Hypoxic Ischaemic Syndrome (HIS) - More commonly referred to as - Dummy foal, Neonatal Maladjustment Syndrome, Wanderer, Barker foal and Perinatal Asphyxial Syndrome.
Hypoxic Ischaemic Syndrome (HIS) is thought to be caused by a lack of oxygen (hypoxia) and poor blood supply (ischaemia) to the body tissues of the foal. It is said to occur during late term pregnancy, during birth or shortly after birth. The organs most commonly affected are the brain, gastrointestinal tract and kidneys. The severity of malformation & visable signs of the disorder depends heavily on which organs are affected and the degree of poor oxygen and blood supply . HIS can be caused by a number of factors however the most common are, Infection or placentitis, difficult & drawn out foaling & premature placental separation or red bag delivery. HIS can also develope in normal and uncomplicated births, therefore close monitoring of all foals postpardom is safest. Post foaling problems such as jaundice, pneumonia and long periods of sleeping can lead to the development of HIS.
Some outwards signs of HIS may be present at foaling & in some cases signs may develop within 48 - 72 hours after foaling. There is a list below of some signs and what organs may be affected.
INTESTINE
MILD
SYMPTOMS
mild colic - straining to defecate or urinate, kicking or biting at stomache
SEVERE SYMPTOMS
severe colic - laying or falling to roll.
blood in feaces
extremely depressed
purple discolouration of gums
cold extremetys
septic shock
BRAIN
foal does not seem to recognise the mare or shows her little interest
runs aimlessly and runs into things (fences, walls, gates etc)
exagerated shock response to sighting objects (trees, mare etc)
inability to locate the udder
super sensitive to touch and sound.
poor or absent suckle reflex
Severe Cases
irregular respiratory rate
convulsions
If the kidneys are affected, the foal may show signs of renal failure including the development of oedema (fluid under the skin that looks like jelly). Gastrointestinal tract involvement may be seen as mild colic, where the foal may kick at its belly or look as though it is straining to urinate or pass faeces. In more severe cases, the foal may display signs of septic shock (very depressed with cold legs and purple gums) or severe colic (rolling on its back and/or falling over with pain), coupled with blood-discoloured diarrhoea.
The treatment regime implemented for a ‘dummy’ foal will, again, depend on which of the organ systems are involved and how severely they have been affected, but the primary aim is to provide support in the way of nutrition, fluids, medications and oxygen until the damaged tissues heal. This may mean the insertion of an indwelling stomach tube (so the foal can be fed until a suckle reflex develops), oxygen being delivered via a nasal tube, the administration of intravenous fluids, providing parenteral nutrition (intravenous glucose, protein and fats) and anti-convulsant therapy.
On a positive note, the majority - over 90%- of HIS foals born with brain involvement recover with appropriate treatment. If other organs are affected, the recovery depends on how badly damaged the organs are, but usually over 80% of the affected foals survive.
Septicaemia
A term used to describe a generalised infection within the blood stream, septicaemia is the leading cause of deaths in foals. It can involve multiple organs and the infection can localise in places such as the lungs (pneumonia), gastrointestinal tract (enteritis), a joint (septic arthritis), bone (osteomyelitis) or other areas. The foal can become infected before it is born - via a placentitis - or after birth.
Septicaemia contracted after birth occurs most commonly due to the foal taking in bacteria, which are everywhere in the environment, via its mouth and nose in the first few hours of life - predominantly when finding the udder to nurse or investigating its surroundings. Infection by bacteria can either cause mild signs such as ‘dullness’ and decreased nursing, or can set off a cascade of reactions in the foal - resulting in shock and sometimes, death. It is therefore imperative that the infection is detected early and appropriate aggressive treatment begun. In some cases, however, even this is not enough to save the foal’s life.
Bacterial septicaemia is treated with antibiotics, while intravenous plasma may also be used to improve the foal’s immunity. Other therapies such as oxygen, intravenous fluids and drugs which improve blood pressure and blood supply to the body tissues may be required.
Measures that can be taken to reduce the risk of septicaemia include not overcrowding paddocks and stable complexes where newborns are to be kept, ensuring foaling areas are clean and dry and checking, once the foal has been born, that it has an adequate immunoglobulin concentration (IgG) of greater than 8g/L. The latter involves a simple blood test, performed by a veterinarian, to measure the level of antibodies circulating in the bloodstream.
Meconium Impaction
Meconium, the first manure passed by a newborn, consists of fluid and cellular debris that was swallowed during the foal’s development in the uterus. Brown to olive green in colour and with a firm to hard consistency, it is usually passed within the first 24 hours after birth. The ‘milk’ faeces, that follow the meconium, are softer and orange to tan in colour.
As foals often strain to pass the meconium, a stool softening product in the form of an enema is frequently given shortly after birth - the most common type used in Australia being the phosphate-based Fleet® brand. Great care is needed when giving enemas, as the consequences of incorrectly and over-zealously administering them can, at worst, be a torn or perforated rectum- and subsequent death- or, at least, rectal irritation.
