Equine Upper Respiratory Tract Disease PDF

APPROACH TO EQUINE UPPER RESPIRATORY TRACT DISEASE VMS3010 NOVEMBER 2024 SUSAN K. ARMSTRONG M.Sci BVMS PhD CertAVP MRCVS Thanks to SO YOUNGKWON DVM, PhD, MRCVS, DACVIM LAIM...

APPROACH TO EQUINE UPPER RESPIRATORY TRACT DISEASE VMS3010 NOVEMBER 2024 SUSAN K. ARMSTRONG M.Sci BVMS PhD CertAVP MRCVS Thanks to SO YOUNGKWON DVM, PhD, MRCVS, DACVIM LAIM 1  LEARNING OBJECTIVES o Demonstrate an understanding of the common conditions affecting the upper respiratory tract (URT) of the horse o Describe different diagnostic modalities used to investigate upper respiratory conditions in horses and understand the benefits of each o Outline the diagnosis, treatment, and control of infectious and non- infectious upper respiratory disease in horses 2  OUTLINE Types of conditions of the URT per clinical presentation I. Bilateral nasal discharge 1. URT infectious diseases II. Unilateral nasal discharge 1. Sinus disease 2. GP empyema 3. Strangles 4. Others III. Epistaxis 1. Trauma 2. GP mycosis 3. Progressive ethmoid haematoma 3  UPPER AIRWAY INTRODUCTION Guttural pouches o Guttural Pouch Sinuses Tympany Empyema Strangles Mycosis Neoplasia Nasal passage o Nasal and paranasal areas Trachea Rhinitis Sinusitis Sinus Cysts Ethmoid Haematoma Nasal/sinus neoplasia Trauma 4 I The picture can't be BILATERAL displayed. NASAL DISCHARGE 1. Infectious diseases of URT  1. INFECTIOUS DISEASES OF URT AEITIOLOGY o Equine influenza virus (EIV) One of the most common infectious dzs of URT in horses Routine vaccination helpful for the prevention of outbreak o Equine herpesvirus (EHV, ‘Equine rhino’) EHV 4: typically, upper respiratory disease in young horses EHV 1: respiratory disease, neurologic disease, late-term abortion, early foal death o Other viral dzs: Equine rhinitis A & B, Adenoviruses o Streptococcus equi subspecies equi: ‘Strangles’ ➪Discussed in the later section 6  1. INFECTIOUS DISEASES OF URT CLINICAL SCENARIO o Risk factors Horses of all ages, particularly common in young horses High traffic, large group herd Virus transmission: air, direct nasal droplets, indirect transmission via people, water bucket, equipment o Clinical presentation Nasal discharge (often bilateral), enlarged LNs, fever, lethargy → typically, transient Consider LRT disease if + cough, tachypnoea Another ddx: oesophageal obstruction 7  1. INFECTIOUS DISEASES OF URT CLINICAL SCENARIO o Diagnosis Nasal swab for respiratory PCR panel o Treatment & prevention Often self-resolving NSAIDs: flunixin meglumine, phenylbutazone Supportive care: palatable foods, monitor hydration status Vaccination o Biosecurity Limit nose-to-nose contact Keep up with good routine hygiene practice 8 II The picture can't be UNILATERAL displayed. NASAL DISCHARGE 1. Sinusitis 2. Guttural pouch empyema 3. Strangles 4. Others  UNILATERAL NASAL DISCHARGE DIFFERENTIAL DIAGNOSIS 1. Sinusitis 2. GP empyema & Strangles 3. Others Sinus cyst nualMa Nasal/paranasal neoplasia inary Veter MSD 10  1. SINUSITIS PARANASAL SINUS ANATOMY o Paranasal & conchal sinuses A. Frontal B. Maxillary (Rostral & Caudal) C. Sphenopalatine D. Dorsal conchal E. Middle (Ethmoidal) conchal F. Ventro conchal UGA iBook Anatomy and diagnostic imaging of the equine paranasal sinuses 11  1. SINUSITIS PARANASAL SINUS ANATOMY o Paranasal & conchal sinuses 12 UGA iBook Anatomy and diagnostic imaging of the equine paranasal sinuses  1. SINUSITIS AEITIOLOGY o Primary sinusitis (subacute, chronic): most frequently seen,45% o Secondary sinusitis Dental/oral disease: 24% Sinus cyst: 13% Others: trauma, neoplasia, mycosis, ethmoid hematoma 13  1. SINUSITIS PATHOPHYSIOLOGY Primary sinusitis Secondary sinusitis URT viral infection Reduced mucociliary clearance Obstruction of drainage e.g. trauma, cyst, neoplasia Accumulation of mucus within sinus Secondary bacterial infection Dental disease Accumulation of purulent material ‘empyema’ 14  1. SINUSITIS SECONDARY SINUSITIS: DENTAL DISEASE o Primary dental dzs with extension into sinus Maxillary molars (9,10,11) roots lie within the maxillary