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02-21-2013 07:15 AM #1
Septicemia and Bacteremia in Dogs
Septicemia and Bacteremia in Dogs
Bacterial Infection of the Blood (Sepsis) in Dogs
Bacteremia and septicemia occur when the persistent presence of bacterial organisms in a dog's bloodstream becomes systemic, meaning that it has spread throughout the body. This is also referred to as blood poisoning, and septic fever. This condition becomes very dangerous when it leads to abnormally low blood pressure and high body temperature, and can be fatal if left untreated. In severe cases, when the condition has progressed to septic shock, treatment alone will not be enough to save an animal.
Symptoms and Types
There are several signs and symptoms of both septicemia (blood infection) and bacteremia in dogs. Remember that septicemia and bacteremia are not the same thing, although they are similar, and are often used interchangeably.
Sepsis and bacteremia in dogs may develop slowly or suddenly
Signs and symptoms may vary, or they may involve many different organ systems, including the cardiovascular system
Symptoms are often confused with the signs and symptoms of many other immune-regulated diseases
Clinical symptoms are often more severe when the organisms involved are gram-negative organisms. These types of organisms are more likely to cause diseases in the dog
Typically, dogs will develop signs and symptoms of the disease in the gastrointestinal tract first
Initial physical signs and symptoms typically include chills, fever, and lethargy
Depression symptoms are common in dogs
Tachycardia (rapid heart beat) and heart murmur are common
The causes for sepsis and bacteremia in dogs typically include exposure to gram negative organisms, or those organisms that cause diseases in their hosts, including the E. Coli bacteria. Risk factors for the disease may include an existing health condition, such as diabetes mellitus, or liver and kidney failure. Dogs that have weakened immune systems, or those that have skin infections and urinary tract infections are also at risk. Any condition that lowers the immune system places a dog at risk for contraction of a bacterial disease.
A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. Before diagnosing your dog, your doctor will want to rule out other possible causes for illness. Diseases that cause similar symptoms may include immune-mediated diseases. Examples of these types of diseases can include autoimmune diseases like thyroidits or lupus.
Radiographic imaging may discover abscesses on the internal organs.
Successful treatment involves diagnosing the problem quickly enough for the affected dog to receive prompt treatment and aggressive intervention. It is important that the problem be addressed as soon as possible due to the possible severity of the condition. Low blood pressure is the most common complication of the disease. Other complications associated with this disease include low blood sugar and electrolyte imbalances. Infections are also common. Dogs may be more prone to developing an abscess from an infected wound under the skin.
Nutritional support can dramatically improve the health of dogs with sepsis and bacteremia. If your dog is not able to eat by itself, it will be necessary to place an intravenous feeding tube until your dog is stable and capable of eating again. Medications that may help improve the outcome include antibiotics, antimicrobials, and specialized antibiotics that work specifically on this type of infection (as opposed to routine antibiotics).
Living and Management
It is possible for complications to occur, and a high rate of mortality is associated with this condition. The primary concerns associated with septicemia and bacteremia are electrolyte imbalances, low blood pressure, and shock. It is extremely critical to seek prompt medical attention for your dog if you suspect any type of infection is imminent or present.
02-21-2013 07:16 AM #2
Re: Septicemia and Bacteremia in Dogs
Treatment of canine sepsis: First identify, eradicate the cause
Products for management of bacterial infection or canine parvoviral enteritis
Sepsis in dogs most commonly originates from the GI tract (e.g., canine parvoviral enteritis), followed by the respiratory tract (e.g., bacterial pneumonia), severe dental disease, chronic urinary-tract disease and contaminated wounds.
Gram-negative bacterial infections predominate, with E. coli being the most common isolate. However, any bacterial, fungal, parasitic or viral organism may cause sepsis.
Sepsis is diagnosed based on the presence of an underlying infection and identification of systemic inflammatory response syndrome (SIRS). Bacteremia often is not identified and therefore a negative blood culture does not rule out the presence of existing sepsis.
