The Rule of 20 is a list of 20 critical parameters that should be evaluated at least daily in all critically ill animals; many of these should be assessed several times per day. Using the Rule of 20 ensures that the clinical status and therapeutic strategy for each animal is comprehensive and meets the patient's ongoing needs. Like any monitoring tool, the Rule of 20 is not a static concept but a dynamic one; the specifics of each parameter will change with advancements in laboratory testing, understanding of disease pathology, and current concepts in critical care. Some more recent applications of the Rule of 20 include monitoring of blood lactate levels, adrenal function, body fluid glucose levels, and ultrasonographic assessment techniques.

Fluid Balance

The goal of fluid therapy (see Fluid Therapy) is to provide adequate perfusion (intravascular volume) and hydration (interstitial volume) without overloading the interstitial space. Peripheral perfusion can be assessed by physical parameters such as heart rate, mucous membrane color, pulse quality, and mentation, as well as by measured parameters such as blood pressure, central venous pressure, urine output, and blood lactate measurements. Hydration can be assessed by physical parameters such as mucous membrane and corneal moistness and skin turgor, and by measured values such as body weight. Animals with systemic inflammatory response syndrome (SIRS) diseases may require more fluid than expected because of peripheral vasodilation and loss of endothelial integrity, making the administration of colloids with crystalloid solutions optimal.

Oncotic Pull

Albumin provides the major intravascular oncotic pull in the normal vasculature. In conditions in which there has been massive blood loss or leakage of plasma protein due to an exudative process, albumin is lost from the intra-vascular space. This loss of intravascular oncotic pressure combined with increased capillary permeability associated with many SIRS diseases requires treatment using artificial colloids that have a higher molecular weight than that of albumin. Colloid oncotic pull (COP) can be measured with colloid osmometry. Normal COP in dogs is approximately 20 mm Hg. In patients with moderate to severe decreases in COP or in total proteins, natural and synthetic colloids should be administered. Examples of natural colloids include plasma, human albumin, and stroma-free hemoglobin. Examples of synthetic colloids include dextrans and hydroxyethyl starches.

Glucose

The goal is to maintain glucose between 80 and 120 mg/dL. Septic animals are at an increased risk of hypoglycemia that can be severe enough to cause hypotension or neurologic dysfunction ranging from weakness to stupor or seizures. Other causes of hypoglycemia include inadequate nutrition, glycogen storage diseases, young age, small size, severe liver disease or portosystemic vascular anomalies, certain neoplasias, hypoadrenocorticism, and iatrogenic insulin administration. Dextrose supplementation is warranted in any patient that is hypoglycemic. Solutions with a dextrose concentration >5% are best administered through a central line. Patients with clinical hypoglycemia despite administration of solutions with high dextrose concentrations should be assessed for insulinoma and may benefit from glucagon infusions. A difference of >20 mg/dL in blood glucose values and abdominal fluid glucose values has high sensitivity and specificity for septic peritonitis.

Insulin treatment of hyperglycemia in diabetic patients is important to offset ketoacidosis or hyperosmolar complications. Constant rate infusion of regular insulin can result in the slow and controlled lowering of blood glucose with close monitoring of blood glucose levels. Tight control of elevated blood glucose has improved neurologic outcome after head trauma in critical human patients. Acutely traumatized animals are prone to insulin resistance because of large amounts of circulating stress hormones, and may develop hyperglycemia severe enough to require treatment with insulin. However, the benefit of tight blood glucose control has not been clearly demonstrated in veterinary medicine.

