Respiratory Disease

Respiratory Disease:Diagnosis, Treatmentand PreventionHal Schott, DVM, PhD, DAVCIM

My Horse University and eXtensions HorseQuest welcome you to this live Webcast.Meet Our PresenterHal Schott, DVM, PhD, DACVIM

Respiratory DiseaseInfectious diseasesViral diseasesEquine herpes virusEquine influenzaOthersBacterial diseasesStreptococcus equi = stranglesRhodococcus equi (foals)Shipping fever = aspiration of multipleorganisms

Respiratory DiseaseNon-infectious diseasesEnvironmental/allergicMature horses = heavesExercise-associatedproblemsUpper airway obstructionLower airway problemsEIPH = bleedersInflammation = IAD

Viral Respiratory DiseaseEquine herpes virus (rhinopneumonitis)EHV-1: respiratory disease/abortion/neurologic disease60% of adult horses infectedEHV-4: respiratory disease90% of adult horses infectedRespiratory disease in younghorses = snotsHerpes is foreverVaccination 5, 7, 9 mos.pregnancy to prevent abortion storms

Thanks, mom!Viral Respiratory DiseaseEquine influenzaAequi-1 and Aequi-2Generally species specificAffects all ages, repeat infectionpossible

Viral Respiratory DiseaseHigh morbidity (30-50%)/mortality rareSick for 3-7 days = fever and decrease in appetiteRecover in 1-3 weeks20-30% may develop secondarybacterial pneumonia and requiretreatment with antibiotics (penicillin G)Diagnosis = nasal swabVaccinations availableEHV-1&4: horses 5 yearsInfluenza: intranasal vaccine 2x/year

Bacterial Respiratory DiseaseStreptococcus equi = stranglesDoes not typically affect humans

Bacterial Respiratory DiseaseStreptococcus equiHighly contagious diseaseCan affect all ages but most seriousin foalsProlonged (but not lifelong)immunity after infectionTreatment controversialLet it run its courseStop it in its tracksAntibiotics = penicillin GIntranasal vaccination be cautious

Bacterial Respiratory DiseaseStreptococcus equiPersists in guttural pouches of 2-3% of normal horsesIs it at a show with 100-200 horses?How is it detected?Outbreaks variableLow morbidityHigh morbidityComplications in 10% of horsesWill also likely be with us forever!

Bacterial Respiratory DiseaseBastard strangles = abscess formation at distant locations

Bacterial Respiratory DiseasePurpura hemorrhagicaVasculitis syndrome

Bacterial Respiratory DiseaseRhodococcus equiInsidious onset pneumonia in foal and weanlingsFarm/herd problemOvercrowdingDust/dirt paddocksHigh environmental temperatureFever, decreased appetite but little nasal discharge or coughQuiet lung sounds due to abscess formationBacterial Respiratory DiseaseRhodococcus equiDiagnosisRadiographs and ultrasonographyTranstracheal aspirate and culture

Bacterial Respiratory DiseaseRhodococcus equiTreatmentAzithromicin for 4-12 weeksFollow-up radiographsPrognosis guarded for both life and performancePreventionClose monitoring of foalsIncreased respiratory rate, fever (in afternoon)Routine ultrasonographyDecrease foal numbers and dustHyperimmune plasma controversialPneumonia in Adult HorsesSpontaneous pneumonia is rareInhale a foreign bodyEsophageal ruptureNeoplasia = cancerShipping feverAspiration pneumoniaLung damage accompanied by fluidoutside the lungsRisk factorsStrenuous exerciseTransport >750 milesTravel with head tied upHay net in front of horse

Shipping FeverWhy is shipping fever less common in the United Kingdom?

Pneumonia in Adult HorsesDiagnosisFever, decreased appetite, pain after transportLung ultrasonographyTranstracheal wash mixed bacterial pneumoniaTreatmentBroad spectrum antibiotics and anti-inflammatory drugs (not steroids) for 4-7 days, better to be safeRelapse after 4-10 days is a serious warning signPleuropneumonia

PleuropneumoniaUncomplicated caseSterile effusionAntibiotics: 2-4 weeksThoracic drainage: 0-2 times1-3 months out of workFavorable prognosisNot inexpensiveOften preventableCareful transportEarly recognition

PleuropneumoniaComplicated caseInfected effusionAntibiotics: 2-6 monthsOpen thoracic drainage forthoracic abscesses6-12 months out of workGuarded prognosis, $$$

Non-infectious Airway DiseaseAirflow obstruction during exerciseUpper airway narrowingLower airways mucus or blood

Upper Airway ObstructionUsually accompanied by a noiseIdiopathic laryngeal hemiplegia = roaringDorsal displacement of soft palate = snoringLess common problems

Diagnosis require resting or treadmill endoscopy or recording airway noiseTreatment generally requires surgery

This research protocol was approved by the Michigan State University All University Committee on Animal Use and Care. To invesitgate our hypothesis four untrained standardbreds, 2 mares and 2 geldings, between 8 and 5 years old, weighing between 900 and 1160 pounds were instrumented unsedated. Restraint , usually a twitch, was applied when necessary and catheter sites were desensitized with carbocaine. Three catheters were placed: a 7 French, 100 cm softtouch was placed using a percutaneous catheter introducer set into the left femoral vein and advanced approximately 54 cm. A 18 gauge, 5 cm Teflon catheter was placed into the carotid artery which had been relocated to a subcutaneous position. And finally a 7 French, 100 cm nylon J tailed catheter was placed via a percutaneous catheter introducer into the pulmonary artery. The placement of the pulmonary catheter was verified by using a pressure transducer and oscilloscope to observe the pressure waveform as the distal end of the catheter passed from the right ventricle into the pulmonary artery. Finally, surface electrodes were super glued to the skin tfor electrocardiographic determination of heart rate.

