Bioterrorism is now a household word. The important role of the veterinarian in addressing the challenges of globalization, emerging zoonoses, and the risks of bioterrorism cannot be overlooked. Although bioterrorism is not a new threat, people are now more cognizant of it than ever before. In 1999, Congress designated the Centers for Disease Control and Prevention (CDC) as the lead agency to address public health planning for bioterrorism. They divided agents of bioterrorism into 3 categories on the basis of their potential for inflicting the greatest number of human casualties. Most of the agents are zoonotic. The 6 agents in category A all have the potential to be dispersed via aerosolization, and 5 cause disease in animals.

Anthrax. Caused by Bacillus anthracis. There are 3 forms in humans: cutaneous, gastrointestinal, and inhalational. Dogs and cats are fairly resistant to B. anthracis but are usually infected through consumption of contaminated raw meat. Clinical signs are associated with the upper portion of the gastrointestinal tract and include edema, local inflammation, and necrosis. Veterinarians should not perform necropsies on an animal suspected to have died of anthrax.

Botulism. From the toxins produced by Clostridium botulinum. The 3 forms in people are food-borne, wound, and intestinal botulism. Inhalational botulism also occurs but almost always results from laboratory exposure. Signs of botulism in dogs and cats are usually ascending weakness from hind limbs to forelimbs with hyporeflexia, hypotonia, weak vocalization, decreased gag reflex and jaw tone, slow papillary reflexes, and eventually respiratory distress and death.

Plague. Caused by Yersinia pestis. In the United States, Y. pestis is found primarily in the western states. Most human infection is acquired from the bites of infected fleas. Dogs are fairly resistant to plague and rarely have clinical signs; however, cats are readily susceptible and can develop pneumonic plague. They can transmit the disease directly to humans through respiratory droplets. Cats present with many clinical signs, including lethargy, anorexia, fever, swollen lymph nodes, discharge from the mouth or nose, and disseminated intravascular coagulation. From 1977 to 1998, there were 23 cases of human plague acquired from sick cats. Six of these were veterinarians or veterinary staff members.

Smallpox. There are 12 known genera of zoonotic poxviruses. Smallpox (Variola major) has thus far been documented only in humans, but other variola viruses occur in both humans and animals. The recent outbreak of monkeypox in the United States shows that transmission of this disease occurs in the same manner as transmission of smallpox. It is not known if dogs and cats are susceptible to monkeypox, but rodents, monkeys, and lagomorphs are. Clinical signs include a macular, papular, vesicular, or pustular rash. Conjunctivitis, coryza, cough, anorexia, and lethargy may also occur. The CDC has released recommendations to veterinarians who might examine animals with monkeypox. (See July 2003 Clinician's Brief, page 8.)

Tularemia. Francisella tularensis was first isolated in Tulare County, California, in 1911. This organism survives for weeks in soil, vegetation, and water and for as long as 6 months in straw litter. Ten to 50 organisms inhaled or injected intradermally are enough to cause illness in humans. Dogs and cats may become infected from ticks, but most become infected by ingesting infected wild rabbits or rodents. Dogs are generally resistant to infection but may have fever, listlessness, or myalgia or may die suddenly. Disease in cats has not been well described but is probably similar to that in dogs and may include lymphadenopathy and organ involvement.

Viral hemorrhagic fever. Ebola virus is probably the most well-known of these viruses but there are several viruses that belong to the viral hemorrhagic fever group.

COMMENTARY: The President and Congress have recently reemphasized the critical role of veterinarians in the global war on terrorism and the protection of animal and human health. The importance of the public health aspects of our profession cannot be overstated, and all types of practitioners from international to local levels can contribute to the effort. This 2-part article is an excellent review of the current issues in bioterrorism and the diseases considered to present the greatest threats.

The ABCs of bioterrorism for veterinarians, focusing on category A agents. Davis R. JAVMA 224:1084-1095, 2004.

The ABCs of bioterrorism for veterinarians, focusing on category B and C agents. Davis R. JAVMA 224:1096-1104, 2004.