Electrolytes and Acid-Base Balance

Hypokalemia can be a contributing factor in weakness and ileus of critically ill animals. These patients commonly have reduced oral intake and/or increased GI and urinary losses of potassium that require potassium supplementation in the IV fluids. Hyperkalemia can be a life-threatening complication of urinary tract rupture or obstruction, renal failure, reperfusion injury, or massive cellular death. Hyperkalemia commonly results in bradyarrhythmias and can be temporarily treated with calcium gluconate and/or insulin and dextrose while the underlying pathology is addressed. Other important electrolytes to monitor include sodium, ionized calcium, phosphorus, magnesium, and chloride. The anion gap (AG) can be calculated when blood electrolytes are measured: AG = [Na] + [K] – [HCO3] – [C1]. Normal AG values are between 12 and 24 mEq/L. The most common cause of metabolic acidosis is lactic acidosis caused by poor perfusion. Lactate production results in an equimolar production of hydrogen ions and subsequent alterations in blood gas values. Lactate measurements can be easily performed with handheld or benchtop analyzers. Resolution of hyperlactatemia with adequate fluid resuscitation is often associated with improved survival. Treatment involves maximizing blood flow and tissue oxygen delivery. Rarely is the administration of sodium bicarbonate (NaHCO₃) warranted for perfusion-related acidosis. Once perfusion and hydration are corrected, the acid-base status is reassessed.

Acidosis is also associated with underlying diseases that produce acids as part of their specific pathology. A high AG acidosis occurs with the disease states included in the acronym “MUD PILES”: methanol toxicity, uremia, diabetic ketoacidosis, paraldehyde or propylene glycol ingestion, indomethacin or isoniazid administration, lactic acidosis, ethanol or ethylene glycol toxicity, and salicylate ingestion.

If severe metabolic acidosis persists after perfusion has been restored, slow administration of fluids with NaHCO₃ supplementation is warranted, restoring serum values to 13–15 mEq/L. The dosage of NaHCO₃ is calculated as follows:

Serum bicarbonate levels are carefully monitored to meet patient requirements.

Oxygenation and Ventilation

Arterial blood gases are used to detect hypoxemia or hypercarbia. In addition, pulse oximetry (SpO₂) is a relatively noninvasive way of determining the oxygen saturation of hemoglobin. Supplemental oxygen and/or therapeutic ventilation may be indicated with SpO₂ values <96%. Hypercarbia can be detected using end-tidal CO₂ endotracheal tube or nasal sampling (also shown to correlate with arterial CO₂ levels) in animals. Serial monitoring is recommended in the initial management of animals with respiratory compromise to determine the adequacy of oxygen supplementation and the need for mechanical ventilation. If hypoxemia is unresponsive to oxygen supplementation (PaO₂ <60 mm Hg or SpO₂ <90%) or hypercarbia is present (PaCO₂ >60 mm Hg), or if respiratory effort (work of breathing) is substantially increased, mechanical ventilation is necessary. One should not wait for respiratory failure or arrest to begin ventilation. Serial arterial blood gas measurements should be performed during mechanical ventilation to determine any need for adjustment of the ventilator settings.

Level of Consciousness/Mentation

A decline in an animal's level of consciousness warrants investigation to exclude metabolic causes, such as hypoglycemia, hyperglycemia, hepatic encephalopathy, acidosis, electrolyte or osmotic derangements, or sudden development of hypertension, hypotension, or shock. An increase in intracranial pressure can result from intracranial hemorrhage, fluid overload, and/or ischemia. The drugs that the animal is receiving should be carefully evaluated for side effects that can lead to altered mentation or level of consciousness.

Blood Pressure

Blood pressure should be monitored via direct or indirect methods. The goal is to maintain mean arterial blood pressure >60 mm Hg (systolic >90 mm Hg). In hypotensive animals with adequate cardiac function, treatment consists of intravascular volume infusion, oxygen administration, and pain control. Hypotension unresponsive to intravascular volume replacement can be due to one or more of the following: hypoglycemia, acidosis, alkalosis, electrolyte disorders (eg, potassium, calcium, magnesium), brain-stem pathology, cardiac arrhythmias, metabolic toxins (eg, hepatic, renal), ongoing fluid loss, relative hypoadrenocorticism (eg, cortisol deficiency), heart disease, excessive vasodilation, and excessive vasoconstriction. The need for cardiac support with positive inotropes should be assessed. Once intravascular volume (central venous pressure >8 cm H₂O) and cardiac function are assessed as adequate, vasopressor therapy with a constant rate infusion of dopamine (5–15 μg/kg/min), beginning at the lower end of the dosage range and increasing by 2-μg increments, is recommended. Stroma-free hemoglobin can be infused for its pressor effects.

