Equine Endoscopy: Upper Respiratory Tract

• Horses are obligate nasal breathers because of the position of the long soft palate, which prevents oral breathing
• Normal horse respiratory rate is 8-16 bpm
• Horses exhibit costoabdominal breathing
• The caudal lung border in horses is 16-11-6

Endoscopic Evaluation of the Upper Respiratory Tract

• Endoscopy is a diagnostic tool used for:
• Dorsal displacement of the soft palate (DDSP)
• Epiglottic entrapment
• Rostral displacement of the palatopharyngeal arches
• Arythenoid chondritis
• Tracheal collapse/stenosis
• Pharyngeal narrowing
• Cleft palate
• Subepiglottic cyst
• Choanal atresia
• Hemorrhage/exudate source
• Ethmoidal hematoma
• Retropharyngeal lymphadenopathy
• Pulmonary hemorrhage
• Examination should include tracheal and lower airway assessments, checking the mucosa for exudates or masses
• Diagnostic samples include tracheal or bronchial secretions, depending on the sampling purpose
• Tracheal secretion collection is best for cultures, while BAL washings of distal airways are appropriate for lower airway cellularity exams

Epistaxis in Horses

• Epistaxis definition: Nose bleed
• Epistaxis can be caused by:
• Guttural pouch mycosis
• Pulmonary abscess
• Exercise-induced pulmonary hemorrhage
• Ethmoid hematoma
• Paranasal sinus abscess or infection
• Traumatic nasogastric intubation
• Upper respiratory tract neoplasm
• Coagulopathy
• Trauma
• Rupture of rectus capitis muscle Pneumonia/pleuritis
• Hemothorax
• Thoracic trauma
• Fractured rib
• Lacerated heart or vessels
• Pulmonary thromboembolism
• Ruptured pulmonary abscess
• Ruptured great vessel
• Neoplasia
• Coagulopathy
• Severity depends on frequency and amount; it can be chronic or acute, consistent or inconsistent; light or heavy flow may be present based on the underlying condition
• Treatment depends on the underlying cause and is typically self-limiting
• Rare severe hemorrhage treatment options:
• ɛ-aminocaproic acid administration
• Nasal packing
• Intranasal phenylephrine (10 mg in 10 mL saline)

Rhinitis

• Rhinitis definition: Infection of the nasal passage independently of the sinuses
• Viral causes:
• Equine influenza virus
• Equine herpes virus 1 & 4
• Equine rhinoviruses
• Adenovirus
• Bacterial causes are not common and usually secondary to trauma or foreign body
• Mycoplasma spp.
• Fungal/mycotic causes:
• Aspergillus spp.
• Connidiobolus spp. (usually C. coronatus)
• Cryptococcus neoformans
• Parasitic causes

Sinusitis

• Sinusitis definition: Inflammation of the sinuses
• Causes are the same as for rhinitis
• Sinonasal disease is common in horses because of the extensive network of six pairs of sinuses that exchange air with the nasal airway
• Frontal sinuses may be affected with granulomatous masses from fungal, parasitic, or bacterial etiologies
• Bacterial causes:
• Streptococcus spp. (S. equi subsp. zooepidemicus and S. equi subsp. equi)
• Staphylococcus spp.
• Polymicrobial infection is also identified among sinus disease in horses
• C. neoformans and Coccidioides immitis may cause granuloma formation
• Secondary sinusitis is caused by:
• Dental disease
• Trauma
• Cysts
• Neoplasia
• Progressive ethmoidal hematoma
• Mycotic infection
• Polyps
• Clinical Signs:
• Unilateral disease unless the infection is viral or involves the nasal septum extensively
• Respiratory stridor and nasal discharge with less airflow on the affected side
• Mucopurulent unliteral discharge
• Serosanguineous unilateral discharge
• Facial swelling
• Lacrimal discharge
• Fungal sinusitis can cause head shaking syndrome but its quite rare
• Diagnosis:
• Clinical signs
• X-ray to see fluid and masses
• Endoscopy to see airway changes and rule out ethmoid hematoma
• CT and MRI
• Treatment requires that underlying conditions be identified and treated, removing debris and infectious agents
• If fluid is present, trephination and flushing or surgical debridement and drainage using a sinus flap is required, accompanied by local flushing
• Systemic antimicrobials are indicated for osteomyelitis signs
  • Itraconazole (per os) for recurrent nasal mycoses

