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.
[A case of diprosopus in a foal]. A case of diprosopus in a foal is described. This is only the second report of such a deformity in the equine species. Hereditary pathology and pathogenesis are discussed.
Atrial septal defect and atrial fibrillation in a foal. Clinical examination of a four-and-a-half-month old foal revealed evidence of progressive heart failure associated with an atrial septal defect and atrial fibrillation. Atrial septal defects are rarely reported in foals and the foal's growth, development and demeanour were normal until a sudden onset of lethargic behaviour. The value of B-mode echocardiography in identifying the congenital lesion is indicated.
Congenital atresia of the parotid salivary duct in a 7-month-old quarter horse colt. A 7-month-old Quarter Horse colt was examined because it had had a tortuous, distended vessel on the side of its head since birth. An abnormality of the parotid salivary duct was suspected on the basis of location and course of the vessel. Atresia of the duct near the parotid papilla was diagnosed by use of contrast sialography. Surgical transpositioning was attempted, but failed because of stricture formation. Chemical ablation of the salivary gland has been used to treat traumatic rupture of the duct. It proved to be an effective and practical method of resolving the problem in this case. Co...
Bilateral colobomas involving the optic discs in a quarterhorse. THIS report describes bilateral colobomas of the optic discs with associated aberrations in ocular differentiation • and unusual hypopigmentation of the uveal tissues.
Iridial hypoplasia (aniridia) accompanied by limbic dermoids and cataracts in a group of related quarterhorses. The clinical, gross and microscopic ophthalmic lesions of iridial hypoplasia, limbic dermoids and cataracts in a Quarterhorse stallion and a group of its offspring are described. It is proposed that the lesions in the stallion were the result of an independent mutation and that the defects were transmitted to its offspring by an autosomal dominant gene.
Overo lethal white foal syndrome: equine model of aganglionic megacolon (Hirschsprung disease). The lethal white foal syndrome (LWFS) is a congenital abnormality of overo spotted horses which is a model for human aganglionic megacolon or Hirschsprung disease. Foals with LWFS have an all white, or nearly all white, coat. They also present clinically with an intestinal obstruction that proves fatal within the first few days of life. The LWFS involves both melanocytes and intestinal ganglion cells, and appears to result from a genetic defect involving neural crest cells. This report describes pathologic studies of two recent cases of LWFS. Two different hypothetical models of inheritance of...
Bilateral congenital cysts in the frontal sinuses of a horse. Congenital frontal sinus cysts were found bilaterally in the frontal sinuses of a one-year-old miniature horse. Diagnosis was based on radiography of the head and cytologic examination of tissue aspirated from the frontal sinuses. The cysts were surgically removed, using a hinged bone flap technique bilaterally over the frontal sinuses.
Staphylectomy for treatment of dorsal displacement of the soft palate in two foals. Dorsal displacement of the soft palate associated with dysphagia and aspiration pneumonia was diagnosed in 2 young foals. The displacement appeared to be congenital. Clinical signs associated with the condition were resolved after staphylectomy. Dorsal displacement of the soft palate is usually recognized in adult animals as an upper respiratory tract disease, but may be a contributing factor to dysphagia and lower respiratory tract disease in young animals.
Agenesis of the corpus callosum with cerebellar vermian hypoplasia in a foal resembling the Dandy-Walker syndrome: pre-mortem diagnosis by clinical evaluation and CT scanning. DORSAL midline dysgenesis of the human brain, a complex
pattern of maldevelopment of sulcation and neuronal migration
occurring before 74 days gestation, has been recognised for over
fifty years. The association (68 per cent) of the so-called Dandy-
Walker syndrome (cystic dilatation of the fourth ventricle and
hypoplasia of the cerebellum) with other brain malformations is
common and often includes agenesis of the corpus callosum
(Hart, Malamud and Ellis 1972; Ral et a1 1980). This report
describes the first pre-mortem identification of such a structural
brain anomaly in a Thoroughbr...
Atresia of the right atrioventricular orifice with complete transposition of the great arteries in a horse. The heart of a 6-week old Arabian filly with a history of poor health and exercise intolerance revealed at postmortem examination, multiple cardiac malformations which included atresia of the right atrioventricular orifice (tricuspid atresia, with associated atrial and ventricular septal defects), complete transposition of the great arteries, anomalous drainage of the venae cavae and coronary sinus into the left atrium, coarctation of the aorta, and a small but patent ductus arteriosus. The course of blood through the heart was suggested and discussed.
Monorchidism in the horse. Six horses with monorchidism, identified at surgery for cryptorchidectomy, are reported. All six presented with a single scrotal testis. Following surgical removal of one testis, they were either hormonally, anatomically or behaviourally determined to be geldings. Three other horses reported in the literature are reviewed. Of these nine cases of monorchidism, eight were thought to be caused by testicular degeneration and one by testicular agenesis. The vaginal process was present in all of the former and absent in the latter. The left side was involved in five of these eight horses. In seven, ...
