Suspected protozoal myeloencephalitis in a two-month-old colt

A two-month-old Appaloosa colt developed neurological signs shortly after birth involving deficits affecting cranial nerves IV, VII, VIII, IX, X and XII, and possibly nerve VI. The most likely differential diagnoses were congenital anomalies, meningoencephalitides, trauma or nutritional causes. The foal was investigated by the analysis of cerebrospinal fluid (CSF), electromyelography (EMG), brain auditory evoked responses, magnetic resonance imaging (MRI), peripheral nerve biopsy, and Western blot analysis for the presence of intrathecal antibodies to Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis. Significantly abnormal EMG findings included spontaneous electrical activity of the tongue, suggesting denervation. The MRI was useful in ruling out masses, congenital anomalies and focal abscessation. The cytology of CSF revealed mild mononuclear reactivity. Western blot testing of CSF was positive, indicating the intrathecal presence of antibodies to S neurona. The foal was treated with pyrimethamine and trimethoprim-sulphadiazine for two months and returned to nearly normal neurologic status.     

Cholangiohepatitis and pancreatitis secondary to severe gastroduodenal ulceration in a foal

A 2-month-old foal was presented with clinical signs of colic. Gastroduodenal ulceration was suspected. A poor response to medical treatment and signs of gastroduodenal obstruction led to celiotomy and an attempted bypass procedure. The foal was euthanized and postmortem examination revealed gastric ulceration, segmental duodenal stenosis, and severe chronic cholangiohepatitis and pancreatitis.     

Hepaticojejunostomy for Treatment of Common Hepatic Duct Obstructions Associated with Duodenal Stenosis in Two Foals

Two female Standardbred foals 2 and 3 months of age were presented with signs of gastroduodenal obstruction that was confirmed with contrast radiography and exploratory surgery. Ventral midline celiotomy was performed, showing stenosis of the duodenum proximal and distal to the hepatopancreatic ampulla. The common hepatic duct, the pancreatic duct, and the sigmoid section of the duodenum proximal to the stenosis were greatly dilated. To bypass the intestinal obstruction, a side-to-side duodenojejunostomy was performed. Obstruction of the common hepatic duct was relieved by side-to-side hepaticojejunostomy. In addition, jejunojejunostomy was performed distal to the other anastomoses. Both foals recovered. On admission, the foals' total bilirubin, aspartate aminotransferase, and gamma glutamyl transferase levels were greatly elevated. During the subsequent 6 to 8 months, they returned to normal. Six months after the first surgery, one foal was readmitted with an acute abdominal crisis. At surgery, there was greater than 360 degrees clockwise rotation of the mesenteric root involving most of the jejunum. At necropsy, the previously created stomas were patent. The liver and bile duct were grossly and histologically normal. The second foal continues to progress normally 12 months after surgery.     

IMAGING DIAGNOSIS — USE OF MULTIPHASE COMPUTED TOMOGRAPHIC UROGRAPHY IN THE DIAGNOSIS OF URETERAL TEAR IN A 6‐DAY‐OLD FOAL

A 6‐day‐old foal was evaluated for depression and inappetence. After initial stabilization, the filly developed a hypochloremic metabolic alkalosis and persistent hypercreatinemia. Abdominal ultrasound revealed fluid accumulation around the left kidney and a well‐defined rounded fluid filled structure dorsal to the urinary bladder. Computed tomography revealed a partial tear of the left ureter with distension of the retroperitoneal membrane. Exploratory celiotomy was performed to allow left kidney nephrectomy. At 6 months follow‐up, the filly was growing normally without complications. Ultrasound and CT imaging in this case provided an accurate diagnosis and a presurgical aid to select the appropriate therapeutic approach.     

Hypogammaglobulinemia predisposing to infection in foals.

