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232 Cystitis, Bacterial

○ Other findings depend on cause (e.g., flail smoke inhalation), a CBC (including examina- Chronic Treatment
chest, paralysis causing hypoventilation) tion of whole blood for methemoglobinemia, if Address underlying cause
VetBooks.ir or pulse abnormalities possible with some of highest priority. A diagnostic approach is Possible Complications
relevant) and thoracic radiographs are usually
○ Heart murmur, gallop sound, arrhythmia,
Worsening hypoxemia leading to respiratory
outlined on p. 1408.
cardiac causes
• Stunted growth if congenital cardiac shunts
Differential Diagnosis arrest
Etiology and Pathophysiology • Methemoglobinemia from oxidative injury to Recommended Monitoring
• Etiology (p. 231) red blood cells (e.g., acetaminophen toxicosis Observation of respiratory effort, mucous
• Deoxygenated (reduced) hemoglobin is blue, in cats) or congenital disorders membrane color, pulse oximetry
whereas oxygenated (oxidized) hemoglobin ○ Methemoglobin gives a muddy color to
is red. the mucous membranes, which may be PROGNOSIS & OUTCOME
• Cyanosis appears when the amount of indistinguishable from cyanosis.
deoxygenated hemoglobin increases in the ○ Gross appearance of the blood helps • Short term: guarded, because of hypoxemia
blood. differentiate methemoglobinemia from • Long term: varies widely, depending on
○ The deep blue color of a deoxygenated cyanosis. A drop of blood is applied underlying cause
hemoglobin molecule overwhelms the to a white paper towel. With cyanosis,
red color of an oxygenated hemoglobin dark blue blood becomes redder with PEARLS & CONSIDERATIONS
molecule. exposure to oxygen, but the brown blood
○ In a patient with a normal hematocrit, of methemoglobinemia remains dark. Comments
cyanosis is clinically apparent when • Normal pigmentation/melanin: differentia- • Cyanosis depends on the absolute amount of
the blood concentration of deoxygen- tion involves evaluation of other, nonpig- deoxygenated hemoglobin in the circulation.
ated hemoglobin is > 5 g/dL (normal mented mucous membranes or measurement Animals with hypoperfusion (e.g., shock) or
total blood hemoglobin concentration: of an arterial blood gas sample for oxygen anemia are less cyanotic despite severe hypox-
12.4-19.1 g/dL [dog], 8.5-14.4 g/dL content. emia, whereas animals with erythrocytosis
[cat]). • Normal pink mucous membranes: observed may show cyanosis with minimal hypoxemia.
• When cyanosis is observed, severe hypoxemia in certain lighting conditions (e.g., fluores- • A patient with marked cyanosis and minimal
exists. In a patient with a normal hematocrit, cent lights) may falsely appear cyanotic. dyspnea should be suspected of having right-
cyanosis becomes apparent when PaO 2 < to-left shunting or methemoglobinemia.
50 mm Hg, which corresponds to SaO 2 Initial Database
≈ 80% (normal PaO 2 = 90-100 mm Hg when • Thoracic and lateral cervical radiographs: Technician Tips
breathing room air; normal SaO 2 > 95%). identify airway or lung structural lesions • Pulse oximetry and/or arterial blood gas
• The absolute amount of deoxygenated hemo- • CBC: clues indicating underlying disease or measurements help quantify response to
globin determines the presence of cyanosis, erythrocytosis due to chronic hypoxemia treatment but are not a replacement for
not the proportion of total hemoglobin that • Arterial blood gas: confirm hypoxemia careful observation of respiratory effort.
is deoxygenated. In anemic patients, severe • Echocardiography: identify cardiac shunts • Cyanotic patients are at risk for respiratory
hypoxemia is needed to observe cyanosis, if or other cardiac disease arrest with stress; avoid excessive restraint,
at all. Conversely, animals with erythrocytosis • Oral and pharyngeal exam if upper airway dorsal positioning.
can be cyanotic with proportionally less dyspnea or apnea: identify and correct
reduced hemoglobin or even under normal obstruction SUGGESTED READING
conditions. Tidholm A: Cyanosis. In Ettinger SJ, et al, editors:
• Carboxyhemoglobin, which is elevated TREATMENT Textbook of veterinary internal medicine, ed 8, St.
in carbon monoxide poisoning, confers a Louis, 2017, Elsevier, pp 210-213.
cherry-colored flush to the skin and mucous Treatment Overview AUTHORS: Shauna Blois, DVM, DVSc, DACVIM;
membranes and may mask cyanosis in Correct critical hypoxemia and address cause. Etienne Côté, DVM, DACVIM
affected patients. EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
Acute General Treatment
DIAGNOSIS Oxygen supplementation (p. 1146): although
usually beneficial, minimal/no response expected
Diagnostic Overview with right-to-left shunts
Cyanosis is recognized on physical exam.
Beyond a history to suggest recent causes (e.g.,

Cystitis, Bacterial Client Education
Sheet

BASIC INFORMATION Synonym RISK FACTORS
Lower urinary tract infection (UTI) • Bladder disease, including cystic calculi and
Definition neoplasia
Bacterial infection of the urinary bladder, a Epidemiology • Congenital or acquired structural defects of
disorder that is very common in dogs and less SPECIES, AGE, SEX the lower urinary tract
common in cats • Dogs affected more often than cats • Conditions causing formation of dilute
• Females affected more often than males urine, including diabetes mellitus and
hyperadrenocorticism

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