Activated Charcoal

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What is activated charcoal and how is it meant to work?

Form of carbon processed and treated chemically to create a large number of small pores which increase available surface area for binding to other substances, i.e. microporosity increases adsorptive capacity.
Adsorbent, i.e. poison molecules adhere to its surface
Not absorption whereby the poison molecules would dissolve into and permeate the activated charcoal

Activated charcoal fed to animals that have ingested poisons; not absorbed or metabolised itself, instead binds to some/most of the poison still in the gastrointestinal tract
Charcoal-poison mixture then excreted in faeces
Gastrointestinal decontamination minimises systemic toxin absorption
Considered core part of management of small animal poisoning

Which poisons does activated charcoal adsorb well?

What sorts of substances does activated charcoal bind most avidly to?
From a clinical point of view, are there poisons for which we should be using it versus ones for which we shouldn’t?
Is there any evidence about the relative adsorbent capacity of activated charcoal for different small animal poisons?

Adsorptive capacity likely dependent on/influenced by poison-specific factors, e.g. size and polarity of molecules, degree of ionisation etc.

Bates N, Rawson-Harris P, Edwards N. Common questions in veterinary toxicology. J Sm Anim Pract 2015. 56:298-306:

“The binding of activated charcoal has not been tested against all (or even many) drugs and chemicals, but is known not to significantly adsorb a number of substances such as acids and alkalis, alcohols and glycols (ethylene glycol), metals (e.g. iron, lead), oils and petroleum distillates (e.g. white spirit) and detergents.”

However no references cited.

Use of activated charcoal generally not recommended for caustic or corrosive substances due to apparent lack of efficacy; however unable to find good quality evidence.

Should we be using activated charcoal at all?

Some debate!
[Human medicine] The American Academy of Clinical Toxicology (AACT) and the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) position paper:

"Single-dose activated charcoal should not be administered routinely in the management of poisoned patients...[as]... there is no evidence that administration of activated charcoal improves clinical outcome."

But…a lack of evidence of a beneficial effect on clinical outcome is not the same thing as evidence of a lack of beneficial effect on clinical outcome.

Veterinary patients?

“What you can know for sure – unless I failed to find them – is that there are no good quality prospective randomised controlled trials in clinical canine and feline patients evaluating the impact of activated charcoal on clinical outcome.” (Shailen Jasani)

Multiple variables to be studied, e.g.

  • Individual poisons
  • Different doses of the same poison
  • Whether or not emesis was induced
  • Time from exposure to administration of activated charcoal
  • Etc.

Risk/Cost-benefit assessment: general perception is low risk and cheap with potential for some/considerable/life-saving benefit.

Relative lack of antidotes and other treatment modalities (e.g. haemodialysis, plasma exchange) in veterinary versus human medicine

Contraindications and potential adverse effects

Not risk free albeit clinically significant adverse effects considered very uncommon/rare
Use common sense – e.g. do not administer orally to patients at increased risk of aspiration due to neurological compromise

Clinically significant acute hypernatraemia:

Most commonly cited mechanism is that activated charcoal draws water osmotically into the GI tract; this is then voided causing volume depletion.
Patients may have other co-existing causes of water loss plus reduced water intake
More likely with concurrent cathartic administration – but anecdotally reported with use of activated charcoal alone

Minimising the risk:

  • Ensure patient is adequately (re)hydrated beforehand
  • Tailor approach with respect to blood testing of hydration parameters and use of fluid therapy to individual patient based on risk assessment (e.g. very young or very old patients, existing vomiting, etc.)
  • Patients discharged on multidose activated charcoal following successful induction of emesis: advise clients to ensure free access to water and to contact clinic if any ongoing vomiting or clinical concern; liberal approach to administering antiemetic/antinausea agent before discharge.  
  • Avoid activated charcoal if ingested poison is known/suspected to be one that (potentially) causes hypernatraemia (e.g. homemade play dough); use cautiously for poisons which may induce diuresis (e.g. theobromine (chocolate)).

Pay attention to dose being dispensed:

  • Recommended dose range 0.5-8 g/kg depending on resource consulted
  • Less precise/more liberal empirical dosing may be acceptable for bigger and asymptomatic patients
  • Calculate and measure out doses in patients where there is clinical/hydration status concern; use low end doses and well-spaced dosing intervals for multidose therapy.

Avoid activated charcoal if possibility of gastrointestinal perforation, obstruction or ileus
Some debate about need to avoid if oral medications or antidotes needed
Avoid if gastrointestinal endoscopy or surgery is likely in the near future
Constipation may occur with multiple dose therapy

Timing of administration

Ideally administer as soon as possible after toxin ingestion; efficacy decreases the more time passes.
Many resources suggest not to administer activated charcoal if more than 2 hours have elapsed; this author typically suggests a longer more liberal time frame.
In reality likely to depend on multiple factors, e.g.

