This book aims to introduce veterinary surgeons to a new concept of pain for a better understanding of what pain is and how it occurs. By describing pain pathways and their regulation, as well as the sophisticated therapeutic systems that are currently being developed, this book shows its readers how to interpret pain, and how to identify it as a pathology in itself and treat it as such.

The management of chronic pain in companion animals is an area in which there is a significant therapeutic void. In many cases, professionals are unaware of the appropriate approach to managing chronic pain, despite the wide range of pharmacological, surgical, and physical therapy options that act directly on the pain pathways. Recent discoveries in the area of pain pathways have opened many avenues for the management of chronic pain. The goal of this book is to present this new knowledge in the context of the small animal clinic.

Author

Belén Ruano Puente
Degree in Veterinary Medicine specializing in pain and rehabilitation. Member of the Spanish Pain Society (SED), the International Association for the Study of Pain (IASP), and the Madrid Association of Companion Animal Veterinary Medicine (AMVAC).
Head of the Pain and Rehabilitation Unit of the Pulso Animal Clinic (Manzanares el Real, Madrid). Pulso Animal is a group of professionals who, in their respective specialties and fields of expertise, seek to develop a method of treating animals with pain using an approach that considers all associated aspects and manifestations.

Table of Contents

1. What is chronic pain?

Introduction

Nociception

Transmission

Anatomy of nerve pathways

Transduction: neurotransmitters involved in chronic pain 

Cellular metabolic mechanisms of chronic pain 

Perception and classification of chronic pain

Pain modulation process

Spinal control

Supraspinal control 

Cortical control 

Pain chronification

2. Diagnosis of chronic pain syndrome

Introduction

Stress

Behavioural changes in states of continuous pain

Diagnostic approach for a patient with pain

Detailed anamnesis

Physical examination

Blood test

Orientative analytical parameters 

Complementary diagnostic techniques 

Thermography

Techniques for assessing neurophysiological function

Pain scales used in animals

3. Treatment of chronic pain

Introduction

Pharmacological therapy 

Anti-inflammatories

Nonsteroidal anti-inflammatory drugs

Corticosteroids

Opioids

Mechanism of action of opioids

Routes of opioid administration

Opioids used in veterinary medicine

Antidepressants 

Tricyclic antidepressants

Selective serotonin reuptake inhibitors

Selective serotonin–noradrenaline reuptake inhibitors

Anticonvulsants

Amantadine

Growth factors

Local anaesthetics

Routes of administration

Most commonly used drugs

α-adrenergic receptor agonists

Medetomidine

Dexmedetomidine 

Cannabinoids

Capsaicin

Ketamine

Routes of administration

Experimental drugs

4. Types of chronic pain

Introduction

Visceral pain

Chronic pancreatitis

Chronic renal failure

Uraemic polyneuropathy

Osteoarthritis: joint pain

Pain due to cancer

Analgesic drugs in oncology

Anti-inflammatories: NSAIDs and corticosteroids

Analgesics

Local anaesthetics

Antiemetics

Anticonvulsants

NMDA receptor antagonists

Bisphosphonates

Other drugs

Geriatric pain

Analgesic drugs in geriatric patients

Diabetic neuropathy

Treatment of diabetic neuropathy

Joint pain

Treatment of joint pain

Joint stress stage

Bone inflammation phase

Bone reorganisation stage 

Degenerative stage

Radicular pain

Treatment of radicular pain

Corticosteroids

Opioids

Muscle relaxants

NSAIDs

Local anaesthetics

Neurolytic agents

Adjuvant analgesics

Other therapies

5. Interventional therapies

Introduction

Ablative techniques

Peripheral neurectomy

Rhizolysis

Facet rhizolysis 

Cordotomy

Dorsal root entry zone (DREZ) lesion

Decompression techniques

Discolysis

Neuromodulatory techniques

Neurostimulation

Spinal infusion 

Electrotherapy

Transcutaneous electrical neurostimulation (TENS)

Interferential currents

Ultrasound

Shockwave therapy

Diathermy

Neuromuscular therapy

6. Functional recovery of a painful limb. Case descriptions

Introduction

Case 1 Shiba. Golden Retriever, aged 14 years

Case 2 Terry. A mixed breed, 30-kg dog with leishmaniasis

Case 3 Pepa. Yorkshire Terrier, aged 5 years

Case 4 Admiral. Labrador, aged 2 years 

Case 5 Terry. Golden Retriever, aged 10 years

Case 6 Miko. Dachshund, aged 6 years