Handbook of Canine and Feline Emergency Protocols

By Maureen McMichael

Handbook of Canine and Feline Emergency Protocols, Second Edition offers practical step-by-step guidance to managing emergency cases in small animal practice.  Presenting more than 165 complete protocols for triaging, stabilizing, and managing emergent patients, the book is designed for fast access in an emergency situation, with a spiral binding and tabs to make it easy to flip to the relevant section.  An ideal resource for veterinary practitioners seeking a quick reference for dog and cat emergencies, this Second Edition provides enhanced imaging information to increase the book’s diagnostic usefulness and full updates throughout.

Logically organized alphabetically by category of emergency, the book includes useful chapters on procedures, shock, toxicology, and trauma in addition to a procedures chapter.  Video clips, additional images, review questions, formula calculations, and quick reference guides are available on a companion website.  Handbook of Canine and Feline Emergency Protocols, Second Edition provides a user-friendly daily reference for any small animal practitioner.

• Language: English
• Publisher: Wiley
• Release date: Aug 7, 2014
• ISBN: 9781118558966

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Cover image:

This book is dedicated to the lights of my life, Alex, Michael, Elizabeth, Hal and Gabby. You are my constant source of inspiration and joy. Also to my mother, Ann and my in-laws, Dr. and Mrs. Schenck for their support and encouragement.

Maureen McMichael

To my parents, William and Pamela, for insisting I always strive for excellence. To Colleen, Jeffrey, Matthew, and Jeremy, for being my resolute foundation and always believing in me. To Hercules, Pandora, Misfit, Sunny and Avery, for teaching me the meaning of unconditional love.

Christopher Byers

To the love of my life, Steven, whose unending support has carried me to my dreams and the three rays of sunshine that have captured my heart, Katrina, Sebastian and Nikolai. You are my world and I love you! To my mentors and friends, Drs. Maureen McMichael and Mauria O'Brien, for their guidance, encouragement and devotion.

Jennifer Herring

To my family, Bob, Tom, Niallan, and Aidan, for always being so supportive of all my career endeavors and my apologies for always being late.

Mauria O'Brien

List of Contributors

Christopher G. Byers, DVM, DACVECC, DACVIM (SAIM)

MidWest Veterinary Specialty Hospital

Mockingbird Drive

Omaha, NE 68131, USA

[e-mail]

Mauria O'Brien, DVM, DACVECC

Clinical Associate Professor

Small Animal Emergency and Critical Care

College of Veterinary Medicine

University of Illinois

W. Hazelwood Dr

Urbana, IL 61802, USA

[e-mail]

Jennifer M. Herring, DVM, MS, DACVECC

University of Tennessee College of Veterinary Medicine

Clinical Assistant Professor of Small Animal Emergency and Critical Care

Small Animal Clinical Sciences

C247 Veterinary Teaching Hospital

Knoxville, TN 37996, USA

[e-mail]

Maureen McMichael, DVM, Diplomate ACVECC

Associate Professor

Service Chief Emergency & Critical Care

College of Veterinary Medicine

University of Illinois

W. Hazelwood Dr

Urbana, IL 61802, USA

[e-mail]

Acknowledgments

First we would like to acknowledge our teachers and mentors for their tireless dedication to teaching, expertise, and guidance. You were and continue to be unending sources of inspiration for us.

We would also like to thank our past and current colleagues for their generous sharing of knowledge and experience with us, and to thank the veterinary students, interns, and residents who challenge us every day.

We also acknowledge the invaluable assistance we have received from our technicians for their compassion, experience, and wisdom. Without you, veterinary medicine could not begin to meet the medical and emotional needs of our patients and pet parents. We would like to thank Drs. Christopher S. Leasure and Gretchen D. Stazt, as well as her adorable dog, Nyse, for their assistance with many of the photos in this book. We would like to thank Dr. Bob O'Brien for his assistance with all of the images in this book.

We would like to thank Ms. Erica Judisch and Ms. Susan Engelken at Wiley for all of their patience and encouragement throughout this endeavor.