Hypertension is a relatively uncommon condition in veterinary medicine, but it can lead to catastrophic problems such as retinal detachment or neurologic derangements. Hypertension can exacerbate proteinuria in patients with chronic kidney disease. Moderate to severe hypertension can be treated with oral antihypertensive agents such as angiotensin-converting enzyme inhibitors (eg, benazepril), calcium channel blockers (eg, amlodipine), direct arterial dilators (eg, hydralazine), or systemic injectable antihypertensive agents such as nitroprusside.

Heart Rate, Rhythm, and Contractility

The electrical and mechanical systems of the heart should be evaluated separately. Specific antiarrhythmic drug therapy should be instituted when perfusion is compromised by the arrhythmia and the first-line therapy of oxygen supplementation and analgesics has been unsuccessful in controlling the arrhythmia. An echo-cardiogram can be performed to evaluate cardiac contractility in SIRS diseases and to detect underlying cardiac diseases. If cardiac contractility is decreased, dobutamine at 5–10 μg/kg/min (dogs) or 2.5–5.0 μg/kg/min (cats) is considered to provide inotropic support.

Albumin

Part of the oncotic activity normally provided by albumin can be provided by synthetic colloids, but only albumin can perform other functions such as drug, cation, and hormone transport. Interstitial albumin stores are drawn upon to replace serum albumin, and a low serum albumin reflects a total body deficit of albumin. Albumin levels <2 g/dL have been associated with a poorer prognosis. Plasma and albumin transfusions are often administered to supplement the albumin to 2 g/dL. Interstitial albumin stores are replenished first, so multiple units of plasma may be necessary to increase serum albumin levels.

Coagulation

Disseminated intravascular coagulation (DIC) can develop in any animal that has undergone a period of relative vascular stasis as occurs during shock, severe tissue or capillary damage such as that which occurs with trauma, or exposure of capillary endothelial cells to circulating inflammatory mediators as occurs during sepsis or SIRS. In the early stages of DIC, there may be few or no clinical signs. However, as DIC progresses, its effects are obvious and catastrophic. The goal is to detect DIC in the early stages and to slow or prevent its progression.

Early DIC is characterized by a hypercoagulable stage in which serum antithrombin (AT) levels are decreased and the coagulation cascade is activated by any of the precipitating causes. Activation of the coagulation cascade throughout the body depletes the clotting factors and decreases the peripheral platelet count as platelets are incorporated into the clots that form. At this stage, the prothrombin time and partial thromboplastin time may be decreased. However, this stage rapidly progresses to a hypocoagulable stage as the coagulation factors are consumed. In this late stage, the prothrombin time, partial thromboplastin time, and fibrinogen degradation products are increased.

Treatment of DIC focuses on treating the underlying disease and removing the stimulus for continued activation of the coagulation cascade. In the early hypercoagulable stages, treatment focuses on maximizing the function of AT, which is the most abundant natural inhibitor of the serine proteases of the coagulation cascade. When AT levels are adequate, heparin can be administered SC at low dosages (50–100 U/kg, tid). If AT levels are <60% of normal, then plasma transfusions should also be given to increase the level to ≥80%. In animals with diseases known to predispose to DIC, coagulation parameters (at minimum, an activated clotting time and platelet estimate) should be monitored daily. Thomboelastography provides another means of global assessment of the clotting cascade and may be a useful tool with suspected hypo- or hypercoagulable states.