Laryngitis

• Laryngitis definition: Inflammation of the larynx
• classified as acute or chronic
• Acute Laryngitis Causes:
• Breathing in cold, polluted air (dust, ammonia, chlorine gas, or smoke)
• Roughly administered drugs/nasogastric tubes
• Choking on foreign bodies

Guttural Pouch Inflammation and Mycosis

• Guttural Pouch Empyema Causes:
• Upper airway infection with S. equi subsp. equi
• Abscess formation in the retropharyngeal lymph nodes leads to rupture and drainage into one or both guttural pouches
• Post-trauma to the stylohyoid bone
• Guttural Pouch Mycosis Causes:
• Aspergillus fumigatus
• Guttural Pouch Empyema Clinical Signs:
• Intermittent, chronic nasal discharge
• Submandibular lymphadenopathy
• Parotid enlargement
• Increased respiratory noise
• Uncommon neuropathy/dysphagia
• Occasional hemorrhage and serosanguineous discharge
• Guttural Pouch Mycosis Clinical Signs:
• Epistaxis (Nosebleed)
• Dysphagia (feed and saliva discharge from nostrils)
• Recurrent laryngeal neuropathy indicates turbulent airflow and altered airway mechanics
• Guttural Pouch Empyema Diagnosis:
• Endoscopy
• Diagnostic testing of samples (microbiological culture and PCR)
• X-ray
• ULS
• Guttural Pouch Mycosis Diagnosis::
• Endoscopy:
• Observation of fungal plaques, often medial compartment roof-internal carotid artery involvement
• Guttural Pouch Empyema Treatment:
• Treat with S. equi subsp. equi
• Drainage with 0.9% saline
• Local penicillin
• Guttural Pouch Mycosis Treatment
• Itraconazole (5 mg/kg PO daily)

Tracheitis

• Tracheitis definition: Inflammation of the trachea
• Causes:
• Bacterial
• Viral
• Dust/smoke/chemicals
• Trauma of any reason

Pneumonia

• Pneumonia definition: Inflammation of the lungs involving the alveoli and interstitial connective tissue
• Bacterial Causes:
• Streptococcus zooepidemicus
• Rhodococcus equi (foals)
• Streptococcus pneumoniae
• Haemophilus influenzae
• Staphylococcus aureus
• Mycoplasma pneumonia
• Infectious agents enter the lungs primarily through inhalation (90%), as well as hematogenous spread and aspiration

Pleuropneumonia

• Pleuropneumonia definition:
• Causes:
• Long-Distance Transport ("Shipping Fever")
• When horses heads are in elevated position → Bacterial colonization within 12-24 hrs
• Viral respiratory infections (EHV and influenza)
• Stress
• General anesthesia
• Secondary bacterial infections (most common)
• Streptococcus zooepidemicus
• Clinical Signs:
• Clinical signs develop within 7 days of transport, or as little as 24 hours
• Fever
• Tachypnea
• Tachycardia
• Depression/lethargy
• Inappetence
• Mild colic
• Cough if present is often soft, shallow, and non-productive
• Bilateral, mucopurulent discharge (not always)
• Decreased lung sounds in the ventral lung fields below the pleural effusion and crackles in dorsal lung fields
• Diagnosis:
• TA → Cytology and bacterial culture
• Thoracocentesis
• Diagnostic imaging
• Blood work Treatment:
• Antimicrobials (broad spectrum) → Penicillin, Genta, Metronidazole
• NSAIDs
• Analgesics
• Oxygen
• Pleural lavage