And finally we would like to thank our patients who show us everyday what unconditional love really is.

The editor will be donating all royalties to This Able Veteran, a nonprofit organization that trains service dogs to support veterans with injuries resulting from their service. TAV-trained service dogs are able to interrupt the cycles of posttraumatic stress disorder (PTSD) and traumatic brain injuries (TBIs) and support veterans with mobility issues. First the trainers shape the skills needed in the dogs. Then, over the course of several weeks, they help the dogs and veterans learn to recognize each other's signals and to form a bond strong enough to carry the veteran through the challenges of recovery. More information can be found at www.thisableveteran.org.

Introduction

The purpose of this handbook is to provide the practicing emergency veterinarian with rapid access to brief, but complete, protocols on the most common dog and cat emergencies encountered in veterinary practice. We have updated this edition with the most recent clinically relevant information. This edition also has the benefit of many images (radiographs, ultrasound images, ECG strips, etc.), as well as an online quick guide.

This book is meant to be a set of starter protocols that will be expanded, altered, and personalized depending on the preferences, case load, and availability of the practice using them. There are numerous accepted ways to treat most emergencies, and we encourage you to optimize these protocols to be of maximum value for your practice.

We recommend that all veterinarians seeing emergency patients set up a minimum data base (MDB) in their practice. This can include, minimally, a packed cell volume (PCV), total solids, azo stick, and blood glucose. Ideally, it would also include electrolytes, lactate, and a venous blood gas. When the term MDB is listed in the book, it includes PCV, TS, azo, BG, electrolytes, and lactate. We suggest you run this minimum data base on all emergencies presented to your clinic to both decrease the time to treat critical variables (electrolyte disturbances, hypoglycemia, etc.) and increase the quality of care provided. In addition, we recommend that all emergency practices include pulse oximetry, blood pressure, and ECG as part of the initial screening; this book assumes these have been done and so they are not listed under diagnostics. In select sections under diagnostics, the terms electrolytes and ECG have been added to highlight the importance of these tests in specific disease states. Recommendations are tiered (MDB, 1st Tier, 2nd Tier) to allow for stepwise testing and financial considerations.

Emergency medicine can be overwhelming! The protocols here provide a set of clear, concise guidelines to streamline this as much as possible. This book is set up in sections in alphabetical order. Each disease entity within a section is also alphabetized.

Although the authors have taken great care to ensure the information in this text is accurate, the reader is strongly advised to confirm the information, especially with regard to drug dosages, is correct and conforms to the current standard of practice.

Good luck out there,

Maureen, Christopher, Jennifer, and Mauria

Abbreviations

ABG—arterial blood gas

ACT—activated clotting time

ACTH—adrenocorticotropic hormone

ALB—albumin

ALP—alkaline phosphatase

ALT—alanine aminotransferase

aPTT—activated partial thromboplastin time

AT—antithrombin

AUS—abdominal ultrasound

AXR—abdominal x-ray

azo—azostick

BAER—brainstem auditory evoked response

BG—blood glucose

BP—blood pressure

CBC—complete blood count

CC—costochondral junction

CHF—congestive heart failure

CM—cardiomyopathy

CP—cryoprecipitate

cPLI—canine pancreatic lipase immunoreactivity

CRI—constant rate infusion

CRT—capillary refill time

C/S—culture and susceptibility

CSF—cerebral spinal fluid

CT—computed tomography

CVP—central venous pressure

CXR—chest x-ray

DCM—dilated cardiomyopathy

DIC—disseminated intravascular coagulation

DV—dorsal ventral

ECG—electrocardiogram

ECHO—echocardiogram

EEG—electroencephalogram

ET—endotracheal tube

FDPs—fibrin degradation products

FFP—fresh frozen plasma

FP—frozen plasma

fPLI—feline pancreatic lipase immunoreactivity

FWB—fresh whole blood

GGT—gamma-glutamyl transferase

HCM—hypertrophic cardiomyopathy

HCT—hematocrit

HE—hepatic encephalopathy

HES—hetastarch

HR—heart rate

IBD—inflammatory bowel disease

ICS—intercostal space

IMHA—immune-mediated hemolytic anemia

ITP—immune-mediated thrombocytopenia

IVF—intravenous fluids

LA—left atrium

LOC—level of consciousness

MDB—minimum database (HCT, TS, azo, BG)

