Equine MidSem Exam

Question 1

What are Epidermal Inclusion Cysts and what are the treatment options?

Answer 1

Definition – usually single, unilateral, spherical nodule (probably made up of remnant epithelium & has fluid in it_
Location – dorsolateral aspects of nasal diverticulum
Size – 3-5cm in diameter

Diagnosis:
- Based on location, consistency, character (white, opaque, viscous fluid)
- Not inflamed unless infected, confirmed by cytologic examination

Treatment:
- Rarely associated with impaired athletic performance – removal typically only for cosmetic reasons
- Treatment options:
* Standing surgical extirpation (scoop out / remove) via dissection without rupturing cyst wall
* Lance cyst into the nasal diverticulum via stab incision
* Aspiration of cystic fluid followed by Formalin injection = best option

Question 2

What are clinical signs of diseases of the nasal cavity & how would you diagnose them?

Answer 2

Clinical signs:
- Nasal stertor (heavy snoring inspiratory sound)
- Unilateral nasal discharge
- +/- fetid odour & facial distortion

Diagnostics:
- Endoscopy and/or radiography, sinuscopy, CT (“gold standard”)

Question 3

Discuss facial fractures & treatment options for them.

Answer 3

Location:
- Para-nasal sinuses / nasal cavities – common, results from direct trauma
- Nasal & frontal bones – most common, may involve maxillae & lacrimal bones

Diagnosis:
- Based on history + clinical exam + radiography
- CT = gold standard for complete assessment of all involved structures

Clinical presentation:
- Skin may be intact
- Always considered open

Treatment:
- Reconstructive surgery ASAP – through debridement & irrigated (primary open reduction > best cosmetic results)
- Large fragment fixation – orthopaedic screws and/or wire
- Incision closure in 2 layers: periosteum + skin
- Pressure bandage
- Systemic antimicrobial (5-6 days) +/- NSAID
- Side effects: serosanguinous nasal discharge normal for up to 2 weeks post-op. If drainage continues can lead to sequestrum or sinusitis.
- Failure to treat can result in: chronic sinusitis, bone sequestra, non-healing wounds, facial deformity secondary to nasal septal thickening, necrosis > fistula formation

Question 4

What is a progressive ethmoid haematoma and what is its aetiology?

Answer 4

Progressive Ethmoid Haematoma = an encapsulated mass originating in / around ethmoid labyrinth / para-nasal sinuses
Surface – smooth, glistening, mottled / green-tinged
Age – 1-20 years (mean age 10 years)
Gender – middle-aged male, young females
Breed – predominantly thoroughbreds

Aetiology:
- Unknown
- Haemorrhage in sub-mucosa of endo-turbinate / sinus

Question 5

Clinical signs and diagnosis of progressive ethmoid haematomas

Answer 5

Clinical signs:
- Mild intermittent unilateral (or sometimes bilateral) epistaxis – may be induced by exercise
- Abnormal respiratory noise
- Other possible clinical signs: malodorous breath, facial swelling / distortion, head shyness / shaking

Diagnosis:
- Tentative diagnosis based on: history, clinical signs, UA endoscopy, radiography, CT (gold standard to see how far it’s progressed into sinuses)
* Early endoscopic findings: trickle of blood (middle meatus), discolouration / enlargement of ethmoturbinate
* Progression to: greenish/yellow to purplish red mass, may obscure fundus of nasal cavity or entire nasal passage
- Histopathologic examination
- Differential diagnoses: paranasal sinus cyst, foreign body, ethmoidal neoplasia, mycosis, skull fracture, infection

Question 6

Treatment for progressive ethmoid haematomas

Answer 6

Treatment:
- Surgery: mass removal / destruction of origin
- Prefer to do standing as if they are recumbent > head is at same level as heart > higher BP > more bleeding
- Trans-endoscopic treatment (standing):
* For lesions limited to fundus of nasal cavity & <5cm diameter
- Fronto-nasal bone flap (standing / GA):
* Best access / versatility to expose origin of lesion (maxillary / frontal sinus + nasal cavity)
* For large lesions extending into nasal passage / sinuses > cryosurgical +/- laser lesion removal
- Firm packing with sterile cotton / gauze
* After 1 day remove one third of the bandage (without reopening the surgical flap), on the 2nd day remove another third & by the 3rd day all the bandage should be removed
- Broad spectrum systemic antibiotics
- Indwelling lavage system:
* Remove exudate, blood clots, tissue debris
Post-op:
- Stall rest + hand walking for 3 weeks

Question 7

In horses, which of the following statements is correct regarding Progressive Ethmoid Haematomas (PEH)?
a) Typical clinical signs are bilateral mucopurulent nasal discharge
b) The prognosis is good when using conservative / medical therapy
c) PEH lesions originate typically from the ventral conchal or maxillary sinus
d) The diagnosis is typically made by sinuscopy and ultrasonography
e) Treatment of choice for small lesions of <5cm is (repeat) LASER ablation

Answer 7

c) PEH lesions originate typically from the ventral conchal or maxillary sinus

Question 8

Discuss diagnostic procedures for diagnosing diseases of the paranasal sinuses

Answer 8

Sino-centesis
- Get a sample from the sinus – have to penetrate the bone
- Rostral + caudal maxillary sinus
- Prepare area for aseptic surgery under sedation
- Local infiltration 2% lidocaine
- Stab incision through skin & periosteum > penetrating bone
- Obtain fluid sample for culture & sensitivity
- Inject 10mL 2% lidocaine & lavage using warm saline

Sinoscopy
- Can be done in the field
- Para-nasal sinuses:
* Diagnosis & treatment
* Standing / conscious or general anaesthesia
* Rostral maxillary sinus difficult in horses <6 years
- Flexible endoscope:
* Superior viewing, allows navigation around structures
* Typically inserted through frontal bone via trephine opening of fronto-nasal bone
* Direct access to frontal & caudal maxillary sinuses
* Indirect access by fenestrating the bulla of the ventral concha > access cranial maxillary sinus / ventral conchal sinus

Question 9

Discuss sinusitis: primary vs. secondary

Answer 9

Most common disease of the para-nasal sinuses
Classification:

Primary bacterial sinusitis:
- Result of upper resp. tract infections – Streptococcus sp. most common
- Diagnosis:
* Radiography to rule out secondary sinusitis – common soft tissue density over the roots of premolar 108/208, molars 109/209, 100/210
* Distortion of sinus – narrowing of nasal passage due to inspissated exudate
- Surgical treatment:
* Removal of exudate + providing drainage
* Access of ventral conchal sinus – maxillary bone flap over the infra-orbital canal, concho-frontal sinus trephination over fronto-maxillary opening + fenestration of ventral conchal bulla
* Lavage – rostral maxillary & ventral conchal sinus
- Principles of therapy:
* Provide adequate drainage
* Systemic antimicrobials (culture + sensitivity)
- Drainage:
* Lavage of sinus once or twice daily
* Indwelling catheter per-cutaneously or by trephine opening
* Lavage with mild salt solution
* If exudate inspissated in ventral conchal sinus > open surgical treatment becomes necessary

Secondary sinusitis:
- Secondary to: dental disease, facial fractures, granulomatous lesions, neoplasms
- Diagnostics: endoscopy / sinuscopy, radiography, CT (gold standard)
- Aetiology:
* Dental disease = most common cause
* More difficult to treat
* Surgical intervention to remove underlying cause

Question 10

Discuss dynamic airway collapse.

Answer 10

Dynamic airway collapse
- Occurs when structures within the URT collapse into the airway during exercise, resulting in obstruction to airflow
- A common cause of poor performance in racehorses
- Also occurs in sport horses during submaximal exercise with poll flexion (flexed neck > increased compliance of soft tissues > soft tissues bulge into airway)
- Often not apparent during resting examination
- Areas prone to collapse: nostrils, nasopharynx (walls, roof, floor), larynx
Definitive diagnosis of dynamic airway collapse requires exercising endoscopy:
- Treadmill endoscopy – until recently was the only method
- Overground endoscopy – enables examination of horse under normal “work conditions” & quicker & cheaper (don’t have to transport horse to specialist centre)
Signs of upper airway obstruction
- Abnormal respiratory sounds (during exercise) – inspiratory or expiratory
- Exercise intolerance
- Respiratory distress
- Nasal discharge
- Cough

Question 11

A bronchoalveolar lavage sample is obtained from a 5 year old Standardbred racehorse with a history of occasional cough, poor race performance and prolonged recovery. The differential cell count reveals 36% neutrophils, 26% lymphocytes and 38% macrophages with occasional cells containing haemosiderin. What is the most appropriate treatment for this horse?
a) Nebulised disodium chromoglycate and reduction of environmental dust levels
b) Oral clenbuterol and trimethoprim sulpha
c) Inhaled corticosteroids and reduction of environmental dust levels
d) Injection of intravenous frusemide before racing

Answer 11

c) Inhaled corticosteroids and reduction of environmental dust levels

Question 12

A 4 year old Thoroughbred racehorse is presented with a history of poor performance and loud respiratory sounds during inspiration. At rest his laryngeal function is graded III.I on the Havemeyer scale. The following image is recorded during an exercising endoscopy. What is the most likely cause of this condition?
a) Axial deviation of the aryepiglottal folds
b) Arytenoid chondritis
c) Recurrent laryngeal neuropathy
d) 4th branchial arch defect

Answer 12

c) Recurrent laryngeal neuropathy

Question 13

Which of the following conditions is most likely to be associated with abnormal “gurgling” respiratory sounds during expiration?
a) Pharyngeal wall collapse
b) Dorsal displacement of the soft palate
c) Vocal fold collapse
d) Arytenoid cartilage collapse