Asthma

• Asthma definition: Umbrella term for recurrent airway obstruction (RAO) and inflammatory airway disease (IAD) + other conditions such as allergy, small airway disease, chronic obstructive pulmonary disease
• Mild-moderate asthma represents horses with IAD, and severe asthma represents horses previously labeled as having RAO (heaves)
• Asthma Causes:
• Hypersensitivity to inhaled agents (< 5 microm)
• Mold, dust, pollen, ammonia, smoke, endotoxins from hay and straw
• Viral agents
• EHV
• EIV
• Bacterial agents
• Streptococcus equi
• Rhodococcus equi (foals)
• Fungal spores
• Aspergillus fumigatus
• Thermoactinomyces vulgaris
• Pathophysiology involves three key components:
  • Airway Inflammation:
    • Neutrophilic airway inflammation → severe equine asthma
    • Neutrophilic/eosinophilic/mastocytic inflammation → Mild-moderate asthma
  • Mucus Hypersecretion → lower airway obstruction
  • Airway Hyperresponsiveness:
  • Inflammatory mediators, bronchospasms + airway smooth muscle relaxation
  • Airway Remodeling:
  • Severe asthma causes chronic inflammation
  • Chronic inflammation causes recurrent injury and remodeling of airway walls
  • This remodeling narrows the Lumen(irreversible in longstanding severe asthma)
• Clinical signs:
• Random or frequent cough
• Difficulty breathing
• Decreased work capacity
• Nasal discharge/Dilated nostrils
• Dyspnea → Heave line
• Clinical signs of young and middle-aged horses:Often sub-clinical, intermittent cough with increased mucoid airway secretions; increased respiratory rate and breathing
• Horses > 7 years present with seasonal and abnormal sounds, chronic cough, and respiratory distress
• Severe Asthma (RAO):
• Includes episodic expiratory dyspnea at rest with frequent coughing episodes
• Ausculation → expiratory wheezes
• Mild-Moderate Asthma (IAD):
• Involves non-specific signs like poor performance and occasional cough/mild tachypnea with mild mucoid discharge; horses with equine asthma aren't febrile w/o bacterial pneumonia
• Diagonsis:
  • Clinical Examination Results and History
  • Endoscopy: Exudate in nasopharynx and Trachea
  • TA
  • Increased Neutrophils > 5%
• Lymphocytosis
• Monocytosis
• Excersice and pulmonary function tests
• Biopsy
• X-ray if bronchointerstitial pneomonia and fibrosis is suspected
• Treatment of equine asthma:

1. Removal of triggering factors through environmental modification (70 percent success)
2. Addressing inflammation in the lung with corticosteroid therapy
3. Use of bronchodilators as necessary for fast relief of bronchospasm

Equine Piroplasmosis and Anaplasmosis

• Definition:
• Piroplasmosis involves intracellular protozoa, while anaplasmosis involves intracellular bacteria
• Causes:
• both are Tick-born pathogens
• Piroplasmosis:
• Babesia caballi and Theileria equi
• Anaplasmosis:
• Anaplasma phagocytophilum
• Clinical symptoms:
• Caused by The pathogens atacking cells in the bloodstream
• Symptoms of both diseases are similar:
• Reluctance to move
• Lack of appetite
• Fever
• Swelling of fetlocks
• Episodes of colic
• In younger horses (more severe) symptoms:
• Jaundice
• Weakness
• Pale mm
• Zojas presentation (anaplasmosis):
  • Pyrexia
  • Diarrhea
  • Edema
  • Ataxia
  • Colic
• Piroplasmosis Diagnosis:
  • Blood smear:
  • Look for Morulae in neutrophils and eosinophils (at least in 3 out of 100 leukocytes)
  • Indirect antibody detection (best for chronic infections)
  • PCR (best for acute infections)
  • Blood test Aanemia -leukopenia Thrombocytopenia Might be increased bilirubin
• Treatment Antiprotozoal drugs and supportive care

