Equine Neonatal Disease

what is prematurity?

foals born before adequate maturation has occurred, generally before 320 days of gestation; foals display physical and physiologic signs of immaturity

what is dysmaturity?

foals born at a normal or prolonged gestational length but exhibit physical or physiologic signs of immaturity

what are some common causes of prematurity/dysmaturity?

• placentitis or premature placental separation

• maternal illness or malnutrition

• twin pregnancy

• tall fescue toxicity (USA)

what are some physical features associated with premature/dysmature foals?

small body size and thin body condition, fine silky haircoat, domed head, floppy ears, tendon and periarticular ligament laxity, incomplete ossification of cuboidal bones, poor thermoregulation

what are some behavioral/neurological signs exhibited in premature/dysmature foals?

delayed standing and nursing, weak or absent suckle reflex, dysphagia, slow righting reflexes, frequently weak and tire easily

what are the key principles of treatment for premature/dysmature foals?

IV fluids, close glucose monitoring with supplementation as needed, thermoregulation (passive rewarming for mild hypothermia or active rewarming for severe cases); assisted feeding and nutritional support as required; assistance with standing and general supportive management

what are some other considerations of premature/dysmature foals?

high susceptibility to sepsis due to immature immune function, poor neutrophil activity, and risk of FTPI

foals with incomplete ossification require strict stall rest to minimize weight bearing and prevent crushing or collapse of cuboidal bones

what is neonatal encephalopathy (NE)?

a common neurological disorder characterized by abnormal mentation, failure to nurse, poor mare recognition, abnormal behavior and seizures

many foals appear normal at birth and develop clinical signs within the first 12-72hrs of life

what risk factors are associated with neonatal encephalopathy?

dystocia, premature placental separation (“red bag” deliver) and placentitis

what clinical signs are associated with neonatal encephalopathy?

wandering behavior, abnormal vocalization, depression stupor or somnolence, intermittent hyperresponsiveness, seizures (partial or generalized), abnormal respiratory patterns, failing to nurse, suckling on objected or other areas of the mare, persistent tongue protrusion and dysphagia

neonatal encephalopathy may be part of broader perinatal asphyxia syndrome affecting multiple organs. what additional clinical signs might you see?

ileus and reflux, abdominal distension, diarrhea and necrotizing enterocolitis, gastric ulceration, persistently increased creatinine, oliguria or anuria, hypotension, pulmonary atelectasis

how is neonatal encephalopathy treated?

maintenance of oxygenation and perfusion (with IV fluids), seizure control (benzodiazepines, phenobarbital), prevention or treatment of concurrent sepsis (broad-spectrum antimicrobials), assisted feeding if required, nursing care

what is neonatal isoerythrolysis (NI)?

an immune-mediated hemolytic disease caused by ingestion of colostral antibodies directed against the foal’s RBCs

foals are born clinically normal and develop disease only after colostrum ingestion (6-72hrs after nursing)

what clinical signs are associated with neonatal isoerythrolysis?

lethargy, weakness, reduced nursing; tachycardia and tachypnea; pale MM; icterus/jaundice; collapse

what lab findings are associated with neonatal isoerythrolysis?

progressive anemia, hyperbilirubinemia, hyperlactatemia, hypoglycemia, agglutination on blood smear

what is the jaundiced foal agglutination test (JFA test)?

a stall-side test assessing compatibility between mare colostrum and foal erythrocytes

involves mixing serial dilutions of mare colostrum with foal erythrocytes and assessing agglutination

negative JFA test

erythrocytes disperse normally

positive JFA test

persistent agglutination of “plug” formation; foal should not nurse the mare if it is a strong positive (≥1:8 dilution)

how is neonatal isoerythrolysis treated?

1. prevent further colostrum ingestion (muzzling may be needed)

2. provide alternative colostrum source (or plasma transfusion if indicated)

3. supportive care - stall rest, cautious IV fluid administration, oxygen supplementation, nutritional support, glucose supplementation

4. blood transfusion - only in severe cases (eg PCV <14%)

how can neonatal isoerythrolysis be prevented?

blood typing mares and stallions and screening mares for anti-erythrocyte antibodies during late gestation; performing JFA testing before nursing; prevent nursing immediately after birth and provide alternative colostrum

what other species can develop neonatal isoerythrolysis?

cats! rare but more commonly seen in purebred cats

what features of colic are more typical for neonatal disease?

straining to defecate or urinate; tail flagging; dorsal recumbency; abdominal distension

concurrent systemic illness, including sepsis and FTPI

what should you considered when examining a foal for potential colic?

meconium impaction? systemically unwell? evidence of abdominal distension or free fluid? is referral required?

what techniques can be used to diagnose colic in foals?

rectal examination - detecting meconium impaction and congenital abnormalities

nasogastric intubation - assess gastric reflux and provide decompression

ultrasonography

radiography - detection of meconium impaction

what treatment principles are used for foals with colic?