Answer 13

b) Dorsal displacement of the soft palate

Question 14

Which of the following best describes the advantage of field anaesthesia compared to standing sedation?
a) It allows for better patient immobility
b) Cardiorespiratory function is maintained better
c) It is more appropriate for longer procedures
d) It requires less personnel to safely implement

Answer 14

a) It allows for better patient immobility

Question 15

A well trained, easily handled and healthy mare is presented for a Caslick’s procedure. Which of the following sedation protocols is the most appropriate choice for this mare?
a) Xylazine and application of a twitch
b) Midazolam and application of a twitch
c) Detomidine followed by Butorphanol
d) Acepromazine followed by Butorphanol

Answer 15

c) Detomidine followed by Butorphanol

Question 16

Which of the following ingredients are included in the ‘triple drip’ for a field anaesthesia?
a) Diazepam, ketamine, xylazine
b) Guiafenisin, ketamine, acepromazine
c) Guiafenisin, ketamine, midazolam
d) Guiafenisin, ketamine, xylazine

Answer 16

d) Guiafenisin, ketamine, xylazine

Question 17

Which of the following is generally not considered to be a complication associated with general anaesthesia in a horse?
a) Hypoxaemia
b) Hypotension
c) Tachycardia
d) Myopathy

Answer 17

c) Tachycardia

Question 18

An 18 year old Arabian horse is suspected of having aortic regurgitation because of which of the following finding during heart auscultation:
a) Holodiastolic, decrescendo cardiac murmur on the left hemithorax
b) Mid-end diastolic squeaking cardiac murmur on the left hemithorax
c) Pansystolic cardiac murmur on the left hemithorax
d) Holosystolic crescendo cardiac murmur on the left hemithorax

Answer 18

a) Holodiastolic, decrescendo cardiac murmur on the left hemithorax

Question 19

In horses with chronic Streptococcus equi subsp. equi infection what is the most appropriate diagnostic technique to positively identify the aetiologic agent?
a) Sterile blood collection and blood culture
b) Nasal swab and culture
c) Guttural pouch lavage and PCR testing
d) Transtracheal wash and culture

Answer 19

c) Guttural pouch lavage and PCR testing

Question 20

Choose the most appropriate diagnosis regarding equine herpes virus (EHV) infection in horses.
a) Vaccination is commonly performed and is highly protective for the neurological form of EHV-1
b) EHV-1 causes respiratory illness and ultimately targets the epithelium
c) Virus isolation and PCR of nasopharyngeal swabs may be used to support a diagnosis of EHV-1
d) EHV-1 is transmitted by infected fomites, vertical transmission and contaminated surgical instruments

Answer 20

c) Virus isolation and PCR of nasopharyngeal swabs may be used to support a diagnosis of EHV-1

Question 21

Based on the bacteria most commonly associated with bronchopneumonia in adult horses, which of the following provides the most appropriate antimicrobial regimen?
a) Enrofloxacin, gentamicin and polymyxin B
b) Trimethoprim sulfate and ceftiofur
c) Penicillin, gentamicin and metronidazole
d) Ceftiofur, chloramphenicol and metronidazole

Answer 21

c) Penicillin, gentamicin and metronidazole

Question 22

A horse is presented in severe respiratory distress and a history of fever, recent travelling, general anaesthesia or previous illness, what would be the most logical and appropriate course of action from the following?
a) Sedate the horse to perform emergency tracheotomy, administration of intranasal O2, broad-spectrum antimicrobials and bronchodilators
b) Perform an endoscopy to obtain a tracheal lavage for culture and susceptibility, administration of broad-spectrum antimicrobials, bronchodilators and NSAIDs
c) Sedate the horse to perform emergency tracheotomy, administration of broad-spectrum antimicrobials, inhaled corticosteroids and laminitis prevention
d) Perform thoracocentesis to drain the pleural fluid, administration of broad-spectrum antimicrobials, NSAIDs and laminitis prevention

Answer 22

d) Perform thoracocentesis to drain the pleural fluid, administration of broad-spectrum antimicrobials, NSAIDs and laminitis prevention

Question 23

A horse is presented for repair of a 5cm laceration over his left eye but the horse is reluctant to allow IV access. Which of the following protocols is the most appropriate choice in this scenario?
a) Administer xylazine IM, top-up IV if necessary and perform local blocks
b) Dispense oral acepromazine, reschedule to later in the day when the horse is sedated
c) Administer midazolam IM, administer medetomidine IV once the horse is sedated and followed by methadone IV
d) Apply a twitch, administer midazolam IM and perform local blocks

Answer 23

a) Administer xylazine IM, top-up IV if necessary and perform local blocks

Question 24

The owner of a horse undergoing colic surgery (with an apparently poor prognosis) decides to euthanise the horse while still under general anaesthesia. What would be the best method of euthanasia for this horse?
a) Intrathecal lignocaine
b) Captive bolt
c) IV potassium chloride
d) IV barbiturate

Answer 24

d) IV barbiturate

Question 25

What would be the best parameter to confirm death in a horse that has been euthanised?
a) No palpable arterial pulse
b) Rigor mortis
c) Apnoea
d) Abscence of cardiac activity

Answer 25

d) Abscence of cardiac activity

Question 26

A systolic murmur on the left hemithorax in a horse is consistent with:
a) Pulmonary valve regurgitation
b) Tricuspid valve regurgitation
c) Aortic valve regurgitation
d) Mitral valve regurgitation

Answer 26

d) Mitral valve regurgitation

Question 27

Which of the following is the best treatment protocol for fungal ulcerative keratitis in a horse?
a) Twice daily topical anti-fungal therapy for 7-10 days
b) Topical anti-fungal therapy every 2 hours for 6-8 weeks
c) Twice daily topical anti-fungal therapy for 6-8 weeks
d) Topical anti-fungal therapy every 2 hours for 7-10 days

Answer 27

b) Topical anti-fungal therapy every 2 hours for 6-8 weeks

Question 28

Describe the diagnostic approach of a horse with a non-healing corneal ulcer:
a) Block the auriculopalpebral nerve, assess eyelids, perform fluorescein test and take swabs for cytology
b) Block the supraorbital (frontal) nerve, perform fluorescein test and assess intra-ocular pressure
c) Block the maxillary nerve, assess eyelids, perform tear test and take swabs for culture
d) Block the infratrochlear nerve, assess eyelids, perform fluorescein test and take a biopsy

Answer 28

a) Block the auriculopalpebral nerve, assess eyelids, perform fluorescein test and take swabs for cytology

Question 29

Consider the endoscopic image below (large / obvious epiglottis). What is the diagnosis and what is the management for this condition?
a) Permanent dorsal displacement of the soft palate: staphylectomy and laryngeal tie-forward
b) Epiglottic entrapment: laser intervention to split the centre of the redundant sub-epiglottic mucosa
c) Axial deviation of the aryepiglottic folds: laser ablation of the aryepliglottic folds
d) Sub-epiglottic cyst: laryngotomy to resect the redundant tissue

Answer 29

b) Epiglottic entrapment: laser intervention to split the centre of the redundant sub-epiglottic mucosa

Question 30

A 7 year old Clydesdale cross gelding is presented with roaring inspiratory sounds, occasional cough and exercise intolerance. He performs low level carriage driving. His resting endoscopy shows grade III laryngeal function. What would be the most appropriate approach for this horse?
a) Rest the horse for 6 weeks with a course of oral prednisolone
b) Refer the horse to perform a bilateral laser ventriculo-cordectomy
c) Refer the horse to perform a laser ventriculo-cordectomy and a laryngeal tie-back procedure
d) Perform a BAL and rule out lower airway inflammatory disease

Answer 30

d) Perform a BAL and rule out lower airway inflammatory disease

Question 31

What lesion is shown in the figure below:
a) A progressive ethmoid haematoma present in the left nasal cavity
b) A progressive ethmoid haematoma in the right nasal cavity
c) Right-sided guttural pouch mycosis
d) Left-sided guttural pouch mycosis

Answer 31

b) A progressive ethmoid haematoma in the right nasal cavity

Question 32

What is the most common type of inflammatory cell response identified in bronchoalveolar lavage fluid in Aus. horses with mild-moderate asthma?
a) Lymphocytic response
b) Neutrophilic response
c) Eosinophilic response
d) Mixed inflammatory cell response

Answer 32

d) Mixed inflammatory cell response

Question 33

What is an important consideration when using ketamine top ups during a castration performed in the field?
a) Active metabolite will build up in the circulation
b) Ketamine is more expensive than guaifenisin
c) Apnoea will develop
d) Hypotension will develop

Answer 33

a) Active metabolite will build up in the circulation

Question 34

Which clinical signs and diagnostic procedures confirm an equine herpes virus infection?
a) Horses with nasal discharge, cough and increased antibody serum titre on serology
b) Horses with nasal discharge, severe cough and virus isolation from a nasal swab
c) Horses with cough, fever and PCR from a guttural pouch lavage
d) Horses with nasal discharge, fever and positive PCR from a nasopharyngeal swab

Answer 34

d) Horses with nasal discharge, fever and positive PCR from a nasopharyngeal swab

Question 35

What is the most appropriate treatment regime for a horse with recurrent airway obstruction (RAO)?
a) Low dust enviro, bronchodilator and corticosteroids
b) Low dust enviro, bronchodilator and NSAID
c) Low dust enviro, antibiotics and corticosteroids
d) Low dust enviro, antibiotics and bronchodilator

Answer 35

a) Low dust enviro, bronchodilator and corticosteroids

Question 36

Which of the following is the least likely explanation for a positive bacterial culture from a tracheal wash, taken via endoscopy, from a horse with recurrent airway obstruction (RAO)?
a) Contamination of the sample due to non-aseptic technique
b) Normal upper respiratory tract flora
c) Primary bacterial infection
d) Opportunistic secondary bacterial infection

Answer 36

c) Primary bacterial infection

Question 37

How can RAO be best distinguished from inflammatory airway disease during the clinical examination?
a) Based on BAL findings. Horses with RAO will have a higher proportion of neutrophils
b) Horses with RAO will cough, whilst horses with IAD will not
c) Horses with RAO will have evidence of increased resp. effort at rest whilst horses with IAD will not
d) Based on TW findings. Horses with RAO will have a higher proportion of neutrophils.

