There were also tunnels that got wider as I approached the heavy muscles of the shoulder.

Finally, I exposed a wide area where the tunnels began. There was an area, 20cm across in the muscles, which had turned completely black.

Gas tunnels radiated from this area and delivered the gas to the space under the skin. Since the skin is impermeable to the gas, the air spread under the skin all the way to the hip. That is why the carcass looked rounded. There were other smaller blackened areas on the neck and thigh muscles.

The lungs were very dark, broke easily when pressed and were full of gas. This was the gas that escaped into the trachea and nose, giving the impression of breathing.

By the time I concluded the examination, my interns had mentally collated the findings. “Doctor, this is black quarter,” Eddy pronounced heartily without prompting. I complimented him for the diagnosis. We took samples for laboratory confirmation.

I affirmed that the animal had died of black quarter. The disease is caused mainly by the bacterium Clostridium chauvoei.

It kills too fast by producing very potent toxins and does not give room for treatment. The good news is that the disease is effectively prevented through annual vaccination of cattle, sheep and goats.

Herd records showed the animals on the farm were last vaccinated in 2018. We agreed with the owner he would immediately vaccinate the animals and routinely boost them every year. The laboratory results were not yet out by the time of publishing this article.

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