mm—mucous membranes

MR—mitral regurgitation

MRI—magnetic resonance imaging

NE—nasoesophageal

NG—nasogastric

OTC—over the counter

OTN—over the needle

PCV—packed cell volume

PLT—platelet

PPN—partial parenteral nutrition

pRBC—packed red blood cells

PT—prothrombin time

RCM—restrictive cardiomyopathy

RR—respiratory rate

SC—subcutaneous

SP—stored plasma

TBI—traumatic brain injury

TBSA—total body surface area

TPN—total parenteral nutrition

TS—total solids

UA—urinalysis

UOP—urine output

USG—urine specific gravity

vWD—von Willebrand disease

vWF—von Willebrand factor

WB—whole blood

Chapter 1

Acute Abdomen

Maureen McMichael

ACUTE ABDOMEN DIFFERENTIAL DIAGNOSES

Gastrointestinal

Gastric dilatation +/− volvulus

Gastritis/enteritis/ulceration

Gastric/intestinal obstruction

Hemorrhagic gastroenteritis

Intestinal/mesenteric volvulus

Intussusception

Obstipation

Hepatic

Bile duct obstruction/rupture

Gallbladder rupture

Hepatic abscess

Hepatic neoplasia

Hepatitis/cholangiohepatitis

Hepatic lipidosis

Intervertebral Disc Disease

Occasionally dogs with back pain present with clinical signs that mimic abdominal pain

Pancreatitis

Peritonitis

Prostate

Prostatic abscess

Prostatitis

Renal

Acute renal failure

Pyelonephritis

Renal calculi

Ureteral obstruction

Reproductive

Dystocia

Metritis/pyometra

Orchitis/epididymitis

Uterine/testicular torsion

Splenic

Rupture/neoplasia

Torsion

Toxin

Arsenic

Lead

Zinc

Urinary

Bladder rupture

Urethral obstruction/rupture

HEMOABDOMEN

History

If chronic, (neoplasia) often has a history of lethargy with intermittent periods of improvement. Occasionally PU/PD, distended abdomen, and vomiting. If acute, (neoplasia, trauma, and coagulopathy) can present in shock.

Clinical Signs

Pale mucous membranes, tachycardia, may have systolic heart murmur (anemia), bounding or weak pulses, and palpable abdominal fluid wave. May be tachypneic, weak, depressed. Sudden loss of volume is not often reflected in HCT/TS. A normal HCT with slightly low TS is often encountered on presentation with the HCT dropping as fluid administration and redistribution of body fluid occurs.

Diagnostics

Minimally: MDB, abdominocentesis (PCV, cytology, fluid analysis).

1st Tier: PT or ACT or coagulation panel, CBC + retic count.

2nd Tier: Blood type and crossmatch, chem panel, CXR (metastasis check), AUS.

Treatment

Oxygen supplementation.

IV catheter (largest catheter possible for rapid replacement).

Administer isotonic crystalloid bolus:

Dogs: 20 ml/kg (up to 90 ml/kg) and then reassess perfusion.

Cats: 10 ml/kg (up to 45 ml/kg) and then reassess perfusion.

Synthetic colloids (HES):

Dogs: 5 ml/kg bolus over 15–20 min and reassess perfusion. Give up to 20 ml/kg total.

Cats: 2–5 ml/kg bolus over 20–30 min and reassess perfusion. Do not bolus colloids rapidly in cats.

Blood:

With clinical anemia (i.e., lethargy, tachycardia, and tachypnea) and normal albumin level, administer crossmatched pRBCs at 6–12 ml/kg over 1–4 h. With clinical anemia and hypoalbuminemia, administer crossmatched fresh whole blood at 10–20 ml/kg over 1–4 h or pRBCs and FFP.