Answer 37

c) Horses with RAO will have evidence of increased resp. effort at rest whilst horses with AID will not

Question 38

Which of the following diagnostic tools is most useful to confirm a definitive diagnosis of lower airway inflammation?
a) Tracheal wash
b) BAL
c) Tracheal endoscopy
d) Nasopharyngeal swab

Answer 38

b) BAL

Question 39

What is the most likely diagnosis for a horse that is presented with bilateral purulent nasal discharge & fever without a cough?
a) Strangles disease
b) Pleuropneumonia
c) Recurrent Airway Obstruction (RAO)
d) Bronchopneumonia

Answer 39

a) Strangles disease

Question 40

A 2-year old horse develops acute swelling of the head 2 weeks after drainage of a submandibular abscess. Your tentative diagnosis is purpura haemorrhagica. What are the 2 most important components of the treatment of equine purpura haemorrhagica?
a) Immunosuppressive corticosteroid treatment (IV or IM) & diuretics (furosemide IV)
b) IV fluids & antimicrobial treatment (procaine penicillin IM)
c) Immunosuppressive corticosteroid treatment (IV or IM) & diuretics (furosemide IV)
d) Immunosuppresive corticosteroid treatment (IV or IM) & antimicrobial treatment (procaine penicillin IM)

Answer 40

d) Immunosuppresive corticosteroid treatment (IV or IM) & antimicrobial treatment (procaine penicillin IM)

Question 41

What is the aetiology of strangles & how is the disease spread?
a) Streptococcus equi subspecies equi, which is transmitted either by direct or indirect contact
b) Streptococcus equi subspecies zooepidemicus, which is transmitted only by direct contact
c) Streptococcus equi subspecies equi, which is transmitted only by direct contact
d) Streptococcus equi subspecies zooepidemicus, which is transmitted either by direct or indirect contact

Answer 41

a) Streptococcus equi subspecies equi, which is transmitted either by direct or indirect contact

Question 42

Which rules should be included in the isolation protocol once strangles is diagnosed at a stable yard:
a) Isolation of horses up to 3 weeks after the diagnosis of strangles disease & clean the environment
b) Isolation of horses up to 3 weeks after the diagnosis of strangles & 2 weeks treatment of the horses with clinical signs
c) Isolation of horses up to 6 weeks after the diagnosis of strangles disease & endoscopy of the guttural pouch of horses to indicate carrier status of horses
d) Isolation of horses up to 3 weeks after resolution of clinical signs of strangles disease & negative culture of nasal-pharyngeal swabs

Answer 42

d) Isolation of horses up to 3 weeks after resolution of clinical signs of strangles disease & negative culture of nasal-pharyngeal swabs

Question 43

In a horse with recurrent laryngeal neuropathy, which muscle is implicated in the failure to abduct the arytenoid cartilage?
a) Thyroarytenoideus
b) Cricothyroideus
c) Cricoarytenoideus dorsalis
d) Cricoarytenoideus lateralis

Answer 43

c) Cricoarytenoideus dorsalis

Question 44

Examine the endoscopic image taken from a racehorse during strenuous exercise. Which treatment option would be most appropriate in this horse?

Answer 44

Prosthetic laryngoplasty & ventriculocordectomy (RACEHORSE)

Question 45

Which of the following forms of dynamic airway collapse is most likely to be associated with abnormal respiratory sounds during expiration?
a) Axial deviation of the aryepiglottic folds
b) Vocal fold collapse
c) Pharyngeal wall collapse
d) Dorsal displacement of the soft palate

Answer 45

d) Dorsal displacement of the soft palate

Question 46

Which of the following diagnostic techniques is the most appropriate for making a definitive diagnosis of dynamic upper airway collapse in the horse?
a) Sound analysis
b) Exercising endoscopy
c) Resting endoscopy
d) Laryngeal ultrasound

Answer 46

b) Exercising endoscopy

Question 46

Which of the following statements best describes the situation in a normal horse during exercise?
a) Soft, blowing sounds are normal during expiration but not during inspiration
b) Loud respiratory noises are audible throughout the respiratory cycle
c) There should be no audible respiratory sounds during inspiration or expiration
d) Soft, blowing sounds are audible during inspiration but not during expiration

Answer 46

a) Soft, blowing sounds are normal during expiration but not during inspiration

Question 46

What is the most likely cause of a holosystolic murmur auscultated over the left apex & radiating dorsally?
a) Pulmonic valve insufficiency
b) Mitral valve regurgitation
c) Aortic valve insufficiency
d) Flow murmur

Answer 46

b) Mitral valve regurgitation

Question 47

A deficiency of which of the following electrolytes is a possible risk factor for development of atrial fibrillation?
a) Sodium
b) Calcium
c) Potassium
d) Chloride

Answer 47

c) Potassium

Question 48

You diagnose atrial fibrillation in a Dutch warmblood dressage horse. It was previously auscultated one month ago and found to be normal sinus rhythm with no murmurs. What are the chances of successfully converting this horse to sinus rhythm using quinidine sulphate and what is the likelihood of recurrence?
a) 25% chance of conversion, 95% chance of recurrence
b) 95% chance of conversion, 65% chance of recurrence
c) 95% chance of conversion, 25% chance of recurrence
d) 65% chance of conversion, 95% chance of recurrence

Answer 48

c) 95% chance of conversion, 25% chance of recurrence

Question 49

Which of the following is likely to be a common side effect following the administration of quinidine for treatment of atrial fibrillation?
a) Tachycardia
b) Colitis
c) Laminitis
d) Bradycardia

Answer 49

a) Tachycardia

Question 50

Which of the following is the most common cause of a systolic murmur on the right side of the thorax in the horse?
a) Mitral regurgitation
b) Tricuspid regurgitation
c) Aortic regurgitation
d) Ventricular septal defect

Answer 50

b) Tricuspid regurgitation

Question 51

Racehorse not impacted by performance has p waves with drop beat on ECG. What is the cause?

Answer 51

This is normal in athletic horses due to high vagal tone.

Question 52

Racehorse with grade IIIa laryngeal dysfunction. What is the best treatment to return to racing quickly?

Answer 52

Prosthetic laryngoplasty and ventriculo-cordectomy

Question 53

What is the mechanism of the “tie-back” technique (prosthetic laryngoplasty)?
a) Replace function of cricoarytenoid dorsalis muscle
b) Displace larynx rostro-dorsally
c) Displace larynx caudo-ventrally

Answer 53

b) Displace larynx rostro-dorsally

Question 54

What is the most likely differential for abnormal noise (“gurgling”) during expiration?

Answer 54

Dorsal displacement of the soft palate

Question 55

You are going to do a dental examination on a horse that is well trained and calm. What is the most appropriate sedation?
a) Medetomidine + twitch
b) Xylazine + butorphanol
c) Romifidine + methadone
d) … + morphine

Answer 55

b) Xylazine + butorphanol

Question 56

Which is LEAST appropriate for standing sedation for a painful procedure?
a) Acepromazine + xylazine
b) … + opioids

Answer 56

?

Question 57

Which is most correct about equine influenza virus:
a) It is a single stranded DNA virus that undergoes antigenic drift
b) It has high mortality but low morbidity
c) Antigenic drift occurs with haemagglutinin
d) Because antigenic drift occurs vaccination is not recommended

Answer 57

c) Antigenic drift occurs with haemagglutinin

Question 58

Which is most correct about equine herpes virus?
a) EHV-1 causes respiratory disease and affects vascular endothelium
b) Transmission occurs via fomites, vertical transmission and contaminated equipment
c) ?
d) ?

Answer 58

b) Transmission occurs via fomites, vertical transmission and contaminated equipment

Question 59

Question about GP empyema…

Question 60

Question about GP mycosis…

Question 61

Horse with face distortion, unilateral purulent nasal discharge, radiographs…?

Question 62

Which of the following cardiac findings would be most likely to negatively affect athletic performance in a standardbred racehorse?
a) Persistent atrial fibrillation
b) Grade 3/6 tricuspid regurgitation
c) Grade 2/6 mitral regurgitation
d) 2nd degree AV block at rest

Answer 62

a) Persistent atrial fibrillation

Question 63

An owner of a show jumping horse calls you for advice: the horse is rushing at fences and knocking down poles in competitions and reluctant to work in an outline. He has been heard to make abnormal respiratory sounds when he pulls and his head and neck is in a more flexed position. He is also reported to cough occasionally at the start of exercise. What is the most appropriate advice?

Answer 63

The horse may have an upper airway obstruction and an endoscopy of the airways at rest and during exercise is advisable.