  • Rate of toxin absorption from gastrointestinal tract
  • Presence of food
  • Type of preparation e.g. delayed or sustained release?
  • Whether enterohepatic circulation occurs
  • Other factors influencing gastrointestinal motility and function

Paper mentioned in this episode:

Bates N, Rawson-Harris P, Edwards N. Common questions in veterinary toxicology. J Sm Anim Pract 2015. 56:298-306.

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Physiotherapy in the Critical Inpatient

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On this episode of the podcast I am joined by Kim Sheader (MSCP HCPC ACPAT Cat A, Chair ACPAT, RAMP), Chartered Veterinary and Human Physiotherapist, to discuss physiotherapy for the critical inpatient. Kim is a highly qualified and experienced physiotherapist and currently works with The Ralph Mobile Physiotherapy & Rehabilitation service.

I start by finding out about Kim’s background, training and experience in human and more recently veterinary physiotherapy. We then go on to discuss:

  • Physiotherapy for the critical patient with prolonged recumbency
  • Physiotherapy for the dog with moderate-to-severe tetanus
  • Respiratory physiotherapy, a subject about which Kim is especially passionate

To contact Kim please email her at or message her via The Ralph MPRS website

Kim and Kev (Musson), one of her many adorable patients!

Kim and Kev (Musson), one of her many adorable patients!

This podcast is closely aligned with the MedEdLIFE Research Collaborative's Quality Checklist for Podcasts.]

Tweet: Check out FREE audio podcasts from @VetEmCC Also available in iTunes/Stitcher. #veterinary #podcast

Dog and Cat Amputees: 'Tripods'

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On this episode of the podcast I am joined by Rene Agredano and Jim Nelson of TRIPAWDS, “the world's largest support community for animal amputees”, to discuss how we as veterinary staff can be better prepared to help clients with dogs and cats that are either facing or have had a limb amputation.

After some background discussion of the Tripawds resource, we discuss:

  • Ethical and moral considerations carers may have around amputation
  • Steps carers can take to prepare for their amputee dog or cat returning home for the first time
  • Client concerns about when their pet will be normal again, pain management, and the surgical incision

The following links were mentioned in the episode:

Tripawds - Help For Three Legged Dogs And Cats

The Tripawds charitable foundation

Tripawds on YouTube

Tripawds Downloads

The PBS Show that Rene mentions, “Why we love dogs and cats”

The Tripawds blog by an ECC vet: Hank the Tank
(backstory for Hank the Tank)

[This podcast is closely aligned with the MedEdLIFE Research Collaborative's Quality Checklist for Podcasts.]

Tweet: Check out FREE audio podcasts from @VetEmCC Also available in iTunes/Stitcher. #veterinary #podcast

A Journal of Veterinary Emergency and Critical Care Papers Episode

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Episode based on May/June 2016 issue of the Journal of Veterinary Emergency and Critical Care

Please get in touch to request a copy of any of the papers discussed in this episode so you can read and critique the paper yourself!

Balakrishnan A, Drobatz KJ, Reineke EL. Development of anemia, phlebotomy practices, and blood transfusion requirements in 45 critically ill cats (2009–2011). J Vet Emerg Crit Care 2016. 26(3):406-411.

Anaemia is a relatively common clinical finding in critically ill patients
Likely multifactorial
Repeated phlebotomy to collect blood samples for diagnostic testing may be one of the causes or at least one of the contributing factors. Has been demonstrated in people, especially children, and suggested anecdotally in small animal patients.

“Critically ill cats that develop significant anaemia are often treated with blood transfusions. Red blood cell transfusions can help improve oxygen carrying capacity and may improve survival. However, at least in people, blood transfusions are associated with an increased expense, longer hospital stays, and carry the risk of several potentially life-threatening medical complications such as immunological transfusion reactions, infectious diseases, transfusion associated circulatory overload, and transfusion related acute lung injury.”

Information on this topic is limited in the veterinary literature and the primary objectives of this study were to:

  • Describe the incidence and development of anaemia in critically ill cats
  • Document phlebotomy practices and transfusion requirements in these cats
  • Evaluate the association between these factors on both duration of hospitalisation and outcome

Retrospective study
University of Pennsylvania ICU from 2009 to 2011
Exclusion criteria:

  • Did not stay in ICU for more than 48 hours (to exclude stable post-operative cases recovering in ICU)
  • Documented to have anaemia secondary to underlying chronic kidney disease
  • Incomplete medical records

Final sample size of 45 cats
Variety of primary diagnoses; respiratory disease, congestive heart failure and neoplasia most common
All of the cats were admitted via the emergency room in which they mostly stayed for less than 12 hours but some up to 24 hours
Approximately 20% were anaemic on admission to the hospital
40% developed anaemia before admission to the ICU (contribution of haemodilution from fluid therapy?)
Approximately 75% of the cats who were not anaemic on ICU admission went on to develop anaemia while in the ICU

Cats that developed anaemia after admission to the ICU had a significantly longer duration of hospitalisation than cats that did not develop anaemia while in the ICU.
Median duration: anaemic group 5 days, non-anaemic group 4 days
Range: anaemic group 3-24 days, non-anaemic group 3-13 days
Development of anaemia in the ICU was not statistically associated with outcome, just duration of hospitalisation.

