Shock Caused by Bacterial Infection in Dogs

Shock associated with generalized bacterial infection of the body is medically referred to as sepsis, a physical condition known as septic shock. It develops as a complication of an overwhelming generalized systemic infection. Septic shock is associated with low blood flow (hypoperfusion) or low blood pressure (hypotension), which may or may not respond to fluids or medical treatment given to maintain arterial blood pressure. Dogs that are very young or very old are at increased risk due to their undeveloped or lowered immune responses, respectively.

Symptoms and Types

Early shock

• Rapid heart rate
• Normal or high arterial blood pressure
• Bounding pulses
• Reddened moist tissues of the body
• The pink or red color of the gums is very quick to return when the gums are blanched by finger pressure
• Fever
• Rapid breathing

Late shock

• Rapid heart rate or slow heart rate
• Poor pulse
• Pale gums or moist tissues of the body
• The pink color of the gums is slow to return when the gums are blanched by finger pressure
• Cool extremities (from lack of circulation)
• Low body temperature
• Mental depression or stupor
• Production of only small amounts of urine
• Difficulty breathing; rapid breathing
• Small, pinpoint areas of bleeding in the skin and moist tissues of the body.
• Fluid build-up in the tissues, especially the legs and under the skin (swollen limbs)
• Gastrointestinal bleeding
• Extreme weakness

Causes

• Possible history of known infection (such as urinary tract infection or infection/inflammation of the prostate)
• Previous surgery may dispose animals to infection
• Other conditions or treatments that potentially decrease the immune response, such as diabetes mellitus; increased levels of steroids produced by the adrenal glands; , or Cushing's disease; treatment with high-dosage steroids or chemotherapy regimens
• Compromise of the lining of the gastrointestinal tract resulting in bacteria moving from the intestinal tract into the body and causing bacterial toxins to accumulate in the blood (endotoxemia)
• Infection/inflammation of the prostate (prostatitis) and abscesses of the prostate
• Bacterial infection of the lining of the abdomen (septic peritonitis)
• Bacterial infection of the lining of the heart (bacterial endocarditis)
• Urinary tract infection
• Pneumonia
• Gastrointestinal rupture
• Bite wounds

Diagnosis

Clinical features include fever, inflammatory response, and collapse of the circulation system. Septic shock associated with circulatory collapse must be differentiated from systemic infection with adequate compensatory cardiovascular response. Circulatory collapse is associated with rapid heart beat or slow heart beat, reduced cardiac output, low blood pressure, reduction of blood flowing into the tissues, and evidence of multi-organ dysfunction such as mental depression, decreased urination, and hemorrhage. Your doctor will want to keep a close watch on blood pressure.

A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. Your veterinarian will depend heavily on a urinalysis and blood tests to determine your dog's condition. Visual diagnostics will include chest X-rays to look for pneumonia and to examine the heart, and echocardiography may be used to determine whether the heart muscle is working properly. Abdominal ultrasound may help for detection of an underlying abdominal disease.

Treatment

Your dog will be hospitalized for circulatory collapse. Vigorous fluid therapy containing crystalloids and colloids will be needed to increase effective circulating blood volume. Crystalloids are fluids that contain electrolytes (chemical compounds such as sodium, potassium, chloride) necessary for the body to function. Crystalloids generally are similar to the fluid content (plasma) of the blood and move easily between the blood and body tissues. Colloids are fluids that contain larger molecules that stay within the circulating blood to help maintain circulating blood volume. Oxygen supplementation is as important as fluid replacement and will be administered by oxygen cage, mask, or nasal cannula (tube). Aggressive treatment and life support may be required if your dog has progressed to a severe stage of shock.

Your veterinarian may surgically remove any source of generalized bacterial infection, such as an abscess. Medications will be chosen according to the underlying infection and source of infection.

Living and Management

Your veterinarian will keep a close watch on your dog's heart rate, pulse intensity, color of gums and moist tissues (mucous membrane), breathing rate, lung sounds, urine output, mental status, and rectal temperature. Aggressive treatment is generally called for, with fluids or medications to improve heart muscle contraction. Electrocardiogram (ECG), a recording of the electrical activity of the heart, and blood pressure measurement are useful; blood-gas analysis (measurements of oxygen and carbon dioxide levels in arterial blood) and pulse oximetry (a means of measuring oxygen levels in blood) to monitor tissue oxygen levels will also yield important information as your veterinarian monitors your dog's progress.

Further treatment will be based on blood work, such as packed cell volume, a means of measuring the percentage volume of red-blood cells as compared to the fluid volume of blood; serum total protein (a quick laboratory test that provides general information on the level of protein in the fluid portion of the blood); serum electrolytes; liver enzymes; blood urea nitrogen and serum creatine levels (the amount of urea and creatine that is found in the blood; they are normally removed from the blood by the kidneys, this test measures kidney function). These tests will be done as often as your veterinarian deems it necessary, based on your dog's status and response to treatment. Septic shock is a life-threatening condition and the prognosis will depend on the underlying cause.