Measurement of serum immunoglobulins in 46 foals less than 2 weeks old revealed 9 foals with hypogammaglobulinemia. The hypogammaglobulinemia was attributed to failure in transfer of immunoglobulins from dam to foal via colostrum. Three of the affected foals did not nurse at all, or only slightly, and 2 of these died of infections within a few days after birth, whereas the 3rd foal did not grow as well as normal foals. Six of the affected foals nursed in an apparently normal manner, and 5 of these had nonfatal respiratory infections between 2 and 5 weeks of age. Analysis of serum samples from surviving foals demonstrated that immunoglobulins were eventually produced. One other foal examined had hypogammaglobulinemia at 57 days of age, an age when the foal should have produced large amounts of immunoglobulin independent of passive transfer. This foal had simultaneous infections and hypogammaglobulinemia, but eventually produced normal amounts of immunoglobulin. Cellmediated immunity was normal at 3 months of age. This condition was designated transient hypogammaglobulinemia and was thought to be due to a temporary inability to make immunoglobulins.     

Use of Renal Replacement Therapy in a Neonatal Foal with Postresuscitation Acute Renal Failure

A newborn foal was presented because it was unresponsive and in cardiopulmonary arrest. Aggressive cardiopulmonary cerebral resuscitation was administered to the foal, which revived the foal; however, acute renal failure developed. Fluid retention and azotemia occurred although the foal was alert and able to suckle. A 6‐hour renal replacement therapy session using hemodiafiltration and a continuous renal replacement therapy machine was administered to the foal at 3 days of age which lowered the foal's azotemia and facilitated removal of some of the excess body fluid. Despite therapy, the foal developed pulmonary edema and was euthanized. Although the foal in this case did not survive, this report highlights the possibility of developing postresuscitation complications such as acute renal failure and describes the use of renal replacement therapy using hemodiafiltration as a viable option in neonatal foals with acute kidney injury.     

Renal failure in a pregnant mare

Although chronic renal disease is uncommon in horses, guidelines for management of the broodmare with kidney disease are needed to ensure successful foaling. Herein, we present a case report of a broodmare with chronic renal disease that produced a live foal, and parturition was predicted by monitoring pH and electrolytes in the milk. A 15-year-old pregnant mare presented with a history of poor body condition and weight loss despite an excellent appetite. At presentation, the mare was bright, alert and responsive, with severe pitting ventral oedema and vital parameters within normal limits. Plasma biochemistry revealed azotaemia, hypercalcaemia and hypophosphataemia. Based on clinical ultrasonographic and biochemical parameters, the mare was diagnosed with renal failure. Pregnancy was assessed by transabdominal ultrasound, and the fetal parameters were within normal limits; however, an increased combined thickness of the uterus and placenta and oedematous fetal membranes were found. Monitoring of mammary secretions accurately predicted the onset of foaling at 326 days of gestation. A healthy filly was delivered, and the fetal membranes were passed in a timely manner without complications. Physical examination and haematological parameters were within the normal limits for a neonate foal, except for a mild elevation in blood urea nitrogen. Two weeks later, the mare was subjected to euthanasia due to worsening of her condition. At necropsy and on histopathological examination, the findings were consistent with chronic renal disease. This case demonstrates that a pregnant horse with chronic renal disease can be managed with supportive care and produce a viable foal. Fetal well-being and mare’s prefoaling milk electrolytes were similar to parameters measured in healthy pregnant mares, suggesting that the feto-placental unit may be spared of the dam’s systemic disease. Prepartum physiological changes in the milk may be unaltered with concurrent maternal renal disease and still be useful for foaling prediction.     

D-xylose absorption in the growing foal

Seven healthy foals (five ponies and two horses) were maintained on grass pasture with their dams. All foals had normal faeces at the time of testing. An oral xylose absorption test was performed on each foal at one, two and three months of age. Following an 8 h fast, 0.5 g/kg D-xylose as a 10 per cent solution was given via a nasogastric tube. Control and 30 min interval plasma samples were collected for 3 h and the plasma was analysed for xylose using the phloroglucinol microassay technique. Maximum xylose concentration levels were reached between 30 and 60 mins for each of the foals. The mean (+/- sem) peak xylose concentration at one, two and three months of age was 3.14 +/- 0.29, 2.19 +/- 0.30 and 1.25 +/- 0.22 mmol/litre respectively, which were all significantly different from each other. Xylose absorption capacity decreased, therefore, with age, becoming similar to the adult horse by three months of age. The oral xylose absorption test can be used to evaluate small intestinal absorptive capacity in the foal provided that the results are compared with foals of the same age group.     

