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  • Author or Editor: Hussni O. Mohammed x
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SUMMARY

Cartilage resurfacing by chondrocyte transplantation, using porous collagen matrices as a vehicle to secure the cells in cartilage defects, has been used experimentally in animals. This in vitro study evaluated the temporal morphologic features and proteoglycan synthesis of chondrocyte-laden collagen matrices. Forty-two porous collagen disks were implanted with a minimum of 6 × 106 viable chondrocytes, covered by a polymerized collagen gel layer, and 6 disks were harvested after 0, 3, 7, 10, 14, 18, or 22 days of incubation in supplemented Ham's F12 medium at 37 C and 5% CO2. Histologic and histo-chemical evaluation of formalin-fixed segments of the cultured disks indicated that the chondrocytes proliferated in the implant, producing small groups and linear segments of cells by day 14. The collagen framework remained intact over the course of the study with thick areas attributable to depositions of matrix material after day 10. Alcian blue-stained matrix was evident in the pericellular region of chondrocytes in sections of disks harvested on days 14, 18, and 22.

Glycosaminoglycan (GAG) assay by dimethyl-methylene blue dye binding after papain digestion of the disk segments revealed negligible amounts of GAG at day 0. Significant (P ≤ 0.0001) increase in total GAG content was observed by day 3 (0.329 M-μg of disk) and further increases were observed until a plateau in GAG quantity was seen on day 14. Mean peak GAG content was 0.553 ± 0.062 μg/mg. Secondary treatment of the papain-digested implants with keratanase and chondroitinase ABC yielded similar trends in chondroitin sulfate (CS) and keratan sulfate (KS) concentrations. The CS content significantly (P = 0.0002) increased for the first 14 days of incubation, then a plateau was observed for the remainder of the study. Peak CS content was 0354 ± 0.037 μg/mg. Concentration of KS reached a plateau earlier than did CS content, with peak amount of 0.193 ± 0.027 μg/mg on day 10. Fluctuations in K5 content were not significant until an increase on day 22.

Chondrocytes actively populated the collagen implants, increasing in number and synthesizing matrix GAG epitopes over the 22 days of incubation. These results indicate that chondrocyte-laden porous collagen matrices may be suitable cartilage analogue materials and the optimal metabolic time for transfer to cartilage defects is 10 to 14 days.

Free access
in American Journal of Veterinary Research

Summary

Serial ultrasonographic examinations were performed on 8 Beagle bitches from 20 to 60 days pregnant to determine time of first detection, appearance, and sizes of selected features of pregnancy. Gestation was timed from the day of the preovulatory luteinizing hormone surge. Findings related to gestational age were consistent among bitches.

Gestational ages at earliest detection of the following features were: chorionic cavity at day 20; placental layers in the uterine wall at day 22 to 24; zonary placenta at day 27 to 30; embryo and heartbeat at day 23 to 25; yolk sac membrane at day 25 to 28; allantoic membrane at day 27 to 31; choroid plexus of the brain at day 31 to 35; fetal movement at day 34 to 36; skeleton at day 33 to 39; bladder and stomach at day 35 to 39; kidney at day 39 to 47; and liver hypoechoic, compared with lung, at day 38 to 42.

Extra-fetal structures were measurable from day 20 or 22 through day 48. Chorionic cavity diameter increased from 0.2 ± 0.0 cm to 3.3 ± 0.2 cm, outer uterine diameter increased from 0.8 ± 0.03 cm to 4.8 ± 0.2 cm, length of chorionic cavity or zonary placenta increased from 0.3 ± 0.03 cm to 4.9 ± 0.05 cm, uterine wall thickness increased from 0.3 ± 0.03 cm to 0.8 ± 0.01 cm, and placental thickness increased from 0.1 ± 0.0 cm to 0.5 ± 0.05 cm. Chorionic cavity diameter, outer uterine diameter, and placental length each increased at a linear rate through day 37, after which time, each had a marked plateau in growth. Of the extra-fetal structures, chorionic cavity diameter was the most accurate for estimation of gestational age.