The meconium can become impacted in the rectum, or small or large colon - even if some has already been passed. When this has happens, the foal may show signs of colic - rolling, kicking at its belly or lying on its back - strain to defaecate, wander around aimlessly or go to the udder but not drink. The signs of colic often occur just after the foal has nursed. If an impaction is suspected, veterinary assistance (other than the administration of an enema) may include an oral drench of paraffin oil, intravenous fluids and/or pain relief. Some impactions may need to be treated surgically, however this is extremely rare if the problem is detected and treated early.
Ruptured Bladder
Contrary to what was traditionally thought to be the case, a ruptured bladder or urine in the abdominal cavity (uroperitoneum) can occur in fillies as well as colts, and can happen after birth as well as during the foaling process. In addition, defects in the urinary tract are not only found in the bladder, but can be located anywhere from the tube connecting the bladder to the amniotic sac while the foal is in utero (the urachus) to the tubes from the kidney to the bladder (ureters).
Foals with uroperitoneum are usually normal at birth and can be seen to urinate normally, but some also strain to urinate - producing only small amounts. It should be noted, however, that foals with colic can also display these symptoms. The foal’s abdomen will begin to increase in size as urine starts to accumulate and, because the body is unable to get rid of this, waste products begin to be absorbed. The end result is the development of electrolyte abnormalities - high potassium concentrations, in particular - that can become life threatening.
Surgery is required to repair the defect in the urinary tract, but only after the foal’s electrolyte levels have been stabilised with intravenous fluids and the urine drained from the abdomen. Once the defect is repaired, the foal has a good prognosis.
Jaundiced Foal
Neonatal isoerythrolysis (NI), also referred to as ‘jaundiced foal’ or ‘haemolytic foal’, occurs when the foal receives colostrum from the mare that contains antibodies against its own red blood cells. These antibodies then destroy the foal’s red blood cells, resulting in anaemia and an increase in bilirubin (a product of red blood cell break down). This, in turn, causes a jaundiced or yellow appearance of the gums.
The mare develops antibodies by being exposed to the blood of a previous foal (such as during foaling or with a placentitis) or having a previous blood transfusion. A foal is then affected if it has inherited the same blood type from the stallion that the mare has produced antibodies against. There are many different equine blood types but, unfortunately, the two most common types are the ones often involved in NI.
Depending on the severity of the destruction of the red blood cells (haemolysis), symptoms can develop within six hours or until around seven days of age; the longer the onset period, the less severe the haemolysis. Signs of NI range from an increased respiratory rate and jaundiced (yellow) mucous membranes, to inability to stand, weakness and seizures.
The treatment for this condition varies from oxygen therapy and/or a blood transfusion to just careful monitoring, with some severely affected foals dying despite intensive intervention. Preventative measures can be taken with mares that are known producers of foals with NI by not allowing their newborn any access to nurse for 48 hours. Arrangements should be made for the foal to receive its colostrum and milk from another source, while the mare is milked out for 48 hours and her milk and colostrum discarded. After this period of time, the foal can then nurse from its dam.
Umbilical Problems
The umbilicus, or navel, needs to be closely monitored for the first few weeks of life. Shortly after birth, it should be moist but if it seems to be bleeding excessively, this requires veterinary attention. It can also become infected, in which case it may be swollen and tender to touch, with or without pus present. Sometimes, an infection can be located in the internal part of the umbilicus, so there are no obvious external signs and an ultrasound examination may be required. The umbilicus may also leak urine (patent urachus).
The umbilicus should be carefully disinfected shortly after it breaks and twice daily for the first 2-3 days after birth. Dilute disinfectants such as 2.5% iodine are recommended, as anything stronger may be caustic and lead to tissue damage. The solution is best applied with a small spray bottle, spraying the umbilicus but avoiding the surrounding skin.
The majority of foals with a patent urachus or infected umbilicus will respond to antibiotic therapy and being kept in a clean dry yard or small paddock. Previously surgery was recommended, however now it has been found that the majority of these conditions resolve with medical treatment alone.
Entropion
Entropion can be present at birth or occur after birth, and is usually associated with prematurity, dehydration, or generalised muscle weakness. It occurs when the eyelid, most commonly the lower one, rolls in. If left untreated, the hair from the eyelid rubs on the cornea and this irritation leads to the formation of a corneal ulcer - which can be a very serious condition resulting in loss of the eye.
If an entropion is seen, the eyelid can be manually rolled out then examined by a veterinarian to determine if an ulcer has formed. The eyelid may also need to be sutured to stop it rolling in until the dehydration or muscle tone improves. Corneas are less sensitive in foals than in mature horses, thus ulceration can be present without evidence of pain and special fluorescein staining is needed to highlight the damaged area. Treatment may involve topical broad-spectrum antibiotic therapy, though severe deep ulcers may require surgical treatment.
Treatment of the critically-ill newborn is time and labour intensive but, when problems are detected at an early stage and if aggressive veterinary treatment is applied, the chances of achieving the successful outcome of a live, healthy foal are considerably higher.
Supplied by Equine Veterinarians Australia (EVA).
For more information go to the web site: www.eva.org.au