Bullous emphysema with haemorrhage in a premature foal

A Warmblood foal was admitted at one day of age because of prematurity and seizures. Clinical and clinical pathology abnormalities were consistent with prematurity and suspected hypoxic seizures that responded to anti‐convulsive therapy. The foal stabilised after several days of intensive care but then developed an airway infection. Thoracic radiographs showed multiple cavitary lesions and ultrasound examination suggested intra‐cavital haemorrhage. The foal went on to develop septicaemia and was subjected to euthanasia. Post mortem examination revealed multiple bullous emphysema with haemorrhage. This disorder should be considered in the differential diagnosis of foals having air‐fluid filled cavities on thoracic radiographs.     

Brain Abscess in a 4-Month-Old Filly: A Case Report

Although recognized as a possible complication to sepsis, there are few published reports on brain abscesses in foals. This case report describes a 4-month-old Icelandic filly that, as a neonate, had a history of pyrexia and lameness, which resolved with antibiotic treatment. Approximately 3 months later, the foal developed neurological signs which were initially attributed to trauma; she was referred for further investigation. The clinical signs were consistent with a lesion of the right forebrain. Computed tomography examination revealed a mass, approximately 6 cm in diameter, located in the right cerebral hemisphere craniolateral to the right lateral ventricle. Because of the poor prognosis, the foal was killed, and a postmortem was performed. The findings confirmed the presence of an abscess of the right cerebral hemisphere, leading to severe atrophy of the cortex and dilation of both lateral ventricles. The left hemisphere was moderate-to-severe atrophic and had displaced to the left. Streptococcus equi subspecies zooepidemicus was isolated in pure culture from the abscess. The clinical features of the foal were compared with the pathological findings.     

Successful surgical debridement of a cerebral Streptococcus equi equi abscess by parietal bone flap craniotomy in a 2-month-old Warmblood foal

Brain abscesses and intracranial masses have been regularly described in horses. Treatment often is difficult and unrewarding and mortality rate high. This case report describes the successful treatment of a cerebral abscess in a 2-month-old female Warmblood foal with severe neurological signs of acute onset. Computed tomography (CT) revealed a 3 × 4 × 4 cm cerebral mass in the left brain hemisphere with severe cerebral oedema. Craniotomy, using a parietal bone flap technique, allowed the abscess to be sampled, drained and lavaged. Immediately, post-surgery the foal showed significant clinical improvement. Sample culture confirmed Streptococcus equi equi infection. The foal was medically treated for 6 weeks, leading to complete clinical and radiographical recovery. Intracranial surgery in equine medicine is limited. Using a parietal bone flap instead of partial craniectomy to gain access to the cerebrum is a less invasive procedure leading to a better aesthetic result and should be considered for the treatment of cerebral masses in the horse.     

Foal with Overo lethal white syndrome born to a registered quarter horse mare

A 16-hour-old white foal, born to a registered quarter horse mare, was examined for signs of colic. The foal had Overo lethal white syndrome, which causes ileocolonic agangliosis. This was confirmed by DNA testing. Since there is no treatment for Overo lethal white syndrome, the foal was euthanized.     

Computed Tomographic Features of Choanal Atresia in a Friesian Foal

A 3-week-old Friesian colt with a history of respiratory distress since birth was presented to our facility. Results after an endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography was performed to further characterize this unilateral blockage. The images demonstrated a complete membranous obstruction of the ventral meatus, along with deviation of the vomer bone toward the left side of the nasal cavity. The diagnosis of unilateral choanal atresia was confirmed. This report is the first to describe computed tomographic features of choanal atresia in a foal.     