Horse Dehydration

• Causes
• Clinical symptoms:
• Weakness
• Muffled diaphragmatic murmurs
• Treatment:
• Water
• Electrolytes (PO or IV)
• Ca IV

Myocarditis and Endocarditis

• Myocarditis Causes:
• Common Complication after:
• Infections
• Blood parasitic diseases
• Sepsis
• Strong Intoxication
• Endocarditis Causes:
• Bactierial
• Myocarditis Clinical Symptoms:
• Apathy, shortness of breath, increased temperature, tachycardia initially, edema, cyanosis, death
• Diagnosis:
• Blood Test
• Leukosis with shift to left (stress leukogram?)
• Basophilia, eosinophilia and neutrophilia
• ECG
• Endocaditis Diagonsis:
• Blood test
• Hematology tests will show a serial positive blood culture
• Echocardiography can find irregular valve thickening
• Treatment:
• Myocarditis:
• Symptomatic
• Endocarditis:
  • Bacterial endocarditis use long-term antibiotics

Pericaditis Types and Causes

• Pericarditis Types:
• Effusion - occurs when you have an Effusion in Pericardial cavity (or heart sac)
• Fibrinous - caused by too much fibrin
• Constrictive - Is caused when theheart is squeezed
• Pericarditis Causes:
• Idiopathic aseptic (most commonly)
• Lung or pleural infections
• Hematogenous spread of infection (septicemia)
• Viral infections (EVA, Equine influenza
• Pathophysiology:

1. • Pathogens make toxins that releasem inflammatory mediators
2. Pericardial Effusions Impede Atrial and Ventricular filling = decreased end-diastolic volume
3. Poor cardiac output causes sympathetic nervous system + Renin released = Tachycardia and Vasoconstriction cause retention of both sodium and water. These causes increase in diastolic atril pressure
4. Increases ventricular filling pressures create backward cardiac failure which icreases the fluid retention

• Clinical Symptoms:
• Ventral edema (legs etc.)
• Tachycardia (muffled heart sounds and rubbing)
• Fluid in pericardium (ULS)
• Fever
• Colic signs
• Lethargy
• Daigonosis:
• Blood biochemistry
• Electrocardiography
• Ultrasound
• Indication of sepsis: Degenerate neutrophils and protein Cells Occasionally Observed:
• Neoplastic cells may be cancer
• Eosinophils observed in percardial fluid
• Treatment:
• Drain with Warm sterile and use local antibiotics for 2day, then repeat until 200ml comes out!

Thrombohlebitis Causes and Clinical Symptoms

• Definiton: Thrombosis w Venous wall inflamation due to catheter usage
• Cininical Diagnosis:
• Ultrasound
• General clinical examination) Treatment
• Nsaids or steroids
• Heating areas
• Sepsis

Meconium Causes and Clinical Symptoms

• Meconium = Feces from newborn
• Happens withing 1-2hrs
• Appearrance:
• Dark Brown
• Sticky!
• Causes:
• Prematurebirth or Dystocia Symptoms:
• Constant Defecation
• X-ray may be requires, and NSAIDS may be precribed

Foal Maladjustmen Definition

• Occurs dur to a lack of oxygen in brain, (Dystocia or Placentais Symptoms include: Apathy and absent reflex Causes : Dystocia, Premature birth

Septicemia

• Is caused by bacteria infection and transfer
• Can come from, the umbilcial cord and respiratory system

Equine Metabolic Syndrome

• Occurs when equids are unable to process carbs
• Main risk: Laminitis
• Test them through Basline test and neck size
• Oral sugar
• Increased appetite and inferility are often symptoms

Hyperlipidemia

• Can be from obesity and stress
• Most Common Reason: Negative energy balance
• Leads to insuline resistance, and ketosis