Question 64

What is the most likely cause of a holosystolic murmur auscultated over the left apex and radiating dorsally?
a) Mitral valve regurgitation
b) Flow murmur
c) Aortic valve insufficiency
d) Pulmonic valve insufficiency
e) Tricuspid valve regurgitation

Answer 64

a) Mitral valve regurgitation

Question 65

What is the most likely diagnosis based on the radiograph (radiograph of GP with horizontal white line)?
a) GP tympany
b) GP empyema
c) GP mycosis
d) Rupture of the ventral straight muscles
e) Temporohyoid osteoarthropathy

Answer 65

b) GP empyema

Question 66

What is the most likely diagnosis based on the image of this 9-month old foal (horse with golf-ball like swelling under jaw)
a) GP empyema
b) GP tympany
c) Progressive ethmoid haematoma
d) GP mycosis
e) Stylohyoid osteoartropathy

Answer 66

b) GP tympany (more likely in younger animals)

Question 67

What is the most likely diagnosis based on the upper airway endoscopic image below (white fungal looking plaques)
a) GP mycosis
b) GP melanoma
c) GP empyema
d) GP chondroids
e) GP temporohyoid osteoarthropathy

Answer 67

a) GP mycosis

Question 68

A veterinarian is presented with a 3-week old TB filly with a large non-painful unilateral swelling in the left parotid region. During the initial physical examination the veterinarian notes that the foal has dyspnoea, has some difficulty swallowing, and the swelling is soft and elastic. Which 3 diagnostic procedures are most strongly indicated?
a) Upper resp. tract endoscopy, radiography of the pharyngeal region and thoracic radiography
b) Lower resp. tract endoscopy, radiography of the ethmoidal region and thoracic radiography
c) Fine needle aspiration of the swelling, bilateral pulmonary US and electrocardiography
d) Thoracocentesis, tracheobronchial aspiration, and positive contrast radiography of the laryngeal region
e) Centesis of the conchofrontal sinuses, percussion of the paranasal sinuses, plain radiography of the sinuses

Answer 68

a) Upper resp. tract endoscopy, radiography of the pharyngeal region and thoracic radiography
(upper resp tract endoscopy & radiography is gold standard. Thoracic rads because dyspnoeic).

Question 69

A BAL sample is obtained from a 5 year old standardbred racehorse with a history of occasional cough, poor race performance and prolonged recovery. The differential cell count reveals 36% neutrophils, 26% lymphocytes and 38% macrophages with occasional cells containing haemosiderin. What is the most appropriate treatment for this horse?
a) Inhaled corticosteroids and reduction of environmental dust levels
b) Nebulised disodium chromoglycate and reduction of environmental dust levels
c) No treatment is required
d) Injection of IV frusemide before racing

Answer 69

a) Inhaled corticosteroids and reduction of environmental dust levels

Question 70

Although there are many acceptable techniques for use in field anaesthesia, there are core principles that should be completed in order for its safe performance. Which of the following BEST describes one of these principles?
a) IV catheters should be placed prior to induction to ensure immediate venous access for drug delivery
b) Monitoring during field anaesthesia is vital and should involve the use of a BP monitor
c) Owners must be fully informed about all stages of the procedure in order to help on the horse’s head for induction
d) A horse can be best assisted during recovery by a person with a lead rope attached to a sturdy halter

Answer 70

a) IV catheters should be placed prior to induction to ensure immediate venous access for drug delivery

Question 71

Recovery from general anaesthesia in horses can be challenging and with a high incidence of complications. What is NOT a common complication seen in recovery of horses.
a) Hypotension
b) Colic
c) Facial nerve paralysis
d) Quadriceps myopathy

Answer 71

d) Quadriceps myopathy (seen rarely in quadriceps)

Question 72

Which of the following propositions is correct?
a) Guttural pouches are crossed by branches of the cranial nerves IX to XII in the lateral compartment
b) On xrays guttural pouches appear as radiolucent areas at the back of the skull and in front of the first and second cervical vertebrae in normal horses
c) Guttural pouches are pair and divided by the basi-hyoid bone into two unequal compartments
d) A large segment of the stylo-hyoid bone divides each guttural pouch in one small lateral compartment and one large medial compartment

Answer 72

d) A large segment of the stylo-hyoid bone divides each guttural pouch in one small lateral compartment and one large medial compartment

Question 73

A 5 month old TB foal is presented with severe resp. distress, bilateral purulent nasal discharge & marked swelling in the throat-latch area. The horse has a markedly increased resp. effort, a loud inspiratory noise which is becoming progressively louder and the foal appears to be agitated and distressed. The most appropriate course of action at this time is to:
a) Place a rebreathing bag over the foal’s nose and auscultate the thorax
b) Perform an emergency tracheostomy to relieve airway obstruction
c) Sedate the foal and obtain lateral radiographs of the thorax
d) Obtain swabs of the exudate and submit for culture and sensitivity testing
e) Administer gentamicin and penicillin and moniter the foal’s repsonse

Answer 73

b) Perform an emergency tracheostomy to relieve airway obstruction
(have to do this before we find cause to prevent collapse before treatment due to severe resp. distress)

Question 74

Choose the most appropriate answer regarding equine influenza virus (EIV) in horses:
a) Vaccination is not commonly performed due to antigenic drift
b) Antigenic drift is caused by a mutation in haemagglutin
c) EIV is a single stranded DNA virus displaying antigenic drift
d) EIV has a high mortality but low morbidity and is commonly identified in outbreaks of resp. disease

Answer 74

b) Antigenic drift is caused by a mutation in haemagglutin

Question 75

Which of the following options is most appropriate for the treatment of a 3cm x 3cm x 4.5cm progressive ethmoid haematoma lesion?
a) Mass removal via maxillary bone flap
b) Cryosurgery via fronto-nasal bone flap
c) Chemical ablation using formalin injection
d) Endoscopy guided transection and removal

Answer 75

c) Chemical ablation using formalin injection
(can inject even bigger ones with formaldehyde but unlikely to get to base. Always choose less invasive option first)

Question 76

A vet is presented with a 4 year old TB stallion which has collided with a fence during training. On physical exam the horse has severe resp distress and there is a dorsally located wound over the 6th and 7th ribs of the left hemithorax. The primary aims of emergency management in this case are to:
a) Prevent air moving into the chest via the wound and early re-expansion of the lungs
b) Control haemorrhage with pressure and achieve primary closure of the wound
c) Control pain with analgesics and administer high doses of antibiotics IV
d) Administer general anaesthesia and surgically explore and debride the thoracic wound
e) Administer a balanced electrolyte solution IV and bronchodilator therapy

Answer 76

a) Prevent air moving into the chest via the wound and early re-expansion of the lungs

Question 77

A 3 year old standardbred gelding is presented with a history of excessive respiratory noise during exercise. Following exam the vet determines that the noise is due to excessive nasal flutter. This noise is best described as:

Answer 77

Low pitched whistling or snoring that is continuous but loudest during expiration

Question 78

A 2 year old TB filly is presented with history of exercise intolerance and abnormal respiratory noise during exercise. During physical exam the vet notes that airflow from the left nostril is markedly decreased compared to airflow from the right nostril. The most appropriate approach to this case is:
a) Collect and submit blood and serum for routine haematology and biochemical evaluation
b) Obtain a tracheal aspirate and submit for cytology, bacterial culture and sensitivity testing
c) Perform both endoscopic and radiographic examinations of the upper respiratory tract
d) Perform a thoracocentesis and a radiographic examination of the lower resp tract
e) Perform centesis of the frontal and maxillary sinuses and submit aspirates for cytology

Answer 78

c) Perform both endoscopic and radiographic examinations of the upper respiratory tract

Question 79

What is an epidermal inclusion cyst (atheroma), it’s diagnosis and treatment.

Answer 79

Epidermal inclusion cyst / atheroma = usually single, unilateral spherical nodule (probably made up of remnant epithelium) that sits on the dorsolateral aspects of the nasal diverticulum.

Diagnosis:
Based on location, consistency, character (filled with white, opaque viscous fluid)

Treatment:
Rarely associated with impaired athletic performance - remove typically only for cosmetic reasons.
- Standing surgical extirpation (scoop out) via dissection without rupturing cyst wall
- Lance cyst into the nasal diverticulum via stab incision
- Aspiration of cystic fluid followed by Formalin injection = best option

Question 80

Discuss facial fractures - diagnosis & treatment.

Answer 80

Diagnosis:
- Based on history + clinical exam + radiography
- CT = gold standard for complete assessment of all involved structures

Treatment:
- Reconstructive surgery ASAP - debridement & irrigation (primary open reduction > best cosmetic results)
- For large fragment fixation - orthopaedic screws and/or wires
- Pressure bandage
- Systemic antimicrobial (5-6 days) +/- NSAID
- Side effects = serosanguinous nasal discharge normal for up to 2 weeks post-op.

Question 81

Discuss progressive ethmoid haematoma. What is it, clinical signs, diagnosis and treatment.

Answer 81

Progressive ethmoid haematoma = an encapsulated mass originating in / around ethmoid labrynth / para-nasal sinuses. Occurs in horses aged 1-20 years (mean age 10 years), predominantly in thoroughbreds.
- On histology the stroma contains blood, fibrous tissue, macrophages, giant cells with haemosiderin

Clinical signs:
- Mild intermittent unilateral (or sometimes bilateral) epistaxis - may be induced by exercise
- Abnormal resp. noise
- Malodorous breath, facial swelling / distortion, head shyness / shaking

Diagnosis:
- Based on history, clinical signs, UA endoscopy, radiography, CT (gold standard to see how far it’s progressed into sinuses)

Treatment:
- Surgery: mass removal / destruction of origin. Prefer to do standing as if they are recumbent > head is at same level as heart > higher BP > more bleeding
- Trans-endoscopic treatment standing - for lesions limited to fundus of nasal cavity & <5cm
- Fronto-nasal bone flap (standing/ GA) - best access to expose origin of lesion
- + broad spectrum AB’s
- + indwelling lavage system to remove exudate, blood clots, tissue debris
- Post-op: stall rest + hand walking for 3 weeks
- Common side effect = fungal & necrotic tissue plaques (these are just temporary, as the epithelium closes over the fungal plaque will slough off)

Question 82

Discuss sinusitis it’s aetiology, diagnosis & treatment.

Answer 82

Sinusitis = most common disease of the para-nasal sinuses.