sinus: covered by fine layer of alveolar bone and sinus periosteum Apical tooth root infections of these teeth can result in sinusitis o Oromaxillary fistula 15  1. SINUSITIS SECONDARY SINUSITIS: SINUS CYST o Unknown aetiology o Can occur at any age o Benign but expansile nature : can distort paranasal structure 16  1. SINUSITIS CLINICAL PRESENTATION o Serous/mucoid/purulent unilateral nasal discharge o Facial swelling/distortion (maxillary or frontal) o Nasal airflow obstruction: abnormal respiratory noise o Difficulty chewing: dental dzs 17  1. SINUSITIS DIAGNOSIS o Physical exam and history Facial symmetry Sinus percussion o Oral exam o Imaging Radiography Endoscopy: URT, sinus CT 18  1. SINUSITIS DIAGNOSIS o Physical exam and history Facial symmetry Sinus percussion o Oral exam o Imaging Radiography Endoscopy: URT, sinus CT 19  1. SINUSITIS DIAGNOSIS o Physical exam and history Facial symmetry Sinus percussion o Oral exam o Imaging Radiography Endoscopy: URT, sinus CT 20  1. SINUSITIS DIAGNOSIS o Physical exam and history Facial symmetry Sinus percussion o Oral exam o Imaging Radiography Endoscopy: URT, sinus CT 21  1. SINUSITIS DIAGNOSIS o Physical exam and history Facial symmetry Sinus percussion o Oral exam o Imaging Radiography Endoscopy: URT, sinus CT 22  1. SINUSITIS TREATMENTS o Goals Remove infection/necrotic tissue Restoration of normal drainage and mucociliary clearance Prevent recurrence Type Treatments Prognosis Primary Broad spectrum abx Very good Acute, uncomplicated Mucolytics Primary + Sinus trephination Good with treatment Chronic Repeat lavage Secondary Fair if 10 cause can be + Removal of inciting cause dental, trauma, neoplasia, etc treated 23  1. SINUSITIS TREATMENTS o Sinus trephination & lavage Frontal, caudal, rostral maxillary Allows high volume lavage or instillation of antimicrobials 24  1. SINUSITIS TREATMENTS o Sinus flap surgery Better surgical access to sinuses Standing surgery Extirpation, curettage to remove cysts or mass 25  2. GUTTURAL POUCH EMPHEMA GUTTURAL POUCH ANATOMY & PHYSIOLOGY o Air-filled pocket extension of Eustachian tube o Function Pressure equalization Warming of inhaled air Resonating chamber for vocalization Cooling of blood to the brain during exercise ota nes M inf ity o vers Uni 26  2. GUTTURAL POUCH EMPYEMA GUTTURAL POUCH ANATOMY & PHYSIOLOGY 27  2. GUTTURAL POUCH EMPHYEMA OVERVIEW o Definition: accumulation of exudate within GP o Usually sequela to URT infection (similar to sinus infections) Streptococcus zooepidemicus: opportunistic infection, very common Streptococcus equi equi : ‘Strangles’, highly contagious infectious agent o Clinical signs Fever and related symptoms: anorexia, lethargy Lymph nodes swelling Unilateral/bilateral purulent discharge o Chronic empyema → chondroid formation 28  2. GUTTURAL POUCH EMPYEMA NON-Streptococcus equi equi RELATED EMPYEMA TREATMENTS o Supportive therapy: NSAIDs, palatable feed o Lavage purulent material via endoscopy o Removal of chondroids via endoscopy or surgery 29  3. STRANGLES Streptococcus equi equi INFECTION o Streptococcus equi equi Gram +, β-haemolytic streptococcus, Lancefield group C Highly contagious URT disease of Equidae: high morbidity (~100%) , low mortality (~1%) Endemic in many countriesincluding the UK Significant economic and social impact within the equine industry Strict codes of practice for disease control and biosecurity 30  3. STRANGLES Streptococcus equi equi INFECTION 31  3. STRANGLES CLINICAL PRESENTATION o Varying severity More severe in young, old & immunocompromised horses o Mild case Pyrexia followed by pharyngitis and subsequent abscess formation in the submandibular and retropharyngeal lymph nodes o Severe case Swollen LNs interfering with breathing and/or swallowing → ‘strangles’ o Strangles related conditions Metastatic infection: ‘Bastard strangles’ Immune-mediated conditions: Purpura heamorrhagica, myositis 32  3. STRANGLES DIAGNOSIS o Sampling Nasal swab: not useful Nasopharyngeal swab/wash: early in the dzs process with some clinical signs Swab from purulent