Topic:Congenital Disorders
Congenital disorders in horses encompass a range of structural, functional, or metabolic anomalies present at birth. These disorders may arise from genetic mutations, environmental factors, or a combination of both, affecting various systems in the equine body. Common congenital disorders in horses include cleft palate, umbilical hernias, and limb deformities. The diagnosis and management of these conditions require a multidisciplinary approach involving veterinary genetics, surgery, and rehabilitation. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, diagnosis, and management strategies for congenital disorders in equine medicine.
Congenital ocular abnormalities of Rocky Mountain Horses. OBJECTIVE: To determine the incidence and describe ocular abnormalities in a cross-section of the population of Rocky Mountain Horses. Design: Prospective study. Animals: Five-hundred and fourteen Rocky Mountain Horses. Procedure: Ophthalmic examinations were performed using a slit-lamp biomicroscope and an indirect ophthalmoscope. Intraocular pressures were measured by applanation tonometry. Eyes from six horses were obtained for histologic examination. RESULTS: Cysts of the posterior iris, ciliary body, and peripheral retina were detected most frequently (249 horses), and were always located...
Developmental anomalies and abnormalities of the equine iris. The iris is derived from interaction between neural crest tissue and the adjacent neuroectoderm of the optic cup. Developmental anomalies of the equine iris are common, and include congenital miosis, iris cysts, various manifestations of iris hypoplasia, heterochromia, and persistent pupillary membrane remnants. They may be found alone or in combination with other ocular defects.
[Case report: (erythro)keratoderma variabilis in a newborn foal]. A case of congenital (Erythro)keratoderma variabilis in a newborn foal is described. The clinical and histological findings are presented.
Congenital hepatic fibrosis and cystic bile duct formation in Swiss Freiberger horses. Congenital hepatic fibrosis with autosomal recessive or dominant inheritance has been described in humans, cats, piglets, and dogs. In horses, only two cases of congenital hepatic fibrosis have been previously reported. This retrospective study of records from the Institute for Animal Pathology, University of Berne, identified 30 foals with liver lesions compatible with congenital hepatic fibrosis. Anamnestic data revealed clinical signs of severe liver injury in most affected animals. Pathologic examination showed severely enlarged, firm livers with thin-walled cysts. Histologically, the live...
Omphalocele in a foal. An omphalocele was detected at birth in a male Arabian foal. The mass contained small intestine and after releasing a constricting band at the body wall, the contents slipped easily back into the abdomen. On the outside was the hairless pink membrane. The interior, now empty of small intestine, contained the umbilical arteries and vein, and a large urachus that extended from the bladder to the opening at the extremity of the mass. Six days after corrective surgery the foal was sent home and remained healthy.
The horse homolog of congenital aniridia conforms to codominant inheritance. Anterior segment dysgenesis syndrome occurs frequently in Rocky Mountain horses and has two distinct ocular phenotypes: (1) large cysts originating from the temporal ciliary body or peripheral retina and (2) multiple anterior segment anomalies including ciliary cysts, iris hypoplasia, iridocorneal adhesions and opacification, nuclear cataract, and megalocornea. To determine if anterior segment dysgenesis syndrome is heritable in horses we performed ophthalmic examinations and collected pedigree information on horses (n = 516) in an extended Rocky Mountain horse pedigree. Logistic regressive se...
Congenital atresia of the parotid duct in a horse. Congenital anomalies of the equine salivary glands and their ductal systems are rare. In man, parotid duct atresia is thought to be due to a congenital malformation of the first branchial arch. One horse with unilateral parotid salivary duct atresia is described. Imaging modalities available for accurate diagnosis, and treatment options, are reviewed.
Jejunoileal incarceration and strangulation through a splenic defect in a mare. A 6-year-old, standardbred mare was presented for colic of 12 h duration. Transrectal palpation revealed intestinal distension of unknown cause. The mare was euthanized. At necropsy, segmental jejunoileal incarceration and strangulation through an opening in the spleen was observed. This opening was considered to be a congenital defect.
