Antibiotics are used to fight
bacteria and fungus in and on the body. Bacteria are classified according to
their ability to cause disease. Pathogenic bacteria are capable of producing a
particular illness or infection. Nonpathogenic bacteria live on or within the
host but do not cause illness under normal conditions. These bacteria are
called normal flora. Some actually produce substances necessary to the
well-being of the host. For example, bacteria in the bowel synthesize vitamin
K, which is necessary for blood clotting. Rarely, nonpathogenic bacteria will
overgrow and cause symptoms due to their sheer numbers.
Antibiotics fall into two categories: Bacteriostatic and fungistatic drugs
inhibit the growth of microorganisms but don’t kill them; bactericidal and
fungicidal drugs destroy the microorganisms outright.
Estrus, or heat, is the stage in a female dog's reproductive cycle during which she becomes receptive to mating with males. At this time, estrogen levels first increase and then sharply decrease, and mature eggs are released from the ovaries. Ideally, your dog should be spayed before she enters her first heat cycle.
Antibiotics may not always be effective, for a number of reasons.
Inadequate Wound Care
Antibiotics enter the bloodstream and are carried to the source of the
infection. Abscesses, wounds that contain devitalized
tissue, and wounds with foreign bodies (dirt or splinters, for example) are
resistant areas. Under such circumstances, antibiotics can’t penetrate the
wound completely. Accordingly, it is essential to drain abscesses, clean dirty
wounds, and remove foreign bodies.
An antibiotic chosen to treat an infection must be effective against the
specific type of bacteria that is infecting the body. The best way to determine
susceptibility is to sample the organism, grow it on a culture plate, and
identify it by the way its colony appears and by microscopic characteristics.
Antibiotic discs are then applied to the culture plate to see which discs
inhibit the growth of bacteria colonies. The results are graded according to
whether the bacteria are sensitive, indifferent, or insensitive to the effects
of the antibiotic. Laboratory findings, however, do not always coincide with
results in the patient. Nonetheless, sensitivity testing is the best way to
select the most effective antibiotic.
Route of Administration
An important medical decision is choosing the best route for administration.
In a dog with severe infections,
antibiotics may be given intravenously or by intramuscular or subcutaneous
injection. Some oral antibiotics should be given on an empty stomach; others
with a meal. Incomplete absorption is one cause of inadequate levels of
antibiotics in the blood. If the dog is vomiting, oral medications may
not be absorbed.