Approach to Upper Respiratory Tract Disease In Equine- Week 10

Question 1

What is Equine Influenza Virus?

Answer 1

• One of the most common infectious diseases of the URT in horses
• Routine vaccination is helpful in preventing outbreaks

Question 2

What is Equine HerpesVirus?

Answer 2

EHV 4:typically, upper respiratory disease in young horses
* EHV 1:respiratory disease, neurologic disease,late-term abortion, early foal death

Question 3

What are the risk factors for Infectious diseases of the URT?

Answer 3

Horses of all ages, particularly common in young horses
* High traffic, large groupherd
* Virus transmission: air, direct nasal droplets, indirecttransmission via people, water
bucket, equipment

Question 4

What is the clinical presentation of URT diseases?

Answer 4

Nasal discharge (often bilateral), enlarged LNs, fever, lethargy → typically,transient
* Consider LRT disease if + cough,tachypnoea
* Another ddx: oesophagealobstruction

Question 5

How might you diagnose infectious diseases of the URT?

Answer 5

Nasal swab for respiratory PCR panel

Question 6

How might you treat/ prevent Infectious diseases of the URT?

Answer 6

Often self-resolving
* NSAIDs: flunixin meglumine,phenylbutazone
* Supportive care: palatable foods, monitor hydrationstatus
* Vaccination

Question 7

What biosecurity measures would you put in place to help prevent URT diseases?

Answer 7

• Limit nose to nose contact
• keep up with good routine hygeine practice

Question 8

What is the aetiology of primary sinusitis?

Answer 8

either subacute or chronic, most common form of sinusitis

Question 9

What is the aetiology of secondary sinusitis?

Answer 9

Dental/oral disease: 24%
* Sinus cyst:13%
* Others: trauma, neoplasia, mycosis, ethmoidhematoma

Question 10

What is the pathophysiology of primary sinusitis?

Answer 10

• URT viral infection
• Reduced mucocilliary clearance
• Accumulation of mucus
• Secondary bacterial infection
• Accumulation of purulent material ‘empyema’

Question 11

What two ways might dental disease cause secondary sinusitis?

Answer 11

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 sinusperiosteum
* Apical tooth rootinfections of these teeth
can result insinusitis
Oromaxillary fistula

Question 12

What is a sinus cyst?

Answer 12

Unknown aetiology
o Can occur at anyage
o Benign but expansile nature
: can distort paranasal structure

Question 13

What is the clinical presentation of sinusitis?

Answer 13

Serous/mucoid/purulent unilateral nasal discharge
o Facial swelling/distortion (maxillary orfrontal)
o Nasal airflow obstruction: abnormal respiratorynoise
o Difficulty chewing: (usually dental disease)

Question 14

How might you diagnose sinusitis?

Answer 14

• Physical exam/ History
• Oral exam
• Imaging (radiography, endoscopy (URT sinus) CT )
  *

Question 15

What are the three main goals of treating sinusitis?

Answer 15

• Removal of the infective/ necrotic tissue
• Restoration of normal drainage and mucocilliary clearance
• Prevent Recurrence

Question 16

How does a sinus trephination and lavage work?

Answer 16

Frontal, caudal, rostral maxillary
* Allows high volume lavage or instillation of antimicrobials

Question 17

How does sinus flap surgery work?

Answer 17

• Better surgical access to sinuses
• Standing surgery
• Extirpation, curratege to remove cysts or mass

Question 18

What is the guttural pouch?

Answer 18

Air-filled pocket extension of Eustachian tube

Question 19

What is the function of the guttural pouch?

Answer 19

• Pressure equalization
• Warming of inhaledair
• Resonating chamber forvocalization
• Cooling of blood to the brain during exercise

Question 20

What is the definition of guttural pouch empyema?

Answer 20

Accumulation of exudate within the Guttural Pouch

Question 21

What are the clinical signs of guttural pouch empyema?

Answer 21

• Fever and related symptoms: anorexia,lethargy
• Lymph nodes swelling
• Unilateral/bilateral purulent discharge

Question 22

How might you treat Guttural Pouch Empyema?

Answer 22

o Supportive therapy: NSAIDs, palatablefeed
o Lavage purulent material viaendoscopy
o Removal of chondroids via endoscopy or surgery

Question 23

What bacteria causes strangles in horses?

Answer 23

Streptococcus equi equi

Question 24

What is streptococcus equi equi?

Answer 24

Gram +, β-haemolytic streptococcus, Lancefield groupC
* 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

Question 25

What is the pathogenesis of Streptococcus equi equi Infection?

Answer 25

1. Inhalation/ Ingestion of S. equii 2. Colonisation of URT epithelium tonsil tissue 3. Rhinitis and paryngitis 4. Spreads to local lymphatics 5. Lymphadenopathy and abscess formation 6. GP Emypema, Abscess Rupture

Question 26

What is the clinical presentation of mild strangles?

