Karol A. Mathews

Pain Assessment and General Approach to Management

To manage pain successfully, assessment of the presence and degree of pain is essential. This article describes the various signs and behaviors that may be presumed to be associated with pain of varying degrees. Conditions that are associated with pain and situations that influence the severity of pain are also discussed. The general approach to management of these situations is outlined, with an introduction to the various articles in this issue dealing with specific mechanisms and modalities involved in the treatment of pain.

Nonsteroidal anti-inflammatory analgesics. Indications and contraindications for pain management in dogs and cats.

Nonsteroidal anti-inflammatory analgesics (NSAIAs) are effective in controlling most acute and chronic pain conditions. In veterinary practice these analgesics may be superior to opioids in that the duration of action is much longer, with equal efficacy in many instances, making effective pain management possible for most veterinary patients. NSAIAs act synergistically in combination with other modalities of pain management, including all opioids, local anesthetics, and various sedatives. Because of their mechanism of action, however, there is a potential for perturbation of several homeostatic functions mediated by prostaglandins. Not all NSAIAs are equal in efficacy and safety, so careful patient and NSAIA selection with appropriate monitoring is advised. This article discusses the indications and contraindications for NSAIA use with a short description of the currently available NSAIAs approved for use in veterinary patients.

Neuropathic Pain in Dogs and Cats: If Only They Could Tell Us If They Hurt

Neuropathic pain is difficult to diagnose in veterinary patients because they are unable to verbalize their pain. By assuming that neuropathic pain may exist based on the history of events that each patient has experienced, a focused client history and neurologic examination may identify a lesion resulting in persistent or spontaneous pain. Once neuropathic pain is diagnosed, a trial analgesic or acupuncture session(s) should be prescribed with instructions for owners to observe behavior. Dosing of the analgesic can be titrated to the patients needs while avoiding adverse effects. When a particular analgesic may be ineffectual, an alternate class should be tried. As research into the neurobiologic mechanisms of neuropathic pain continues, specific therapies for its management should eventually appear in the human clinical setting and subsequently be investigated for veterinary clinical use.

Non‐steroidal anti‐inflammatory analgesics: a review of current practice

Objective: This review is intended to update the reader on the clinical aspects of the non-steroidal anti-inflammatory analgesics (NSAIAs) currently used in veterinary practice. Most NSAIAs act by selectively, or preferentially, inhibiting the synthesis of cyclooxygenase (COX)-1 or COX-2, or both COX-1 and COX-2 enzymes which oxidize arachadonic acid to a series of prostenoids. The prostenoids are precursors of various prostaglandins required for many homeostatic functions throughout the body. The COX-1 and COX-2 enzymes are constitutive, however the COX-2 enzyme is also induced following injury or inflammation facilitating the transmission of pain. As the newer NSAIAs focus on the inhibition of COX-2, this review offers a more detailed discussion of this enzyme. Data synthesis: This data was obtained from recent review articles and original published reports in both the veterinary and human literature. A CAB and Medline search was also used. Conclusions: The NSAIAs are effective analgesics for managing moderate to severe pain in many species of animals; however, potential adverse effects may occur if used inappropriately. Guidelines, including indications, contraindications and dosing regimens for the commonly available NSAIAs are included.

Retrospective cohort study on the incidence of acute kidney injury and death following hydroxyethyl starch (HES 10% 250/0.5/5:1) administration in dogs (2007-2010).