Coagulopathy:

If prolonged PT this may be anticoagulant rodenticide. Although this rarely presents as hemoabdomen (more commonly presents as retroperitoneal bleed or hemothorax), it is most likely in young dogs with significantly prolonged PT. If ACT or aPTT is prolonged and the pet has signs of inflammatory disease, consider DIC. Plasma administration may be helpful to replace coagulation factors.

Monitoring:

End points of fluid/blood/colloid resuscitation are normalizing of HR, pulse quality, mentation, lactate, HCT/TS, CVP, and urine output.

Prognosis

Prognosis depends on the underlying disease. Prognosis is good for trauma that responds to fluid resuscitation (surgery may not be needed). May need surgical correction of lacerated vessel if not stabilized by transfusion/fluid therapy. Prognosis is guarded to poor for ruptured splenic or liver masses due to hemangiosarcoma. Prognosis guarded for ruptured adrenal masses presenting as hemoabdomen. Approximately 75% of dogs with nontraumatic hemoabdomen on presentation have neoplasia.

SPLENIC TORSION

History

Acute: Shocky, painful abdomen, and enlarged spleen. Chronic: Lethargy, anorexia, enlarged spleen, and possibly painful abdomen. Large breeds and Great Danes predisposed.

Clinical Signs

Tachycardia, weak pulses, pale or icteric mucous membranes, painful abdomen, enlarged spleen, and cardiac arrhythmias.

Diagnostics

Minimally: MDB, AXR.

1st Tier: CBC with retic count, platelet count, ACT or coag panel, chem panel, lactate. May see anemia with fragmented RBCs, hemoglobinemia, hemoglobinuria, elevated liver enzymes, elevated bilirubin.

2nd Tier: CXR, AUS. Abdominal ultrasound may reveal enlarged splenic vessels (Figs 1.1 and 1.2).

c01f001

Fig. 1.1. Partial splenic torsion. Ultrasound image of a 4-year-old Great Dane with evidence of a hypoechoic and roughly triangular region (outlined by arrowheads) in the distal tail of the spleen consistent with a partial splenic torsion

(courtesy Dr. Robert O'Brien, DVM, DACVS).

c01f002

Fig. 1.2. Splenic torsion. Ultrasound image from a 6-year-old Great Dane with a splenic torsion. Note the lacey appearance to the spleen with Doppler evidence (green dashed lines) of decreased flow

(courtesy Dr. Robert O'Brien, DVM, DACVS).

Treatment

Administer isotonic crystalloid bolus:

Dogs: 20 ml/kg (up to 90 ml/kg) and then reassess perfusion.

Cats: 10 ml/kg (up to 45 ml/kg) and then reassess perfusion.

Synthetic colloids (HES):

Dogs: 5 ml/kg bolus over 15–20 min and reassess perfusion. Give up to 20 ml/kg total.

Cats: 2–5 ml/kg bolus over 20–30 min and reassess perfusion. Do not bolus colloids rapidly in cats.

Blood products:

With clinical anemia (i.e., lethargy, tachycardia, and tachypnea) and normal albumin level, administer crossmatched pRBCs at 6–12 ml/kg over 1–4 h. With clinical anemia and hypoalbuminemia, administer crossmatched fresh whole blood at 10–20 ml/kg over 1–4 h or pRBCs and FFP.

Analgesia:

Multimodal analgesia is ideal and should include a pure μ-opioid agonist along with additional analgesics. Options include fentanyl at 2–6 µg/kg/h or morphine at 0.12–0.36 mg/kg/h or hydromorphone at 0.024–0.072 mg/kg/h along with lidocaine at 25–50 µg/kg/min (dogs) +/or ketamine at 2–5 µg/kg/min. Other options include methadone at 0.25–0.75 mg/kg IV/IM/SC q4 h (dogs) or methadone at 0.05–0.5 mg/kg IV/IM/SC q4 h (cats) or Gabapentin at 5–10 mg/kg PO q8–12 h.

Surgery should be performed as soon as the patient is resuscitated.