All of the fetal structures studied increased at an increasing (second order) rate. Crown-rump length increased from 0.3 ± 0.05 cm on day 24 to 9.2 ± 0.2 cm on day 48. Body diameter increased from 0.2 ± 0.03 cm on day 24 to 4.6 ± 0.15 cm on day 60. Head diameter increased from 0.8 ± 0.05 cm on day 34 to 2.7 ± 0.04 cm on day 60. Of the fetal structures, head diameter was the most accurate for estimation of gestational age.

Free access
in American Journal of Veterinary Research

Objective

To identify intrinsic, management, nutritional, and environmental risk factors associated with equine motor neuron disease (EMND) and to determine whether epidemiologic evidence supports oxidative stress as a risk factor for developing EMND.

Design

Case-control study.

Animals

87 horses with EMND and 259 control horses.

Procedure

Information concerning each horse’s history of exposure to multiple environmental factors prior to developing EMND was obtained by means of a questionnaire or personal interview. Exposure histories of horses with EMND and control horses were compared, and the association of each risk factor with EMND was evaluated, using logistic regression analysis.

Results

Factors significantly associated with risk of developing EMND included age, breed of horse, duration of residence at the farm, not vaccinating against rabies, and certain feeding practices. Horses that were exercised on green pasture or in grass paddocks were less likely to develop EMND, compared with horses that were exercised in dirt paddocks. Feeding complete pelleted feed as the only source of concentrate or combined with sweet feed was associated with a significant increase in the risk of EMND. Supplementary feeding of vitamin and mineral mixtures not formulated to provide vitamin E or selenium was associated with increased risk of EMND. Horses with a history of cribbing or coprophagia were also at higher risk of developing EMND.

Clinical Implications

Several husbandry practices and intrinsic characteristics of horses appear to modify the risk of EMND. The relationship of specific nutritional factors to EMND supports the hypothesis that a deficiency of vitamin E contributes to the disease. (J Am Vet Med Assoc 1997;211:1261–1267)

Free access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To determine the effects of orally administered raltegravir in cats with experimentally induced ocular and respiratory feline herpesvirus-1 (FHV-1) infection.

ANIMALS

14 healthy 6-month-old unvaccinated specific pathogen–free cats.

PROCEDURES

On day 0, all cats were experimentally inoculated by topical application of 0.1 mL of a solution containing 106 plaque-forming units of FHV-1 strain FH2CS to the inferior conjunctival fornix of each eye. Cats were randomly assigned to receive either raltegravir (80 mg; n = 7) or lactose (250 mg; vehicle; 7), PO, every 12 hours for 14 days beginning on day 1. Cats were assigned clinical ocular and respiratory disease scores every other day from days 0 to 30. Conjunctival swab specimens were collected for detection of FHV-1 by virus isolation and real-time PCR assay at 3-day intervals from days 0 to 30. Confocal microscopy was performed on days 0 and 10 to assess corneal epithelial leukocyte infiltration. The assessed variables and duration of FHV-1 shedding were compared between the 2 treatment groups.

RESULTS

Cats in both groups developed moderate to severe conjunctivitis and ulcerative keratitis characteristic of FHV-1 infection. Median duration of FHV-1 shedding was shorter and signs of ocular and respiratory disease were less severe for raltegravir-treated cats than for vehicle-treated cats. However, the mean conjunctival FHV-1 titer and corneal epithelial leukocyte count did not differ between the 2 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested orally administered raltegravir might be effective for alleviation of ocular and respiratory signs of FHV-1 infection in cats. (Am J Vet Res 2019;80:490–497)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To differentiate early (1 to 8 days) from late (9 to 14 days) inflammatory phases and assess relationships between leukocyte phenotype and bacterial recovery in cows with Staphylococcus aureus-induced mastitis.

Animals—10 first-lactation Holstein cows.

Procedure—Blood and milk samples were collected from 4 or 6 cows before and after intramammary infusion of sterile broth or S aureus, respectively. Flow cytometric expression of CD3 and CD11b antigens on blood and milk leukocytes, leukocyte differential counts, bacterial counts in milk, and somatic cell counts were determined longitudinally.