Objective To determine the incidence of in-hospital adverse outcomes including acute kidney injury (AKI) and death in a population of dogs admitted to the intensive care unit (ICU) receiving 10% hydroxyethyl starch (HES) [250/0.5/5:1] compared with the general ICU population, while controlling for illness severity. Design Cohort study conducted between January 2007 and March 2010. Setting Veterinary teaching hospital. Animals Consecutive sample of dogs receiving HES (n = 180) were compared with a randomly selected sample of dogs (n = 242) admitted to the ICU over the same period. Interventions None Measurements and Main Results AKI was defined as an at least 2-fold increase in baseline creatinine concentration or new onset of oliguria/anuria persisting for ≥12 hours. The primary outcome was a composite of in-hospital death or AKI. Unadjusted and adjusted analysis controlling for illness severity using the acute patient physiologic and laboratory evaluation (APPLEfast) score and other confounders was performed. HES was administered either as incremental boluses (median dose 8.2 mL/kg/day, interquartile range [IQR] 5.0–11.3 mL/kg/day) or as a continuous rate infusion (CRI; median dose 26mL/kg/day, IQR 24.0–48 mL/kg/day). In unadjusted analysis, HES administration was associated with increased risk of mortality (odds ratio [OR] = 2.33, 95% confidence interval [CI] = 1.51–3.58, P < 0.001) or AKI (OR = 3.87, 95% CI = 1.21–12.37, P = 0.02). In an adjusted analysis after controlling for illness severity, admission type, and concurrent administration of blood products, HES administration remained an independent risk factor for the composite adverse outcome (OR = 1.98, 95% CI = 1.22–3.22, P = 0.005), with a number needed to harm (NNH) = 6 (95% CI = 4–23). Conclusions HES therapy is associated with increased risk of an adverse outcome including death or AKI in dogs. A randomized controlled trial investigating the safety of HES therapy in canine patients is warranted.OBJECTIVE To determine the incidence of in-hospital adverse outcomes including acute kidney injury (AKI) and death in a population of dogs admitted to the intensive care unit (ICU) receiving 10% hydroxyethyl starch (HES) [250/0.5/5:1] compared with the general ICU population, while controlling for illness severity. DESIGN Cohort study conducted between January 2007 and March 2010. SETTING Veterinary teaching hospital. ANIMALS Consecutive sample of dogs receiving HES (n = 180) were compared with a randomly selected sample of dogs (n = 242) admitted to the ICU over the same period. INTERVENTIONS None MEASUREMENTS AND MAIN RESULTS AKI was defined as an at least 2-fold increase in baseline creatinine concentration or new onset of oliguria/anuria persisting for ≥12 hours. The primary outcome was a composite of in-hospital death or AKI. Unadjusted and adjusted analysis controlling for illness severity using the acute patient physiologic and laboratory evaluation (APPLEfast ) score and other confounders was performed. HES was administered either as incremental boluses (median dose 8.2 mL/kg/day, interquartile range [IQR] 5.0-11.3 mL/kg/day) or as a continuous rate infusion (CRI; median dose 26mL/kg/day, IQR 24.0-48 mL/kg/day). In unadjusted analysis, HES administration was associated with increased risk of mortality (odds ratio [OR] = 2.33, 95% confidence interval [CI] = 1.51-3.58, P < 0.001) or AKI (OR = 3.87, 95% CI = 1.21-12.37, P = 0.02). In an adjusted analysis after controlling for illness severity, admission type, and concurrent administration of blood products, HES administration remained an independent risk factor for the composite adverse outcome (OR = 1.98, 95% CI = 1.22-3.22, P = 0.005), with a number needed to harm (NNH) = 6 (95% CI = 4-23). CONCLUSIONS HES therapy is associated with increased risk of an adverse outcome including death or AKI in dogs. A randomized controlled trial investigating the safety of HES therapy in canine patients is warranted.

Adjunctive analgesic therapy.

Adjuvant analgesics are drugs that have weak or nonexistent analgesic action when administered alone but can enhance analgesic actions when coadministered with known analgesic agents. Such agents are often administered in cases of refractory pain. For some chronic pain syndromes, however, they may constitute a first-line approach. Because pain is such an individual experience, analgesic regimens may require several drugs at varying dosages to confer a comfortable state. Adjunctive therapies such as the tricyclic antidepressants, anticonvulsants, N-methyl-D-aspartic acid receptor antagonists and low-dose intravenous local anesthetics, to name a few, have proved to be efficacious in relieving certain types of pain, especially neuropathic and cancer pain. Their use in animals is increasing, with anecdotal reports of some success.

Illness Severity Scores in Veterinary Medicine: What Can We Learn?