Thrombosis occurs without DIC when there are alterations in Virchow's triad: endothelial injury, blood stasis, and hypercoagulable states. Abnormalities in one or more of these components may occur with vascular anomalies, atrial enlargement, severe systemic illness (SIRS, immune-mediated hemolytic anemia), trauma, neoplasia, renal disease, and hyperadrenocorticism. The most common severe manifestations of hypercoagulability are aortic and pulmonary thromboemboli. Pulmonary thromboemboli should be suspected when there is significant hypoxemia with minimal lung changes on thoracic radiographs. Anticoagulation therapy and oxygen support should be implemented, and oxygenation and ventilation monitored.

Disease states that result in relative hypocoagulability may include anticoagulant rodenticide ingestion, fulminant liver failure, severe thombocytopenia, snake bites, dilutional hypocoagulability from fluid and colloid administration, and congenital defects in the coagulation cascade such as von Willebrand's deficiency or hemophilia A or B. Therapy should be specific to the inciting cause.

Red Blood Cell and Hemoglobin Concentration

Because Hgb carries most of the oxygen in the blood, maintaining adequate Hgb levels is essential to maintaining adequate oxygen delivery. When anemia is associated with clinical signs of tachycardia, increased respiratory rate, altered mentation, and/or weakness and hypotension, packed RBC, whole blood or stroma-free hemoglobin should be administered to bring the PCV to >20% or the Hgb level to 7 g/dL. In some cases of hemolytic or chronic anemia, the PCV can be maintained at a lower percentage before transfusion if there are no corresponding clinical signs.

Before an RBC-containing blood product is administered, a crossmatch should be performed. If multiple transfusions are anticipated, blood typing should be performed as well. Only type-specific blood should be administered to cats.

An alternative means to increase oxygen-carrying capacity of the blood is a commercial stroma-free hemoglobin product.

Animals with a PCV >55% (other than sight hounds and at high altitudes), have microvascular sludging and hypertension. Treatment with IV fluids, and phlebotomy in cases of absolute polycythemia, are performed to improve microvascular flow and oxygen delivery to the tissues.

Renal Function

In animals that have had a hypotensive episode, are receiving potentially nephrotoxic medications, or have primary renal compromise, renal function should be evaluated daily. Urinalysis performed on a sample collected before fluid administration will help to assess renal function. Urine output should be at least 1 mL/kg/hr and can be closely monitored with an indwelling urinary catheter. Animals in polyuric renal failure are most often managed medically; however, animals in oliguric or anuric renal failure may require some form of dialysis to maintain fluid and electrolyte balance. Serial measurement of serum BUN, creatinine, electrolytes, and phosphorus will detect changes and help guide therapy. Serial urinalyses to detect glucosuria, proteinuria, or renal tubular casts are useful for evaluating acute tubular injury before the damage progresses to overt renal failure and azotemia.

Immune Status, Antibiotic Dosage and Selection, and WBC Count

Strict aseptic technique should be observed when examining or treating animals that are neutropenic or receiving immuno-suppressive drugs. These animals should be isolated from other animals and handled by a single person who adheres to appropriate barrier nursing techniques (washes hands, wears gloves and gown before handling the animal, etc).

Ultimately, antibiotic selection should be based on the results of culture and sensitivity, but empiric treatment, based on site of infection and suspected type of bacteria, is necessary pending these results.

In animals that have sustained a hypotensive episode or have a GI disease that would allow bacterial translocation, broad-spectrum bacterial coverage should be provided until the results of culture are available or until the risk of systemic infection has passed.

An antibiotic protocol should be established for veterinary hospitals to minimize the number of antibiotics administered empirically on a routine basis in order to reduce the development of resistant organisms in the hospital environment and improve their susceptibility patterns. Periodic environmental cultures and monitoring culture and sensitivity results for evidence of nosocomial infections and bacterial resistance patterns can help identify sources of and limit nosocomial infections. A first-generation cephalosporin (eg, cefazolin) useful for gram-positive and gram-negative infections is administered at a dosage of 22 mg/kg, tid; an alternative choice is an aminopencillin with a β-lactamase inhibitor (such as clavulanic acid or sulbactam), which has good gram-negative, gram-positive, and anaerobic coverage. If a resistant bacteria is suspected, gentamicin (3–5 mg/kg, IV, sid) can be given to more specifically target gram-negative organisms after hydration and perfusion have normalized. The once-daily dosage is less likely to cause renal toxicity and has the same antibacterial effect as a divided dosage schedule. Metronidazole (7.5–12.5 mg/kg) given slowly IV over 20 min every 6–8 hr, is used for suspected anaerobic infections.