Primary bacterial sinusitis:
- Result of upper resp. tract infections - Streptococcus most common
Diagnosis:
- Radiography to rule out secondary sinusitis
Treatment:
- Removal of exudate + providing drainage - lavage of sinus once or twice daily with mild salt solution using indwelling catheter.
- Systemic antimicrobials (culture + sensitivity)
- If exudate inspissated in ventral conchal sinus > open surgical treatment becomes necessary

Secondary sinusitis:
- Secondary to: dental disease (most common), facial fractures, granulomatous lesions, neoplasms
Diagnostics: endoscopy / sinuscopy, radiography, CT (gold standard)
Treatment:
- More difficult to treat - surgical intervention to remove underlying cause

Question 83

Discuss neoplasia of the para-nasal sinuses - what is the most common type of tumour?

Answer 83

Squamous cell carcinoma is the most common tumour of para-nasal sinuses.
Clinical signs differentiating neoplasia from other sinus diseases = malodorous breath without evidence of dental disease & radiographic evidence of widespread bone destruction
Prognosis: generally unfavourable unless solid, non-invasive (majority malignant)

Question 84

Discuss dynamic airway collapse, it’s clinical signs and diagnosis.

Answer 84

• Occurs when structures within the URT collapse into the airway during exercise > results in obstruction to airflow
• Areas prone to collapse = nostrils, nasopharynx, larynx

Clinical signs:
- A common cause of poor performance in racehorses and in sport horses with poll flexion (flexed neck > increased compliance of soft tissues > soft tissues bulge into airway)
- Abnormal resp sounds during exercise - inspiratory or expiratory
- Exercise intolerance
- Resp distress
- Nasal discharge
- Cough

Diagnosis:
- Endoscopic examination at rest + exercising
- Additional investigations may include US, radiography MRI

Question 85

Discuss pharyngeal lymphoid hyperplasia.

Answer 85

• An acquired disorder of the nasopharynx (upper airway obstructive condition).
• Looks like lots of spots / hives in the airway
• Common in young horses
• Exacerbated inflammatory reaction secondary to immunological stimulation
• Diagnosis: on endoscopy (grade 0-4)
  Clinical signs:
• May not cause obstruction per se - effect on upper airway function & performance is questionable (link with pharyngeal collapse?)
• May cause rough / harsh resp. sounds

Question 86

Discus Dorsal Displacement of the Soft Palate (DDSP).

Answer 86

• An acquired disorder of the nasopharynx
• Caudal border of the soft palate becomes displaced dorsal to the epiglottis
• Mainly occurs in racehorses during strenuous exercise
  Clinical signs:
• Associated with poor performance
• Abnormal EXPIRATORY noise (gurgle / choking)
  Aetiology:
• Old studies suggest neuromuscular dysfunction, new studies suggest fatigue

Question 87

Discuss arytenoid cartilage collapse (recurrent laryngeal neuropathy).

Answer 87

• An acquired disorder of the larynx
• Left arytenoid cartilage collapse due to recurrent laryngeal neuropathy (RLN) most common (also known as idiopathic laryngeal hemiplegia)
• Severe cases show arytenoid collapse at rest, others only show collapse during exercise

Recurrent laryngeal neuropathy (RLN):
- Most common in larger horses (TB’s, hunter types, clydesdales)
- Clinical signs = inspiratory noise (whistle / roar), exercise intolerance
- Diagnosis: endoscopy at rest & during exercise, palpation of larynx (atrophy of cricoarytenoideus dorsalis muscle)

Question 88

Discuss laryngeal dysplasia / 4th branchial arch defect.

Answer 88

• A congenital disorder of the larynx
• Failure of the development of some or all of the derivatives of the fourth branchial arch
• Unilateral (usually R side) or bilateral (uncommon)
• Palpation of larynx reveals wing of thyroid absent on right side in many cases
• Diagnosis: endoscopy may reveal some degree of right sided laryngeal dysfunction, US, MRI

Question 89

Discuss arytenoid chondritis.

Answer 89

• Microabscessation of arytenoid cartilage > deformation of cartilage & collapse torwards the midline
• Cause: likely trauma to arytenoid with invasion of bacteria into cartilage
• Clinical signs: may mimic RLN - includes resp noise airway obstruction & cough

Question 90

Discuss bilateral arytenoid cartilage collapse.

Answer 90

• Rare
• Results in severe resp distress > very distressing > often need a tracheotomy placed for airflow

Question 91

Discuss vocal fold collapse.

Answer 91

• Invariably accompanies arytenoid collapse
• Also common in horses with incomplete laryngeal abduction (Grade B) during exercise
• Unilateral or bilateral
• Clinical signs: horses make INSPIRATORY noise but appear normal on resting endoscopic exam. Less airway obstruction than with arytenoid cartilage collapse > may not affect exercise tolerance.
• Diagnosis: requires exercise endoscopy

Question 92

Discuss axial deviation of the aryepiglottal folds.

Answer 92

• Common
• Often occurs in association with palatal dysfunction
• May also occur following tieback surgery
• Clinical signs: abnormal INSPIRATORY noise
• Diagnosis: exercising endoscopy (looks like hourglass shape). Normal on resting endoscopy.

Question 93

Discuss epiglottal entrapment.

Answer 93

• Clinical signs: abnormal resp noise (inspiratory + expiratory)
• Diagnosis: resting endoscopy (looks like very large / obvious epiglottis)

Question 94

Discuss treatment options (medical & surgical) for dorsal displacement of the soft palate (DDSP).

Answer 94

Medical treatment:
- Often have pharyngeal inflammation (including GP’s) > needs to be treated with anti-inflammatories (Dexamethasone - more potent, or prednisolone)
- Antimicrobials for 10-21 days (Trimethoprim-sulfadiazine or Enrofloxacin)
- NSAIDs: phenylbutazone
- Steroid inhaler
- Tack with altered functions: keeping the tongue under the bit, decreasing head flexion, tongue-tie & figure-8 dropped noseband, bitless bridle for sport horses)

Surgical treatment:
- Candidates = horses with intermittent DDSP after 2 or more races where medical / tack modification has failed or horses presenting with permanent DDSP.
3 options:
- Target primary intrinsic nasopharyngeal or laryngeal structure abnormalities (removal of granulomas, cysts, abnormal sub-epiglottic tissues)
- Increase palatal stiffness (partial surgical / laser staphylectomy, palatoplasty)
- Targeting the relative position of the larynx & hyoid bone (strap muscle resection or laryngeal tie-forward)
- Success rate only 50-60% regardless of which procedure

Question 95

Discuss treatment options for arytenoid collapse (recurrent laryngeal nerve neuropathy).

Answer 95

Bilateral ventriculo-cordectomy:
- Removal of mucosal lining
- Preferred treatment for use in sport & draft horses where noise is main complaint (resolution of 82%)

Laser ventriculo-cordectomy:
- Removal of the mucosal lining & vocal fold of the laryngeal ventricle
- Indication: unilateral / bilateral vocal cord collapse at exercise in a non-racehorse (horses with grade 3-4 arytenoid movement + resp noise but not exercise intolerant)

Prosthetic laryngoplasty (tie-back):
- Effective technique but less noise reduction than ventriculo-cordectomy on its own
- Indicated in RACEHORSES (gold standard therapy): racehorses have improved airflow, reduced impedance but still not back to normal
- Younger horses do better (grade 3-4)

Laryngeal re-innervation:
- Implantation of nerve muscle pedicle graft into CAD
- In training 6-12 months post-op (vs. 2 months after laryngoplasty)
- 82% successful

Arytenoidectomy:
- Option after failed laryngoplasty
- Improves airflow but still less than normal
- Success rate similar to laryngoplasty

Question 96

Discuss guttural pouch tympany.

Answer 96

• GP tympany = distension of GPs with air under pressure (+/- fluid). Can be unilateral or bilateral.

Occurs in:
- Fillies 3x more likely than colts
- Genetic link in Arabian & Paint foals
- Develops shortly after birth up to 1 year of age

Clinical signs:
- GP distended with air > non-painful elastic swelling in the parotid region
- May cause stertor, dyspnoea, dysphagia, inhalation pneumonia, secondary empyema

Diagnosis:
- Endoscopic exam: pharyngeal openings normal, pharyngeal roof collapsed
- Radiographs: GP enlargement with air +/- fluid

Treatment:
- Indwelling catheter in pharyngeal GP orifice > temporary pressure alleviation
- Permanent intervention for unilateral cases = surgical (fenestration of median septum - laser > air moves into other side’s GP > air escapes).
- Permanent intervention for bilateral cases = surgical (medial lamina removal - laser > fistula into pharynx)

Prognosis:
- Favourable for complete recovery / successful racing career

Question 97

Discuss guttural pouch empyema.

Answer 97

• Purulent material and/or chondroids (inspissated purulent material) within one or both GPs
• Most common disease of GP
• Usually occurs in young horses

Aetiology:
- Streptococcus equi (Strangles) until proven otherwise

Clinical signs:
- Intermittent nasal discharge
- Swelling of adjacent lymph nodes
- Parotid swelling & pain
- Extended head carriage
- Respiratory noise (stridor)
- Severe GP empyema can cause cranial neuropathy > dysphagia

Diagnosis:
- Endoscopy - purulent discharge at pharyngeal orifice, pharyngeal collapse. Aspirate fluid - culture & sensitivity testing.
- Radiographs - fluid, masses, chondroids, fractures

Treatment:
- Isolate & biosecurity
- Systemic antimicrobials, gelatin & penicillin in the guttural pouch
- GP catheterisation & daily lavage
- Once chondroids have developed treatment is much more difficult - requires surgical removal

Question 98

Discuss guttural pouch mycosis.

