Equine neonatology Flashcards
What age foal is defined as premature vs dysmature
Premature = <320 days gestation
Dysmature = >320 days gestation
Treatment of dysmature foals
Hyperimmune plasma
Broad spectrum antibiotics; either prophylactically or if signs of infection shown
FLuids, inotropes
Parenteral nutrition
Oxygen (intranasal)
Slow physiotherapy
Why do we avoid encouraging dysmature foals to stnad
Due to incomplete ossifications of small cuboidal bones in hock; risk of collapse in early weight bearing
Why do premature foals that experience in utero stress have a better prognosis
Due to exposure to cortisol
What is complete vs partial failure of passive transfer
Complete failure = IgG <2g/L
Partial failure = IgG 2-4g/L
Normal should be >8g/L
What might cause inadequate availability of antibodies for the foal (FPT)
- Premature delivery
- Running milk
- Agalactia
- Poor quality colostrum
When do we measure IgG in foals to assess for passive transfer
> 18hrs after birth
Use ELISA SNAP test usually
How much does 1L hyperimmune plasma increase the IgG of a foal by
1L will increase the IgG by 2g/L
Why do we recheck IgG in a foal after transfusion a couple days later
Because if the foal is septic, the antibodies will be used up very quickly and may need to be replaced
What are the two ways to detect failure of passive transfer
SNAP ELISA test = very sensitive but not specific
Radial immunodiffusion test = more accurate and specific but costly and takes longer
What type of antibiotic to do use in neonatal sepsis
Broad spectrum
- Generally is gram -ve organisms but there has been an increase in gram +ve organisms causing this
Causes of neonatal sepsis; bacterial entrance
> Pneumonia; then get haematogenous bacteraemic spread - e.g in bottle feeding foals with aspiration pneumonia
> Enterocolitis; esp clostridia, salmonella
> Omphalophlebitis
What should we do if a foal has an infected umbilicus
Probably just go straight for surgery to remove umbilical stump; so don’t have continued risk of it seeding infection
- Not too different to cost of long term antibiotics etc
Clinical signs of neonatal sepsis
Fever/hypothermia
Tachycardia or bradycardia
Tachypnoea
Abnormal WBCs; >10% band ones
Diagnosis = leokopaenia
What are two potential later manifestations of neonatal sepsis
Meningoencephalitis
Septic arthritis
What is the aetiology of neonatal maladjustment syndrome
= due to lack of cerebral oxygen delivery due to lack of blood flow of poor oxygenation of blood
All body systems affected by this hypoxia
What might cause neonatal maladjustment syndrome
Gestational issues; placental separation, colic, prolonged or shortened gestation, placental insufficiency, C-section
Haemorrhage due to blood vessel rupture in delivery
ASphysixa
Interference with blood flow pre or during delivery
What after birth factor might cause neonatal maladjustment syndrome
Congenital respiratory or cardiovascular abnormalities that result in poor brain perfusion
Clinical presentation of foal with NMS
i) Mild NMS: lose affinity for mare, weak suck reflex, wandering, depression, star-gazing, facial spasms, lip-curling, chomping, deep sleeping
ii) Severe NMS: totally unaware of environment, blindness, partial or generalised seizures, stupor or coma
How do we distinguish between NMS and meningitis
Only have a fever in meningitis
Treatment for neonatal maladjustment syndrome
Deal with any seizures using diazepam/midazolam
ANtibiotics
Nutritional supplementation; may need IV nutrition if recumbent
Fluid threapy; but do not overload
Why do we need to be careful not to overload dummy foals with fluid
Will make cerebral oedema worse
What is the main prognostic indicator for dummy foals
Whether seizures are present; much worse if they are
What is foal heat diarrhoea
Diarrhoea seen from 6-10 days old which is probably just related to inoculation of the hind gut with flora needed for fermentation
= self-limiting
What is a significant viral cause of diarrhoea in newborn foals
Rotavirus ; from 2 days to 2 months
Maldigestion and malabsoprtion
Diagnosis via ELISA
Which bacteria cause diarrhoea in neonatal foals
Clostridia; C difficile and C perfringens
–> Diagnosis = toxin testing; may be peracute with haemorrhage and death
Salmonella typhimurium due to infection from mare
What to do if S typhi is diagnosed in a foal
= reportable
What infectious causes are there of diarrhoea in foals 2-6 weeks (on top of those that affect neonates)
Rhodococcus equi (but usually even older)
Strongyloides westeri
What does it mean if we see +ve crypto test
Not necessarily the cause of diarrhoea
can shed asymptomatically
Generally causes diarrhoea in older foals
What age group do we tend to see rhodococcus equi affected foals
> 6 weeks
Why do we see strongyloides westeri in foals that are a few weeks old
PPP is short due to larvae being part way through life cycle when they are transferred from mare to foal via milk
What diarrhoeic agents are di-tri-octahedral smectite biosponges good for
Clostridial intestinal dysbiosis
Risk factors for meconium impaction
Seen more in colts
Long gestation, delay in colostrum ingestion, prematurity, NMS
Signs of meconium impaction
Usually in foals 18-24hrs
- Straining to pass faeces, fail flagging, can show colic, poor appetite
On digital palpation feel rigid tarry faeces
See black faeces still being passed not ‘milk faeces’
How to treat meconium impaction
Enema; can use preparatory bottles or high volume, gravity based soapy water enema via foley catheter
What might we suspect in an older foal showing bruxism (teeth grinding) and low grade colic
Gastro-duodenal ulceration
Use anti-acids
What might lead to patent urachus
Meconium impaction
Colic
Infection?