Cats that required a blood transfusion for anaemia were found to have a significantly longer duration of hospitalisation but transfusion was not statistically associated with outcome. 


  • Median number of phlebotomies per day for all cats in the ICU was 3 (range 1–6).
  • The 20 cats that developed anaemia during their ICU stay had a significantly greater number of phlebotomies per day (median 3, range 1–5) than the 7 cats that did not develop anaemia (median 1, range 1–2).
  • Cats that required a pRBC transfusion had a significantly greater number of daily phlebotomies (median 3, range 1–6) than cats that did not require a transfusion (median 2, range 1–4).
  • Cats that had a sampling or central venous catheter had a significantly greater number of phlebotomies (median 3, range 1–6) than cats without either of these catheters (median 1, range 1–2).

Results suggest that cats that developed anaemia after admission to their ICU had a longer duration of hospitalisation, likewise cats that received a blood transfusion. And probably this is because these cats were sicker.
These cats also had more blood samples taken, again probably because they were sicker.
Vicious circle: sicker cats have more blood samples taken = more blood loss = tendency towards or worsening of anaemia
Sicker cats also more likely to have anaemia as a result of other factors, potentially including a poorer regenerative response

Authors did not attempt to calculate any sort of illness severity scores because of the limitations in getting all the necessary data.

“In light of our study findings, adoption of blood conservation strategies should be considered. Blood conservation strategies are widely advocated in human intensive care medicine, particularly in critically ill children and include minimizing daily routine diagnostic phlebotomies, use of small volume or pediatric phlebotomy tubes, point of care and bedside microanalysis, minimization of blood sample wastage, lowering transfusion thresholds and transfusing only in response to physiologic need, and removing central venous and arterial catheters when no longer needed for patient monitoring purposes.”

For cats that do not have an in-dwelling sampling catheter in place, venepuncture is not entirely benign or risk free; unnecessary sampling can also contribute to patient stress, distress and reduced welfare.

Beer KS, Drobatz KJ. Severe anemia in cats with urethral obstruction: 17 cases (2002–2011). J Vet Emerg Crit Care 2016. 26(3):393-397.

“We hypothesized that cats with urethral obstruction and severe anemia requiring transfusion would have higher morbidity and mortality than cats with urethral obstruction without severe anemia.”

From an evidence-based perspective, this study was not able to prove or disprove this hypothesis.

Retrospective study from University of Pennsylvania over nine year period
Several limitations with respect to materials and methods, including small sample size:

  • 46 tomcats with urethral obstruction and anaemia
  • 17 tomcats met inclusion criteria, one of which was a PCV during hospitalisation of less than or equal to 20%
  • 2132 tomcats were treated for urethral obstruction during study period; 17 study cats = incidence of 0.8%

Authors suggest severe anaemia may largely be due to haemorrhage into urinary bladder – but this study does not provide evidence for this suggestion.

Full AM, Barnes Heller HL, Mercier M. Prevalence, clinical presentation, prognosis, and outcome of 17 dogs with spinal shock and acute thoracolumbar spinal cord disease. J Vet Emerg Crit Care 2016. 26(3): 412–418.

“Spinal shock is uncommonly reported in veterinary medicine and occurs when the spinal reflex arcs are anatomically normal but the patient exhibits transient hyporeflexia or areflexia caudal to a lesion….This is followed by a period of gradual return of the segmental spinal reflexes, and eventually hyperreflexia days to months later…In dogs with spinal shock the neurologic examination may yield a multifocal disease process or a lesion within the reflex arc, which could lead a clinician to an inaccurate neuroanatomic localization and differential diagnoses, and inappropriate diagnostic and treatment plan. An increased awareness of the prevalence, clinical presentation, common etiologies, and progress of spinal shock will aid the clinician in recognizing this syndrome.”

Upper motor neuron (UMN) lesion: expect hyperreflexia
Lower motor neuron (LMN) lesion: expect hyporeflexia
Authors key point is: If you examined a patient and found hyporeflexia you may suspect a LMN spinal reflex arc lesion when in fact the actual lesion is an UMN spinal cord lesion cranial to the localisation and the hyporeflexia is the result of spinal shock.

“The purpose of this study was to describe the prevalence and clinical presentation for dogs with thoracic vertebrae 3 (T3) to lumbar vertebrae 3 (L3) spinal lesions and suspected spinal shock.”

