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Summary

Ninety-five aborted bovine fetuses received from California dairies over a 4.5-year period had histologic lesions of focal encephalitis. Protozoa that reacted with Neospora caninum antiserum were detected in the brain of 88 of these fetuses and in the heart of 1 fetus. Sarcocystis spp schizonts were seen in the vascular endothelium of 1 fetus. It was concluded that a Neospora-like cyst-forming coccidian may be a major cause of abortion in California dairy cattle.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To identify Sarcocystis neurona-specific DNA sequences in the nuclear small subunit ribosomal RNA (nss-rRNA) gene that could be used to distinguish S neurona from other closely related protozoal parasites, and to evaluate a polymerase chain reaction (PCR) test, using broad based primers and a unique species-specific probe on CSF for detection of S neurona in equids.

Procedures

Sequencing of the nuclear small subunit ribosomal RNA gene from a new S neurona isolate (UCD 1) was performed. The sequence was compared with that of other closely related Sarcocystidae parasites. From this sequence, conserved DNA sequence primers were selected and an oligonucleotide probe was designed to hybridize with a unique region of the S neurona gene. For clinical evaluation, horses were considered test positive for S neurona infection on the basis of immunohistochemical detection of the parasites in the CNS.

Results

Sensitivity of this PCR and probe-based detection system was approximately 1 to 5 merozoites. Cerebrospinal fluid from 2 of 5 horses with histologic lesions consistent with equine protozoal myeloencephalitis were PCR- and probe-positive in a blind test of this procedure, and all uninfected horses were test negative.

Conclusion and Clinical Relevance

This PCR- based system is a useful method of confirming S neurona in CSF and has the advantage of facilitating detection of other apicomplexan protozoans that may be infective for horses. The usefulness of this test is limited by the presence of parasites free in the CSF of clinically affected horses. (Am J Vet Res 1996;57:975–981)

Free access
in American Journal of Veterinary Research

Summary

Staggers was diagnosed in sheep and cattle from the northern California coast. The diagnosis was made on the basis of history of ingestion of perennial ryegrass (Lolium perenne) stubble, clinical signs of transient ataxia, which was aggravated by stimulation, and nearly complete recovery after removal of ryegrass as the primary forage. Morbidity was high, but death did not occur in any affected animals. The toxic endophyte, Acremonium lolii, was in most lower leaf sheaths from the ryegrass. Injection of extracts of the ryegrass from affected farms into mice induced signs of toxicosis. Additionally, ryegrass from all 3 farms contained the tremorgenic mycotoxin, lolitrem-B.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine sensitivity and specificity of western blot testing (WBT) of CSF and serum for diagnosis of equine protozoal myeloencephalitis (EPM) in horses with and without neurologic abnormalities.

Design—Prospective investigation.

Animals—65 horses with and 169 horses without neurologic abnormalities.

Procedure—CSF and serum from horses submitted for necropsy were tested for Sarcocystis neuronaspecific antibody with a WBT. Results of postmortem examination were used as the gold standard against which results of the WBT were compared.

Results—Sensitivity of WBT of CSF was 87% for horses with and 88% for horses without neurologic abnormalities. Specificity of WBT of CSF was 44% for horses with and 60% for horses without neurologic abnormalities. Regardless of whether horses did or did not have neurologic abnormalities, sensitivity and specificity of WBT of serum were not significantly different from values for WBT of CSF. Ninety-four horses without EPM had histologic evidence of slight CNS inflammation.

Conclusions and Clinical Relevance—The low specificity of WBT of CSF indicated that it is inappropriate to diagnose EPM on the basis of a positive test result alone because of the possibility of false-positive test results. The high sensitivity, however, means that a negative result is useful in ruling out EPM. There was no advantage in testing CSF versus serum in horses without neurologic abnormalities. Slight CNS inflammation was common in horses with and without S neurona-specific antibodies in the CSF and should not be considered an indication of CNS infection with S neurona. (J Am Vet Med Assoc 2002;221:1007–1013)

Full access
in Journal of the American Veterinary Medical Association

Objective—

To determine whether heifers with naturally acquired congenital exposure to Neospora sp would transmit the infection to their offspring during gestation.

Design—

Prospective cohort study.

Animals—

Neonatal heifers on a dairy with a history of Neospora sp infections were selected for the study on the basis of their serum titers to Neospora sp, as determined by the use of indirect fluorescent antibody testing. Seropositive heifers (n = 25) had titers ≥ 1:5,120 and seronegative heifers (25) had titers ≤ 1:80. All heifers were raised and bred on the dairy, and samples were obtained from heifers and their calves at the time of calving.

Procedure—

Blood samples were tested for Neospora sp antibodies. Histologic evaluations, Neospora sp immunohistochemical examinations. and protozoal culturing were performed on samples obtained from selected offspring (second-generation calves).