pain management (NSAIDs, opioids, sedatives), supportive care (fluids, nutritional support)

what might cause colic in a foal?

meconium impaction, gastric ulceration, strangulating SI lesions, bladder rupture (uroperitoneum), ascarid impaction

what clinical signs are associated with meconium impaction?

tail flagging, straining and abdominal distension most common

how is meconium impaction diagnosed?

digital rectal examination, radiography of caudal abdomen to assess extent of impaction in severe cases

how is meconium impaction treated?

warm soapy enemas; refractory cases may benefit from acetylcysteine retention enemas; commercial phosphate enemas (eg Fleet) may be used once only

surgery rarely required

what causes gastric ulceration in foals?

reduced perfusion (eg with sepsis) → glandular ulcers, duodenal ulcers

complications: perforating ulcer, duodenal structure

what clinical signs are associated with gastric ulcers in foals?

decreased appetite, bruxism, colic post-nursing

how are gastric ulcers treated in foals?

treat underlying disease (eg sepsis), fluids for perfusion, protein pump inhibitors or histamine blockers and sucralfate for mucosal protection

what causes strangulating SI lesions in foals?

intussusception (most common), volvulus, herniation

what clinical signs are associated with strangulating SI lesions in foals?

severe colic, abdominal distension, reflux

requires referral for surgery!

what clinical signs are associated with bladder rupture in foals due to post-partum rupture?

decreased urination, straining, progressive abdominal distension

how is bladder rupture in foals treated?

stabilize with potassium-free fluids; drainage via abdominocentesis; broad-spectrum antimicrobials; refer for surgical repair

what causes ascarid impaction in foals?

heavy Parascaris burden; seen in older foals and weanlings 4-6 months of age; occurs post-recent deworming

how is ascarid impaction treated in foals?

supportive care; benzimidazole deworming (kill worms slowly); surgery if severe

when should referral be considered for foals with colic?

• diagnosis is uncertain

• foal is systemically ill

• abdominal distension is progressive

• gastric reflux is present

• pain is severe or worsening

• surgical disease is suspected

• intensive monitoring or nutritional support is required

what should you assess for in foals with diarrhea?

hydration status, mentation, suckle reflex, body temperature, evidence of abdominal pain, signs of systemic disease

what are non-infectious causes of diarrhea in foals?

foal heat diarrhea (most common, age 5-15 days); nutritional diarrhea (any age, common in orphans)

what are infectious causes of diarrhea in foals?

rotavirus (common, <2 months), Clostridiosis (C. perfringens, C. difficile, <10 days), Salmonellosis (any age)

what are the treatment principles for foals with diarrhea?

• mild diarrhea without abdominal discomfort - continue nursing

• ileus, gastric reflux or abdominal distension: reduce or temporarily withhold milk intake; consider parenteral nutrition

• monitor closely for electrolyte and acid-base disturbances; correct promptly

• hypoglycemia will require glucose supplementation

• higher risk of bacteremia (most foals require systemic antibiotics)

what congenital conditions may be seen in foals?

cleft palate; intestinal, ani and rectal atresia; lethal white foal syndrome

what clinical signs are associated with synovial sepsis in foals?

lameness, joint swelling, heat and pain on palpation, reluctance to stand or move;

may have multiple joints affected, show signs of systemic illness, be depressed or weak, have evidence of sepsis elsewhere

how do you diagnose synovial sepsis in a foal?

complete physical examination (including umbilicus); careful assessment of all joints; synovial fluid sampling from affected joints; investigation for underlying systemic disease

why is prompt referral recommended for foals with synovial sepsis?

affected foals often require intensive treatment and lavage of the affected synovial structures

initial management may include stabilization, pain relief, broad-spectrum antimicrobial therapy

what are common developmental orthopedic conditions in foals?

incomplete ossification of cuboidal bones, angular limb deformities, flexural limb deformities, physitis

when are radiographs important when orthopedic abnormalities are identified?

in premature foals, suspected incomplete ossification (to grade severity), moderate or severe angular limb deformities (to assess degree of deviation), suspected physitis (to assess physis irregularity)

how do you treat incomplete ossification?

strict stall rest; exercise restriction, splints/tube casts to maintain alignment

refer for serial radiographs, advanced casting and monitoring to prevent collapse/deformity

how do you treat angular limb deformitity?

stall rest; corrective trimming; foot extension (glue-on/shoes)

refer for surgical correction guided by growth stage

how do you treat flexural limb deformity?

controlled exercise, NSAIDs, bandaging/splinting, toe/heel extension, ± oxytetracycline for hyperflexion/contracted tendons

refer for surgical intervention if refractory; supervised rehabilitation

how do you treat physitis?

rest, NSAIDs, nutritional correction, controlled exercise

refer for imaging and investigation of complications; intensive management if severe or septic

what fractures are most common in foals and why?

ribs - seen in ~20% of foals due to thoracic trauma during parturition

long bones - accidents in the paddock

how are fractures treated in foals?

initial management should prioritize stabilization and appropriate coaptation prior to referral