Illness severity scores are gaining increasing popularity in veterinary medicine. This article discusses their applications in both clinical medicine and research, reviews the caveats pertaining to their use, and discusses some of the issues that arise in appropriate construction of a score. Illness severity scores can be used to decrease bias and confounding and add important contextual information to research by providing a quantitative and objective measure of patient illness. In addition, illness severity scores can be used to benchmark performance, and establish protocols for triage and therapeutic management. Many diagnosis-specific and diagnosis-independent veterinary scores have been developed in recent years. Although score use in veterinary research is increasing, the scores available are currently underutilized, particularly in the context of observational studies. Analysis of treatment effect while controlling for illness severity by an objective measure can improve the validity of the conclusions of observational studies. In randomized trials, illness severity scores can be used to demonstrate effective randomization, which is of particular utility when group sizes are small. The quality of veterinary scoring systems can be improved by prospective multicenter validation. The prevalence of euthanasia in companion animal medicine poses a unique challenge to scores based on a mortality outcome.

The therapeutic use of 25% human serum albumin in critically ill dogs and cats.

Twenty-five percent human serum albumin (HSA) is a foreign protein and can potentially cause immune-mediated reactions. For this reason, the author only recommends 25% HSA use after risk analysis shows that the benefits outweigh the potential risks of adverse events. If it is apparent that a critically ill animal may succumb to its illness because of the problems associated with severe hypoalbuminemia, the benefit outweighs the risk. The veterinarian must inform the owner of potential delayed immune-mediated reactions, describe these lesions, and follow the case weekly to ensure that no reaction has occurred. Although there are many positive attributes to the administration of 25% HSA, there seems to be specific situations in which 25% HSA may be indicated and others in which it may not be indicated.

Pain management for the pregnant, lactating, and neonatal to pediatric cat and dog.

Little information on the approach to analgesia in pregnant, nursing, or extremely young animals is available in the veterinary literature. Various analgesics and analgesic modalities are discussed, with emphasis placed on preference and caution for each group. Management of pain is extremely important in all animals but especially in the extremely young, in which a permanent hyperalgesic response to pain may exist with inadequate therapy. Inappropriate analgesic selection in pregnant and nursing mothers may result in congenital abnormalities of the fetus or neonate. Inadequate analgesia in nursing mothers may cause aggressive behavior toward the young. Review of the human and veterinary literature on the various analgesics available for use in this group of patients is discussed.

Low central venous oxygen saturation is associated with increased mortality in critically ill dogs.

OBJECTIVES To investigate relationships between central venous oxygen saturation (ScvO(2)) and survival to hospital discharge in dogs. Central venous oxygen saturation is an accessible measure of the balance between systemic oxygen delivery and consumption. METHODS Prospective observational cohort study, enrolling 126 client-owned dogs with central venous catheters. Central venous oxygen saturation was measured over the 24 hours following intensive care unit admission. Poor outcome was defined as death or euthanasia performed for moribund status. Regression analysis identified independent predictors of non-survival and physiologic parameters associated with central venous oxygen saturation. Area under the receiver operator curve analysis identified a cut-off point of central venous oxygen saturation, below which central venous oxygen saturation decrease was associated with increased mortality risk. RESULTS Mortality risk was 30·9%. Low central venous oxygen saturation was associated with poor outcome (P<0·05). Area under the receiver operator curve analysis selected a central venous oxygen saturation of 68% as the point below which a fall in central venous oxygen saturation was associated with increased mortality risk. For each 10% drop in central venous oxygen saturation below 68%, odds of non-survival increased by 2·66 times (P=0·0002, 95% confidence interval of odds ratio=1·45 to 4·85). Central venous oxygen saturation was equivalent to lactate in predicting non-survival. Predictors of central venous oxygen saturation (packed cell volume, mean arterial blood pressure, fever, % arterial haemoglobin saturation as measured by pulse oximeter) were consistent with hypothesised physiologic mechanisms. CLINICAL SIGNIFICANCE Central venous oxygen saturation was a strong mortality predictor. Further work is needed to determine if therapy targeting central venous oxygen saturation can reduce mortality in canine intensive care unit patients.