It is not always that the doctor would diagnose a disease, give treatment and the patient is up and running.
This is particularly complicated with animals, where sophisticated medical equipment cannot be routinely used for diagnosis. In any case, such equipment may not even exist because of costs and the kind of environments they are supposed to operate in.
Most of the farm animal diseases are thus diagnosed by clinical examination and limited laboratory analysis. If cases are severe enough and laboratory diagnosis shows that the sick animal is a risk to humans and other animals, then full-scale investigation is carried out.
Two weeks ago, I encountered a perplexing case in Kamulu, Machakos County. David reported one of his Friesian dairy cows had breathing difficulties and had been under treatment for the previous four days. The incident had started as a drop in milk yield, followed by poor appetite before the animal completely went off feed.
The cow was treated by a local service provider and it appeared to be getting well but deteriorated on the third day.
On my way to the farm, I discussed the cow’s case with Dan, who had treated the cow. I confirmed he was a paravet licensed by the Kenya Veterinary Board. He told me he had diagnosed red water, gull sickness and pneumonia four days earlier and given treatment. I was satisfied with the treatment he had given based on his diagnosis.
However, on the third day, he was told the cow was breathing heavily and had stopped eating completely. He went and treated the animal further for pneumonia and asked David to call me.
On arrival, I noticed the animal was lying on the left side but the eyes were alert. It had deep strained breathing but the mucous membranes were healthy pink. The eyes were watering and there was heavy salivation with some foam.
The lips and nose kept twitching menacingly, as though the cow wanted to bite something. I put a piece of wood between the teeth and she bit it hard.
The farm manager told me the cow had shown weakness of the hind legs and hind quarters before going down. The temperature was 36.7 degrees Centigrade, which is lower than the normal 38.2. This was an indication that the cow’s body was shutting down.
DISPOSING OF THE CARCASS
The heart beat was rapid and weak while the breathing sounds were harsh. The cow exhibited signs of a nervous condition that was not clear to me. However, the heavy salivation, tearing, menacing twitching of the lips and biting of the piece of wood led me to suspect the cow could have been suffering from rabies.
Having suspected rabies, I briefed the farm manager, his team and David on phone and informed him that I would not be giving any treatment to the cow.
I told him the animal was close to dying and the head would need to be severed, packaged properly and delivered to the National Veterinary Research Laboratories at Kabete for rabies testing. I would also take a blood sample for microscopic examination.
I told the farm manager that while disposing of the carcass, everybody should avoid direct contact with any fluids from the animal. As I finished the discussion, the cow went into a frenzy, clawing the ground with its front legs and breathed its last.
I provided all the farm staff with gloves. They dragged the animal to a burial site in the maize field where I cut off the head and packed it in a watertight plastic material.
I instructed the manager to keep the package safely on the farm and take it to the laboratory early the next morning together with the case notes I had written.
The lab confirmed receiving the sample and would communicate the results in 48 hours. I advised the paravet to get rabies post-exposure shots, just in case the results turned out positive.You see, rabies is a disease that no one should take chances with.
The blood sample I took showed indications of a blood parasite or viral infection. Microscopic examination is limited in such a situation where the rabies virus is suspected and the animal had already been treated for red water.
The red water parasites, medically called babesia, can also cause a blood cell reaction that mimics a viral infection.
However, the parasites would not be seen because they would already have been destroyed by the treatment given.
The laboratory called after 72 hours and said the sample had tested negative for rabies. This was highly welcome news but the question remained, “What was the killer disease that resisted treatment and evaded clinical detection?”
The suspicion of rabies had precluded my carrying out a post-mortem examination on the farm. The cow went into the grave with the secret in her body.
There are a number of diseases that cause nervous signs in cattle such as what David’s cow exhibited. They include the brain form of red water, heart water, a bacterial infection called listeriosis, mad cow disease and a tapeworm that affects the brain.
I had ruled out the diseases because the differentiating signs for each of them were missing in this case. Rabies had also been doubtful because the mucous membranes of the eyes were a healthy pink as opposed to being red and engorged as it happens with rabies infection.
However, we always say diseases do not read books to show all the documented signs. In addition, the set of disease signs documented for any ailment do not necessarily have to all occur in one case at the same time.
I shared with David the laboratory findings, and like myself, the mysterious disease is still confounding.
For now, the case is rested because no further investigations are possible without the carcass. However, if another animal shows similar signs, I will refer it to the University Veterinary School at Kabete for higher level pathological laboratory diagnoses on both the live and dead animal.