Prolonged recumbency
What are the more common sites of urinary tract rupture (causes uroperitoneum)
Most common = dorsal bladder wall
> urachus > ventral bladder wall > bladder apex
Rare to get ureter rupture
Aetiology and risk factor for urinary tract rupture
Bruising of tract during periparturient trauma –> necrotic phase occurs which leads to urine leakage
Infection or ischaemic injury possible
Clinical signs and diagnosis of uroperitoneum
Signs = abdominal distension (can cause breathing issues), ventral oedema, abdominal pain
Diagnosis:
Electrolyte abnormalities = high K+, very low Na+ and Cl-
+ elevated peritoneal: serum creatinine
Ultrasound
What should we do before entering surgery for uroperitoneum
Medically stabilise the foal
i.e correct hyperkalaemia (to avoid bradycardia risk in surgery); use saline, can drain peritoneal cavity to lower K+
What fluids would we put a foal with uroperitoneum onto before surgery
Saline (NaCl) - because it doesn’t contain K+ unlike Hartmann’s and these foals are low in sodium and chloride
What is neonatal isoerythrolysis
= immune mediated anaemic due to RBC destruction by mare produced anti-RBC antibodies
What red cell factors are most associated with neonatal isoerythrolysis and which breed are these common in
Qa and Aa
Common in thoroughbreds
Clinical signs of neonatal isoerythrolysis
Normal at birth but signs within a couple days
* Death, weakness, pale MMs, depression
* Tachycardia and tachypnoea
* Jaundice/icterus
* Pigmenturia (brown/red urine
Treatment of neonatal isoerythrolysis
Whole blood transfusion to replace ost RBCs
Muzzle foal to avoid colostrum ingestion until mare starts producing ‘milk’
Giving fluids to a collapsed foal; how much and which
Go for Hartmann’s + can add glucose to make it isotonic
Give 1L bolus then re-assess; give up to 4 in total
How much and how often to give diazepam to control seizures in foal
1-2ml IV every 5-20 mins
What sedative would we use in foals <1 month old
Benzodiazepines
Gives sedation and relaxation without cardiovascular depressoin
Fluid maintenance rate in a foal
250ml/hr
What 3 things cause issues in older foals and weanlings
1) Rhodococcus equi
2) Lawsonia intracellularis
3) Internal parasitism [strongyloides westeri, parascaris]
What type of pathogen is rhodococcus equi
Facultative intracellular; lives in macrophages and causes microabscessation in lungs
Common cause of pneumonia in foals from 3 weeks to 6 months
What confers virulence in rhodococcus equi
VapA plasmid; NB can be transferred to previously non-virulent strains
What is the key environmental factor assocaited with rhodococcus equi risk
Bacterial load in the AIR
Clinical signs of rhodococcus equi
- Vague signs of ill-thrift
- Increased respiratory rate and effort; ‘rattles’ due to fluid and phlegm in airways
- Nasal discharge
How do we treat pneumonia due to rhodococcus equi
macrolide (clarithrymycin) with rifampicin
What consideration do we need to take when using macrolides in foals
Wipe off their mouth before putting them back in with mare since macrolides cause diarrhoea in adults
What does rhodococcus equi pneumonia look like on radiograph
Interstitial pattern throughout which becomes an alveolar pattern more ventrally
Multifocal round soft-tissue densities consistent with abscessation
How sensitive is chest auscultation for rhodococcus equi pneumonia
Not very; can head nothing despite pathology being present
Diagnosis of rhodococcus equi
Same tracheal aspirate sample and do cytology for intracellular bacteria present, culture, PCR (+ can check for VaPA plasmid this way)
Strongyloides westeri in foals
Rarely causes clinical signs
Foals get resistance by 4-5 months old
Disease due to parascaris in foals
= jejunal impactions after wormers that cause NMJ blockade
What is the PPP of parascaris and what does this mean for worming timings
75-90 days
Do not worm foals before 60 days since there is no justification and promotes resistance
How can we prevent obstructions when worming those with parascaris burden
- Use benzimidazoles since these don’t cause NMJ blockde so slower death
- Use liquid paraffin prophylactically
Pathology of lawsonia intracellularis infection
protein losing enteropathy via invasion and proliferation of ileum/jejunum
Get malabsorption/maldigestion and hypoalbuminaemia
Clinical signs of lawsonia intracellularis infection
weight loss, lethargy, diarrhoea; can get subcut oedema
What is a cartwheel shape in small intestine characteristic of
= small intestine thickening e.g in Lawsonia intracellularis
How can we diagnose lawsonia intracellularis
Ultrasound findings; thickened SI (carthweel)
PCR; but 20% false -ves
CANNOT do histopath because would need a full thickness biopsy and this is contraindicated
Treatment of lawsonia intracellularis
- Tetracyclines; oxytet in more affected ones
May need plasma/fluids
What is a potential sequelae to lawsnia intracellularis
Severe necrotising enteritis
How do we have to give the vaccine for lawsonia intracellularis
Intra-rectal to avoid inactivation by gastric acid
What consideration should we take before giving tetracyclines to foals
It is nephrotoxic
May want to check creatinine/SDMA first
What do we add in when treating diarrhoea in hospital in neonatal foal to food - related to a non-infectious cause of diarrhoea
Add in lactase; in case they are lactose intolerant
Where do we give fluid boluses to a foal
Cephali vein