Answer 98

Aetiology:
- Opportunistic fungal colonisation (Aspergillus sp.) of the GP

Clinical signs:
- Nasal discharge
- Epistaxis = an emergency!
- Cranial nerves may also be affected > facial nerve paralysis, horner’s syndrome, RLN

Diagnosis:
- Upper airway endoscopy - challenging with acute haemorrhage

Treatment:
- Medical - antifungal agents can be used but poor prognosis
- Surgical - carotid artery embolisation
- Give Acepromazine for sedation
- Don’t give fluids (don’t want to dilate vessels & send infection elsewhere)
- Post-op - 24hrs antibiotics

Prognosis:
- Generally good except those with neurological defects have fair to guarded prognosis

Question 99

Discuss trauma to the guttural pouch.

Answer 99

• Trauma to the GP is uncommon but when it occurs it requires immediate action

Aetiology:
- When horses fall over backwards whilst rearing onto the poll of their head > muscle damage (longus capitis muscle)

Clinical signs:
- Severe epistaxis +/- ataxia & other neurologic signs > recumbency / paresis

Diagnosis:
- History of trauma
- Endoscopy - roof of pharynx collapsed, haemorrhage & swollen muscle bellies
- Radiograph - partial obliteration of GP

Treatment:
- Stall rest for 4-6 weeks limiting head & neck movement
- Antimicrobials to prevent secondary infection

Prognosis:
- Good if no neurologic signs

Question 100

Discuss mild-moderate equine asthma (inflammatory airway disease).

Answer 100

• Can affect horses of all ages including young horses
• High prevalence in racehorses & sport horses (as using lungs at max. capacity)

Aetiology:
- Non-specific response to respirable particulate matter including organic dust, pollens, moulds and/or atmospheric pollutants

Clinical signs:
- Exercise intolerance / decreased performance
- Prolonged recovery after exercise
- Chronic intermittent cough (>3wks)
- Increased resp secretions & nasal discharge

Diagnosis:
- History & physical exam
- Pulmonary auscultation (including rebreathing bag) - often unremarkable for mEA but abnormal resp sounds in sEA
- BAL = gold standard for diagnosing equine asthma
- BAL findings in mEA = >10% neutrophils, >5% mast cells, >5% eosinophils
- Tracheal wash / aspirate - diagnoses tracheal inflammation (>20% neutrophils or tracheal inflammation score >6/9 indicates tracheal inflammation)

Treatment:
- Environmental management = most important component (low dust enviro., turn out to pasture where possible, have low dust bedding, optimise ventilation, avoid hay lofts over stables, remove horses from stable when mucking out, feed from ground rather than hay net or round bale)
- Corticosteroid therapy - inhaled corticosteroids = treatment of choice (Fluticasone, Beclomethasone)

Question 101

Discuss severe equine asthma (sEA) / recurrent airway obstruction (RAO).

Answer 101

Aetiology:
- Exposure to airborn organic dust (stabling & feeding hay)
- Delayed hypersensitivity response to inhaled allergens
- Summer pasture associated recurrent airway obstruction - more common in southern hemisphere in hot, humid conditions in late spring-early autumn
- Heritable - if both parents have equine asthma then offspring have 80% chance

Clinical signs:
- Cough
- Nasal discharge
- Increased tracheal mucous
- Decreased exercise tolerance
- Resp. distress / dyspnoea at rest (flaring of nostrils, increased breathing effort = flank flattening > heave line)

Diagnosis:
- History & physical exam
- Pulmonary auscultation (including rebreathing bag) - unremarkable in mEA but in sEA abnormal resp sounds (wheezes, crackles)
- BAL = gold standard for diagnosing equine asthma
- >25% neutrophils with decreased macrophages & lymphocytes on BAL indicates sEA
- Tracheal wash / aspirate to diagnose tracheal inflammation

Treatment:
- Enviro management = most important component (aim = low dust enviro)
- Corticosteroid therapy - inhaled corticosteroids = treatment of choice (Fluticasone, Beclomethasone, Ciclesonide)
- Bronchodilator (e.g. Clenbuterol, Albuterol, Salmeterol) as a rescue treatment to relieve bronchospasm but only use in combo with corticosteroids! If used >2wks without corticosteroids then tolerance develops

Question 102

Discuss exercise induced pulmonary haemorrhage (EIPH).

Answer 102

• Common in racehorses: 44-75% horses have blood in trachea after racing, 0.1-9% of horses have epistaxis after racing.

Aetiology:
- Haemorrhage originates from pulmonary vascular system & occurs from the caudo-dorsal lung lobes
- Rupture of alveolar capillaries occurs secondary to an exercise-induced increase in transmural pressure

Clinical signs:
- Epistaxis after strenuous exercise
- Reduced exercise tolerance / poor performance
- Swallowing (of blood) during exercise
- Prologed recovery post-exercise
- +/- coughing

Diagnosis:
- Endoscopy - presence of blood in trachea 30-120 mins after strenuous exercise (G1-4)
- RBC’s & haemosiderin-laden macrophages in TW & BALF (present for 1 wk after strenuous exercise)

Treatment:
- Frusemide pre-race decreases incidence & severity of EIPH *but not allowed under many racing jurisdictions including Aus.
- Nasal dilator strips (Flair) - decreases the inspiratory airway resistance by dilating the nasal valve
- Rest for 1 month

Prognosis:
- Guarded - severe EIPH horses are likely to have repeated episodes regardless of treatment
- Racecourse rules in Aus: horses with blood in both nostrils (not from external trauma) cannot be exercised on a racecourse for 2 months or compete in a race for 3 months. If the horse then bleeds on a second occasion it is banned for life.

Question 103

What are the 2 most common viral causes of upper respiratory tract disease in horses?

Answer 103

• Equine Influenza Virus (EIV) - outside Aus.
• Equine Herpes Virus (EHV) - type 1 & 4

Question 104

Discuss Equine Influenza Virus (EIV).

Answer 104

• The most frequently diagnosed cause of equine viral resp. disease in the world - EXCEPT IN AUS.
• Single stranded RNA
• Disease of young horses <3 yrs
• High morbidity (60-90%), low mortality (<1%)

Aetiology:
- Mixing of horses > outbreaks
- Spread via aerosol, inhalation or contact with infected buckets

Pathogenesis:
- Virus has tropism for resp. epithelium > attachment to ciliated epithelium in trachea & bronchi

Clinical signs:
- 1-3 day incubation, shedding within 48hr
- Infectious until 3-6 days after last signs
- Fever (up to 40.5), loss of appetite, dry persistent cough, nasal discharge, myositis (reluctant to move)

Vaccination:
- Only mandatory to vacc FEI competing horses in Aus.
- Vaccine decreases severity of infection but does not prevent infection

Question 105

Discuss Equine Herpes Virus (EHV) - type 1 & 4.

Answer 105

• Double stranded DNA virus
• Most horses infected in first weeks-months of life (<2yr)
• Establishment of latency of virus in lymph nodes > can then be reactivated & spread with stress (e.g. transport)

Pathogenesis:
- Transmission via aerosol, fomites, vertical transmission
- In resp. tract invasion of local epithelial tissue > local lymph nodes > viraemia (in blood) > organs such as uterus or CNS > ataxia and/or abortion

Clinical signs:
- Abortion
- Neurologic disease
- Resp disease: fever, malaise, nasal discharge, ocular discharge, enlarged lymph nodes, coughing, limb oedema

Control of outbreaks:
- Quarantine for min. 28 days
- Early diagnosis with D1 nasal swab PCR

Treatment:
- Supportive care: rest & ventilate stable (reduce dust)
- NSAIDs: Flunixin meglumine
- Antiviral drugs: Ganciclovir

Prevention:
- Vaccination - some protection against resp. infection & abortion but not protective against neurologic form

Question 106

Discuss the most common cause of bacterial resp disease (strangles).

Answer 106

• Streptococcus equi subsp. equi (strangles)
• High morbidity (100%), relatively low mortality (<10%)

Aetiology:
- Transmission: nasal shedding 2-3 days after fever, for 2-3 weeks
- Indirect spread: equipment, people, tack
- Direct spread: ingestion or inhalation
- Often young horses (1-5yrs)
- Found throughout the world

Clinical signs:
- Fever up to 42 degrees for 2-3 wks, depression, anorexia, lymphadenopathy > abscess, purulent nasal discharge, resp distress due to enlarged retropharyngeal LN > tracheal compression (may need emergency tracheostomy)

Diagnosis:
- History - strangles on farm, travel, new horses introduced
- Classic clinical signs
- Haematology: neutrophilia 7-10 days
- Endoscopy of URT & GP

Treatment:
- Let the disease run its course (reserve ABs for very sick horses with fever - penicillin 5-7 days)
- NSAIDs - control fever & analgesia
- Monitor appetite - provide palatable feeds
- Hot pack / drain abscess
- 75% develop immunity against it

Prevention:
- Strict isolation of horses affected & exposed
- Isolate horses for 2-3 weeks after resolution of clinical signs
- Before lifting isolation protocol want 3x PCR negative results

Question 107

Discuss the most common cause of bronchopneumonia in foals.

Answer 107

• Rhodococcus equi = most common cause of bronchopneumonia in foals >1 mths old

Clinical signs:
- Fever, cough, increased inflammatory markers (fibrinogen), pulmonary abscesses on US

Diagnosis:
- Blood analysis - inflammation (most commonly mature neutrophilia)
- Thoracic US - great screening tool for lung surface & GI tract
- Trans-tracheal wash - cytology, culture & PCR (gold standard)

Treatment:
- Many infections heal on their own
- Antimicrobial therapy - macrolides
- Supportive therapy & monitoring by US

Prevention:
- Reduce contact time of young foals in high risk areas (e.g. reduce time in group yards & reduce moving foals along laneways)

Question 108

Discuss pleuropneumonia in adult horses.

