Lesson 101 - Equine Medical Respiratory Conditions

What is the easiest way to differentiate if there is an issue in the lower or upper airway?

rebreathing bag

When is the rebreathing bag contraindicated?

respiratory distress

What is being shown here?

rebreathing bag

What are the upper respiratory specific diagnostic tools?

1. nasopharyngeal swabs

2. skull radiographs

3. endoscopy of the nasal passages, gutteral pouches, epiglottis, vocal cords, arytenoids, sinuses, and upper trachea

4. CT scan

What are the lower respiratory specific diagnostic tools?

1. rebreathing bag

2. arterial blood gas

3. ultrasound

4. radiographs (referral, or in foals)

5. trans tracheal wash

6. bronchoalveolar lavage

7. thoracocentesis

8. lung biopsy

What diagnostic tool is nonspecific to upper or lower respiratory system?

hematology

What are the less invasive diagnostic tests?

1. rebreathing bag

2. ultrasound

3. percussion of sinuses

4. nasal swab for PCR or culture

5. hematology

What are the more invasive diagnostic tests?

1. bronchoalveolar lavage

2. endoscopy

3. transracheal wash

4. thoracocentesis

5. lung biopsy

Which form of fluid assessment is more invasive?

transtracheal wash

What is the preferred method is imaging in the field?

ultrasound

What is the significance of "comet tails" on an ultrasound of an equine thorax?

abnormal lung parenchyma

Which form of fluid assessment is sterile and used for suspected infectious causes?

transtracheal wash

Which form of fluid assessment is not sterile because it goes through the nostril?

bronchoalveolar lavage

Which image shows the proper head positioning for bronchoalveolar lavage?

A

Where will the tube go in B?

esophagus

What are the characteristics of transtracheal wash?

1. Collects secretions from distal trachea

2. Central and peripheral airways assessed

3. Low risk of cellulitis at incision site

What are the characteristics of bronchoalveolar lavage?

1. Retrieves fluid from distal airways/alveoli

2. Only localized region of lung sampled

3. Used to diagnose diffuse lower airway disorders

4. Typically for nonseptic conditions

What are the characteristics of thoracocentesis?

1. Used to collect fluid from the pleural space (cytologic and/or bacteriologic exam)

2. Usually, U/S guided

3. Recommended spot: 6th/7th ICS, 10 cm dorsal to olecranon, dorsal to lateral thoracic vein

4. Aseptic preparation - local anesthetic, small stab incision followed by trocar

When is a lung biopsy performed?

when all less invasive diagnostic modalities have failed

What is the most serious complication with lung biopsies?

death

What is a lung biopsy most suited for?

diffuse lung diseases like neoplasia and pulmonary infiltrative diseases

What diagnostic tests would you order for a gelding with flared nostrils and abdominal breathing?

1. ultrasound

2. hematology

3. transtracheal wash

What is this?

heave line

What can cause a heave line?

abdominal breathing

What is non-infectious pneumonia?

equine asthma

Which horses typically get mild inflammatory airway disease (IAD)?

younger athletic horses

Which horses typically get moderate to severe recurrent airway obstruction (RAO) or "heaves"?

older horses or horses with seasonal allergies

What are the characteristics of equine asthma?

1. bronchospasm

2. excess mucous

3. tissue damage

4. constriction/scarring of airways

How is equine asthma diagnosed?

PE, CBC, BAL, radiographs

An Appaloosa gelding presents with flared nostrils and abdominal breathing. Pictures are the results of the BAL you performed. What is the predominant cell type?

neutrophils

What are some environmental management strategies to control equine asthma?

low dust bedding, soaking hay, well-ventilated barn, keeping the horse outside, pelleted hay

What drugs can be used to treat equine asthma?

1. albuterol

2. clenbuterol

3. corticosteroids

What is the prognosis for equine asthma?

fair to good with management

What medications are used in emergency to reduce bronchospasm?

atropine or buscopan

What systemic medications reduce bronchospasm?

clenbuterol, aminophylline, pentoxyfylline

What inhaled medications reduce bronchospasm?

albuterol and ipratroprium

When do you give medications for bronchospasm?

before and with steroids

What systemic steroids are used for asthma management?

dexamethasone or prednisolone PO, triamcinolone IM

What inhaled steroids are used for asthma management?

fluticasone, beclomethasone, budesonide

What is used to diagnose strangles?

1. culture or PCR of purulent material from the guttural pouch, abscess, nasal wash/swab

2. serology to detect antibodies to SeM proteins

What is strangles serology useful for?

determine need for vaccination, recent infection, and bastard strangles

How should you treat a non-critical case of strangles?

1. no antibiotics

2. NSAIDs and pain relief

3. soft feed

4. hot pack abscesses

5. flush the guttural pouch

6. antibiotic guttural pouch infusions

How should you treat a critically sick case of strangles?

penicillin

How are strangles cases managed?

isolate any suspect infected horse

How long is bacteria shed after a fever with strangles?

2-3 days and continues for 2-3 weeks

How many negative PCRs or cultures does a horse need before being released for isolation?

3

What are the key points of strangles management?

1. Monitor Temperatures

2. Isolate any horse with fever

3. Culture/PCR to look for carriers

4. Quarantine all new horses

What is the prognosis for strangles?

