with Phil Rennie
Given how much valuable time and effort is spent on raising young calves; their primary vaccination course is a particularly important part of your stock’s health plan. The main (‘core’) diseases that are controlled by vaccination of calves are a range of Clostridial diseases and some Leptospirosis serovars. Other disease such as salmonella and BVD can also be vaccinated against at an early age as required.
At present there are several Clostridial formulations available on the market, offering immunity for up to 10 different types of Clostridial bacteria. This article will focus on the 5 most common types encountered here in New Zealand.
Clostridium species are a type of bacteria that live in soil and intestinal tracts of animals and humans, which can cause tetanus, pulpy kidney, blackleg, malignant oedema and black disease. Once affected by Clostridial bacteria, animals are very difficult to treat. The typical presentation is sudden death and with understandable frustration these deaths are often in the best grown animals!
Affected cattle are usually found dead with little sign of struggling prior to death. There may be gas under the skin and the animal will usually be bloated. There is usually a blood stained discharge from the nose or mouth. Post mortem decomposition is very rapid (even in cold weather). The main alternative to consider is death from stomach and/or ruminal bloat due to a sudden change in diet. Excess gas production would occur and the huge physical pressure on breathing ultimately causes respiratory and heart failure. An autopsy can help clarify if this is the case.
The specific disease syndromes caused by the main harmful Clostridia bacteria are noted below.
Blackleg: This sporadic disease is caused by infection of the muscles by Clostridium chauvoei. It can occur after wound contamination, grazing muddy winter feed crops, after calving, using dirty vaccination needles or ear markers.
Malignant oedema: This disease is caused by Clostridium septicum and progress’ much like blackleg.
Black disease: This causes rapid death due to infection of the liver by Clostridium novyii. It can be associated with liver fluke infection particularly during the autumn/ early winter period when fluke activity is most prevalent.
Pulpy kidney: This causes convulsions and sudden death by Clostridium perfringens. It can cause diarrhoea by a rapid build-up of toxins in the intestine. Much like sheep it inevitably affects the best grown and well-fed cattle. Typically they are being fed highly nutritious pasture or the allowance of high energy grain supplements has been increased suddenly.
Tetanus: This is seen when Clostridium tetani spores enter deep wounds and dead and damaged tissue. Tetanus is most commonly seen after castration and usually appears 10-14 days after the injury. Affected animals appear to be stiff and go into a rigid spasm if stimulated. There face may appear strained due to contraction of the facial muscles, but otherwise look normal.
Vaccination is very effective and young stock should be vaccinated for the first time by four to six weeks of age. Full protection is not achieved until around ten days after the booster shot, which is given four weeks after the initial shot. An annual booster shot is required for longer term protection.
If you would like further advice on a suitable vaccination programme for your calves or young stock then feel free to give your local vet clinic a call.