Hypovitaminosis A in pigs

Congenital Microphthalmic Syndrome in a Swine

A 17-week-old crossbred finishing pig was presented for lameness of approximately one week. Clinical evaluation, including ophthalmologic examination, revealed ataxia, partial flaccid paresis of the pelvic limbs, skin lesions at feet and claws, and severely reduced vision/blindness. Both eyes had multiple persistent pupillary membranes (iris-to-iris and iris-to-lens) and hypermature cataracts. Histopathological examination of the eyes revealed microphthalmia, microphakia with cataract formation, myovascularised membrane in the vitreous, retinal detachment, and retinal dysplasia. Microscopic examination of tissues collected postmortem demonstrated nonsuppurative polioencephalomyelitis with the most prominent inflammatory lesions in the lumbar spinal cord. Subsequently, presumed Teschen/Talfan disease was confirmed by porcine teschovirus identification in the spinal cord using the reverse transcription-polymerase chain reaction (RT-PCR). To the authors' knowledge, this is the first case report describing in detail histopathological changes in the porcine congenital microphthalmic syndrome.

Hypovitaminosis A coupled to secondary bacterial infection in beef cattle

Background

Vitamin A is essential for normal growth, development, reproduction, cell proliferation, cell differentiation, immune function and vision. Hypovitaminosis A can lead to a series of pathological damage in animals. This report describes the case of hypovitaminosis A associated with secondary complications in calves.

Case presentation

From February to March in 2011, 2-and 3-month old beef calves presented with decreased eyesight, apparent blindness and persistent diarrhea occurred in a cattle farm of Hubei province, China. Based on history inspection and clinical observation, we made a tentative diagnosis of hypovitaminosis A. The disease was confirmed as a congenital vitamin A deficiency by determination of the concentrations of vitamin A in serum and feed samples. Furthermore, pathological and microbiological examination showed that the disease was associated with pathogenic Escherichia coli (E. coli) infection and mucosal barriers damage in intestines. The corresponding treatments were taken immediately, and the disease was finally under control for a month.

Conclusions

To our knowledge, this is the first report of hypovitaminosis A coupled to secondary infection of E. coli in beef cattle, advancing our knowledge of how vitamin A affects infection and immunity in animals. This study could also be contributed to scientific diagnosis and treatments of complex hypovitaminosis A in cattle.

Vitamin A deficiency and hepatic retinol levels in sea otters, Enhydra lutris

Vitamin A deficiency has rarely been reported in captive or free-ranging wildlife species. Necropsy findings in two captively housed southern sea otters (Enhydra lutris nereis) included irregular thickening of the calvaria characterized by diffuse hyperostoses on the internal surface. One animal also had moderate squamous metaplasia of the seromucinous glands of the nose. There was no measurable retinol in the liver of either sea otter. For comparison, hepatic retinol concentration was determined for 23 deceased free-ranging southern and northern (Enhydra lutris kenyoni) sea otters from California and Alaska. Free-ranging otters were found to have similar hepatic retinol concentrations (316 +/- 245 mg/kg wet weight) regardless of their location and subspecies. All of these values were significantly higher than the levels in the affected animals. Consumption of a diet with very low vitamin A concentrations and noncompliance in daily supplementation are hypothesized as the causes of vitamin A deficiency in these two sea otters.

Diagnosis and surgical treatment of a Chiari I-like malformation in an African lion (Panthera leo)

A 13-mo-old intact male African lion (Panthera leo) presented with a 3-mo history of lethargy, ventral flexion of the neck, abnormal vocalization, and ataxia. Hemogram and serum biochemistries were within normal limits except for the presence of hypokalemia (2.7 mEq/L) and hypochloridemia (108 mEq/L). When no improvement was noted with oral potassium gluconate supplementation, a computed tomography scan of the brain and skull was performed, and no abnormalities were noted. However, magnetic resonance imaging detected occipital bone thickening, crowding of the caudal cranial fossa with cerebellar compression and herniation, and cervical syringohydromyelia, which was consistent with a Chiari I-like malformation. Foramen magnum decompression was performed to relieve the compression of the cerebellum. The animal recovered well with subsequent resolution of clinical signs. Hypovitaminosis A has been proposed previously as the underlying etiology for this malformation in lions with similar clinical presentations. This lion's serum and liver vitamin A concentrations were low (100 ng/ml and 25.31 microg/g, respectively) compared to concentrations reported for domestic carnivores and support hypovitaminosis A as the underlying cause of this animal's Chiari I-like malformation.