Retrospective study; November 2005 to 2010; private referral hospital in North America
986 dogs had spinal MRI performed
263 dogs remained after exclusion criteria applied
17/263 (6%) were diagnosed with spinal shock
94% of these 17 dogs presented within 24 hours of the onset of clinical signs 

Spinal shock following spinal cord injury has previously been described in association with severe spinal cord injury or transection causing loss of motor and sensory function in humans.
Also been observed and reported in a limited number of dogs with severe paraparesis or paraplegia.

“Our study is the first report specifically evaluating the prevalence and clinical presentation of spinal shock in dogs with acute thoracolumbar spinal injury.”

Spinal shock pathophysiology:

  • Studied in both human medicine and limited experimental veterinary studies
  • Complex syndrome
  • Underlying disease processes associated with spinal shock not been clearly defined

In people, a 4 phase model has described the alterations in spinal reflexes and time frame expected for return to function:

  • Phase 1: occurs within 0-24 hours; characterised by areflexia or hyporeflexia caudal to the spinal cord injury 
  • Phase 2: begins 1-3 days after injury; correlated with denervation hypersensitivity
  • Phase 3: 4-30 days post-injury; characterized by reappearance of deep tendon reflexes and the flexor withdrawal reflex
  • Phase 4: 1–12 months post-injury with return of all reflexes; reflexes often exaggerated during phase 4
“Mechanisms for recovery of spinal shock have been described including unveiling of latent synapses, alterations to the density or distribution of neurotransmitters and collateral sprouting of intact axons….The timing of segmental spinal reflex return has been suggested to be dependent on the individual’s amount and type of physical fitness prior to the injury. For example, highly trained athletes may have a shorter recovery of reflexes due to decreased tendon excitability, when compared to an untrained person.”

In this study, fibrocartilaginous embolism FCE) was most commons cause of spinal injury (7/17 dogs)
Acute non-compressive nucleus pulposus extrusion and intervertebral disk herniation were other causes

Results here indicate that dogs with clinical evidence of spinal shock have a high probability of at least partial neurological improvement:

  • 88% of dogs with documented neurological examinations at the time of discharge (1–12 days following diagnosis) had improved or normal reflexes, 75% of which specifically had improved withdrawal reflexes.
  • Remaining dogs lacking recorded neurological examinations at discharge, had improved or normal reflexes on subsequent recheck examinations with the exception of 1 dog.
  • Findings consistent with the previous literature suggesting reflexes often recover faster in non-primates compared to people
  • However, recovery of the withdrawal reflex was longer than 48 hours in many of the dogs in this study
“The lack of standardized follow-up time, especially in the immediate post-injury period, limits interpretation of the recovery process. A concise timeline of recovery is difficult in a retrospective study; therefore, caution should be taken when providing expected recovery times to clients.”
“In conclusion, although uncommon, spinal shock should be considered in any dog presenting with an acute history of thoracolumbar spinal injury and reduced reflexes in the pelvic limbs. Imaging should be pursued between the T3-S3 spinal segments in these patients to account for lesions in the T3-L3 spinal cord segment, which may result in spinal shock. The presence of spinal shock should not dissuade a veterinarian from pursuing appropriate diagnostic testing and therapy for the underlying etiology.”

Swann JW, Maunder CL, Roberts E, et al. Prevalence and risk factors for development of hemorrhagic gastro-intestinal disease in veterinary intensive care units in the United Kingdom. J Vet Emerg Crit Care 2016. 26(3): 419–427.

In human medicine, stress-related mucosal disease (SRMD) refers to the development of erosive lesions of the stomach and intestines in patients admitted to intensive care units (ICUs) for management of severe illness.
SRMD covers a spectrum of disease, from superficial mucosal injury detectable only by gastroduodenoscopy to severe ulceration that results in clinically important haemorrhage.
Overt clinical bleeding due to SRMD was reported to occur in approximately 4% of human patients admitted to a group of ICUs in Canada…
…and development of this disease significantly increased the risk of death during the period of hospitalisation.

“Impaired perfusion of the gastric mucosal barrier (GMB) is the proximate cause of SRMD, but development of the disease is reflective of systemic changes in hemodynamic status and inflammatory cascade”
“several factors have been identified in human patients that increase the risk of development of SRMD…particularly respiratory failure necessitating mechanical ventilation and coagulopathy. Administration of prophylactic gastro-protectant medications reduces the risk of SRMD…but this may be associated with development of other complications, such as aspiration pneumonia, because increased gastric pH permits bacterial colonization of the stomach.”

