Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

C h a p t e r
INFECTIOUS
DISEASES
Infectious diseases are caused by bacteria, viruses, protozoa, fungi, and rickettsia
that invade the body of a susceptible host and cause an illness. They are
transmitted from one animal to another by contact with infected urine, feces,
and other bodily secretions, or by inhaling pathogen-laden droplets. They may
also be acquired by contact with spores in the soil that enter the body through
the respiratory tract or a break in the skin. A few are sexually transmitted.
Although pathogens exist everywhere in the environment, only a few cause
infection. Fewer still are contagious. Many infectious diseases are speciesspecific.
For example, a dog cannot catch a disease that is specific to a horse,
and vice versa. Other infectious diseases are not species-specific, and are capable
of causing disease in many animals, including humans. In instances where
a disease is zoonotic, public health considerations are discussed.
Many infectious agents are able to survive for long periods outside the host
animal. This knowledge is important in determining how to contain the
spread of infection.
For many diseases, the best way to prevent them is by vaccination.
Immunity and vaccinations are discussed at the end of this chapter.
Bacterial Diseases
Bacteria are single-celled microorganisms that are noted for their ability to
cause disease.
BRUCELLOSIS
This disease is caused by the bacteria Brucella canis. It is a major cause of
sterility and spontaneous abortion in dogs. Puppies infected in utero are typically
aborted at 45 to 59 days after conception. Suspect this disease in any
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