Newer generations and classes of anti-biotics such as fluoroquinolones (eg, enrofloxacin), carbapenems (eg, imipenim), third-generation cephalosporins (eg, ceftazidime), and vancomycin should be reserved for use in patients with bacterial infections that have been demonstrated to be resistant to other antibiotics.

GI Motility and Mucosal Integrity

Critically ill animals, even those without a primary GI disease, are prone to gastric atony, ileus, and stress-induced gastric ulceration. Auscultation for bowel sounds should be performed 3 times a day. Metoclopramide (1–2 mg/kg/day as a constant rate infusion) is useful because of its central antiemetic effects and its ability to increase progressive gastric and intestinal motility. Other motility modifiers to consider include cisapride, ranitidine, and erythromycin. Motility modifiers should be avoided if gastric or intestinal obstruction is suspected or has been confirmed.

Placement of a nasogastric tube to allow removal of accumulated gas and fluid reduces the possibility of aspiration of refluxed gastric contents and allows continuous decompression. The nasogastric tube also can be used to introduce small amounts of a glucose and electrolyte solution or a liquid diet to provide nutrition to the enterocytes, which will help prevent gastric ulceration and intestinal mucosal compromise with secondary bacterial translocation. Antiemetics are used in animals that continue to vomit frequently despite placement of a nasogastric tube, thus improving patient comfort and reducing the incidence of aspiration, vagal-induced collapse, and bradycardia that can accompany the vomiting reflex. Metoclopramide blocks the dopaminergic receptors in the chemoreceptor trigger zone (CRTZ) and central vomiting center and acts peripherally by promoting gastric emptying. Ondansetron and dolasetron are potent antiemetics that block serotonin receptors and act at the CRTZ and the central vomiting center; they are administered at 0.6 mg/kg, sid. Maropitant is an NK₁ receptor antagonist that blocks vomiting at the CRTZ, vomiting center, and peripheral receptors. Vomiting that is refractory to all other treatments in an otherwise stable animal with normal blood pressure can be treated with chlorpromazine (dogs: 0.05–1 mg/kg, IV, every 4–8 hr; cats: 0.01–0.025 mg/kg, IV, every 4–8 hr). A combination of antiemetics that have different mechanisms of action is often required to arrest refractory emesis.

GI ulceration often accompanies critical diseases such as hypotension, hypergastrinemia of liver and kidney disease, and neurologic and respiratory disorders requiring ventilation. Histamine₂-receptor antagonists such as ranitidine and famotidine, and proton pump inhibitors such as omeprazole and esomeprazole be administered to prevent gastric ulcers. However, changing the pH of the stomach can change its microbial flora. Agents such as sucralfate and barium are administered to bind to esophageal and gastric erosions and ulcers.

Drug Dosages and Metabolism

An active medications list should be kept with each patient's record and carefully reviewed daily for potential drug interactions, drug dosages, and possible adverse effects. If renal or hepatic function is compromised, some drug dosages should be decreased to account for decreased elimination. The daily review also should ensure that the dosage has been calculated correctly and that it is appropriate for the animal's current weight. The sudden onset of any new clinical signs should be investigated in light of the medications and their potential adverse effects.

Nutrition

When nutritional needs are not met, patients rapidly develop a negative energy balance, which can result in GI dysfunction, organ dysfunction, poor wound healing, and even death. Direct enteral nutrition will improve the normal GI barrier, function, and motility. Enteral feeding is always preferred, and most patients will tolerate trickle flow feeding techniques. A nasogastric feeding tube will aid in this process and allow decompression of the stomach, providing antiemetic effects. For longterm feeding, an esophagostomy, gastrotomy, nasojejunostomy, or jejunostomy tube can be placed and is well tolerated by most animals.