ULTRASOUND‐GUIDED CERVICAL CENTESIS TO OBTAIN CEREBROSPINAL FLUID IN THE STANDING HORSE

Horses with intracranial lesions and severe ataxia are not good anesthesia candidates; however, only one method to obtain cerebrospinal fluid (CSF) from the cervical region in a standing horse has been reported. This method is not performed routinely due to the difficulty for sample acquisition. Our hypothesis is that standing cervical centesis can be performed in horses without complication. Ultrasound‐guided centesis of the CSF between C1 and C2 in 11 clinically normal horses and two horses with neurologic signs were performed. Horses were sedated and ultrasound was used to identify the subarachnoid space and spinal cord between C1 and C2. With ultrasound guidance, a needle was introduced into the dorsal aspect of the subarachnoid space using a lateral approach. Ten milliliters of CSF was obtained and analyzed. Two normal horses in this study had moderate red blood cell contamination in the CSF (940 and 612 RBC/μl). One horse had 11 RBC/μl and the remaining horses had <4 RBC/μl. The total procedure time was approximately 2 min. No reaction was observed and no complications were detected up to 48 h after the procedure. Ultrasound‐guided centesis between C1 and C2 is a rapid procedure that causes minimal to no reaction in standing, sedated horses used in this study. The use of ultrasound to guide a standing C1–2 centesis of the subarachnoid space provides an additional route to obtain CSF for analysis in the equine patient.     

Management of bilateral choanal atresia in a foal

CASE DESCRIPTION: A 1-day-old Standardbred foal with a history of extreme respiratory distress after birth consistent with upper airway obstruction was evaluated. A temporary tracheostomy tube was placed by the referring veterinarian. CLINICAL FINDINGS: On initial examination, there was evidence of hypoxic-ischemic syndrome, secondary to perinatal asphyxia. Endoscopy revealed obstruction of both nares at the level of the choanae; a diagnosis of bilateral choanal atresia was made. TREATMENT AND OUTCOME: The foal was anesthetized and underwent transendoscopic laser fenestration of the buccopharyngeal membranes. Three weeks after surgery, cicatricial narrowing of the choanae was apparent and further transendoscopic ablation was performed. Recurrent stenosis necessitated revision surgeries involving a combination of laser ablation with topical administration of mitomycin and, subsequently, a combination of radial incisions into the stenotic tissue and repeated bougienage with a cuffed endotracheal tube. The degree of stenosis decreased, and at 1 year of age, the horse was an appropriate size for its age, had choanae that were almost maximally open (> 85%), and had entered training. Mild stenosis was still evident when the horse was reexamined the following year, although there was no evidence of exercise intolerance or respiratory compromise. CLINICAL RELEVANCE: Bilateral choanal atresia in a foal can be successfully treated via transendoscopic fenestration of the buccopharyngeal membranes, enabling the horse to subsequently participate in athletic activities. Secondary problems resulting from initial asphyxia and recurrent stenosis at the surgical site can be overcome but may require prolonged and extensive treatment.     

Maternal behavior

Parturition in mares is rapid and is followed by a brief period of sensitivity to imprinting on a foal. There is large individual variation in normal maternal style, but normal mothers actively defend their foal, remain near the foal when it is sleeping, tolerate or assist nursing, and do not injure their own foal. Disturbance of a mare and foal during the early imprinting period can predispose a mare to rejection of her foal; therefore, it should be avoided. There are a variety of forms of foal rejection and numerous etiologies. Therefore, each case should be evaluated individually.     

Faecal composition in foal heat diarrhoea

Developmental changes of the gastrointestinal tract were probably responsible for the changes in faecal composition during the first week of the foals' life, which resembled small intestinal ingesta of adult horses, suggesting a minimal colonic modification. Faecal composition at the time of foal heat diarrhoea was suggestive of a secretory-type diarrhoea, in that the electrolyte concentration accounted for most of faecal osmolality and the faecal pH was alkaline. After foal heat diarrhoea faecal composition slowly approached that of adult horses. These data suggest that foal heat diarrhoea is most likely caused by hypersecretion in the small intestinal mucosa, which may overwhelm an immature colon that is unable to compensate by increased fluid and electrolyte absorption.     

External hydrocephalus in two cats

External hydrocephalus describes an accumulation of cerebrospinal fluid (CSF) between the cerebral hemispheres and the overlying arachnoid membrane, rather than within the lateral ventricles. Two young cats with encephalopathic signs were diagnosed with external hydrocephalus, one via magnetic resonance imaging and one via computed tomography. Both cats had abnormally large, broad heads, with no evidence of open fontanelles. A surgical shunt was placed in each cat to divert the accumulated CSF within the cranial cavity to the peritoneal space. Both cats improved dramatically soon after surgical shunting was performed, and they continue to do well clinically, approximately 42 months and 8 months postoperatively, respectively.