Foals Flashcards
What is the difference between a premature and dysmature foal?
Premature: a foal born <320 days of gestation, that displays immature physical characteristics
Dysmature: a full-term foal that displays immature physical characteristics (full-term=340 days)
What is the gestation period of a mare?
Around 340 days
Give some physical characteristics of a premature or dysmature foal
Domed head Short, silky hair coat Floppy ears Low birth weight Weakness, prolonged time to stand Flexor tendon laxity Incomplete ossification of carpal and tarsal bones (not visible on x-ray) Severe cases: multiple organ dysfunction
By what age do foals have autogenous IgG adult levels?
4 months of age
Which immunoglobulins are found in colostrum?
IgG, IgG(T), (IgA, IgM)
What is the half-life of maternal IgG in foals?
20-23 days
Declines by 1-2 months (more rapid if poor levels initially)
How are immunoglobulins absorbed from colostrum?
When does maximum absorption occur?
Specialist enterocytes absorb the immunoglobulins by pinocytosis
They have a maximum lifespan of 24 hours
Maximum absorption occurs within 8 hours of life (foal must ingest 1L of colostrum within the first 6 hours of life)
When do IgG levels peak in a foal’s blood?
18 hours
When should you test IgG levels to evaluate passive transfer?
12-24 hours (later than 24 hours: foal wont be able to absorb colostrum as specialist enterocytes will have died)
Define failure of passive transfer
Inadequate transfer of colostral IgG
What is the normal value for transfer of colostral IgG?
What would be defined as failure of passive transfer?
Normal: >8g/L
FPT: <4g/L
When do foals normally stand after birth?
Within 1 hour
When do foals normally suck after birth?
Within 2 hours
When is IgG not detectable?
< 6hrs old
Give some predisposing factors for failure of passive transfer
- Loss of colostrum via premature lactation (twinning, placentitis, premature placental separation)
- Inadequate colostrum (IgG/volume) production (severe illness, premature foaling, endophyte-infected fescue (plants))
- Failure to ingest adequate volume of colostrum (neonatal weakness, rejection of foal)
- Failure to absorb colostrum (premature foals, concurrent illness of foal, glucocorticoids may hasten maturation of specialist enterocytes)
When is colostrum produced in the mare?
Last 2-4 weeks of pregnancy
How can you test for failure of passive transfer?
- ELISA SNAP test
- RID (radial immunodiffusion)
- ZnSO4 turbidity
- Glutaraldehyde coagulation
- TSP/globulins (not always accurate in sick foals; <50=too few globulins)
- Colostrum specific gravity can be checked pre-suck
How can you treat failure of passive transfer?
- Give plasma (if >12-24 hours old) (from mare, commercial, geldings)
- Give colostrum (from mare, banks, commercial)
What is an immediate risk of failure of passive transfer?
Septicaemia
Give some less immediate risks of failure of passive transfer
When do they tend to occur?
Rotavirus, respiratory disease, joint sepsis
Occurs ay 1-4 moths old after rapid waning of ingested IgG
When do foals normally begin their suckling reflex after birth?
Within 20 minutes
What is the temperature of a newborn foal?
37.2-38.9oC
What is the normal heart rate of a newborn foal?
Birth: 40-80
First week: 60-100
What is the normal resp rate of a newborn foal?
Newborn= 45-60
7 days old= 35-50
By when should meconium be passed in a newborn foal?
Within 24 hours
By when should urine be passed in a newborn foal?
Colts: 6 hours
Fillies: 10 hours
Large volumes of dilute urine
What is the average weight of a newborn foal?
45-55kg
What is the average daily weight gain of a newborn foal?
0.5-1.5kg/day
How much milk should a newborn foal consume?
20-28% BWT (feed every 2 hours)
Which lungsounds are normal in a newborn foal?
Harsh bronchovesicular sounds
Crackles are present in the ventral dependent side if in lateral recumbency
Give some signs of sepsis in a foal’s mm
Petechiae, congestion
How would you identify sepsis in a newborn foal?
Blood culture (do AB sensitivity; bacteria results take 3 days)
What are the 4 components of a sepsis score in newborn foals?
I: complete blood count (neutrophil count and morphology)
II: other lab data (fibrinogen concentration, blood glucose-will be low if high numbers of bacteria, IgG)
III: clinical exam findings
IV: historical data
How can you diagnose an umbilical infection?
- Ultrasound (compare size of umbilical vessels; also helps differentiate from haematoma/hernia)
- Enlarged umbilicus
- Drainage of pus from umbilicus, may be pain on palpation
How can you diagnose pneumonia in a newborn foal?
Radiography
Blood gas analysis
How can you diagnose osteomyelitis/arthritis in a newborn foal?
Synovial fluid analysis
Radiography
How would the lungs appear on radiography with viral and bacterial pneumonia and atelectasis?