A congenital malformation of the maxilla of a horse. A 1-month-old male American Paint Horse was evaluated for a hard swelling on the right side of the maxillary region. On radiographs there was a large, expansile outpouching of the right maxillary bone between the second and third premolar teeth. Computed tomography further characterized the expansile lesion to have a soft tissue component and to originate in the region of a caudal maxillary tooth. Surgical reconstruction of the defect was unsuccessful and the animal was euthanetized. Based on failure to find histopathologic evidence of a neoplasm or cyst, the diagnosis was a congenital malform...
Persistent right aortic arch in a yearling horse. A 14-month-old filly with chronic pharyngitis was diagnosed with incomplete esophageal constriction and megaesophagus due to a persistent right aortic arch. This report is unusual because clinical signs of respiratory dysfunction secondary to chronic regurgitation occurred prior to the recognition of dysphagia.
Congenital dental disease of horses. Equine congenital dental deformities are not limited merely to those presented here; however, the examples discussed offer the reader an appreciation for the range of severity and complexity that may be found in affected horses. The veterinarian is obligated to provide the best possible care for the patient and to relieve animal suffering. The lack of definitive evidence for heritability of many of these defects can place the veterinarian in an untenable position, particularly when presented with literature that proclaims or suggests without evidence that a particular condition is inherited. I...
A dinucleotide mutation in the endothelin-B receptor gene is associated with lethal white foal syndrome (LWFS); a horse variant of Hirschsprung disease. Lethal white foal syndrome (LWFS) is a congenital anomaly of horses characterized by a white coat colour and aganglionosis of the bowel, which is similar to Hirschsprung disease (HSCR). We decided to investigate possible mutations of the endothelin-B receptor gene ( EDNRB ) in LWFS as recent studies in mutant rodents and some patients have demonstrated EDNRB defects. First, we identified a full-length cDNA for horse EDNRB . This cDNA fragment contained a 1329 bp open reading frame which encoded 443 amino acid residues. The predicted amino acid sequence was 89, 91 and 85% identical to human, bo...
Congenital defects in newborn foals of mares treated for equine protozoal myeloencephalitis during pregnancy. Three weak, recumbent neonatal foals with skin lesions, including a thin wooly coat, were born to mares being treated for equine protozoal myeloencephalitis. Mares received sulfadiazine or sulfamethoxazole-trimethoprim, pyrimethamine, folic acid, and vitamin E orally. Foals were anemic, leukopenic, azotemic, hyponatremic, and hyperkalemic. Serum folate concentrations in the 3 foals and 2 mares were lower than those reported in the literature for clinically normal brood mares. Treatment was unsuccessful. For each foal, necropsy revealed lobulated kidneys with thin cortices and a pale medulla, a...
The effects of partial thyroidectomy on the development of the equine fetus. A syndrome of congenital hypothyroidism and dysmaturity has been an important cause of reproductive loss and foal mortality in western Canada. The cause and pathogenesis of this syndrome is under investigation. One issue to be addressed is whether all the anomalies present in affected foals are produced concurrently by the same agent, or if affected foals are primarily hypothyroid in utero which induces the associated lesions. This study was designed to document the effects of fetal thyroidectomy, at about 215 days of gestation, on the growth and development of the equine fetus and to compare ...
Incomplete nasomaxillary dysplasia in a foal. Atresia of the nasal punctum is the most common congenital anomaly for the equine nasolacrimal system. Nasomaxillary dysplasia has not been previously documented in foals, is of unknown etiology, and appears to be a rare condition. Conjunctivomaxillary sinostomy was successful in resolving the epiphora.
Microphthalmia, brachygnathia superior, and palatocheiloschisis in a foal associated with griseofulvin administration to the mare during early pregnancy. An 18 year old Friesian mare was treated with griseofulvin for dermatomycosis in the second month of pregnancy. Pregnancy was uneventful and after 331 days a male foal was born. The foal showed bilateral microphthalmia, severe brachygnathia superior, and palatocheiloschisis. The lesions were incompatible with life and the animal was euthanized. As similar lesions have been described in other species associated with griseofulvin administration during pregnancy, and the development of the eyes and facial bones in the horse occurs in the second month of pregnancy, the lesions most likely can be a...
