resp disease in foals and weanlings Flashcards
what are the risk factors for lower resp disease in foals?
- Systemic sepsis (FPT)
- Congenital abnormalities
- Meconium aspiration
- Milk aspiration
- Birth trauma
what are the causes of acute resp distress immedialtely following birht in foals?
- Extrapulmonary Disorders causing URT obstruction
◦ Bilateral choanal atresia (blockage of both nasal passages)
◦ Stenosis of the nares
◦ Severe laryngeal oedema or collapse
◦ DDSP
◦ Subepiglottic cyst
◦ Severe pulmonary abnormalities - Congenital cardiac abnormalties
what is acute lung injury and acute respiratory destress syndrome in the foal? what occurs, what is the treatment and prognosis?
Syndrome of respiratory failure associated with noncardiogenic pulmonary oedema, decreased pulmonary compliance, and ventilation/perfusion mismatching
- Exaggerated inflammatory response – severe tissue damage
- Not primary diseases – occur secondary to other disease processes
- Surfactant deficiency – progressive atelectasis (lung collapse)
Treatment
◦ Intranasal oxygen,
◦ Ventilation
◦ Anti-inflammatories – corticosteroids
◦ Broad spectrum anti-microbials
- Prognosis poor
what is meconium apsiration syndrom?
when does it occur?
what can it lead to?
what is the treatment?
Respiratory distress in a foal born through amniotic fluid stained with meconium
* Can occur before, during or immediately after parturition
Meconium aspiration can lead to:
◦ Mechanical airway obstruction
◦ Regional air trapping
◦ Surfactant inactivation and displacement
◦ Chemical pneumonitis and alveolitis
◦ Persistant pulmonary hypertension
Treatment
* Aspiration of the material from the nasal passages and pharynx
* Nasotracheal intubation followed by careful suction
* Intranasal oxygen supplementation +/- mechanical ventilation
* Anti-inflammatory therapy
* Pentoxyfylline - has effect on the downstream effects of SIRS
* Treatment of secondary bacterial pneumonia – broad spectrum abs. (due to this typically being a mixed infection)
what is milk aspiration in foals secondary to?
how is it diagnosed?
what is the treatment?
Secondary to:
* Generalised weakness
* Poor suckle reflex
* Dysphagia – prematurity or neonatal maladjustment
* Congenital abnormalities
Risk exacerbated by attempts at bottle feeding foals affected with these problems
Diagnosis
* Detection can be difficult
* History of milk regurgitation
* Physical exam findings
◦ Abnormal lower respiratory sounds
◦ Systemic inflammation
◦ Pulmonary dysfunction
* Endoscopic examination of URT
* Thoracic radiography
◦ consistent with aspiration pneumonia, with pathology concentrated in the cranial ventral lung lobes. increased soft tissue opacity, alveolar pattern.
Treatment
* Correction of the cause
* Naso-oesophageal feeding tube
* Broad spectrum antimicrobial therapy
what are the complications of rib fractures in foals?
where do rib fractures commonly occur?
how are they diagnosed?
what is the treatment?
complications: Trauma to the thoracic viscera
◦ Pulmonary contusions
◦ Lacerations of lungs, major arteries, heart or diaphragm
- Most commonly at the costochondral junction or immediately dorsal to it
- Flail chest - two fractures involving several ribs, so a section of the ribcage is separate from the rest of the thorax
◦ Inward during inspiration and outward during expiration - opposite to the rest of the chest
Diagnosis
* Physical exam
◦ Crepitus
◦ Auscultation – grinding or clicking sound
* Ultrasonography - More sensitive than radiography
Treatment
* Most managed conservatively
◦ Box rest, avoidance of pressure during handling
* If substantial air is presented within the pleural cavity it will cause respiratory distress and should be evacuated
* Surgical repair may be required if multiple fractures and risk of further damage to thoracic viscera
* Haemothorax – address primary cause of haemorrhage and patient stabilization and support
although uncommon what viruses are associated with viral pneumonia in foals?
- EHV-1
- EHV-4
- Equine Influenza
- Equine arteritis virus
- Equine adenovirus
what are the clinical sings of viral pneumonia in older foals? what viruses are more likley to cause this?
- EHV-1, EHV-4, EIV and EAV
- C/S similar to adults
- Dry cough and fever +/- mucopurulent nasal discharge (secondary bacterial)
- Usually self limiting
- EAV – ventral and limb oedema due to vasculitis
what virus is typically fatal to neonatal foals? what are the presenting sings, diagnosis and treatment?
equine herpes virus
- Presenting signs very similar to neonatal sepsis
- Late term abortion
- C/S
◦ Cardiovascular and respiratory insufficiency
◦ Congested MMs - Clin Path
◦ Leukopenia + neutropenia + lymphopenia
diagnosis - PCR testing of nasal secretions or whole blood
Treatment
* Anti-virals (acyclovir, valacyclovir) – some efficacy in less severely affected foals
* Supportive care
what causes parasitic pneumonia in foals? what occures within the foal, what are the clinical signs? what is the treatment?
Parascaris spp.
injestion of larvated eggs, the infective larvae emerge in the intestinal lumen
* Migrate through liver and lungs
* Coughed up and reingested
- Passage through lungs associated with substantial inflammation
◦ C/S of LRT disease - Ultimately self limiting
Anthelmintic treatment recommended
‣ Fenbendazole or Pyrantel
in neonatal foals what is the cause of bacterial pneumonia?
associated with haematogenous spread secondary to bacteraemia
* May also occur secondary to in utero infection or meconium or milk aspiration.
* Typically Gram negative (+/- gram positive)
◦ E.coli most common
* Successful treatment depends on early and effective support of resp function, control of systemic and pulmonary inflammation and appropriate antimicrobial therapy
in foals 1- 6months what pathogens causes bacterial pneumonia? why does this occur?
Strep equi subs. Zooepidemicus most common, followed by Rhodococcus Equi
* Decreasing maternal Ig, delayed endogenous production
* Stress of weaning, changes in environment
* Can be secondary to viral infection
how do foals get infected with Rhodococcus equi?
- Ubiquitous (present) in the environment - Infection predominantly by inhalation
what are the clinical signs of rhodococcus equi?
Clinical disease
* Insidious
* Lower respiratory tract infection
* Fever
* Lethargy
* Coughing
* Tachypnoea
* Dyspnoea
◦ Can be severe with nostril flaring and prominent abdominal expiratory effort
Extrapulmonary disorders - common
* Diarrhoea
* Ulcerative enterotyphlocolitis
* Immune mediated synovitis
* Intra-abdominal lymphadenitis or abscessation
* Uveitis
foals with rhodococcus equi will have Peripheral pulmonary consolidation or abscesses how are these scored?
a pulmonary abscess as a focal hypoechoic area with a diameter >1cm
* No. of abscesses identified is recorded and diameter measured – totalled to generate a total abscess score (cms)
* Foals less than 8-10cm typically not receiving treatment, but are monitored with serial ultrasound examination