Haemorrhagic gastro-intestinal (GI) disease has not been described specifically in veterinary ICUs

“The primary aim of this study was to determine the proportion of animals that developed overt hemorrhagic GI disease in veterinary ICU patients. It was hypothesized that this would occur at similar rates to those reported in human ICUs, and that dogs would develop the disease more frequently than cats based on previous evidence suggesting that the GI tract is not the shock organ of cats. Secondary aims were to investigate risk factors for the development of hemorrhagic GI disease, and to determine whether development of these signs was associated with mortality during the period of hospitalization.”

Retrospective multicentre study in three UK teaching hospital ICUs; a lot of the data was collected prospectively
All cases presenting consecutively to the ICUs were considered eligible for enrolment during the period of the study if they were hospitalised for at least 24 hours
Exclusion criteria:

  • History of haemorrhagic GI disease in 48 hours prior to hospitalisation
  • Developed signs of haemorrhagic GI disease within the first 24 hours after admission
  • Surgical procedures involving the GI or upper respiratory tracts
  • Presented with or developed epistaxis or haemoptysis
  • Presented for management of GI disease
  • Sustained 1 or more skull fractures

Cases were not excluded if they:

  • Received gastro-protectant drugs, NSAIDs, glucocorticoids, or anticoagulants prior to admission or during hospitalisation
  • Were diagnosed with diseases that may cause secondary GI signs, such as hypoadrenocorticism

SRMD was defined as haemorrhagic GI disease manifesting as hematemesis, melena, or haematochezia or as mucosal erosions and haemorrhage observed during GI endoscopy.

Final sample size: 272 dogs and 94 cats
Some results:

  • 7.0% (CI: 4.5–10.7) (= 19 dogs) of dogs and no cats across the three centres developed SRMD
  • Among the dogs that received prophylactic gastro-protectant medications, the proportion that developed SRMD was 16.4% (CI: 8.9–28.3), compared to only 4.2% (CI: 2.2–7.8) in dogs that did not receive prophylaxis
  • Decreased serum albumin concentration, the ICU in question, and administration of prophylactic gastro-protectant medications were risk factors for the development of SRMD.
  • The proportion of dogs with SRMD that did not survive to discharge was significantly greater than for dogs that did not develop SRMD
  • Placement of a feeding tube and development of SRMD were associated with mortality

SJ comment:

“Now look as always, please don’t just take these points at face value and start repeating them. That would be entirely inappropriate. For starters we would need more studies, ideally prospective and blinded where possible, to evaluate all of this and demonstrate repeatability. And even then we would need to still be careful to distinguish association from causation.”


“Limitations of this study include the relatively small number of cases included, especially for investigation of risk factors for development of SRMD and mortality…it is possible that unmeasured differences between centers could have acted as confounding or modifying factors. Although much of the data included in this study were collected prospectively, some information regarding development of GI disease was collected retrospectively from clinical records, reducing the reliability and consistency of these findings. Data were also collected by a number of different investigators who may not have been involved in the primary care of the case.


SRMD was observed in dogs from 3 different veterinary ICUs but was not observed in cats. Decreased serum albumin concentration was associated with development of SRMD, but, using a clinically relevant cut off value, this variable had a poor sensitivity and specificity for prediction of the disease. Development of SRMD and placement of a feeding tube were independently associated with increased mortality while hospitalized, but further studies will be required to determine the effects and potential benefits of prophylactic gastro-protectant therapy in veterinary ICU patients.”

If you would look a copy of any of the papers mentioned in this episode, let me know.

[This podcast is closely aligned with the MedEdLIFE Research Collaborative's Quality Checklist for Podcasts.]

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Antimicrobial Stewardship in Companion Animal Practice

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Bacteriology Refresher

Bacteria: single-celled microbes; often function as multicellular aggregates (biofilms)
Five morphological groups: cocci (spherical) and bacilli (rods) most common
Exist as single cells, in pairs, chains or clusters
Gram positive: thick cell wall
Gram negative: comparatively thin cell wall which includes a lipid membrane containing lipopolysaccharides (LPS, endotoxin) and lipoproteins
Also aerobic versus anaerobic growth; obligate or facultative

Antibacterials Refresher

Must remember the distinction between theoretical in vitro assertions and in vivo behaviour/effects in real clinical patients with different diseases and sites of infection

Broad- vs. narrow-spectrum classification according to the range of bacteria they are meant to be effective against. Commonly used but no clear and logical definitions for these terms. 

Bactericidal vs. bacteriostatic:

  • Bactericidal antibiotics kill bacteria directly
  • Bacteriostatic antibiotics stop bacteria from growing
  • May be much more relevant under strict laboratory conditions; more arbitrary and inconsistent in clinical situations

Time- vs. concentration-dependent:


  • Key pharmacodynamic parameter = time that plasma concentration remains above the minimum inhibitory concentration (MIC) during the dosing interval
  • MIC = lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation
  • Higher concentration does not result in greater antibacterial activity
  • Key element is how long the concentration remains above the MIC at the site of infection rather than how high the concentration reaches
  • Dosing interval is critical; missing doses can compromise efficacy
  • Examples include penicillins, cephalosporins and carbapenems


  • Key pharmacodynamic parameter = ratio between peak plasma drug concentration and the MIC of the antibiotic in question
  • I.e. antibacterial activity is related to how high the concentration reaches at the site of infection rather than how long it remains above the MIC during the dosing interval.
  • Examples include the fluoroquinolones and the aminoglycosides.

