Dog - Anthrax

Anthrax has been in the news. Should I be concerned for my dog?

Anthrax has been used as a method of bio-terrorism. Dogs can be infected, as can most mammals. Birds are normally resistant to the disease. Different animals have different levels of susceptibility to anthrax infection. Herbivores (cattle, sheep, horses) are the most susceptible and humans, dogs and cats relatively less so. Under normal circumstances cases of anthrax in dogs are very rare.

What causes anthrax?

Anthrax is an infection caused by the bacterial microorganism, Bacillus anthracis. This type of bacterium can develop small spherical bodies called spores within the bacterial cell. These spores, each of which can develop into a new anthrax bacterial cell, are much more capable of surviving in the environment than the more fragile parent cell. Spores are also more resistant to disinfectants. Spores may survive in an environment for many years, but it takes quite a large number of spores to cause an infection with symptoms. Environmental spores need not necessarily be considered a threat.

Is anthrax a new disease?

No, anthrax has been described for hundreds of years. It occurs in all parts of the world and is most usually seen as a sporadic disease in farm animals and occasionally in wild animals.

How is anthrax spread?

Anthrax is not normally passed from animal to animal (contagious). Most livestock infections occur by inhalation or ingestion of large numbers of spores from pasture that has been contaminated by a decomposing infected carcase. In carnivores such as dogs ingestion of infected meat is the usual route of infection. People affected are typically farm workers, veterinarians or slaughterhouse personnel etc., who are likely to come into contact with infected carcasses. Even in these cases it usually takes a high dose of spores to cause any more than a local skin infection. Historically sheep fleeces were a source of anthrax spores and anthrax in those workers was called 'wool-sorters disease'.

What are the symptoms?

Anthrax can show several different types of disease.

• Skin form: This is most common in people that come in contact with the anthrax organism or its spores. There is local inflammation of the skin and black pustules form.

• Intestinal form: Here the organism has been ingested in large amounts and the tissues lining the alimentary tract (gut) from the throat down are inflamed with resulting bloody diarrhoea.

• Pneumonic form: Large numbers of the anthrax organisms or spores have been inhaled into the respiratory tract. The lungs are usually severely inflamed.

• Generalised form: This affects most or all body systems including the brain.

Cases are rare in dogs. Infection is usually by ingestion of infected meat and the intestinal form is shown. There is acute gastroenteritis with vomiting and diarrhoea. The throat may be very swollen and there may be obvious swelling of the neck extending to the face and head. The tongue and lips may also be inflamed and swollen.

How can anthrax be treated?

The anthrax bacterium is susceptible to a number of antibiotics including penicillins. Currently the antibiotic of choice is ciprofloxin. Treatment is highly effective in the early stages of infection.

Can my dog be vaccinated against anthrax?

There is currently no commercial anthrax vaccine available for dogs although a number of vaccines of varying effectiveness have been produced starting with the pioneer work of Louis Pasteur in the 1880s. Vaccines are used in some countries for domestic livestock and humans regarded as being at high risk.