Answer 108

Pleuropneumonia = otherwise known as travel sickness, shipping fever, or pleurisy

Risk factors:
- Decreased mucociliary clearance from: viral infection, EHV-4, influenza, confinement, head elevated / transport
- Strenuous exercise - large no. & vol. of respirations in & out > aspiration of dirt & debris > pathogens seeded in LRT
- Often recent transport!

Clinical signs:
- Often young horses
- Cough, nasal discharge +/- epistaxis, exercise intolerance, restrictive breathing pattern, weight loss, nostril flare / cyanosis, depression, anorexia, fever, tachpnoea, tachycardia, dyspnoea, pain > grunting & reluctance to move (mimic of colic signs)

Physical exam signs:
- Fetid odour nasal discharge or breath - can indicate anaerobes
- Increased crackles / wheezes in dorsal lung fields, abscence of breathing sounds in ventral lung fields (auscultation)

Diagnosis:
- History (recent travel!)
- Physical exam
- Thoracic auscultation
- Thoracic radiographs
- Thoracic ultrasound

Treatment:
- Drainage of pleural fluid (fluid is septic)
- Antimicrobials - broad spectrum / based on C&S findings
- Maintenance fluid therapy
- Bronchodilation (if dyspnoeic)

Prognosis:
- Guarded to poor (require prompt, aggressive treatment)
- 90% survival rate but only 50% return to previous athletic level

Question 109

What are some goals, advantages and disadvantages of standing sedation.

Answer 109

Goals of standing sedation:
- Enable to tolerate the procedure & adequate pain management
- Relative immobility, stress-free experience

Advantages:
- Maintenance of cardiorespiratory function
- Decreased risk compared to general anaesthesia
- Fast return to normal function
- May need to proceed to field anaesthesia if: you have a back up plan in place, you are prepared with appropriate equipment & personnel

Disadvantages:
- The horse will move
- Extra doses / drugs may be required to allow adequate sedation & analgesia
- Adequate sedation may result in excessive ataxia (poor muscle control)
- Increased risk to personnel: well sedated horses may suddenly bite, kick, strike, rear etc.

Question 110

What are some physical signs of sedation?

Answer 110

• Head is lowered with weight shifted onto front legs
• Drooping lips & ears, half-closed eyes, penile prolapse

Question 111

Discuss drugs which are commonly used for standing sedation: a2 agonists, acepromazine & opioids.

Answer 111

A2 agonists:
- E.g. Xylazine, detomidine & romifidine
- Provide dose-dependent sedation, analgesia, muscle relaxation (ataxia)
- Reversible by Atipamezole - with overdose or excessive ataxia
- Used alone or with analgesics (e.g. xylazine + butorphanol)
- Side effects: increased urination during the procedure, decreased GI motility for several hours, cardiovascular depression in foetus (if mare is pregnant), impaired thermoregulation > increased sweating

Acepromazine (ACP):
- A phenothiazine
- Antagonism of dopamine receptors
- Mild sedative & calming effect in horses, unreliable if excitement prior to administration
- Does not provide analgesia
- More predictable when used in combo with other drugs (e.g. Acepromazine + xylazine)
- Long duration of action & not reversible
- Causes vasodilation = contraindicated in hypovolaemia / shock
- Causes priapism (abnormal relaxation of penis) - caution in breeding stallions

Opioids:
- E.g. Butorphanol, Buprenorphine, Morphine
- Opioids produce excitement & dysphoria in non-sedated, non-painful horses
- Analgesia provided by opioids in horses is not as clear as in small animals
- Do not consistently reduce MAC of inhalant anaesthetics in horses

Question 112

Discuss field anaesthesia in horses.

Answer 112

Patient preparation:
- Fasting 8-12hrs, water ad-lib
- First of all obtain patient IV route - ensures drug effect & top ups, emergency medication

Pre-medication:
- Xylazine (a2 agonist) - 0.5-1mg/kg IV
- Adding in 0.02mg/kg Butorphanol (opioid) as well adds time & analgesia

Induction:
- Ketamine 2.2mg/kg IV (inject Xylazine first IV then followed by Ketamine ~2 mins later - once horses head has dropped to its knees)
- Anaesthesia lasts for 15-20 mins
- To prolong anaesthesia 25-50% of the original dose of ketamine or of both ketamine + xylazine may be given IV
- Can also give Guaifenesin to effect to deepen sedation / muscle relaxation (then becomes “triple drip” = Guaifenesin + Ketamine + Xylazine) - best used for procedures up to 1h duration (if used for longer drugs start to accumulate > prolonged recovery)

Question 113

What are some anaesthetic monitoring standards of care?

Answer 113

• BP monitoring considered standard of care with inhalants but not injectables
• HR & RR
• Quality of respiration, depth & pattern
• Some recording of what happens
• Eye reflexes / pulse-ox could be useful in the field

Question 114

Discuss a common / general anaesthetic plan for a horse from pre-anaesthetic to post-op recovery.

Answer 114

Pre-anaesthetic procedure:
- Place IV catheter in jugular vein (may have to sedate horse first)
- Give NSAIDs & antibiotics
- Wash mouth to remove feed material > decrease choke
- Feet cleaned & shoes removed or wrapped
- Place patient in induction area

Pre-medication:
- Goal = tranquilise / sedate the animal to improve handling & decrease the dose of induction & maintenance agents. Provide analgesia.
- Xylazine (a2 agonist) - provides good dose-dependent sedation & also analgesia
- Acepromazine - most clinics will use ACP for pre-med (40-60 mins before induction) except in particular cases e.g. stallions (penile prolapse), pregnant mares, horses with colic
- Butorphanol (opioid) - promotes good sedation before induction but it is a poor analgesic (only lasts 2 hours - short procedures)
- Methadone (opioid) - can be used to add analgesia & can be used for long procedures (lasts ~4 hrs)

Induction:
- Goal = to render the horse unconscious as quickly as possible so that the transition from standing to lateral recumbency occurs with minimal risk of injury
- Induction drugs administered by rapid bolus injection rather than to effect (except Guaifenesin)
- Ketamine IV either alone or in combination with other drugs (Diazepam, Midazolam)
- Propofol alone or in conjunction with ketamine in foals - high volumes are necessary in adult animals = difficult to administer quickly

Once induced:
- Check vital signs
- Eye lube
- Intubation: use mouth gag otherwise horse can chew on ET tube & damage it.

Anaesthetic maintenance:
- Changes to inhalant anaesthetic & O2 flow rate occur slowly - start with 10L/min O2 & Iso at 3%
- Ketamine or Propofol IV can be used for top-ups

Recovery:
- Prevent horse from standing too soon as can injure itself (25-40 mins is adquate time)
- If horse has a lot of nystagmus (eye movement) it is likely to stand soon - can give it 100mg Xylazine for calmer recovery
- Transfer patient to padded recovery area
- Continue ventilation
- Extubate once swallowing / regain spontaneous breathing

Complications seen on recovery:
- Facial nerve paralysis - drooping eyelid & lip on affected side
- Radial nerve paralysis - inability to fully extend forelimb
- Myopathy - hard swollen muscles, stiff & painful gait
- Colic - rolling, looking at abdomen

Question 115

Differentiate the various different cardiac murmurs into systolic vs. diastolic and right / left side.

Answer 115

Diastolic (longer than systole):
- All diastolic murmurs occur on the left side (none occur on the right side)
- PMI over apex & duration is short (early or late diastole) = PHYSIOLOGICAL FILLING
- PMI over left base & long duration = AORTIC REGURGITATION

Systolic:
- Right side + radiates cranioventrally = VENTRICULAR SEPTAL DEFECT
- Right side + radiates concentrically = TRICUSPID REGURGITATION
- Left side + PMI over apex = MITRAL REGURGITATION

Question 116

List the 6 different grades of heart murmurs.

Answer 116

I: very difficult to hear & only over the PMI (inconsistent)
II: readily heard over the PMI but not as loud as S1 or S2
III: readily heard over the PMI & approx. the same intensity as S1 or S2
IV: murmur louder than S1 & S2 but no palpable thrill
V: palpable thrill but murmur inaudible without using stethoscope
VI: palpable thrill & murmur audible when stethoscope is removed

Question 117

What are some clinical findings of cardiovascular disease (heart failure).

Answer 117

• Pulse quality - decreased
• Venous distension - hypertension
• Jugular pulsation - higher pulsation
• LHF signs due to low cardiac output & pulmonary venous hypertension: exercise intolerance / poor performance, lethargy / depression, cachexia
• RHF signs: peripheral oedema (ventral thorax & abdomen)
• Cough / crackles
• Cyanosis
• CRT >2sec
• Collapse or syncope
• Weak arterial pulse

Question 118

Where should the 3 ECG leads be placed on a horse?

Answer 118

Lead I: between right arm & left arm
Lead II: between right arm & left leg
Lead III: between left arm & left leg
*In horses we don’t tend to put the leads on the legs themselves (body instead) as too much movement interference

Question 119

What is sinus arrhythmia?

Answer 119

• R-R intervals are irregular but every P wave is followed by a QRS complex & every QRS complex is preceded by a P wave
• Waxing & waning of HR
• Has no clinical significance
• Can occur in resting horses but appears much more frequently during the recovery period following exercise

Question 120

What is sinus bradycardia (sinus block / sinus arrest).

Answer 120

• Results from slow firing from the SAN, with long P-P intervals. ECG is otherwise normal.
• Infrequent & rarely pathological
• Associated with high vagal tone. Disappears with increased HR.

Question 121

What is an atrioventricular (AV) block?

Answer 121

• Most common physiological arrhythmia in horses
• ECG shows an isolated P wave that is not associated with a QRS complex because the impulse is blocked at the AV node
• On auscultation there is an underlying regular rhythm with occasional dropped beats.