Beta-lactam Antibacterials

Most widely used antibiotics in dogs and cats?


Amoxicillin ‘potentiated’ by addition of potassium clavulanate
British Small Animal Veterinary Association’s Formulary (8th edn.):

  • Amoxicillin active against certain Gram-positive and Gram-negative aerobic organisms and many obligate anaerobes but not against those that produce beta-lactamases (e.g. E. coli, Staph aureus)
  • Clavulanate increases spectrum of action and restores efficacy against amoxicillin-resistant bacteria that produce beta-lactamases
  • More difficult Gram-negative organisms (e.g. Pseudomonas, Klebsiella) usually resistant 


  • First-generation (e.g. cefalexin (cephalexin)) active predominantly against Gram-positive bacteria
  • Successive generations (e.g. cefuroxime is second generation) have increased activity against Gram-negative bacteria (albeit often with reduced activity against Gram-positive organisms)


British Small Animal Veterinary Association’s Formulary (8th edn.):

“Ideally fluoroquinolone use should be reserved for infections where culture and sensitivity testing predicts a clinical response and where first- and second-line antimicrobials would not be effective”.

Active against Mycoplasma and many Gram-positive and Gram-negative organisms, but relatively ineffective against obligate anaerobes


Treatment of anaerobic infections, giardiasis and other protozoal infections

Antimicrobial Stewardship

Derived from this review article:

Guardabassi L, Prescott JF. Antimicrobial Stewardship in Small Animal Veterinary Practice: From Theory to Practice. Vet Clin N Am – Sm Anim Prac 2015. 45(2):361–376.

Nature of the problem:

“Antimicrobial resistance [or AMR] is one of the greatest challenges currently facing small animal veterinary medicine. During the past decade, various multidrug-resistant bacteria (MDR) have emerged and spread among dogs and cats on a worldwide basis. The major current MDR organisms of concern are methicillin-resistant Staphylococcus pseudointermedius (MRSP) and Escherichia coli producing extended-spectrum β-lactamase (ESBL). However, these bacteria are just the tip of the iceberg because multidrug resistance has diffused in other common bacterial pathogens encountered in general practice, such as Pseudomonas aeruginosa and enterococci. Additional MDR bacteria that are more likely to be isolated from animals presenting to referral centers include methicillin-resistant Staphylococcus aureus (MRSA), carbapenemase-producing E coli and Klebsiella pneumoniae, and MDR Acinetobacter baumannii.

All these MDR bacteria are frequently resistant to all conventional antimicrobials licensed for animal use and therefore pose a serious threat to animal health by increasing the risk of therapeutic failure and the recourse to euthanasia. MRSP/MRSA and MDR gram-negatives are important hospital-associated pathogens that can be transmitted from patient to patient through contact with personnel, with healthy animal carriers, and with contaminated environmental surfaces. Significant public health concerns exist because of the possible risk of animal-to-human transmission and in part also because of the increasing use in small animals of critically important antimicrobials authorized for human use only, such as carbapenems.

From the owner’s perspective, infections caused by MDR bacteria contribute to increased veterinary expenditures because of additional and more expensive antimicrobial treatments, longer hospitalization, more visits, and more diagnostic tests. Moreover, the negative consequences of MDR infections in household pets include emotional and social effects on the owners and their families. Hospitals and clinics affected by outbreaks of MDR bacterial infections also can be impacted economically by the loss of revenue due to loss of reputation and decreased case load, decontamination procedures, closure, and coverage of patient bills. This situation is worsened by the slow development of new antimicrobial drugs observed over the past decades. The few truly new agents are reserved for human use in hospitals and it is unlikely that these drugs will be authorized for veterinary use in the years to come. Thus, it is of paramount importance to preserve the efficacy of the veterinary antimicrobial products available today.”

Antimicrobial stewardship programs (ASPs) are a cornerstone of the response to the AMR crisis in human medicine; still largely underdeveloped in veterinary medicine.

“the aim of this article is to indicate the necessary steps that should be taken to establish ASPs in small animal veterinary practice, taking into consideration the many and remarkable differences between the human and the veterinary sector, and indeed the remarkable differences within veterinary medicine. Although the article highlights the structural and economic constraints that make implementation of ASPs used in human health care facilities difficult in small animal practice, it provides suggestions and approaches to overcome such constraints and to move toward practical implementation of effective veterinary-specific ASPs in small animal hospitals and clinics. We emphasize the multidimensional and the “mind-set” nature of “good stewardship practice” (GSP), as well the importance of an entire team-based commitment similar to that required for implementation of infection control practices.”