Systemic Inflammatory Response Syndrome (SIRS): a clinical syndrome caused by systemic inflammation of infectious (i.e., sepsis) or non-infectious origin. In dogs, the diagnosis of SIRS is based on fulfillment of at least two of these criteria: tachycardia, tachypnea, hypothermia or hyperthermia and leukocytosis, leukopenia or greater than 3 percent band neutrophils.
Sepsis: the systemic inflammatory response to infection
Severe sepsis: the systemic inflammatory response to infection associated with organ dysfunction and manifestations of hypoperfusion or hypotension
Septic shock: the systemic inflammatory response to infection with hypotension refractory to volume expansion
Bacteremia: the presence of bacteria in the blood stream
The sequence of events leading to sepsis is complex and not completely understood. In the initial phases of infection, microbial products (e.g., endo-toxin from gram-negative bacteria; exotoxins, peptidoglycans and super antigens from gram-positive bacteria; and fungal cell-wall material) induce systemic inflammation through activation of immune cells, resulting in an imbalance between pro-inflammatory mediators (e.g., TNF) and anti-inflammatory mediators (e.g., IL-10).
Tumor necrosis factor (TNF), IL-1 beta, IL-6, IL-8 and leukotrienes are examples of important pro-inflammatory mediators contributing to the pathologic effects of sepsis in dogs. Ultimately, induction of pro-inflammatory mediators leads to inflammatory cell infiltration, altered thermoregulation, vasodilation, vascular leakage and coagulation.
Dogs can have either a hyper-dynamic or hypodynamic response during sepsis. The hyperdynamic response is characterized by fever, brick-red mucous membranes, tachycardia and bounding pulses. With disease-process progression, a hypodynamic response characterized by hypotension, pale mucous membranes and hypothermia can be observed.
Often dogs will have GI or respiratory signs associated with the sepsis. Possible serum chemistry profile abnormalities may include hyperglycemia or hypoglycemia, hypoalbuminemia, azotemia, hyperbilirubinemia and elevated serum ALT and/or ALP.
Coagulation abnormalities are common. Anticoagulant proteins (protein C and antithrombin) are significantly decreased and PT, PTT and D-dimer concentrations are significantly increased in naturally occurring sepsis in dogs.
Altered microcirculation and tissue hypoxia may lead to metabolic acidosis in septic dogs. Little is known about the prevalence of organ dysfunction or failure during canine sepsis, although hemodynamic derangement, renal failure and respiratory failure are recognized.
The most important aspect of treating sepsis in dogs centers on the identification and eradication of the inciting cause (see "Products for management of canine parvoviral enteritis or bacterial infection" below).
An effort should be made to identify the causative microorganism through cytologic examination and culture. Although stringent effort should be made to identify the cause of sepsis, antimicrobial treatment should not be withheld pending these results.
The use of appropriate broad-spectrum antimicrobial agents is recommended. Since bacteria are the leading cause of sepsis in dogs, typically broad-spectrum antibiotic therapy (e.g., fluoroquinolone plus penicillin derivative) is instituted. The remainder of medical therapy centers on maintenance of tissue perfusion and aggressive supportive care. Treatment should, however, be tailored to the needs of the individual dog.
Cardiovascular support is an important aspect of maintaining good tissue perfusion. Intravenous fluid therapy should be instituted in any dog suspected of having sepsis. For some dogs, the administration of colloids and vasopressors will be indicated. Dogs should be volume-resuscitated prior to the institution of vasopressor therapy because vasopressors may alter microvascular circulation, leading to increased tissue hypoxia.
In one experimental study of canine sepsis, epinephrine was found to adversely affect organ function, systemic perfusion and survival as compared to the use of norepinephrine or vasopressin. Along with maintaining good tissue perfusion, maximizing cellular oxygenation is an important aspect of the treatment of sepsis. This may be accomplished by ensuring good oxygen-carrying capacity, providing supplemental oxygen when indicated and preventing microthrombi formation.