Viral: diffuse interstitial pattern
Bacterial and aspiration pneumonia: focal, bronchoalveolar ventral and hilar area
Atelectasis: alveolar pattern
Which intense medical therapies should you include when caring for a sick foal?
Fluids
Antibiotics
Immunoglobulins (plasma or hyperimmune serum)
Anti-inflammatories (Flunixin for septicaemic foals; 0.5-1mg/kg BID)
Anti-ulcer meds (Sucralfate TID or Omeprazole SID); debated
Circulatory support (Dobutamine)
Resp stimulants (eg caffeine)
Diuretics if persistent oliguria (furosemide or mannitol)
What kind of intensive nursing should you include when caring for a sick foal?
Resp support (intranasal O2, mechanical ventilation, drugs-bronchodilators, central stimulators)
Nutrition (need 20% BWT in milk/day; 10L split into 2-hourly feeds)
Heat
Sternal recumbency
Monitor urine output (good measure of CO)
Which ABs shouldn’t you use in foals and why?
Which can you use?
Aminoglycosides- nephrotoxicity
Can use penicillins and other beta-lactams, ceftiofur (5mg/kg QID), cefquinome (1mg/kg)
How long does it take foals to adapt to the external environment after birth?
24-48 hours
Give some common pathogens that cause septicaemia in foals
E coli, Actinobacillus, Salmonella, Proteus, Klebsiella, other gram negative spp
Beta-haemolytic Streptococcus, Staphylococcus, Clostridia
Mixed infections possible
How do septicaemia-causing pathogens enter the foal?
Openings eg umbilicus
Open gut
Inhalation
In utero (mare placentitis)
What is a common cause of resp disease in an older foal?
CID/SCID (severe combined immunodeficiency)
What is CID/SCID?
Which breed does it occur in? What age?
Severe combined immunodeficiency
Failure to produce functional T and B lymphocytes -> resp dz, esp infections (Pneumocystis carini, adenovirus pnuemoni)
Autosomal recessive in Arabs and part-breds
Normal at birth, dz begins at 1-2 months old
Lethal
How do you diagnose CID/SCID?
Clinical signs
Persistent lymphopenia (<1x10^9/L) but normal total WBCC
Confirm with PM- hypoplasia of LNs, thymus, spleen
Genetic testing available
What is Perinatal Asphyxia Syndrome and how does it occur?
Dummy foals, HIE (hypoxic ischaemic encephalopathy)
Ischaemia, oedema, reperfusion injury to brain, kidneys, intestines and other organs due to lack of oxygen (in-utero hypoxia, or interruption of blood supply during birth)
What are the clinical signs of Perinatal Asphyxia Syndrome (3 forms)?
May not be apparent until 12-24 hours old
Mild: unable to attach to mare, poor suck reflex
Moderate: aimless wandering, blind, abnormal phonation (‘barkers’)
Severe: seizures, coma
Give some clinical signs of septicaemia in a newborn foal
Off-suck, lethargic
Increased respiratory effort and rate
Acute severe lameness
Discharge/swelling of umbilicus
Congested, dark mm or severe petechial haemorrhages
Hypopyon (pus in anterior chamber of eye)
Diarrhoea
Meningitis
SARS-high temp (severe acute resp syndrome; SARS coronavirus)
How does septic shock occur?
Vasoactive inflammatory mediators -> vasodilation
Increased metabolic rate and oxygen consumption
CO is usually high initially (hyperdynamic phase)
Microvascular permeability -> volume maldistribution
Increased CO can no longer be maintained (hypodynamic phase)
What does septic shock culminate in?
Multiple organ failure
CNS depression
Renal failure
Autonomic exhaustion and decompensation of circulation
Give some differentials for a neonate with resp signs
Neonatal septicaemia (bacterial pneumonia) Viral pneumonia Meconium aspiration Aspiration pneumonia Haemothorax, pneumothorax Resp distress syndrome Pulmonary hypertension Central resp depression
How do you treat Perinatal Asphyxia Syndrome?
Antibiotics (short-term)
DMSO (1g/kg BID diluted in fluids if cerebral oedema)
Control of seizures: diazepam, phenobarbital
Why are males more likely to get a ruptured bladder than females?
Longer urethra
Why do ruptured bladders occur?
Excessive pressure during parturition on distended bladder
Congenital defect possible (change in muscle of bladder wall on dorsal site)
How does a foal with a ruptured bladder present?
2-3 days old
Dysuria esp stranguria (frequent small amounts of urine)
Depression, abdominal distension
Which lab findings would you see in a newborn foal?
Creatinine= 30-40% higher than adults
Proteinuria
Develop hyposthenuria (dilute urine) after 2 days old - several months
Plasma urea very low from 2 days old - several months
How do you diagnose a ruptured bladder?