Antimicrobial paradox in small animal practice:

“One of the most effective strategies to manage AMR in human hospitals is to reduce the overall consumption of antimicrobial agents and rationalize the use of the most valuable drugs (eg, carbapenems, fourth-generation cephalosporins, glycopeptides), which are generally reserved for empirical treatment of life-threatening infections or infections that cannot be treated otherwise on the basis of susceptibility data. This strategy is almost completely flipped in small animal practice, where the listed drugs are not authorized and the most powerful veterinary antimicrobials, namely β-lactamase–resistant penicillins, cephalosporins, and fluoroquinolones, are widely used as empiric first-line agents in primary care, including treatment of mild or self-limiting infections….

…High consumption of these drugs provides a strong selective pressure in favor of MDR bacteria resistant to extended-spectrum β-lactams and fluoroquinolones” but the authors acknowledge that “they are indispensable drugs for management of common bacterial infections in small animals, including complicated skin and urinary tract infections and various life-threatening conditions”.

What is antimicrobial stewardship?

“The term “antimicrobial stewardship” is used to describe the multifaceted and dynamic approaches required to sustain the clinical efficacy of antimicrobials by optimizing drug use, choice, dosing, duration, and route of administration, while minimizing the emergence of resistance and other adverse effects. The word stewardship implies the obligation to preserve something of enormous value for future generations, and resonates in a way that “prudent use” or “judicious use” does not. GSP is the active, dynamic process of continuous improvement in antimicrobial use, and is an ethic with many steps of different sizes by everyone involved in antimicrobial use. Stewardship thus links, for example, front-line veterinary practitioners with laboratory diagnosticians, owners, drug regulators, and pharmaceutical companies.”

Examples of elements encompassed by the term antimicrobial stewardship that affect the emergence and spread of resistance include practice guidelines, dosage considerations and clinical microbiology data.
Also “A 5R approach to stewardship: Acceptance of responsibility for resistance as a potential effect of antimicrobial use, and for reduction, replacement, refinement, and review of antimicrobial use on an ongoing basis.”

In human medicine antibiotic stewardship is very much something that is attended to at the individual hospital level. In veterinary medicine it tends to be more about national and international surveillance and guidelines and potentially “legal (regulatory) interventions imposed by national authorities to restrict or ban specific drugs, to limit profit derived from antimicrobial dispensation, and taxes or penalties to prevent antimicrobial overuse”. While the authors support this “broad, multifaceted, approach to sustaining the efficacy of antibiotics for the long term” they also “recognize the need for establishing hospital-based ASPs in small animal practice.”

Establishing an antibiotic stewardship programme:

“No guidelines are available for development of ASPs in small animal clinics”
Article presents information and guidelines from non-veterinary specific resources

Role of microbiology laboratory:

“Liaison with a microbiologist at the diagnostic laboratory, which in contrast to human hospitals is normally placed outside the clinic environment, is an essential aspect for implementation of ASPs in small animal veterinary practice. The microbiology laboratory is not only supposed to provide timely and accurate species identification and antimicrobial susceptibility testing. Its role and responsibilities go beyond correct specimen testing and reporting of results, and include attention to the preanalytical...and postanalytical...components of testing. Selective reporting of susceptibility profiles can be used to discourage unnecessary use of broad-spectrum agents that are not licensed for veterinary use...Indiscriminate reporting of positive culture and susceptibility data on likely contaminants or nonpathogenic commensals should be avoided, because this practice may lead to inappropriate antimicrobial use. Last, but not least, the microbiology laboratory should generate annual reports summarizing the trends of AMR at the clinic level or at least at the regional level.”

Antimicrobial stewardship strategies:

“Various strategies have been shown to improve appropriateness of antimicrobial use and cure rates, decrease failure rates, and reduce health care–related costs in human hospitals”.
Article provides an overview of the most successful strategies used in human hospitals with focus on their implementation in small animal veterinary practice. Including:

Educational approaches:

“outstanding example of a readily and freely accessible Web-based and app-linked resource aimed to support companion animal veterinarians to develop practice policies for antimicrobial stewardship is the PROTECT site of the British Small Animal Veterinary Association”

PROTECT = Practice policy, Reduce prophylaxis, Other options, Types of bacteria and drugs, Employ narrow spectrum, Culture and sensitivity, and Treat effectively.

Federation of European Companion Animal Veterinary Associations has released several posters addressing responsible use of antimicrobials, appropriate antimicrobial therapy, and hygiene and infection control in veterinary practice.