Degenerative myelopathy and vitamin A deficiency in a young black-maned lion (Panthera leo)

Degenerative myelopathy and vitamin A deficiency were diagnosed in a 1-year-old, female, black-maned lion (Panthera leo). Diffuse white matter degeneration characterized by dilated myelin sheaths, Wallerian degeneration, and reactive astrocytosis was present at all levels of the spinal cord. With luxol fast blue-resyl echt violet stain, bilaterally symmetrical demyelination was observed in the fasciculus cuneatus of the cervical spinal cord and in peripheral white matter of cervical, thoracic, and lumbar segments. Additionally, the ventral gray columns and brain stem nuclei contained rare chromatolytic neurons with abnormal neurofilament accumulation. Leptomeninges of the cervical spinal cord were focally adhered to the dura and thickened by fibrosis and osseous metaplasia. Vitamin A deficiency was diagnosed based on hepatic vitamin A concentration of 1.71 microg/g dry weight. Adequate hepatic vitamin A concentration for yearling to adult domestic animals ranges between 150 and 1000 microg/g dry weight. Lesions were distinct from those previously described in young captive lions with vitamin A deficiency, which had thickened skull bones and cerebellar herniation. The pathogenesis of vitamin A-associated myelopathy in this lion may be similar to that described in adult cattle, which is believed to result from spinal cord compression secondary to elevated pressure of cerebrospinal fluid.

Aural abscesses in wild-caught box turtles (Terapene carolina): possible role of organochlorine-induced hypovitaminosis A

Wild-caught box turtles (Terapene carolina carolina) with aural abscesses were observed over a period of several years. Histopathologic evaluation of epithelial tissues (conjunctiva, pharynx, trachea, auditory tube) revealed mucosal hyperplasia and squamous metaplasia, and accumulated keratin-like material in the middle ear cavity. These manifestations suggested the possibility of vitamin A deficiency. A nonsignificant trend toward reduced serum and hepatic vitamin A levels was observed in turtles with abscesses (mean serum and hepatic vitamin A levels 71 and 49% of respective levels in turtles without abscesses). Three organochlorine (OC) compounds (alpha-benzene hexachloride, heptachlor epoxide, and oxychlordane) and total (microg/g) OC compounds were significantly higher in turtles with abscesses compared with turtles without abscesses. No OC compounds were higher in turtles without abscesses compared with turtles with abscesses. These data suggest a possible effect of environmental chemicals on metabolism or utilization of vitamin A in wild box turtles, resulting in hypovitaminosis A.

Congenital diseases and abnormalities of pigs

Several congenital developmental anomalies are not listed in this review because they have no proposed cause. It is the author's hope that this article will serve practicing veterinarians and the swine industry by being an informative guide for stimulating independent thought toward diagnosing congenital diseases. Remember that the cause may have exerted its effects weeks or months before being observed. A detailed history of the dam as well as the rest of the herd is important. If possible, a history of neighboring herds should also be examined for similar problems. Either conduct a thorough necropsy with appropriate tissues submitted for diagnostic analysis, or send representative pigs to a diagnostic center for a complete evaluation. If chromosome evaluation is desired, contact the evaluating laboratory for submission procedures. Breeding records should be evaluated for intragenerational frequencies and intergenerational patterns typical of genetic transmission. When evaluating pedigrees, the frequent occurrence of an individual is not proof of its involvement. The frequency of occurrence in the diseased population must be significantly greater than it is in a random population of pigs. Dr. H.W. Leipold, in the pathology department at the Kansas State University College of Veterinary Medicine, maintains an extensive database of congenital anomalies in domestic animals. I recommend that he be contacted in all cases of undiagnosed or unusual cases of congenital disease. He possibly can help with a definitive diagnosis and your contact will help expand this important central database of congenital diseases.