Feeding by trickle flow is initiated with small volumes of a dilute veterinary liquid diet solution. If an animal has been starved for an extended period of time, nutrition should be increased slowly (25% increase per day) to avoid the hyperglycemia, hypokalemia, hypophosphatemia, and hypomagnesemia of the refeeding syndrome.

For the first 12–24 hr, the diet should be calculated to provide one-third of the daily caloric requirement and is diluted 1 part liquid diet to 2 parts water. This volume is delivered by constant rate infusion over 12–24 hr or divided into small boluses every 2–4 hr. Each time a bolus feeding is administered and every 6 hr during a constant infusion, the feeding tube should he suctioned to determine if any residual volume is present that would necessitate decreasing the volume infused or adding prokinetic agents. After suctioning, the tube should be flushed with saline. If this initial feeding is tolerated, the concentration is increased to 2 parts liquid diet mixed with 1 part water during the next 12–24 hr. If this is tolerated, then the undiluted diet can be delivered to provide the full caloric requirements. As the animal recovers, bolus feeding can be introduced by gradually decreasing feeding frequency and increasing volumes.

When nutritional needs cannot be met by enteral feeding, parenteral feeding is used. Partial parenteral nutrition, consisting of amino acid and carbohydrate solutions, can be infused through a peripheral vein, providing part of the animal's caloric requirements in a readily metabolizable form. Total parenteral nutrition must be delivered through a central venous catheter because of the high osmolarity of the solutions. In animals with prolonged anorexia, vitamin supplementation may be necessary.

Appetite stimulants, such as the serotonin antagonist cyproheptadine and the serotonin agonist mirtazapine, are commonly used in cats to decrease food aversion associated with syringe or force feeding. Benzodiazepines are not good alternatives in cats. The use of appetite stimulants provides inconsistent food intake and is not recommended as the primary means of administering nutrition in the critical feline patient.

Pain Control

Pain activates the stress hormone systems of the body and contributes to morbidity and mortality. Signs of pain, such as increased heart rate and pale mucous membranes, can mimic signs of shock. (Also see Systemic Pharmacotherapeutics of the Nervous System and see Pain Assessment and Management.) Animals that may not show obvious signs of pain but are known to have a painful condition should receive analgesics as part of their treatment (see Monitoring Procedures for the Critically Ill Animal: Analgesics Used in Emergency Practice). Preemptive administration of analgesics is recommended, when possible.

Table 1
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Analgesics Used in Emergency Practice Drug Dosage Comments Morphine Dogs: 0.05–0.4 mg/kg, IV, every 1–4 hr; 0.2–1 mg/kg, IM or SC, every 2–6 hr; 0.1 mg/kg diluted with 0.9% saline administered epidurally at 0.23 mL/kg, every 8–24 hr Cats: 0.05–0.2 mg/kg, IM or SC, every 2–6 hr Incremental IV bolus technique: dogs—increments of 0.1 mg/kg until analgesia appears adequate; cats—increments of 0.02 mg/kg. In dogs, this can be followed by a constant rate infusion at 0.1 mg/kg/hr that can be increased incrementally if needed. Oxymorphone/hydromorphone Dogs: 0.02–0.1 mg/kg, IV, every 2–4 hr; 0.05–0.2 mg/kg, IM or SC, every 2–6 hr Minimal cardiovascular effects; may cause panting Cats: 0.02–0.05 mg/kg, IV, every 2–4 hr; 0.05–0.1 mg/kg, IM or SC, every 2–6 hr Can be given as a constant infusion with the dose divided over 4 hr Fentanyl Dogs: 2–10 μg/kg, IV, every 30–60 min; 2–20 μg/kg/hr, IV as a constant rate infusion With short half-life, fentanyl is best administered as a constant rate infusion. Fentanyl transdermal patch 12.5 μg/hr for animals <2.5 kg body wt; 25 μg/hr for animals 2.5–10 kg body wt; 50 μg/hr for animals 10–20 kg body wt; 75 μg/hr for animals 20–30 kg body wt; 100 μg/hr for animals >30 kg body wt The patches cannot be cut. More than one patch may be used in larger animals. Butorphanol Dogs: 0.2–0.5 mg/kg, IM, IV, or SC, every 1–3 hr Has a ceiling effect; short duration of effect in most dogs. Cats: 0.1–0.4 mg/kg, IM, IV, or SC, every 1–6 hr Can be given as a constant infusion with the dose divided over 4 hr Buprenorphine Dogs: 0.005–0.02 mg/kg, IM or IV, every 1–6 hr May be more difficult to reverse Cats: 0.005–0.01 mg/kg, IM, IV, or sublingual every 4–8 hr Sublingual absorption reported to be excellent in cats

