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When your sheep suddenly die, the first disease that usually comes to mind is pulpy kidney. Although there are various reasons for sudden mortalities among sheep, pulpy kidney is the most common cause and is especially prevalent in lambs from the ages of three weeks to three months or six to twelve months.
According to Dr Danie Odendaal of Veterinarian Network, pulpy kidney is not transmitted from one farm to the next, or from newly bought-in sheep that come into contact with your flock. Rather, the disease is usually already present on your farm. It is caused by the bacterium Clostridium perfringens type D, which is found on all farms. It is therefore not unique to a specific farm and is present everywhere in the soil.
C. perfringens is ingested by the animal and survives in its gastrointestinal tract; however, under normal veld conditions it does not necessarily cause disease. The disease is attributed to other factors:
- A rapid switch from a low-starch to a high-starch diet.
- A rapid switch from dry pasture to green, succulent pasture.
- Deworming of sheep that present with a high internal parasite loads.
The bacterium therefore remains inside the animal without necessarily having any adverse impact. The problem arises when it starts to divide rapidly, producing a toxin in the process.
Quick onset of pulpy kidney
Dr Odendaal says every Clostridium turns into a toxin upon rapid multiplication. In the case of pulpy kidney, it is the epsilon toxin (also known as ETX). Once absorbed into the blood it spreads to the rest of the animal’s body, where it proceeds to destroy the cells in the most important organs such as the liver, kidneys, lungs, and brain. From there it takes but a few hours for the animal to die.
A dead animal is the only visible sign of disease, he says. A few cases have been recorded of lower toxin levels with animals exhibiting visible signs of disease, but such cases are rare. Furthermore, there is no effective treatment since mortality is caused by the toxin already present in the blood.
Although the disease cannot be treated, it can be prevented – a vaccine was developed years ago. It is crucial to note that the disease develops as soon as the animal experiences any changes to its diet or upon receiving extra nutrition. Vaccination is the only way to prevent the disease.
Vaccination of lambs
Because it is not a disease to trifle with and it is prevalent on most farms, proper planning is essential. Such a plan must be aimed at preventing the disease over the course of a year. The plan also makes provision for timeous procurement of the vaccine.
Lambs obtain the pathogen from the environment or from their mother’s manure/excretions soon after birth, which makes vaccination essential. The only thing protecting these lambs within the first six to eight hours after birth is the immunity-supplying colostrum they get from their mothers.
Your plan must also make provision for the vaccination of ewes six to eight weeks before lambing. The aim is not necessarily to protect the ewe, since ewes that are four or five years old already have good resistance to pulpy kidney. The vaccination is aimed at ensuring that the ewe has enough antibodies, which will find their way to the colostrum and into the lamb upon ingestion.
Colostrum provides immunity
A newborn lamb has no immunity since antibodies are not transferred in the womb. They only start building up immunity upon ingesting colostrum.
Lambs of unvaccinated ewes must be vaccinated at a very young age. Such a lamb will be protected from the pulpy kidney causing pathogens for two to three months. After that, the lamb can be vaccinated again, depending on the prevailing conditions on the farm. On farms on which diseases occur only occasionally, such as in the Karoo, vaccination is only necessary once a year. On farms making use of intensive systems where more complementary feed is given, lambs must be vaccinated once every six months. Active protection is therefore necessary to keep the antibodies active. – Koos du Pisanie, Stockfarm
For more information, contact Dr Danie Odendaal at 082 454 0532.