Monitoring

End points for fluid and blood product resuscitation include normalization of HR, lactate, mentation, and urine output. These are temporary as surgery is the only corrective measure.

Prognosis

Good if surgery is corrective and there is no predisposing underlying cause (i.e., neoplasia).

PERITONITIS

History

May have history of previous surgery, penetrating wound, pregnancy, previous cystocentesis, pyometra, or no prior history (perforated intestinal neoplasia).

Clinical Signs

Pale or muddy mucous membranes, tachycardia (except cats, see bradycardia), weak or bounding pulses, painful abdomen (cats may not have abdominal pain with peritonitis), fever, or hypothermia (cats—hypothermia).

Diagnostics

Minimally: MDB, AXR (check for loss of detail, free gas), abdominocentesis (intracellular bacteria are hallmark of septic peritonitis, and also can check lactate, blood glucose, creatinine, bilirubin, and lipase on the fluid in addition to cytology and culture). Abdominal effusion glucose <50 mg/dl and/or an effusion to venous lactate of >4.6 mmol/l are highly indicative of bacterial peritonitis. It is best to do radiographs before abdominal tap, as the latter can introduce free gas into the abdomen and confuse radiographic interpretation.

1st Tier: lactate (may be increased with hypoperfusion), CBC (look for left shift, toxic changes in leukocytes), chem panel (may see hypoglycemia).

2nd Tier: ACT/coagulation panel, CXR, AUS (Figs 1.3 and 1.4).

c01f003

Fig. 1.3. Peritonitis. Ultrasound image of a 5-year-old Coonhound with peritonitis secondary to a uroabdomen. Note the abdominal free fluid (arrowhead) and severe corrugation of the intestinal loop (arrow)

(courtesy Dr. Robert O'Brien, DVM, DACVS).

c01f004

Fig. 1.4. GI Septic peritonitis with free gas. Lateral radiograph from a 6-year-old Labrador Retriever with septic peritonitis. Note the multiple small gas bubbles in the ventral aspect of the abdomen (arrows). Loss of serosal detail is also present. Some loops of bowel in the mid-ventral abdomen are gas distended (arrowheads)

(courtesy Dr. Robert O'Brien, DVM, DACVS).

Treatment

Oxygen.

Administer isotonic crystalloid bolus:

Dogs: 20 ml/kg (up to 90 ml/kg) and then reassess perfusion.

Cats: 10 ml/kg (up to 45 ml/kg) and then reassess perfusion.

Synthetic colloids (HES):

Dogs: 5 ml/kg bolus over 15–20 min and reassess perfusion. Give up to 20 ml/kg total.

Cats: 2–5 ml/kg bolus over 20–30 min and reassess perfusion. Do not bolus colloids rapidly in cats.

Antibiotics:

Broad-spectrum antibiotics (ticarcillin/clavulanate or imipenim) ideally after culture and susceptibility have been submitted. Enrofloxacin may convert Strep canis to a highly pathogenic form seen in Strep toxic shock syndrome and necrotizing fasciitis; therefore, should be used cautiously (or not at all) in septic canines.

Coagulopathy:

If prolonged ACT/coag panel, consider vitamin K1 (2.5 mg/kg SC), fresh frozen plasma, or fresh whole blood.

Surgery:

Emergency surgery should be performed as soon as the animal is resuscitated (not necessarily stabilized). The goals of resuscitation and throughout surgery are HCT ≥ 25%, TS ≥ 4.0 (artificial colloids register at 4.5 g/dl on refractometer), normal coagulation panel, systolic blood pressure >90 mmHg, urine output >1 ml/kg/h, pulse ox >95%, and adequate analgesia.

Analgesia:

Multimodal analgesia is ideal and should include a pure μ-opioid agonist along with additional analgesics. Options include fentanyl at 2–6 µg/kg/h or morphine at 0.12–0.36 mg/kg/h or hydromorphone at 0.024–0.072 mg/kg/h along with lidocaine at 25–50 µg/kg/min (dogs) +/or ketamine at 2–5 µg/kg/min. Other options include methadone at 0.25–0.75 mg/kg IV/IM/SC q4 h (dogs) or methadone at 0.05–0.5 mg/kg IV/IM/SC q4 h (cats) or Gabapentin at 5–10 mg/kg PO q8–12 h.