Analgesia in critically ill animals can safely be provided by opioids titrated to effect. Opioids provide potent analgesia (given IV, IM, or SC) with minimal cardiovascular adverse effects, and their actions are reversible with antagonists (eg, naloxone). Long-acting opioids are best avoided in unstable animals. Reports of IV morphine causing hypotension due to histamine release do not seem to be clinically significant if the drug is given over 5–10 min. Other medications such as hydromorphone, oxymorphone, and fentanyl can be given without this risk. A constant rate infusion provides constant analgesia and is often more convenient and less painful than intermittent IM or SC injections. In cats, injectable buprenorphine is absorbed systemically after sublingual administration.

For longterm control of pain, transdermal fentanyl patches are used but require up to 12 hr to reach therapeutic blood levels; analgesia must be provided by injection until adequate blood levels have been reached.

For animals that do not have adequate pain control with opioids alone, ketamine, an NMDA receptor antagonist, can be delivered by constant rate infusion with the opioids. Ketamine may have variable effects on the cardiovascular system, making patient selection crucial, and it should not be used as a sole agent for pain relief. Lidocaine, a local anesthetic, can be used as an adjunct for systemic pain relief when delivered as a constant rate infusion and combined with ketamine and/or an opioid.

Local pain relief can be provided using local infiltrative or nerve blocks on extremities. Intermittent infusions of bupivicaine administered through thoracotomy tubes or abdominal catheters can provide pleural and peritoneal analgesia. Epidural injections by needle or catheters can provide pain relief from pelvic, hindlimb, and abdominal injuries or disease.

Nursing Care

Providing nursing care to critically ill animals requires a skilled, knowledgeable, attentive, and highly trained nursing staff. Recumbent animals should be turned from one side to the other every 4 hr or maintained in variations of sternal recumbency to prevent decubital ulcers and atelectasis. Physical therapy 3–4 times a day is important for maintaining range of motion and muscle tone and blood flow. Catheters should be labeled and marked with the date of placement, and catheter sites should be inspected daily for signs of infection or displacement. When catheters are removed, the tips should be saved for possible culture if there is evidence of inflammation at the catheter site. Urine and fecal soiling should be immediately cleaned. Recumbent animals require regular inspection and cleaning to prevent urine scalding of the skin; tail wraps minimize contamination from diarrhea.

Wound Care and Bandage Changes

Bandages should be changed anytime they become soiled or wet. Distal limb edema can be improved by placing light compression wraps that are changed every day. (Also see Wound Management.) Open wounds should be bandaged on arrival to prevent further contamination or nosocomial infection until surgical debridement can be done. Areas of skin swelling or bruising should be marked to determine progression or resolution of the pathology.

Tender Loving Care

Owner visits should be encouraged. Animals should be handled and spoken to kindly to minimize stress and anxiety. Having familiar items such as toys or blankets from home are helpful for some pets. Consolidating several treatments at one time and turning down the lights at night, when the animal's condition permits, allow the animal some time to rest and sleep undisturbed.

Last full review/revision March 2012 by Rebecca Kirby, DVM, DACVIM, DACVECC; Andrew Linklater, DVM, DACVECC