Additional supportive care, including nutritional management, frequent reassessment and good nursing care are key aspects in the management of sepsis. Because bacterial translocation from the GI tract is a substantial concern, the early introduction of preferably enteral or, in dogs with vomiting, parenteral nutrition is paramount. Often these dogs require a feeding tube, and this measure should be taken as soon as possible in a hyporexic or anorexic dog.
Additionally, medication aimed at maintaining normal GI-protective mechanisms (e.g., omeprazole, famotidine, Carafate) should be considered. Careful monitoring for any change in the dog's status (e.g., hypotension, dehydration, organ dysfunction, serum chemistry profile or coagulation abnormalities) is prudent and appropriate therapy should be administered as indicated.
Finally, care should be taken to ensure adequate nursing care, including careful use of aseptic technique during catheter manipulation and frequent turning/movement of the afflicted dog.
Polymyxin B is a cyclic cationic polypeptide antibiotic that binds the endotoxin that is released from gram-negative bacteria during sepsis, causing activation of inflammatory cells. Endotoxin that is bound to polymyxin is unable to activate inflammatory cells, preventing cytokine production and development of systemic inflammation.
Administration of polymyxin may be an efficacious, affordable and safe means of inhibiting gram-negative, bacteria-induced inflammation dogs. In a placebo-controlled clinical trial, dogs treated with polymyxin (12,500 IU/kg, IM BID) had significantly improved hydration, capillary refill time, pulse quality and significantly lower plasma TNF concentrations than the control group during naturally occurring gram-negative sepsis.
Potential dose-dependent side effects of polymyxin B include respiratory depression, nephrotoxicosis, cardiovascular compromise and neuro-toxicosis. However, the dose needed to achieve anti-endotoxic effects is low, making these side effects unlikely. Polymyxin B is routinely used in the treatment of gram-negative sepsis in horses with good success. Therefore, polymyxin B may be considered as a potential treatment for gram-negative sepsis in dogs.
Activated protein C is an anticoagulant protein. It possesses anti-inflammatory, profibrinolytic and anti-apoptotic effects. During sepsis, there is a clear interrelation between the coagulation system and the inflammatory system. In a multi-center, randomized, controlled, clinical trial, recombinant human-activated protein C decreased mortality from severe sepsis in humans. A canine form of activated protein C is not available but, if developed, could be a promising novel treatment for sepsis in dogs.
Corticosteroids: The use of cortico-steroids for treating sepsis has fallen out of favour due to their immunosuppressive, ulcerogenic and prothrombotic nature. Additionally, clinical trials of the use of corticosteroids in human sepsis have been disappointing. One exception may be the use of low or physiologic doses of corticosteroids for management of relative adrenal insufficiency during sepsis.
In human medicine, relative dysfunction of the adrenal glands does occur during severe sepsis. Corticosteroids have been shown to decrease the need for vasopressors during septic shock in patients with relative adrenal insufficiency. Reports of the effects of corticosteroids on mortality in this situation have been mixed, but lower doses appear to be associated with better outcome. At this time, there is little information about the incidence of relative adrenal insufficiency in dogs with sepsis. Therefore, it is unknown if corticosteroids may be an appropriate adjunctive therapy in dogs. Care should be taken to avoid corticosteroids except in rare cases where adrenal insufficiency is highly suspected and/or documented.
Insulin: Alterations in glucose metabolism during sepsis are well documented. The administration of regular insulin to maintain tight glycemic control has decreased mortality by approximately 40 percent in humans with post-surgical sepsis. Additionally, in experimental models, administration of insulin decreases inflammation and mortality from sepsis. Although this management strategy has not been evaluated in dogs, it warrants further attention and good glycemic control should be a consideration.
Anesthetic/analgesic drugs: Most anesthetic/analgesic drugs possess anti-inflammatory properties during sepsis. Drugs like the opiate sufentanil and the NMDA-receptor antagonist (e.g., ketamine) have been shown to decrease the production of TNF during experimental endotoxemia in dogs. The clinical impact of these findings is unknown and further study is indicated to determine the role of anesthetic/analgesic drugs for the management of sepsis.
Note: Owners do not want their beloved sick dog to be in pain.
