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494 Hyperemia

Hyperemia Bonus Material
Online
VetBooks.ir Initial Database

BASIC INFORMATION
on the underlying cause. Hyperemia usually
manifests as erythema (redness of the skin • Temperature, heart rate, respiration rate
Definition and mucous membranes) due to vessel ○ Hyperthermia warrants consideration of
• Active hyperemia: increased volume of blood engorgement with oxygenated blood. true fever (e.g., infectious, inflammatory,
in an affected tissue or area due to arterial • Generalized hyperemia drug reaction, neoplastic causes) versus
dilation ○ Tachycardia, tachypnea, hyperthermia environmental hyperthermia (e.g., hot
• Passive hyperemia: increased volume of blood ○ Increased respiratory effort weather, thick haircoat, anxiety, tremor).
in an affected tissue or area due to venous ○ Shortened capillary refill time • Diascopy: superficial lesions blanch with
distention ○ Episodic increased levels of activity external pressure, such as with a glass slide.
• Localized hyperemia ○ This maneuver helps confirm whether
Synonyms ○ Regional dermal redness, swelling, and/ hyperemia is present versus normal
• Active hyperemia: arterial hyperemia, reactive or pain coloration or an area of subcutaneous
hyperemia, metabolic hyperemia ○ Site may be warmer than normal and less hemorrhage.
• Passive hyperemia: venous hyperemia functional
Advanced or Confirmatory Testing
Epidemiology Etiology and Pathophysiology Use of these tests depends on determination
SPECIES, AGE, SEX • Arteriolar dilation usually is in response of need. For example, in animals that are
Any dog or cat to tissue hypoxia, sympathetic neurogenic otherwise clinically normal (routine exam),
mechanisms, and/or exposure to vasodilatory behavioral agitation/anxiety, benign environ-
RISK FACTORS metabolites released locally or systemically, mental hyperthermia, and exercise are common
• Increased tissue metabolic demand (e.g., such as adenosine, nitric oxide, lactate, causes of hyperemia that do not warrant further
fever, physical exertion) potassium ion, and carbon dioxide. evaluation.
• Vascular occlusion: extravascular or • Venous distention, however, occurs in • Blood pressure measurements (p. 1065)
intravascular response to obstruction of blood outflow ○ Systemic
due to obstruction within the capillaries ○ Localized (if embolic occlusion suspected)
GEOGRAPHY AND SEASONALITY or veins due to thickening of the walls or • CBC (infectious, inflammatory, neoplastic,
Vasodilatory cooling related to high envi- thrombi or to external pressure such as from polycythemia)
ronmental temperature is a normal cause of a tumor or tight bandaging. • Serum biochemistry panel (hepatic, renal
hyperemia. dysfunction)
Clinical Presentation DIAGNOSIS • Radiographs (organomegaly, neoplasia)
• Neurologic evaluation (in cases of suspected
DISEASE FORMS/SUBTYPES Diagnostic Overview intoxication or other systemic disorders with
• Primary complaint Hyperemia is a clinical sign associated with a neurologic effects) (p. 1136)
○ Obvious extravascular occlusion such as wide variety of conditions. Rule out obvious • Abdominal ultrasound (neoplasm, infection/
limb constriction causes by a careful history and physical exam abscess, chronic passive congestion)
○ Gross tissue changes and determine whether the presence of hyper- • Echocardiogram (endocarditis, embolic
• Secondary finding emia is clinically significant. disorder, other [p. 1094])
○ Abnormal finding during examination • Aspirates and/or biopsies (masses, lesions)
prompted by another problem Differential Diagnosis • Tick-borne disease titers
○ Incidental finding of no clinical sig- Hyperemia (p. 1234) • Blood gas analysis
nificance (e.g., due to anxiety, physical
activity, hot weather)
• Hyperemia may also be classified as regional
or generalized.

HISTORY, CHIEF COMPLAINT
• Highly variable depending on underlying
cause
• Examples of generalized hyperemia
○ Recent exposure to allergen (e.g., insect
bite, vaccine, food allergen)
○ Exposure to toxic agent (e.g., smoke
inhalation)
○ Exposure to high environmental tempera-
ture (e.g., thick haircoat, locked in car)
○ Systemic disease (e.g., pheochromocytoma,
mast cell disease, shock)
○ Anxiety, restlessness (incidental finding
during routine exam)
PHYSICAL EXAM FINDINGS HYPEREMIA Conjunctival hyperemia in a 5-year-old shih tzu. The image was captured from a digital movie
• Because hyperemia is a clinical sign and not clip obtained by the owner at home. The chief complaint was episodic restlessness and generalized hyperemia,
a disease entity, physical findings depend noted intermittently by the owner for a period of weeks. (Courtesy Dr. Etienne Côté.)

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