Prognosis

There is a very brief window where volume resuscitation will improve parameters but expect decompensation within 1–3 h after improvement if definitive correction (surgery) is not performed. Guarded to poor depending on cause and systemic complications that may develop several days postop (ARDS, DIC, aspiration pneumonia, sepsis, etc.).

Further Reading

Drobatz KJ. Acute abdominal pain. In Silverstein DC, Hopper K (eds): Small Animal Critical Care Medicine, 1st ed. St. Louis, Saunders Elsevier, 2009, p. 534.

Chapter 2

Allergic Reactions

Maureen McMichael

ANAPHYLAXIS CANINE

History

Contact with bees, wasps, spiders, new medication, vaccinations, heartworm microfiliaria treatment, unknown (went into yard and collapsed shortly afterwards).

Clinical Signs

Restlessness and vomiting/diarrhea progress to cardiovascular collapse with weak pulses, cold extremities, tachycardia, and severe hypotension (from massive splanchnic pooling of blood). AXR may show loss of abdominal detail (massive abdominal vasodilation), and diarrhea often turns bloody. Clinical, laboratory, and radiographic signs may mimic sepsis. Anaphylaxis responds rapidly to medical treatment (2–6 h). Any response to medical treatment with septic animals is short-lived unless the septic focus is eliminated. The splanchnic circulation (liver and GI) is affected primarily in dogs, and allergic response causes massive vasodilation and pooling of blood in this region, leading to a form of distributive shock.

Diagnostics

Minimally: MDB.

1st Tier: AXR, CBC, chem panel.

2nd Tier: AUS, ACT/coag panel, UA. AXR may show loss of detail that can mimic free abdominal fluid. Abdominal ultrasound may also reveal a scant amount of free fluid.

Treatment

Fluids: Place one to two large gauge IV catheters and give a rapid bolus of IV crystalloids (45 ml/kg) and colloids (5–10 ml/kg) and reassess perfusion. If continued dull mentation, cold extremities, weak pulses, and high lactate, repeat bolus.

Epinephrine at 0.01 mg/kg IV or IM.

Dexamethasone at 0.05 mg/kg or prednisone sodium succinate at 1.0 mg/kg slow IV after bolus fluids.

Diphenhydramine at 0.5–1.0 mg/kg IV (maximum total dose of 50 mg) after fluids.

Monitoring

Monitor mentation, pulse quality, extremity temperature, and urine output. Anaphylaxis responds rapidly to epinephrine and fluid therapy (2–6 h or less). If no response or animal is worsening, reconsider diagnosis.

Prognosis

Guarded to good if treated early.

ANAPHALAXIS FELINE

History

Contact with bees, wasps, new medication, triple ophthalmic ointment, vaccinations.

Clinical Signs

The shock organ in cats is the lung. Cats often have ptyalism and facial pruritis initially, then dyspnea, vomiting, and acute collapse. Increased pulmonary capillary permeability leads to rapid pulmonary edema, also see bronchoconstriction, pulmonary hemorrhage, and laryngeal edema.

Diagnostics

Minimally: MDB.

1st Tier: CXR (if stable, may see diffuse alveolar pattern indicative of severe pulmonary edema), CBC, chem panel.

2nd Tier: ACT/coag panel, UA.

Treatment

Decrease stress!!

Oxygen: On presentation, place cat in O2 cage while preparations are made for diagnosis and treatment. Have everything ready for rapid sequence before removing the cat from oxygen.

Albuterol inhaler attached to Aerokat Feline Chamber® (give two actuations into chamber after attaching to facemask, place facemask on cat, and let cat take 5–10 breaths).

IV catheter: Rapid placement of IV catheter (if too stressful, give drugs IM and return cat to oxygen cage).

