Enteric diseases caused by bacteria and their treatment
Actinobacillosis
This disease occurs worldwide and is called ‘wooden tongue’. The causal organism is Actinobacillus lignieresii. Treatment with streptomycin daily for 5 days is often successful. See below under ‘Diseases of the Integument’, ‘Bacterial skin diseases’ for more information.
Actinomycosis
The disease occurs worldwide and is called ‘lumpy jaw’. The causal organism is Actinomyces bovis. Treatment with streptomycin daily should be continued for a minimum of 2 weeks. See the under ‘Diseases of the Integument’, ‘Bacterial skin diseases’ for more information.
Calf diphtheria
This is an infection of the oral cavity caused by Fusobacterium necrophorum. The main sign is excess salivation with only a transient illness. It may develop into hard golfball-sized abscesses in the head region. Treatment will require these to be lanced, and antibiotics – normally a mixture of penicillin and streptomycin – to be injected im for 3 days.
Campylobacter jejuni and Campylobacter coli
These organisms can cause mild self-limiting enteritis in calves. No treatment is required and diagnosis can be confirmed on culture.
Clostridial disease
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.
Escherichia coli (E. coli) O157
This is not a pathogen in cattle. However, it is carried by them and therefore carriers are a danger to man. The commensal bacterium of concern is VTEC 0157:H7. It causes no clinical signs in cattle.
Escherichia coli
Certain strains are pathogenic to calves particularly if they are the bacteria with the K99 antigen. These will cause septicaemia. The condition may be peracute so that death may occur before the calf is seen to scour. Most of the strains are resistant to ampicillin. Amoxicillin with clavulanic acid is likely to be the antibiotic of choice, together with rehydration and NSAIDs.
Johne’s disease
Johne’s disease, or paratuberculosis, is caused by Mycobacterium paratuberculosis (M. avium subsp. paratuberculosis). This chronic debilitating disease occurs throughout the world and causes chronic untreatable diarrhoea. It is spread to calves soon after birth but is only seen as a clinical disease in adults, normally after their second calf. The organisms may be seen in the faeces with Zeihl-Neelson (ZN) stain, but the gold standard for diagnosis is culture. Johne’s disease is seen most commonly in the UK in Jersey cows. There is also a serological test, for which blood samples may be taken from the tail vein (see Fig. 3.1). There is a vaccine available.
Fig. 3.1. Blood can be taken from the cow’s tail vein in a test for Johne’s disease.
Salmonellosis
The main causative organisms are Salmonella typhimurium and S. dublin; the former is highly zoonotic. The main condition is in calves but these organisms will cause acute diarrhoea and death in freshly calved cows. The faeces have a distinct and unpleasant smell. Diagnosis is by culture of the faeces in enrichment media. Calves should be treated with rehydration and an appropriate antibiotic per os, e.g. amoxicillin and clavulanic acid, until culture and sensitivity results have been obtained. Cows should receive fluids per os using an Agger’s pump, and parenteral antibiotics and NSAIDs. See also ‘Salmonellosis’ under ‘Abortion and its causes’ in the section ‘Diseases of the Reproductive System’ below.
Enteric diseases caused by protozoa and their treatment
Candida albicans
This yeast can cause diarrhoea in calves after prolonged antibiotic treatment. Peracute deaths from septicaemia have been reported. Treatment is stopping the antibiotic treatment, giving probiotics and fluid replacement.
Coccidiosis