1st degree AV block:
- One p wave without QRS complex after it
- Not clinically significant - disappears with increased HR

2nd degree AV block:
- More than 2 consecutive p waves (without QRS complexes)
- Less safe to ride
- May have inappropriate HR response during exercise > exercise intolerance

3rd degree AV block:
- Total block in conduction at the AV node
- Very slow resting HR (10-25bpm) which does not show an appropriate increase in response to exercise
- May result in syncope / collapse - often requires pacemaker

Question 122

What is atrial fibrillation?

Answer 122

• The most common pathological arrhythmia affecting athletic performance in horses
• On ECG p waves are absent, f (fibrillation) waves with a variable morphology are present, the QRS morphology & duration are normal but RR intervals are irregular

Paroxysmal atrial fibrillation (PAF):
- Atrial fibrillation but then spontaneous reversion to normal sinus rhythm occurs within 72hr

Question 123

What are ventricular premature depolarisations?

Answer 123

• An early beat originating from the ventricular myocardium or conducting system
• No p wave
• QRS morphology typically wide & bizarre

Ventricular tachycardia:
- More than 3 consecutive VPDs in quick succession (>120bpm)

Question 124

Investigation and treatment of ventricular arrhythmias?

Answer 124

Investigation should involve:
- Resting ECG
- Exercising ECG
- 24hr holter monitor

Treatment:
- Treat underlying cardiac / systemic disease where present
- Rest & empirical use of corticosteroids
- Antiarrhythmic drugs may be administered if symptomatic or when rapid VT is present: Lidocaine (sodium channel blocker), MgSO4 (calcium channel blocker)

Question 125

What are some clinical signs associated with dental abnormalities?

Answer 125

• Head shaking
• Behavioural issues
• Resentment of the bit
• Oeseophageal obstruction
• Colic
• Weight loss
• Gastric ulceration
• Lethargy
• Inappetence
• Ptyalism (excessive drool)
• Halitosis (bad breath)
• Facial swellings
• Sinusitis
• Nasal discharge
• Ocular discharge
• Dysphagia (difficulty swallowing)

Question 126

What are some equine dental developmental abnormalities?

Answer 126

Oligodontia:
- The absence of teeth
- Aetiology: failure of formation of a tooth bud
- Clinical signs: displacement of adjacent teeth, abnormal occlusion & wear
- Treatment: possible removal of opposite tooth

Polyodontia:
- The presence of extra teeth
- Aetiology: splitting of a developing tooth bud due to trauma, extra tooth germ budding from dental lamina
- Clinical signs: misshapen, malformed, misplaced or malerupted teeth, occlusal wear abnormalities
- Treatment: early extraction if possible

Brachygnathia:
- Overbite / parrot mouth
- Aetiology: unknown, hereditary in QH & TB
- Treatment: breeding? tension band wire (foals <6 mths)

Prognathia:
- Underbite
- Aetiology: unknown, less common than brachygnathia
- Clinical signs: may be associated with nasal or nostril deformity
- Treatment: breeding? tension band wire (foals <6 mths)

Campylorrhinus lateralis (wry nose):
- Unilateral dysplasia of one side of the maxilla / pre-maxilla > lateral deviation of nose > nasal obstruction
- Aetiology: arabians? foetal malpositioning
- Treatment: facial reconstruction

Question 127

What are some abnormalities of wear in equine dentistry?

Answer 127

Excessive incisor wear:
- E.g. crib biter

Pre-molar & molar sharp points:
- Develop naturally due to occlusion of teeth & masticatory forces
- Sharp points on buccal aspect of maxillary arcades can damage & ulcerate the buccal mucosa
- Exacerbated by modern husbandry & reduced ‘rough grazing’
- Treatment = routine floating

Step mouth / wave mouth:
- Generally develop due to missing teeth or reduced crown height
- Far more common in older horses (15+)
- Causes severe restriction to normal mastication, reduction in the occlusal ‘grinding’ surfaces & significant oral pain
- Can be difficult to correct if well established

Question 128

What is dysphagia - some clinical signs & causes of it

Answer 128

Dysphagia = difficulty swallowing

Clinical signs:
- Depends on underlying cause
- Ptyalism (excess salivation)
- Quidding (dropping feed)
- Nasal discharge (usually bilateral)-
- Resp signs - aspiration pneumonia
- Weight loss - esp. chronic cases

Causes of dysphagia:
- Pain / inability to eat (dental disease most common, mandibular or maxillary fractures, trauma to mouth/pharynx/tongue, pharyngeal inflammation from trauma/infection, cleft palate, snake bite)
- Obstruction of upper GI (choke) (strangles, foreign body, megaoesophagus in friesian’s, ulceration, neoplasia, impacted food, strictures, botulism)

Question 129

Discuss equine gastric ulcer syndrome (EGUS) & it’s 2 types.

Answer 129

Equine squamous gastric disease (ESGD):
- Aetiology: constant gastric acid production + inadequate roughage / grazing time + increased carbs + decreased time masticating (>decreased saliva so less buffer) leads to increased exposure time of HCl to squamous mucosa > squamous ulcerations

Equine glandular gastric disease (EGGD):
- Aetiology: ulcers caused by primary issues - stress, NSAIDs, bacterial infection > breakdown of normal glandular defence mechanisms

EGUS clinical signs:
- No or variable clinical signs
- Girth sensitivity / sensitivity to touch
- Poor performance
- Reduced appetite, poor body condition
- Behavioural changes - nervousness, aggression, self-mutilation

EGUS diagnosis:
- Gastroscopy - essential to examine the entire stomach - requires fasting of 12h +/- 4h & water withheld for min. 2h

EGUS treatment:
- Omeprazole (proton pump inhibitor)
- + Sucralfate for glandular gastric disease
- Treatment duration ~4 weeks
- Nutritional management: continuous access to good quality grass pasture, minimise grain & concentrates, provide water continuously, offer 2L of chaff in the 30 min prior to exercise (ball of feed in stomach prevents splashing of low pH gastric juices during exercise)

Question 130

What is the difference between hypovolaemia & dehydration?

Answer 130

Hypovolaemia = state of intravascular volume depletion > decreased effective circulating volume

Dehydration = reduced total body water volume - mostly affecting intracellular & interstitial spaces & no change in circulating volume

Question 131

What is the 5-step fluid therapy plan?

Answer 131

1. Determine if the horse needs fluids & how much fluids
2. Determine route of administration: IV or enteral (or rectal)
3. Determine type of fluids: iso-, hypo-, or hypertonic fluids
4. Formulate fluid plan: how much? what rate? for how long?
5. Monitor your patient: reassess & reformulate plan

Question 132

What are some indications for fluid therapy & goals of fluid therapy?

Answer 132

Indications for fluid therapy:
- Hypovolemia or shock
- Dehydration
- Decreased water intake and/or increased fluid loss (diarrhoea, exercise)
- Electrolyte and/or acid-base imbalance (diarrhoea, exercise)
- Dehydration of GI contents and/or delayed GI transit

Goals of fluid therapy:
- Restore volume & improve haemodynamic status
- Treat dehydration
- Treat electrolyte and/or acid base imbalance
- Promote hydration of GI contents & stimulate GI transit

Question 133

What are some signs of hypovolemia and signs of dehydration?

Answer 133

Hypovolemia signs:
- Abnormal mentation
- Tachycardia
- Weak peripheral pulse
- Reduced jugular fill
- Prolonged CRT, abnormal MM colour
- Cold extremities
- Reduced urine output

Dehydration signs:
- Tacky / dry MM
- Prolonged skin tent
- Sunken eyes
- Tear film
- Reduced bodyweight

Question 134

How to calculate how much fluid to give.

Answer 134

Fluid requirement = deficit + maintenance + ongoing losses

Litre to administer = % dehydration x bodyweight (kg)
- 5-8% dehydration (mild) = normal / mildly tacky MM, CRT <2s, skin tent 1-3s, HR normal, decreased urine output
- 8-10% dehydration + hypovolemia (moderate) = tacky MM, CRT 2-3s, skin tent 3-5s, HR 40-60, depressed & sunken eyes, weaker peripheral pulse
- 10-12% dehydration + hypovolemia (severe) = dry MM, CRT>5s, skin tent >5s, HR >60, severely sunken eyes, cold extremities, slow jugular fill

Question 135

How to calculate fluid requirement for a 500kg horse with acute diarrhoea, 8% dehydration & diarrhoea +/- 30L/day.

Answer 135

Resuscitation boluses:
20ml/kg = 10L (do this x2 = 20L)

Ongoing losses from diarrhoea = 30L

Maintenance requirement = 60ml/kg/day = 30L

Total = 20L + 30L + 30L = 80L

Question 136

What is colic, what are some risk factors for it & when should a colic case be referred?

Answer 136

Colic = an attack of acute abdominal pain.

Risk factors:
- Breed
- Older age
- History of previous colic
- Cribbing
- Change in weather
- Diet change: large amounts of concentrate
- Recent transport

Indications for referral:
- Pain requires repeated analgesia or cannot be controlled
- HR >50bpm & remains high
- You get reflux from a stomach tube
- Rectal exam findings are abnormal
- Has not defecated in >24h

Question 137

Examination of a colic patient?

Answer 137

Physical exam:
- Observe for demeanour & pain - continued pain that is minimally or unresponsive to analgesia requires prompt referral - most colic cases will respond to a single dose of Flunixin
- TPR - usually no fever, resp. rate, pulse rate & quality
- Evaluate abdomen for abdominal distension
- Auscultation & percussion of abdomen - assess GI motility
- Nasogastric intubation: do first before anything else if the horse is very painful to prevent gastric rupture
- Transrectal palpation
- Imaging
- Abdominocentesis