Epinephrine at 0.01 mg/kg IV or IM.

Dexamethasone at 0.05 mg/kg or prednisone sodium succinate at 1.0 mg/kg IV or IM.

Furosemide (2 mg/kg IV or IM) is controversial. Pulmonary edema is from increased endothelial permeability.

Prognosis

Guarded to poor in cats, as they often have rapid onset and rapid progression to death.

ANGIOEDEMA/URTICARIA

History

Insect bite, drug ingestion, contact allergies, etc.

Clinical Signs

Erythema and swelling of face (especially eyes and muzzle despite location of sting), may see wheals on skin.

Diagnostics

Minimally: MDB, electrolytes.

1st Tier: CBC, chem panel.

2nd Tier: ACT/coagulation panel, UA in more severe cases.

Diagnosis usually based on the history and clinical signs, rarely find bite.

Treatment

Diphenhydramine at 0.5–1.0 mg/kg IM or SQ; can be repeated once in 20 min.

Dexamethasone: In moderate-to-severe cases, an anti-inflammatory dose of corticosteroids (dexamethasone at 0.05 mg/kg IV) can be given in addition to diphenhydramine.

Monitoring

Monitor swelling, respiratory effort (rule out inflammation interfering with ventilation), BP, pulse oximetry, and ECG in more severe cases.

Prognosis

Good if mild, attempt to identify allergen (referral to a dermatologist) in more severe cases and discuss avoidance of the offending agent in the future. We have occasionally seen cases that appear to recur repeatedly after the antihistamine wears off. We often need to treat these cases with anti-inflammatory prednisone and diphenhydramine for up to a week.

Further Reading

Dowling PM. Anaphylaxis. In Silverstein DC, Hopper K (eds): Small Animal Critical Care Medicine, 1st ed. St. Louis, Saunders Elsevier, 2009, p. 727.

Shmuel DL, Cortes Y. Anaphylaxis in dogs and cats. J Vet Emerg Crit Care 2013;23:377–394.

Chapter 3

Cardiac Emergencies

Jennifer M. Herring

ATRIAL FIBRILLATION

History

Usually giant/large breed dogs, may have concurrent DCM. Often acute onset lethargy, weakness, and exercise intolerance. In cats usually associated with severe underlying cardiomyopathy. Owner may mention something wrong with the heart, as they may be able to palpate the arrhythmia.

Clinical Signs

May have any or all of the following: weakness, abdominal fluid wave (ascites), pale to cyanotic mucous membranes, tachycardia with chaotic heart sounds (very irregular), weak pulses, pulse deficits, and hypothermia. Often pulse rate is much lower than the heart rate.

Diagnostics

Minimally: MDB, ECG (tachycardia with irregularly irregular rhythm, no visible P waves, usually upright, narrow QRS).

1st Tier: Lactate, CXR (cardiomegaly, pleural effusion, pulmonary edema).

2nd Tier: Echo (underlying heart disease), CBC, chem panel, UA, thyroid panel, taurine level.

Treatment In Dogs

Oxygen supplementation.

IV catheter.

Diltiazem: To slow the ventricular rate if HR > 180 bpm and affecting perfusion dosed at 0.25 mg/kg IV over 5 min through a peripheral vein, followed by a CRI at 1–5 µg/kg/min.

Or procainamide bolus (5–15 mg/kg IV over 3 min, to effect), followed by a CRI at 25–40 µg/kg/min.

Oral medication: In less emergent cases, try oral medications and start oral medications in all when stable;

Diltiazem (0.5–2 mg/kg orally q8 h).

Or digoxin (0.005–0.008 mg/kg/day orally divided q12 h) and check levels in 5–7 days.

If no response, add β-blocker:

Propranolol (0.2–1 mg/kg orally q8 h).

Or sotalol (1–2 mg/kg orally q12 h).

Monitor perfusion (urine output, extremity temperature, and lactate) while using any of the above drugs (they can decrease the cardiac output).

Congestive heart failure: If concurrent CHF, give furosemide (2 mg/kg IV) and consider nitroglycerin