Page 1489 - Small Animal Internal Medicine, 6th Edition

CHAPTER 94 Polysystemic Bacterial Diseases 1461

BOX 94.1
VetBooks.ir Clinical Findings in Cats With Yersinia pestis
Infection (Plague)
Signalment
All ages, breeds, and gender

History and Physical Examination
Outdoor cats
Male cats
Hunting of rodents or exposure to rodent fleas
Depression
Cervical swellings, draining tracts, lymphadenopathy
Dyspnea or cough
FIG 94.3
Clinicopathologic and Radiographic Evaluation Lymph node aspirate from a cat with bubonic plague
Neutrophilia with or without a left shift stained with Wright stain. Bipolar rods are scattered
Lymphopenia throughout the field.
Neutrophilic lymphadenitis or pneumonitis
Homogenous population of bipolar rods cytologically
(lymph node aspirate or airway washings) hypoalbuminemia, hyperglobulinemia, hyperglycemia, azo-
Serum antibody titers, either negative (peracute) or temia, hypokalemia, hypochloremia, hyperbilirubinemia,
positive
Interstitial and alveolar lung disease and increased activities of alkaline phosphatase and alanine
transaminase are common. Pneumonic plague causes
Diagnosis increased alveolar and diffuse interstitial densities on thoracic
Culture or PCR assay of blood, exudates, tonsillar region, radiographs, and consolidated lung lobes may be detected.
respiratory secretions Cytologic examination of lymph node aspirates reveals lym-
Fluorescent antibody identification of organism in phoid hyperplasia, neutrophilic infiltrates, and bipolar rods
exudates (Fig. 94.3).
Fourfold increase in antibody titer and appropriate Cytologic demonstration of bipolar rods on examination
clinical signs of lymph node aspirates, exudates from draining abscesses,
or airway washings combined with a history of potential
exposure, the presence of rodent fleas, and appropriate clini-
cal signs lead to a presumptive diagnosis of feline plague.
Because some cats survive infection and antibodies can be
Clinical Features detected in serum for at least 300 days, detection of antibod-
Bubonic, septicemic, and pneumonic plague can develop in ies alone may indicate only exposure, not clinical infection.
infected human beings, dogs, and cats (Box 94.1). Bubonic However, demonstration of a fourfold increase in antibody
plague is the most common form of the disease in cats, titer is consistent with recent infection. A definitive diagno-
but individual cats can show clinical signs of all three syn- sis is made by culture, fluorescent antibody demonstration
dromes. Most infected cats or dogs are allowed outdoors of Y. pestis in smears of the tonsillar region, lymph node
and have a history of hunting. Anorexia, depression, cervi- aspirates, exudates from draining abscesses, airway wash-
cal swelling, dyspnea, and cough are common presenting ings, or blood or PCR amplification of Y. pestis DNA from
complaints; fever is detected in most infected cats. Unilateral blood, fluids, or tissues.
or bilateral enlarged tonsils, mandibular lymph nodes, and
anterior cervical lymph nodes are detected in approximately Treatment
50% of infected cats. Cats or dogs with pneumonic plague Supportive care should be administered as indicated for any
commonly have respiratory signs and may cough. In a series bacteremic animal. Cervical lymph node abscesses should
of 62 suspected dog cases, the most common clinical signs be drained and flushed with the clinician wearing gloves, a
included fever (100%), lethargy (97%), and anorexia (77%); mask, and a gown. Parenteral antibiotics should be admin-
only 23% of the dogs had lymphadenopathy (Nichols et al., istered until anorexia and fever resolve. Optimal antibiotics
2014). for treatment of plague in infected cats in the United States
are unknown. Streptomycin administered intramuscularly
Diagnosis at 5 mg/kg q12h was used historically but is not widely
Hematologic and serum biochemical abnormalities reflect available. Cats treated with gentamicin intramuscularly or
bacteremia and are not specific for Y. pestis infection. intravenously at 2 to 4 mg/kg q12-24h, or enrofloxacin intra-
Neutrophilic leukocytosis, left shift and lymphopenia, muscularly or intravenously at 5 mg/kg q24h, have resolved