23Lower Airway ObstructionInflammatory airway disease (IAD)Lower airway inflammation in youngracehorses and adult performance horsesEnvironmental diseaseHay and barn dustIncreased airflowClinical signsHealthy horseGood appetite, no feverDecreasedperformance CoughEndoscopy = mucusaccumulation

one-third of racehorses affected

This research protocol was approved by the Michigan State University All University Committee on Animal Use and Care. To invesitgate our hypothesis four untrained standardbreds, 2 mares and 2 geldings, between 8 and 5 years old, weighing between 900 and 1160 pounds were instrumented unsedated. Restraint , usually a twitch, was applied when necessary and catheter sites were desensitized with carbocaine. Three catheters were placed: a 7 French, 100 cm softtouch was placed using a percutaneous catheter introducer set into the left femoral vein and advanced approximately 54 cm. A 18 gauge, 5 cm Teflon catheter was placed into the carotid artery which had been relocated to a subcutaneous position. And finally a 7 French, 100 cm nylon J tailed catheter was placed via a percutaneous catheter introducer into the pulmonary artery. The placement of the pulmonary catheter was verified by using a pressure transducer and oscilloscope to observe the pressure waveform as the distal end of the catheter passed from the right ventricle into the pulmonary artery. Finally, surface electrodes were super glued to the skin tfor electrocardiographic determination of heart rate. 24Does Mucus Accumulation Matter?MSU research yes, in racehorsesAdult performance horses???Compete at submaximal exerciseintensitiesMucus probably not alimiting factor but causesa cough at start of exercise

This research protocol was approved by the Michigan State University All University Committee on Animal Use and Care. To invesitgate our hypothesis four untrained standardbreds, 2 mares and 2 geldings, between 8 and 5 years old, weighing between 900 and 1160 pounds were instrumented unsedated. Restraint , usually a twitch, was applied when necessary and catheter sites were desensitized with carbocaine. Three catheters were placed: a 7 French, 100 cm softtouch was placed using a percutaneous catheter introducer set into the left femoral vein and advanced approximately 54 cm. A 18 gauge, 5 cm Teflon catheter was placed into the carotid artery which had been relocated to a subcutaneous position. And finally a 7 French, 100 cm nylon J tailed catheter was placed via a percutaneous catheter introducer into the pulmonary artery. The placement of the pulmonary catheter was verified by using a pressure transducer and oscilloscope to observe the pressure waveform as the distal end of the catheter passed from the right ventricle into the pulmonary artery. Finally, surface electrodes were super glued to the skin tfor electrocardiographic determination of heart rate.

25Lower Airway ObstructionExercise-induced pulmonary hemorrhage (EIPH)

Epistaxis 2-3%

Lung washing100%Endoscopy25-50%

Exercise-induced Pulmonary HemorrhageWhy do horses bleed?Stress failure of pulmonary capillariesWeak link between high driving pressure of blood through lungs and a stuff left ventricle that may limit cardiac filling during strenuous exerciseIs EIPH a cause of poor performance?EIPH Scoring System

Does EIPH Affect Performance

Hinchcliff et al. JAVMA 227:768-774, 2005Does Furosemide Decrease EIPH?152 TBs raced 2x (furosemide vs. placebo)3.4x more likely to have EIPH score >17.1x more likely to have EIPH score >2

Hinchcliff et al. JAVMA 235:76-82, 2009 Non-infectious Airway DiseaseAirflow obstruction at restLower airways recurrent airway obstruction = heavesExcessive mucus leads to coughingBronchoconstrictionleads to increasedrespiratory effort

RAO = Heaves

MucusaccumulationHeave line, nostril flareRAO = HeavesBoth allergy and non-specific airway inflammationAllergy to hay dust (genetic predisposition in some lines)Barn dustexacerbatesinflammation

RAO = HeavesTreatment/managementImprove environment = outside 24/7Pasture, soaked hay or hay cubes, complete pelleted feedBronchodilators may alleviate sudden bronchoconstriction clenbuterol and othersCorticosteroids control inflammation, steroids are the mainstay of treatment after improving environmentAllergy testing may help in some horsesMSU Animal Initiative Studies

This research protocol was approved by the Michigan State University All University Committee on Animal Use and Care. To invesitgate our hypothesis four untrained standardbreds, 2 mares and 2 geldings, between 8 and 5 years old, weighing between 900 and 1160 pounds were instrumented unsedated. Restraint , usually a twitch, was applied when necessary and catheter sites were desensitized with carbocaine. Three catheters were placed: a 7 French, 100 cm softtouch was placed using a percutaneous catheter introducer set into the left femoral vein and advanced approximately 54 cm. A 18 gauge, 5 cm Teflon catheter was placed into the carotid artery which had been relocated to a subcutaneous position. And finally a 7 French, 100 cm nylon J tailed catheter was placed via a percutaneous catheter introducer into the pulmonary artery. The placement of the pulmonary catheter was verified by using a pressure transducer and oscilloscope to observe the pressure waveform as the distal end of the catheter passed from the right ventricle into the pulmonary artery. Finally, surface electrodes were super glued to the skin tfor electrocardiographic determination of heart rate.

35MSU Animal Initiative Studies

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