1. 75% horses recover & develop strong immunity (> 5 years)

2. 10% become carriers (biosecurity nightmare)

3. 20% develop complications (guarded prognosis)

What are the different strangles vaccines?

extract (IM) and attenuated live (IN)

What horses should never receive strangles vaccines?

1. infected animal

2. exposed animal

3. titer of > 1600 on ELISA

4. During an outbreak

A 1-year-old Paint horse is being evaluated because of pyrexia, anorexia, and depression. Clinical examination shows a bilateral nasal discharge and submandibular swelling. Which of the following is the most likely diagnosis?

strangles

What respiratory conditions would cause a horse to have bleeding from the nostrils?

1. guttural pouch mycosis

2. ethmoid hematoma

3. trauma after tubing

A horse presents with spontaneous, severe, unilateral epistaxis. Which of the following respiratory conditions associated with epistaxis is most likely to be the underlying cause? A horse presents with spontaneous, severe, unilateral epistaxis. Which of the following respiratory conditions associated with epistaxis is most likely to be the underlying cause?

guttural pouch mycosis

What are the characteristics of guttural pouch mycosis?

1. can be seen in any horse

2. diagnosed with endoscopy and wash

3. treated with antifungals and surgical removal of plaques

What are the characteristics of exercise induced pulmonary hemorrhage (EIPH)?

1. usually in high-intensity sport horses

2. diagnosed by visualization of blood on endoscopy, history, and BAL (will see RBCs)

3. treat with furosemide (lasix) to reduce blood volume before racing

What are the characteristics of equine asthma?

1. in young and old horses

2. BAL definitive diagnostic

3. can be diagnosed with PE and clinical signs

4. treat with corticosteroids, bronchodilators, and environmental management

What are the characteristics of strangles from strep. equi infection?

1. seen in foals with waning MABs

2. diagnosed with nasopharyngeal swab culture/PCR

3. treat with supportive care, NSAIDs, hot pack on submandibular lymph nodes

What are the characteristics of equine influenza virus?

1. seen in young horses

2. diagnosed with PCR

3. treat with supportive care

What are the characteristics of equine herpes virus 1 and 4?

1. can be seen in any horse

2. diagnosed with PCR

3. treat with supportive care

4. antivirals in severe cases

What are the characteristics of bacterial/fungal pneumonia?

1. can be seen in any horse

2. diagnosed with transtracheal wash

3. treated with specific antibiotics after culture and sensitivity

What are the characteristics of rhodococcus equi infections?

1. seen in foals

2. diagnosed with ultrasound and radiographs

3. treated with macrolide antibiotics

What are the characteristics of pleuropneumonia (shipping fever)?

1. seen in sport horses that travel and horses that are transported with their heads tied up for a long time

2. diagnosed with ultrasound and radiographs

3. treated with antibiotics

What are the characteristics of ethmoid hematomas?

1. seen in old horses

2. diagnosed with endoscopy

3. treated with formalin injection and surgery

A 6-year-old Thoroughbred racehorse presents with intermittent epistaxis after high-speed exercise. Physical exam is normal at rest. You perform an endoscopic exam 60 minutes post-race and observe blood in the trachea.

Which diagnostic finding would most strongly support your suspected diagnosis?

red blood cells on cytology of BAL fluid

A 10-year-old horse presents with chronic cough, poor performance, and increased respiratory effort. BAL reveals inflammatory cells. No fever is present.

What is the most appropriate mainstay treatment plan?

corticosteroids and environmental management

A 4-month-old foal presents with fever, cough, and increased respiratory effort. Thoracic imaging shows pulmonary abscesses.

Which diagnostic approach is most appropriate?

thoracic ultrasound and radiographs

A 3-year-old horse presents with acute fever, nasal discharge, and rapid spread through the barn.

Which diagnostic test is most appropriate to confirm the diagnosis?

PCR testing

A horse recently transported long distance with its head tied up develops fever, depression, and pleural effusion.

Which diagnostic test is most appropriate to confirm your suspicion?

ultrasound of thorax

A horse presents with acute respiratory disease and neurologic signs. PCR confirms Equine Herpesvirus.

What is the most appropriate treatment?

supportive care ± antivirals (severe cases)

A horse presents with fever, cough, and mucopurulent nasal discharge. You suspect bacterial pneumonia.

Which diagnostic method is most appropriate to guide therapy?

transtracheal wash

A horse presents with respiratory disease. You are deciding between BAL vs TTW.

Which scenario best supports choosing BAL?

suspected inflammatory airway disease

A horse presents with respiratory disease. You are deciding between BAL vs TTW.

Which scenario best supports choosing TTW?

suspected infectious airway disease

A horse presents with unilateral nasal discharge and epistaxis. No cough or abnormal lung sounds are noted.

Which diagnostic modality is most appropriate first?

endoscopy

A group of young horses develops:

fever

nasal discharge

lymph node enlargement

Which finding most strongly supports Strep equi over equine influenza?

submandibular lymph node abscessation

Which of the following diagnostic tests is least invasive?

rebreathing exam

A 6-year-old horse presents with:

poor performance

no fever

intermittent cough

Rebreathing exam: abnormal BAL: neutrophilic inflammation TTW: negative culture

What is the best treatment?

corticosteroids and environmental management