US
Creatinine concentration of peritoneal fluid: serum is > 2:1
May see calcium carbonate crystals in peritoneal fluid
May see increased inflammation in abdomen
Clinical signs
Post-renal azotaemia with hyponatraemia, hypochloraemia, hyperkalaemia
How do you manage a ruptured bladder?
Emergency surgery not required
Stabilise and manage medically, then do sx (remove urachus)
Correct electrolytes and metabolic acidosis with IV fluids
Hyperkalaemia may induce arrhythmias- give 0.9% saline with 5% glucose (avoid insulin and bicarb in foals)
O2 therapy, reduce abdo fluid (drain slowly)
How will a foal with colic present?
Quiet, lie down, curl up
Give some differentials for colic in a foal
Meconium impaction Ruptured bladder/uroperitoneum Overfeeding/lactose intolerance Distension associated with diarrhoea Gastric ulcers SI/LI obstruction Congenital abnormalities (eg gut segment doesn't form)
How would you differentiate between blood loss and haemolysis in a foal with anaemia?
Blood loss: low protein
Haemolysis: normal protein
Give a cause of haemolysis in an anaemic foal
Neonatal isoerythrolysis
How does neonatal isoerythrolysis occur?
Aa and Qa negative mares are mated to positive stallions
Mare has antibodies against the blood type of the foal -> foal receives these in colostrum -> haemolysis
Give some clinical signs of neonatal isoerythrolysis
When does it occur?
Haemolytic anaemia from 24 hours old
Jaundice and weakness
How do you diagnose neonatal isoerythrolysis?
Clinical signs
Confirm by detecting antibodies on RBCs (Coombs test)
Show RBC antibodies in colostrum using agglutination or haemolytic assays
How do you prevent neonatal isoerythrolysis?
Blood type both parents
Prevent Abs entering foal
If mare is known to be at risk from previous history or blood typing, sera can be tested for ABs
Can withold colostrum from foal or use jaundiced foal agglutination test (JFA) to detect ABs against foal RBCs
How do you treat neonatal isoerythrolysis?
Blood transfusion if PCV 12-15% or less
Donor: Aa or Qa negative/washed mare red cells/JFA test
If PCV >15%: remove source, limit movement and stress, supportive care (ABs, anti-ulcer meds, fluids, glucose)
What is Fell Pony Syndrome?
Anaemia, rapid loss of condition from 2-3 weeks old
Severe immunodeficiency
Severe secondary illness (diarrhoea, pneumonia)
Fatal
Give some differentials for diarrhoea in neonates
Foal heat diarrhoea
Neonatal septicaemia (E.coli, Salmonella, other gram negatives)
Clostridia
Campylobacter
Describe foal heat diarrhoea
5-12 days old (mare’s first oestrus)
Changes in bacterial flora
Alteration in milk composition due to hormonal changes in mare
Mild, self-limiting diarrhoea
Remains bright and sucking
Tx: nothing, probiotics, intestinal protectants eg kaolin
Good prognosis
Describe clostridial disease in neonates
Severe, peracute, frequently fatal
Necrotising (foul-smelling)
Individuals and outbreaks- contagious- isolate!
Cl. difficile and perfringens most common (normal GI inhabitants)
Severe gas distension and colic
Dx: culture, ELISA or PCR for toxins, gas in mucosa on US
Tx: metronidazole, penicillin
Give some causes of diarrhoea in older foals
Rotavirus Other viruses (coronavirus, adenovirus, parvovirus) Strongyloides westeri (high burdens) Crypto Giardia Rhodococcus equi
Describe Cryptosporidium diarrhoea in older foals
Faeco-oral infection
Attach to brush border
Incubation: 3-7 days
Dx: faecal oocysts on sugar floatation or direct FA
Tx: supportive; no specific coccidiostats are effective
Prevention: good hygiene
How do viruses cause diarrhoea?
Invade epithelial cells lining intestinal villi
Cell death and blunting of villi
Maldigestion (loss of enzymes)
Malabsorption (loss of surface area)
Describe Rotavirus as a cause of diarrhoea in older foals
1-4 weeks old
Highly infectious
Dx: electron microscopy, ELISA
Tx: passive immunisation, supportive therapy
Prevention, phenolic disinfectants (not bleach), passive immunisation, vaccinate pregnant mares?
Describe Rhodococcus equi diarrhoea in older foals
Excreted in dams faeces -> builds up in warm, dry conditions -> ingested -> colonises WBCs -> abscessation
Persistent diarrhoea, fever, colic
What causes Equine Proliferative Enteropathy (EPE)?
What are the clinical signs?
How do you diagnose and treat?
Lawsonia intracellularis
Weight loss, oedema, lethargy, depression, weakness, diarrhoea, mild colic, episodic pyrexia less common
3-11 months old
Infection from faeces (horse and wild animals)
Dx: US, hypoproteinaemia, PCR of faeces and serology
Tx: Erythromycin with Rifampin, oxytetracycline