Development and implementation of guidelines:

“General (generic) guidelines providing statements of principles of prudent antimicrobial use have been developed in recent years by most national veterinary organizations…Although important from a conceptual standpoint, their clinical guidance and impact is likely limited. Standard texts have included investigator recommendations on first-choice, second-choice, and last-resort antimicrobial agents… More recently, evidence-based clinical antimicrobial use guidelines have been developed using approaches similar to those for human guidelines. These have typically involved national or international expert panels reviewing and assessing the quality and strength of published literature to produce recommendations for diagnosis and management of specific conditions….The impact of national practice guidelines is likely higher than for international guidelines, because they take into account local factors regarding legislation, drug market availability, and prevalence of resistance.

Many veterinary specialty organizations also have developed guidelines, ranging from generic prudent use guidelines to practice-specific or disease-specific guidelines…Veterinary practice guidelines are negatively affected by numerous knowledge gaps regarding dose-effect relationships between antimicrobial use and resistance, antimicrobial consumption, resistance prevalence, drug-to-drug superiority, and optimal duration of treatment. However, although there are limitations, national guidelines are an essential milestone for development of [local antimicrobial policies] and more complex [antimicrobial stewardship programs] at the clinic level”.

Generic guidelines provided in paper (with references):

  1. Antimicrobials should be used only when there is evidence or at least a well-founded clinical suspicion of bacterial infection
  2. Antimicrobials should not be used for treatment of self-limiting infections
  3. Antimicrobial, pathogen, infection site, and patient factors should be considered when choosing an appropriate treatment
  4. Cytology should be used as a point-of-care test to guide antimicrobial choice for relevant disease conditions (eg, otitis and urinary tract infections)
  5. Antimicrobial susceptibility testing should be performed if:
    • There is suspicion of a complicated or life-threatening infection
    • The patient does not respond to initial treatment
    • The patient has a recurring or refractory infection
    • The patient is immunosuppressed
    • There is a need to monitor the outcome of therapy (eg, long treatment period)
    • The patient is at risk of infection with multidrug-resistant bacteria
  6. As narrow a spectrum therapy as possible should be used
  7. Topical therapy should be preferred over systemic therapy for treatment of superficial skin infections
  8. Antimicrobials should be used for as short a time as possible
  9. Extra-label use should be avoided when on-label options are reasonable
  10. Use of critically important antimicrobials not authorized for veterinary use should at least be restricted to rare and severe patient conditions (eg, diagnosed, life-threatening bacterial infections that cannot be treated by any other available antimicrobials, provided that treatment has a realistic chance of eliminating infection)
  11. Antimicrobial therapy should never be used as a substitute for good infection control, and good medical and surgical practices
  12. Perioperative prophylaxis should be used only when indicated, and follow standard guidelines
  13. Clients should be educated to ensure compliance

“Although there has been a marked increase in available guidelines, there has been little assessment of their impact on practice.”

“The effort spent on introducing guidelines, on educating health care providers, and in monitoring the response to guidelines is often slight compared with the effort of development, but critical to success. Compliance with guidelines may be poor because of inadequate communication, differences in opinion regarding recommended treatments, and resentment of measures to prescribe individual decisions….Thus, it is crucial that national and local veterinary professional and regulatory organizations allocate sufficient time and resources to promote guidelines and facilitate compliance.”

Other antimicrobial stewardship strategies mentioned:

  • Prescription approval
  • Post-prescription review
  • Computer-based decision support

Article also covers:

  • Measuring the outcomes of antimicrobial stewardship programs
  • Potential barriers to their implementation

Key points:

  • “There is increasing recognition of the critical role for antimicrobial stewardship and infection control in preventing the spread of multidrug-resistant bacteria in small animals.
  • Establishment of antimicrobial stewardship programs requires (1) coordination ideally by an infectious disease specialist or at least by a clinician with strong interest in and good knowledge of antimicrobial resistance and therapy, (2) commitment by the clinical staff, and (3) collaboration with the microbiology laboratory.
  • Even in the absence of specialist help, by accessing the increasingly available resources, veterinary clinics should at least develop, implement, and periodically update local antimicrobial policies indicating first-choice, restricted, and reserve drugs.
  • Educational approaches, clinical guidelines, preprescription approval, postprescription review, and computer-based decision support are the most effective strategies to accomplish best practices in antimicrobial stewardship.
  • The main barriers to implementation of antimicrobial stewardship programs comprise (1) economic sustainability; (2) lack of formally trained infectious disease specialists; (3) limited use of culture and antimicrobial susceptibility testing; (4) scientific knowledge gaps for assessment of resistance, development of evidence-based guidelines, and optimization of antimicrobial therapy; and (5) absence of standardized methods for evaluating the outcomes of antimicrobial stewardship programs.”

In 2015 ACVIM published a “Consensus Statement on Therapeutic Antimicrobial Use in Animals and Antimicrobial Resistance” in the Journal of Veterinary Internal Medicine.

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