Bilateral colobomas in a horse. Bilateral true colobomas with retrobulbar cysts located over the optic nerves are described in an 8-year-old Quarterhorse mare with a history of progressive blindness. Colobomas result from the failure of an embryonic fissure to close and retrobulbar cysts result from eversion of the neuroectoderm through the colobomas. It could not be determined whether the small optic nerves and the scars, rosettes and disorganization of the cell layers in the retina were the result of concurrent dysplasia or were secondary to degeneration.
Congenital malignant melanoma in two foals. Two cases of congenital malignant melanomas in horses are described in this report. In each case, wide surgical excision of the mass was performed; no recurrence or metastasis was detected after a minimum of 15 months' follow-up. Melanomas are among the most common neoplasms of horses, but they typically develop in gray horses greater than 6 years old.
Occipitoatlantoaxial malformation with duplication of the atlas and axis in a half Arabian foal. An unusual occipitoatlantoaxial malformation is described in a 2-week-old male part Arabian foal that was unable to stand at birth and showed signs of spastic tetraparesis due to a cervical spinal cord compression. There were 2 atlases present. One was fused to the occipital bones. The other articulated with the first atlas and an axis which had a long dens that projected into the vertebral canal. Examination of the ossification centers of the axis indicated partial duplication of that bone.
Surgical management of congenital and perinatal abnormalities of the urogenital tract. Surgical management of various congenital and perinatal abnormalities of the urogenital tract are discussed, including ruptured bladder, ruptured urachus, ureteral defect, patent urachus and umbilical remnant infection, ureteral ectopia, congenital inguinal hernia, and atresia ani and rectourethral or rectovaginal fistula.
Congenital inguinal hernias associated with a rent in the common vaginal tunic in five foals. Five foals were admitted because of colic that developed within 24 hours after birth. Physical examination revealed swelling from the inguinal region to the cranial aspect of the prepuce. Through the skin overlying the swelling, distended loops of bowel could be palpated. The hernias could be reduced with the foals restrained in dorsal recumbency. Surgical exploration showed the swelling to be an inguinal hernia with small bowel herniation through a rent in the common vaginal tunic. Concurrent rupture of the vaginal tunic should be suspected when a congenital inguinal hernia is associated with...
Chylothorax associated with a congenital diaphragmatic defect in a foal. PLEURAL effusions (the presence of excessive quantities of pleural fluid) have been associated with a variety of disease processes affecting the equine thorax. The majority of reported cases have involved exudative effusions associated with pneumonia, lung abscesses or neoplasia (Raphel and Beech 1982 Mair 1987). Transudative effusions have been less com• monly described, being associated with such conditions as hypoproteinaemia. cardiac failure and diaphragmatic rupture. Chylothorax, the accumulation of chylous fluid in the mediastinum and/or pleural cavity, is a relatively uncommon conditi...
Incomplete subaortic stenotic rings in domestic animals–a newly described congenital anomaly. A newly described congenital heart anomaly, the incomplete subaortic stenotic ring was detected at necropsy in four dogs, one cat, one cow, one horse, one sheep and one pig. These structures were grossly and histologically similar to complete subaortic stenotic rings, being composed of variably dense interlacing bands and sheets of fibrous connective tissue. In all nine cases, their presence at necropsy was considered an incidental finding.
Heterotopic polyodontia in horses: nine cases (1969-1986). Nine horses with heterotopic polyodontia, examined at Purdue University since 1969, were treated surgically and had a favorable outcome. Six of the horses had received prior medical or surgical treatment, but without success. An understanding of the congenital nature of the problem contributed to an accurate diagnosis in each case. General anesthesia, aseptic technique, removal of all aberrant tissue, and wound suture for primary healing appeared to be essential for preserving ear function and obtaining an effective treatment.
Aortic valve insufficiency in a one-year-old colt. Aortic insufficiency was suspected in a thin 1-year-old colt with a grade IV/V decrescendo holodiastolic murmur and a bounding arterial pulse. Echocardiographic findings (diastolic fluttering of the septal leaflet of the mitral valve, left ventricular volume overload, and incomplete aortic valve closure) were diagnostic for aortic valve insufficiency. Moderately thick fibrotic aortic valve leaflets were found at necropsy. Fenestrations were found in the aortic and pulmonic valve cusps. Congenital valvular disease may have led to aortic valvular insufficiency in this horse.
Echocardiographic detection of tricuspid atresia in two foals. M-mode, 2-dimensional, and contrast echocardiographic studies were used to detect tricuspid atresia in 2 foals. M-mode echocardiographic findings included a small right ventricle, large left ventricle, large mitral valve excursion, large left atrium (foal 2), dropout of the cranial aspect of the aortic root, and a thick band of echoes in the tricuspid valve region. These findings were confirmed by 2-dimensional echocardiography. In addition, a large right atrium, persistent foramen ovale, ventricular septal defect, and large mitral valve apparatus were imaged. One foal also had a thick right a...