Results—Density of CD3 molecules decreased on blood lymphocytes and increased on milk lymphocytes after infusion of bacteria. Density of CD11b molecules on lymphocytes and phagocytes and percentage of CD11b+ lymphocytes in milk increased significantly after infusion; maximum values were achieved during the early inflammatory phase. Density of CD3 and CD11b molecules on milk lymphocytes and macrophages, respectively, 1 day after inoculation were negatively correlated with bacterial recovery on day 1 and days 9 to 14, respectively. Density of CD11b molecules on milk macrophages and the ratios of phagocyte to lymphocyte percentages and polymorphonuclear cell to macrophage percentages in milk differentiated the early from the late inflammatory phase.

Conclusions and Clinical Relevance—Activation of bovine mammary gland macrophages and T cells in response to intramammary infusion of S aureus was associated with an inability to culture this bacterium from milk. Identification of specific inflammatory phases of S aureus-induced mastitis in cows may allow for the design of more efficacious treatment and control programs. (Am J Vet Res 2001;62:1840–1851)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate whether administering a tart cherry juice blend (TCJB) prior to exercise would reduce skeletal and cardiac muscle damage by decreasing the inflammatory and oxidative stress response to exercise in horses.

Animals—6 horses.

Procedures—Horses were randomly allocated into 2 groups in a crossover study with a 2-week washout period and orally administered either TCJB or a placebo solution (1.42 L, twice daily) in a double-masked protocol for 2 weeks prior to a stepwise incremental exercise protocol. Horses were tested for serum activities of creatine kinase and aspartate aminotransferase (AST) and concentrations of cardiac troponin I (cTnI), thiobarbituric acid reactive substances (TBARS; an indicator of oxidative stress), and serum amyloid A (SAA; an indicator of inflammation). To ensure that treatment would not result in positive results of an equine drug-screening protocol, serum samples obtained from each horse prior to and after 2 weeks of administration of TCJB or the placebo solution were tested.

Results—All horses had negative results of drug screening at both sample times. The exercise protocol resulted in a significant increase in TBARS concentration, SAA concentration, and serum AST activity in all horses. Administration of TCJB or placebo solution was not associated with an effect on malondialdehyde or SAA concentrations. However, administration of TCJB was associated with less serum activity of AST, compared with administration of placebo solution.

Conclusions and Clinical Relevance—Administration of TCJB may diminish muscle damage induced by exercise.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare cardiac troponin I (cTnI) concentrations determined by use of a point-of-care analyzer with values determined by use of a bench-top immunoassay in plasma samples obtained from clinically normal horses with and without experimentally induced cardiac disease, and to establish a reference range for plasma equine cTnI concentration determined by use of the point-of-care analyzer.

Animals—83 clinically normal horses, 6 of which were administered monensin to induce cardiac disease.

Procedures—A blood sample was collected from each of the 83 clinically normal horses to provide plasma for analysis by use of the point-of-care analyzer; some of the same samples were also analyzed by use of the immunoassay. All 83 samples were used to establish an analyzer-specific reference range for plasma cTnI concentration in clinically normal horses. In 6 horses, blood samples were also collected at various time points after administration of a single dose of monensin (1.0 to 1.5 mg/kg) via nasogastric intubation; plasma cTnI concentration in those samples was assessed by use of both methods.

Results—The analyzer-specific reference range for plasma cTnI concentration in clinically normal horses was 0.0 to 0.06 ng/mL. Following monensin treatment in 5 horses, increases in plasma cTnI concentration determined by use of the 2 methods were highly correlated (Pearson correlation, 0.83). Peak analyzer-determined plasma cTnI concentrations in monensin-treated horses ranged from 0.08 to 3.68 ng/mL.

Conclusions and Clinical Relevance—In horses with and without experimentally induced cardiac disease, the point-of-care analyzer and bench-top immunoassay provided similar values of plasma cTnI concentration.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To investigate potential sources of an epizootic of listerial encephalitis, using molecular diagnostic and typing methods.

Sample Population

A flock of about 655 sheep.

