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Vet on Call: If you keep dairy cows, don’t let dogs out

Friday January 20 2017

Dairy cattle graze in a farm in Njoro.

Dairy cattle graze in a farm in Njoro. Rabies transmission is mainly through domestic dogs in areas where the animals are not routinely vaccinated. FILE PHOTO | NATION MEDIA GROUP 

DR JOSEPH MUGACHIA
By DR JOSEPH MUGACHIA
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As a veterinary surgeon, several case reports reach my desk, some dire while others tend to be hilarious. I nonetheless take every presentation seriously because I know that farmers report events as they see them.

Some observe an occurrence so strange that they have no words to describe the situation.

Months ago, a phone came in from Ruai at about 11am from Ms Njoroge, a mixed livestock farmer. She told me she had observed a strange behaviour on one of her dairy cows. She giggled and then continued, “Doctor, my cow appears to be overheated.”

Her statement was strange because while cows can get “overheated” leading to heat stroke, that is not known to happen in the country.

Furthermore, the time was April, the period of the year when temperatures are cool in Nairobi. I detected a sense of shyness in her voice and prodded her to provide further information.

“I have seen cows on heat, I mean wanting the bull, but Joyce is acting strange since early this morning. She appears to have too much heat and has even chased the bull out of the pen for lacking interest in her,” she said.

Njoroge’s report didn’t sound quite accurate to me but then in veterinary medicine, we deal with biological systems which do not always conform to what is written in books.

What we consider normal in any situation is the average of many diverse observations. In some situations, you may just be seeing the extreme of an occurrence.

As a rule of thumb, any veterinary medical situation that sounds abnormal must be treated as an emergency because it is difficult to predict the direction of progression.

Mind you, a cow that chases a bull could be developing some form of mental derangement and could as well injure humans in due course.

I got into my ambulatory service truck and started the 40-minute drive journey to Njoroge’s farm. Along the way, I wrestled with many thoughts on disease scenarios that could fit the presentation of the cow I was about to see.

THE DISEASE CONTROL POLICY

In veterinary language, we call this differential diagnosis. We look at all symptoms presented and match them to the most likely disease.

My mental differential diagnosis just drew a blank and I decided it was better for me to revisit the exercise once I had done the full examination of the cow.

On the farm, I found the situation was grave and a recipe for human injury. About 15 people, from the neighbouring farms and Njoroge’s employees, had gathered around the pen to see Joyce, the “overheated” cow.

They were talking animatedly, gesticulating at the cow that would sometimes charge at them and they would move further away from the barriers, then draw closer again.

When the cow came close to the barrier, I saw her eyes were bloodshot.

Njoroge told me the situation had changed since we talked. Joyce was producing foam at the corners of the mouth. She had become aggressive towards people and her hips were swaying as she walked.

The voice had also become hoarse and sometimes she would not even produce any sound when she opened the mouth.

It immediately occurred to me that Joyce had an attack of the furious form of rabies, a disease caused by a virus. It affects all mammals and has no cure.

All animals and people infected with rabies normally die. But the good thing is that rabies is preventable in dogs, cats, humans, horses and donkeys through vaccination.

Food animals like cows are not vaccinated against rabies. The disease control policy is to destroy all infected food animals.

In Kenya, the disease causes the death of more than 2,000 people every year. Rabies transmission is mainly through domestic dogs in areas where the animals are not routinely vaccinated.

The disease occurs in the furious form as seen in Joyce, Njoroge’s cow, and a dumb form. In the dumb form, the affected animal or person becomes weak and paralysed.

RESTRAINS THE DOGS

In both forms, rabies patients have fear of water called hydrophobia, which is associated with painful swallowing.

Having made my diagnosis, I briefed the crowd present at Njoroge’s farm and instructed all of them to wash their faces and hands with plenty of water and soap and then leave the compound.

I asked Njoroge to take the names and contacts of those around because the Directorate of Veterinary Services and that of public health may later be interested in determining if they got any exposure to the rabies virus through the saliva of the cow.

This procedure is called contact tracing and is very important in the control of disease outbreaks in both humans and animals.

I further sought information from Njoroge regarding the possible source of the cow’s infection. It turned out that about three months earlier, one of her dogs had bitten the cow just below the elbow, ran out of the compound and was never seen again.

The wound on the cow healed on its own.

I informed Njoroge that the Kenya Disease Control and Rabies Control Acts required me to report all cases of suspected rabies to the Directorate of Veterinary Services and submit a head sample of the suspect animal where possible.

Together with her staff, we slaughtered the cow, observing all precautions, so as not to be contaminated with fluids from the animal. I separated the head from the body and packed it medically for laboratory analysis.

I then supervised the deep burial of the carcass and advised Njoroge to thoroughly clean and disinfect the cow pen.

Thereafter, I submitted the cow’s head sample to the Veterinary Laboratory at Kabete where rabies was confirmed.

The Veterinary Directorate carried out a rabies awareness and vaccination campaign in the outbreak area a few days after I reported the case.

I have not heard of any other rabies case on Njoroge’s farm. She vaccinated her other dogs and restrains them so that they do not reach her cows.