Canine parvoviral enteritis or bacterial infection History and physical examination
Acute gastrointestinal problems in puppies younger than 6 months
Gastrointestinal signs such as vomiting, diarrhea, anorexia, depression
Fecal parvovirus antigen test
Serum chemistry profile and electrolytes
Intestinal parasites are likely to be present such as hookworms, roundworms, giardia.
Medical and/or surgical procedures
Aseptically place an intravenous or intraosseous in-dwelling catheter.
Provide adequate fluids for reperfusion of vital organs, using lactated Ringer's solution or Normosol-R at a volume and rate adequate to restore perfusion to the vital organ at a supranormal level.
If perfusion is poor, rapidly infuse an intravenous bolus of hetastarch or dextran 70 at a rate of 20 ml per kg for initial resuscitation and provide supplemental oxygen by nasal catheter.
Do not use hypertonic saline solution in this resuscitative process, because the animal is usually severely dehydrated.
Rehydrate with lactated Ringer's solution or Normosol-R at a rate of 3 ml to 10 ml per kg per hour initially until hydration is restored over four hours; maintenance rate is 2 ml to 3 ml per kg per hour.
Note: Using hetastarch or dextran 70, less fluid is lost into the gastro-intestinal tract, and the total volume of fluid required for rehydration is approximately 50 percent of what is used when lactated Ringer's solution or Normosol-R is used alone
Administer intravenous antimicrobial agents such as first-generation cephalosporins.
If the animal appears to be septic, consider cephalosporins, an aminoglycoside and metronidazole once perfusion has improved.
Palpate the animal's abdomen at least every four hours to detect intussusception.
Give nothing orally until vomiting is controlled.
Flush indwelling catheter with heparinized saline solution every six hours.
Warm or cool the animal as deemed necessary once perfusion has been restored.
Listen for bowel sounds; if decreased or no bowel sounds are detected, put the animal on metoclopramide via the intravenous drip.
Control significant vomiting with administration of metoclopramide or chlorpromazine.
If vomiting is persistent, place a nasogastric tube and suction the gastric contents every one to two hours initially; back off the frequency of suctioning as directed by withdrawal of gastric fluid.
Use the nasogastric tube to give microenteral nutrition.
Once the vomiting has been controlled, begin the administration of oral electrolyte solution supplemented with glucose; this can be done by giving 2 ml to 10 ml of a oral electrolyte solution by dosing syringe, or the oral electrolyte solution can be placed in a fluid bag and dripped continuously into the nasogastric tube at a rate of 2 ml to 10 ml per hour.
Once the animal tolerates the oral electrolyte solution for at least four to six hours, begin liquid nutritional supplementation.
Packed-cell volume, total plasma solids, blood urea nitrogen, glucose, sodium, and potassium every four to six hours.
Supplement and adjust fluid rate as deemed necessary.
Check perfusion parameters (mucous-membrane color, pulse rate and intensity, capillary refill time, blood pressure, central venous pressure) every two to four hours, and resuscitate with fluids plus or minus hetastarch or dextran 70 infusion as necessary.
Estimate quantity of vomiting, diarrhea and urine output, and record observations every two hours.
Monitor rectal temperature every four to six hours.
Anticipate the problems of poor perfusion, severe dehydration, hypokalemia, hypoglycemia, hypoproteinemia, aspiration pneumonia, sepsis/septic shock, intussusception, hyperthermia or hypothermia, and massive fluid replacement requirements.
Maintain the albumin concentration above 2 g/dl, which likely needs to be done with fresh-frozen plasma on hospital days 2 to 4.
Administer hetastarch or dextran 70 at a rate of 10 ml to 20 ml per kg over four hours, decreasing lactated Ringer's solution or Normosol-R during this time interval, on hospital days 2 and 3.
02-21-2013 08:04 AM #3
Re: Septicemia and Bacteremia in Dogs
Septic Shock 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
Rapid heart rate
Normal or high arterial blood pressure
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
Rapid heart rate or slow heart rate
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)
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
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.
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.
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