Procedure

An epizootiologic investigation was performed. Clinical, feed, and environmental samples were tested for Listeria monocytogenes, using polymerase chain reaction and culture methods; recovered isolates were “fingerprinted,” using an automated ribotyping system.

Results

Listeria monocytogenes was recovered from brain specimens of 7 sheep with clinical signs of listerial encephalitis. All clinical isolates had fingerprints identical to those of isolates from farm equipment used to transport silage. Corn silage, which was not fed to the sheep, also contained L monocytogenes of the same pattern type as defined by ribotyping. Listeria monocytogenes was not isolated from the stored haylage designated for feeding the sheep (the cut-off point for isolation being < 102 colony-forming units/g).

Conclusions

Corn silage was implicated as the source of a listeriosis epizootic. It appears to have cross-contaminated the haylage destined for the sheep during handling with a front-end loader. Suspension of silage feeding coincided with cessation of listeriosis cases.

Clinical Relevance

Use of advanced molecular techniques can help to identify the sources and restrict the scope of an epizootic. In epizootics, a single L monocytogenes strain can lead to infection of multiple animals, with rapid progression of the disease. (Am J Vet Res 1997;58:733–737)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To examine the regional variations in the distribution of equine motor neuron disease (emnd) in the United States and the factors that might explain those variations.

Design

Cluster investigation and case-control study.

Sample population

The study population consisted of 97 horses with histopathologically confirmed emnd and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base.

Procedure

The total horse population of the United States was divided into 21 regions, and the regional incidence rates of emnd from January 1985 through January 1995 were estimated. Moran's index of spatial autocorrelation was calculated to test for spatial clustering of the disease. The 21 regions were then joined in broader areas according to the similarity of their emnd rates by means of the cluster analysis statistical technique. Finally, the role of potential confounding factors (age at diagnosis, month of diagnosis, breed, and sex) in the present distribution of emnd was assessed, using logistic regression analysis.

Results

Differences in estimated rates across the 21 regions resulted in a strong pattern of spatial clustering of emnd in the United States. The geographic units were grouped into 5 risk regions, with the gradient of emnd incidence rates increasing from the western states (almost 0 cases/1,000,000 horse-years) toward New England (20.78 cases/1,000,000 horse-years). Reported risk factors of emnd (age, breed) and other extraneous factors (sex, month of diagnosis) could not explain the observed geographic variations of disease rates. Nevertheless, there is evidence of some confounding attributable to age and breed.

Conclusions

Although the mechanism responsible for the clustering of emnd in northeastern states is still unexplained, it is not an epiphenomenon caused by regional differences in the distribution of the factors investigated.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe the clinical, endoscopic, and serologic features of an outbreak of besnoitiosis in 2 donkey operations in northeastern Pennsylvania and to report the outcome of attempted treatment of 1 naturally infected individual.

Design—Observational study.

Animals—29 donkeys (Equus asinus) in northeastern Pennsylvania.

Procedures—Donkeys were examined for lesions suggestive of besnoitiosis in an outbreak investigation. Information was collected regarding the history and signalment of animals on each premises. Rhinolaryngoscopy was performed to identify nasopharyngeal and laryngeal lesions. Serum samples were collected for immunofluorescent antibody testing and immunoblotting for Besnoitia spp. Skin biopsy samples were obtained from 8 animals with lesions suggestive of besnoitiosis for histologic examination. Quantitative real-time PCR assay for Besnoitia spp was performed on tissue samples from 5 animals.

Results—Besnoitiosis was confirmed in 6 of the 8 suspected cases. The most common lesion site was the nares, followed by the skin and sclera. Donkeys with clinical signs of disease had higher serum antibody titers and tested positive for a greater number of immunoblot bands than did donkeys without clinical signs of disease. All animals evaluated by PCR assay tested positive. Putative risk factors for disease included age and sex. Ponazuril was not effective at treating besnoitiosis in a naturally infected donkey.

Conclusions and Clinical Relevance—Knowledge of clinical and serologic features of besnoitiosis in donkeys will assist clinicians in the diagnosis and prevention of this disease in donkey populations. Besnoitiosis may be an emerging disease of donkeys in the United States.

Full access
in Journal of the American Veterinary Medical Association