Answer 26

Pyrexia followed by pharyngitis and subsequent abscess formation in the submandibular and retropharyngeal lymphnodes

Question 27

What is the clinical presentation of severe strangles?

Answer 27

Swollen LNs interfering with breathing and/or swallowing → ‘strangles’

Question 28

Nmae two strangles-related conditions

Answer 28

1. Metastatic infection- bastard strangles 2. Immune-Mediated conditions- Purpura haemorrhagica, myositis

Question 29

What samples would you take for strangles?

Answer 29

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

Question 30

How might you diagnose strangles through bacterial culture?

Answer 30

Positive when there is live organism * False negative if insufficient sampling

Question 31

How might you diagnose strangles through molecular diagnosis?

Answer 31

High sensitivity and specificity

Question 32

How might you diagnose strangles using serology?

Answer 32

dentify recent infection(2w)* * Peak ~5 weeks & remain high ~6 months * One time testis no indication of active infection * Often miss-used as a ‘screeningtool’ * A guide for strangles relateddzs

Question 33

How would you treat Strangles with NSAIds?

Answer 33

NSAIDs: Flunixin meglumine,phenylbutazone * Palatable food

Question 34

How would you treat strangles with antibiotics?

Answer 34

* Penicillin gel: local infusion to theGP * 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, compromisedcases

Question 35

What is bastard strangles?

Answer 35

Hematogenous or lymphatic spread ofthe 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

Question 36

What is immune mediated purpura haemorrhagica and myopathy?

Answer 36

Necrotizing vasculitis: edema, petechialhemorrhage * Peripheral oedema: head, limbs,torso * Petechiation of themucousmembranes * A history of exposure to S. equi, suggestive CS, high S. equi Ab titer, skin biopsy * Treatment: steroids +/- systemicabx

Question 37

What biosecurity issues are associated with strangles?

Answer 37

Highly contagious among equidfamily * Transmission via nasal discharge material, contaminated water andequipment o Shedding of S.equi equi usually ceases 2-3 weeks after clinical signs resolve o Silent carriers: some horses harbourinfection in GPs o Detection, segregation, and treatment of carrierhorse

Question 38

What should you do with a positive Strangles case?

Answer 38

Strict isolation * Test & release: need multiple tests over weeks

Question 39

What should you do with an in-contact strangles case?

Answer 39

* In contact with + case but no clinical signs * Monitoring RT &CS * Test if suspicious

Question 40

How would you treat a strangles carrier animal?

Answer 40

GP local abxinfusion * Test & release * May need multiple treatments & tests e.g. penicillin geltreatment q 1 week x 3 then test GP wash twice over weeks apart

Question 41

What are the main differentials for epistaxis?

Answer 41

Trauma * Ethmoidal hematoma * Guttural pouch mycosis * Lower airway disease: exercise-induced pulmonary haemorrhage(EIPH)

Question 42

What is the iatrogenic cause of epistaxis?

Answer 42

usually nasogastric intubation

Question 43

What is the general approach to blood loss?

Answer 43

Identify & stop the source of blood loss Blood transfusion * If PCV <12% * Ongoing, moderate to severe bloodloss

Question 44

What are the clinical signs of Progressive Ethmoidal Haematoma?

Answer 44

Intermittent epistaxis: ‘mucky’blood * Varying degrees of nasal/sinusobstruction

Question 45

How would you treat progressive ethmoidal haematoma?

Answer 45

Small lesions (<3/4 cm): intralesional formalin(10%) * Large lesions: surgical resection via sinusflap

Question 46

What is the aetiology of guttural pouch mycosis?

Answer 46

Aspergillus fumigatus and Emericella nidulans * Most commonly identified fungal agent +/- otherfungal spp. * Opportunistic infection: uncertain why some horses develop clinical dzs * Climatic factors: global warming and increasing prevalence in certain areas

Question 47

How might you diagnose Guttural Pouch Mycosis?

Answer 47

Suggestive clinical signs * Recurrent uni/bilateralepistaxis * Severe epistaxis **Endoscopy** * Stabilize the horse before the imagingstudy

Question 48

How might you treat Guttural Pouch Mycosis using medical management?

Answer 48

Anti-fungals: Itraconazole, enilconazole * Topical infusion via Indwelling catheter inserted into GP +/- systemic administration * Careful case selection:time to respond & success rates vary * Risk of fatal haemorrhage secondary to the erosion ofthe carotid arteries

Question 49

How might you treat Guttural Pouch Mycosis using Surgical options?

Answer 49

Occlude blood supply (cranial & distal) → fungal growth stops and eventually resolve * Balloon catheterisation * Coil embolisation

Question 50

What is the prognosis for guttural pouch mycosis?

Answer 50

Good if treated surgically in timelyfashion * Poor to guarded if complications (e.g. neurological dysfunction)