Cervical meningomyelocele associated with spina bifida in a hydrocephalic miniature colt. Cervical meningomyelocele, spina bifida, and hydrocephalus were diagnosed in a newborn miniature colt that was unable to stand and had a cystic mass in the caudal portion of the dorsal cervical region. Results of physical examination and ultrasonographic imaging of the brain supported the diagnosis of hydrocephalus. Results of radiographic evaluation of the vertebral column were consistent with spina bifida at C5-C6. Fluid aspirated from the cervical mass resembled CSF. Radiography of the cervical region after injection of iohexol into the mass revealed herniation of the spinal cord through a ...
Congenital polyalveolar lobe in three foals. Three cases of congenital polyalveolar lobe (pulmonary hamartoma) were diagnosed in female Thoroughbred foals. Foal 1 was born at full term but died shortly afterwards. Foal 2 was aborted at the seventh month of gestation. Parturition was induced at the tenth month of gestation in foal 3 because it developed hydrops of the amnion and ascites. In all three foals, the polyalveolar lobe occurred on the right side and affected the entire right lung. In each case, the right lung formed a tumour-like mass, and expanded into the left chest cavity. The lung masses were pink to dark red and spongy to r...
A case-control study of the congenital hypothyroidism and dysmaturity syndrome of foals. A case-control study was conducted to identify risk factors for the congenital hypothyroidism and dysmaturity syndrome of foals. A questionnaire was used during personal interviews of foal owners and farm managers to collect information on animal signalment, farm environment, and mare management. Information on 39 foals with the congenital hypothyroidism and dysmaturity syndrome were compared with 39 control foals. Foals with the syndrome had a significantly (P < 0.0001) longer gestation (357.6 d) than control foals (338.9 d). Pregnant mares that were fed greenfeed, did not receive any supplem...
[Polydactyly in a foal–a case report]. Polydactylism, an excess deformity in a foal is described. The hereditary pathology and etiopathogenesis are discussed. A method of surgical correction of the deformed extremity is introduced. Indication and prognosis of the surgical correction of polydactylism and aspects concerning the breeding management are discussed.
The diagnosis and surgical correction of congenital portosystemic vascular anomalies in two calves and two foals. Two calves and two foals presented with episodic clinical signs of diffuse central nervous system disease. Portosystemic anomalies were tentatively diagnosed based on the history, clinical signs and increased serum concentrations of blood ammonia and total serum bile acids with normal concentrations of liver derived enzymes. one calf died before intraoperative contrast portography, whereas the other calf and both foals had marked clinical improvement after intensive medical therapy. Surgical correction was attempted in these three animals and was successful in one foal. A right paracostal celi...
[Congenital bile duct cysts and liver fibrosis in a foal]. A three-week-old foal was submitted to the clinic because of a minor traumatic injury at the lower jaw. At admission the foal exhibited diarrhea, a distended abdomen and reduced general condition. These findings could not be associated with the injury. On abdominal radiography decreased abdominal detail and a dorsocaudal displacement of the intestine was present. Ultrasonographically multiple fluid-filled cystic structures of several centimeters in diameter were identified. These cystic structures appeared to be associated with the liver. At laparotomy and at necropsy the liver was markedly en...
Multiple congenital cardiac anomalies and idiopathic thoracic aortitis in a horse. An echocardiographical and clinical pathological investigation of the rapid loss of weight by a yearling thoroughbred filly revealed an atrial septal defect, a ventricular septal defect and hyperfibrinogenaemia. A post mortem examination confirmed the cardiac abnormalities and revealed a severe thoracic aortitis. It is proposed that the idiopathic thoracic aortitis contributed to the horse's compromised cardiovascular homoeostasis.
Congenital cleft vertebral centrum and intra- and extraspinal cyst in a foal. A midsagittal centrum cleft of T5-6, malformation and fusion of T3-7, intra- and extraspinal cyst, and myelodysplasia were found in a 3-month-old female Arabian foal that had experienced posterior ataxia since birth. Based on studies in other species, ecto-endodermal adhesions early in embryogenesis leading to formation of an enterogenous cyst is the most probable pathogenesis.