discharge from an abscess: high yield GP wash: best dx sampling esp. in chronic carriers 33  3. STRANGLES DIAGNOSIS o Laboratory work Positive when there is live organism Bacterial culture False negative if insufficient sampling Molecular diagnosis High sensitivity & specificity qPCR Identify recent infection (2w)* Serology Peak ~5 weeks & remain high ~6 months SeM ELISA One time test is no indication of active infection Combined Antigen Often miss-used as a ‘screening tool’ A & C ELISA* A guide for strangles relateddzs 34  3. STRANGLES TREATMENTS o Symptomatic & supportive therapy NSAIDs: Flunixin meglumine, phenylbutazone Palatable food o Encourage drainage of abscesses Hot pack, surgical lancing, daily cleaning/lavage o Judicious use of antibiotics Penicillin gel: local infusion to the GP 75% of horses develop long-term mucosal immunity as a result of infection Systemic abx may interfere with the development of natural immunity Systemic abx: reserve for very sick, compromised cases 35  3. STRANGLES STRANGLES RELATED CONDITIONS o ‘Bastard strangles’ Hematogenous or lymphatic spread of the organism Metastatic abscess: brain, abdomen, mammary, brain, eyes,etc A history of exposure to S. equi, recurring fever, high S. equi Ab titer Treatment: systemic abx o Immune-mediated purpura hemorrhagica and myopathy Necrotizing vasculitis: edema, petechial hemorrhage Peripheral oedema: head, limbs, torso Petechiation of themucous membranes A history of exposure to S. equi, suggestive CS, high S. equi Ab titer, skin biopsy Treatment: steroids +/- systemic abx 36  3. STRANGLES BIOSECURITY o Highly contagious among equid family Transmission via nasal discharge material, contaminated water and equipment o Shedding of S.equi equi usually ceases 2-3 weeks after clinical signs resolve o Silent carriers: some horses harbour infection in GPs o Detection, segregation, and treatment of carrier horse 37  3. STRANGLES BIOSECURITY - DETECTION o Horse with relevant clinical signs Is it Strangles? NP wash, GP wash, abscess sample → bacterial culture + PCR Isolate awaiting test results o Confirmed case Strict isolation Limit horse traffics Supportive care Test & release: often require multiple test over weeks period 38  3. STRANGLES BIOSECURITY - SEGREGATION Strangles positive case POSITIVE Strict isolation Test & release: need multiple tests over weeks In contact with + case but no clinical signs IN-CONTACT Monitoring RT & CS Test if suspicious No contact with + case and no clinical signs NAIVE Monitoring RT & CS Test if suspicious 39  3. STRANGLES BIOSECURITY – TREATMENT OF CARRIER o Carrier animals Recovering from a recent infection Silent carrier: may not show any clinical signs o Treatment GP local abx infusion Test & release May need multiple treatments & tests e.g. penicillin gel treatment q 1 week x 3 then test GP wash twice over weeks apart 40  3. STRANGLES BIOSECURITY o New horse protocol? Serology is often used to ‘screen’ a carrier: is it right? o What is best practice? Isolation on arrival? GP wash test? Serology + GP wash test? 41 III The picture can't be displayed. EPISTAXIS 1. Trauma 2. Ethmoid hematoma 3. Guttural pouch mycosis  EPISTAXIS APPROACH o Main differentials list Trauma Ethmoidal hematoma Guttural pouch mycosis Lower airway disease: exercise-induced pulmonary haemorrhage (EIPH) o Severity Mild, temporary Mild, intermittent Severe, life threatening 43  1. EPISTAXIS: TRAUMA OVERVIEW o Trauma to the head/nose o Iatrogenic: nasogastric intubation Relatively common risk Trauma to ethmoid → pass tube ventromedially! o Treatments Usually, self-limiting Supportive care General approach to blood loss 44  1. EPISTAXIS: TRAUMA GENERAL APPROACH TO BLOOD LOSS o Blood loss evaluation Blood loss HR CRT BP Mentation (%blood volume) (bpm) (sec) Up to 15% 32-48 2 Normal Anxiety 30-40% 60-80 >2, pale Decreased QAR >40% >80 Very pale Shock Obtunded Adopted from American College of Surgeons 2004 45  1. EPISTAXIS: TRAUMA GENERAL APPROACH TO BLOOD LOSS o Identify & stop the source of blood loss o Blood transfusion If PCV