Results—

Seropositive heifers gave birth to calves with titers ≥ 1:1,280 to Neospora sp. All offspring from seropositive heifers that were necropsied had evidence of Neospora sp infection. All seronegative heifers and their offspring had titers < 1:80 to Neospora sp.

Clinical Implications—

Congenitally acquired Neospora sp infection can persist in clinically normal heifers and be transmitted transplacentally to their offspring. Vertical transmission can be a way by which neosporosis is maintained in herds. (J Am Vet Med Assoc 1997;210:1169–1172)

Free access
in Journal of the American Veterinary Medical Association

Summary:

Four dairy cows that had been successfully rebred following fetal Neospora infection and abortion were identified from 2 drylot dairies. All 4 cows had uncomplicated pregnancies with the birth of 5 full-term calves. The calves all had high precolostral serum IgG antibodies. The precolostral antibodies to Neospora sp as determined by indirect fluorescent antibody test ranged from 5,120 to 20,480, compared with maternal serum and colostral antibody titers from 320 to 1,280. Two calves had mild neurologic limb deficits. Three calves had mild nonsuppurative encephalomyelitis and Neospora organisms were found in the CNS of 3 calves. Findings indicate that repeat transplacental Neospora infections occur in cows. Additionally, calves born from cows with a history of Neospora fetal infection and abortion may have congenital Neospora infections and/or neurologic dysfunctions at birth. The Neospora indirect fluorescent antibody test appears to be a useful antemortem test for detection of calves exposed in utero to Neospora organisms.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe clinical and scintigraphic abnormalities in horses with a bone fragility disorder.

Design—Retrospective case series.

Animals—16 horses with scintigraphic evidence of multiple sites of increased radiopharmaceutical uptake (IRU).

Procedures—Medical records were reviewed for information on signalment; history; clinical, clinicopathologic, and diagnostic imaging findings; and treatment. Follow-up information was obtained through telephone interviews with owners.

Results—Horses ranged from 4 to 22 years old; there were 8 castrated males and 8 females. Foci of IRU most commonly involved the scapulae, ribs, sternebrae, sacral tubers, ilia, and cervical vertebrae. Most horses were examined because of chronic intermittent (n = 10) or acute (6) lameness involving a single (10) or multiple (6) limbs that could not be localized by means of regional anesthesia. Cervical stiffness (n = 3), scapular bowing (3), swayback (3), and ataxia (1) were also seen in more advanced cases. Signs of respiratory tract disease and exercise intolerance were evident in 4 horses. Ultrasonographic or radiographic evidence of bone remodeling or degeneration was seen in 19 of 33 affected bones. Histologic examination of bone biopsy specimens revealed reactive bone. Improvement was initially seen with conservative treatment in some horses, but the condition worsened in all horses, and 11 horses were euthanized within 7 years.

Conclusions and Clinical Relevance—Results suggested that horses may develop a bone fragility disorder characterized clinically by an unlocalizable lameness and scintigraphically by multiple sites of IRU involving the axial skeleton and proximal portion of the appendicular skeleton.

Full access
in Journal of the American Veterinary Medical Association

Objective—

To estimate the minimum rate of abortion attributable to infection with Neospora sp in selected California dairy herds.

Design—

Prospective study.

Animals—

Twenty-six dairy herds containing 19,708 cows were studied. Fourteen herds had a history of abortions attributable to neosporosis, and 12 were herds in which neosporosis had not been identified as a cause of abortions.

Procedure—

During a 1-year period, all available aborted fetuses were submitted to veterinary diagnostic laboratories to determine the cause of abortion. Reproductive records of cows that aborted were reviewed.

Results—

Neospora sp infection was the major cause of abortion identified (113/266 abortions, 42.5%). The majority (232/266, 87.2%) of the aborted fetuses were submitted from herds with a history of abortions attributable to neosporosis, and Neospora sp infection was identified as the causative agent in 101 of 232 (43.5%) of the abortions from these herds. Fewer aborted fetuses were submitted from the 12 herds that did not have a history of abortion attributable to Neospora sp; however, neosporosis was confirmed as a cause of abortion in 6 of these 12 herds and was identified as the causative agent in 12 of 34 (35.3%) abortions from these herds. The disease was widespread throughout the state (19/26 herds in our study). Available reproductive histories of cows that had abortions attributed to neosporosis were evaluated, and 4 cows were identified that twice aborted Neospora-in-fected fetuses.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses.

Animals

95 Thoroughbred racehorses that died between 1994 and 1996.

Procedure

38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios.

Results

Odds of CMI were 0.62 times lower for a 5- mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10° increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3° increase in toe angle, 0.15 times lower with a 5- mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference.

Clinical Relevance

Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury. (Am J Vet Res 1998;59: 1545-1552)

Free access
in American Journal of Veterinary Research