Читать книгу Farm Animal Medicine and Surgery - Graham R Duncanson - Страница 107

There are several separate clostridial species which affect cattle, causing different disease entities:

• Bacillary haemoglobinuria has been reported in the UK but is rare, although it is common in central Ireland. The disease is sometimes called bacterial redwater and is caused by Clostridium (Cl.) novyi type D. It occurs in areas of high rainfall, particularly when summers are wet. The signs shown include abdominal pain, jaundice and dysentery, and, as the name suggests, haemoglobinuria. Aggressive treatment is required with penicillin and fluid therapy.

• Blackleg is found worldwide. It is caused by Cl. chauvoei. The first sign is lameness. On examination, the animal will show a very swollen painful area over a wound. Treatment with high doses of penicillin and NSAIDs is rarely successful. There is a vaccine available. See also the section on ‘Clostridial cellulitis’ under ‘Diseases of the Integument’,‘Bacterial skin diseases’.

• Black’s disease or infectious necrotic hepatitis is caused by Cl. novyi type B. The trigger factor is acute fluke infection, i.e. the migration of immature flukes through the liver, which is unusual in cattle. Acute fluke occurs in the autumn. Control can easily be carried out by vaccinating all animals against Cl. novyi type B. Fluke control is vital not only to prevent Black’s disease but also to prevent the damage caused by the flukes in the liver.

• Botulism is caused by the organism Cl. botulinum which multiplies in the soil and in silage but not in the cow. The organism produces toxin outside the body. Therefore the severity of the disease will be related to the amount of toxin ingested. Diagnosis is not difficult if the pathognomic sign of a flaccid anus is seen. There is no specific treatment. Animals will recover if they can be kept alive with oral fluids.

• Enterotoxaemia is found in growing cattle which have overeaten. It is caused by Cl. perfringens type D. There is normally violent scouring. Treatment is with fluids and NSAIDs. Antibiotics are ineffective.

• Malignant oedema is caused by several clostridial organisms, namely Cl. septicum, Cl. chauvoei, Cl. perfringens and Cl. novyi. Animals can be found dead or in extremis. They show swellings, which are often gaseous. The disease may follow wounds, particularly to the vulva at parturition, and cause massive swelling of the hindquarters. Aggressive treatment with penicillin and NSAIDs may be successful if started promptly.

• Necrotic enteritis is a disease of calves caused by Cl. perfringens type C. It is a disease of suckler calves up to 4 months of age. The main signs are diarrhoea, dysentery, tenesmus, abdominal pain and pyrexia. These lead to dehydration and death. Treatment with intravenous fluids, NSAIDs and antibiotics is rarely successful.

• Sordellii abomasitis is caused by Cl. sordellii. It attacks the abomasum and releases lethal toxins causing so-called sudden death, but of course the animals do have a brief period of sickness. There is a vaccine available.

• Tetanus is caused by Cl. tetani. It is rare. Stiffness and rigor will be seen before the jaws become clamped together. Initial treatment should be large doses of tetanus antitoxin (TAT) and also large doses of penicillin. Some practitioners think that injections of acetylpromazine reduce the symptoms but this has not been the author’s experience. Animals may recover if they are given adequate nursing.