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SUMMARY

We tested the hypothesis that treatment of growing, susceptible (to hip dysplasia) pups by im administration of glycosaminoglycan polysulfates would mitigate the signs of incipient hip dysplasia. In 1 experiment, 7 pups, selected at random from 2 litters, were administered glycosaminoglycan polysulfates (2.5 mg/kg of body weight, im) twice weekly, and 7 control pups from the same litters were given sterile buffered 0.9% saline solution from the age of 6 weeks to 8 months. Hip joints were examined by radiography, with pups in the standard, limbs-extended position. At 8 months of age, all pups in this experiment did not manifest femoral head subluxation radiographically. The Norberg angle, a measure of coxofemoral congruity, improved from a mean ± sem value of 102° ± 1° in controls to 106° ± 1° in treated pups (P = 0.008). Pups were not subjected to necropsy.

In the second experiment, 8 pups were selected at random from 2 litters and were administered 5 mg of glycosaminoglycan polysulfates/kg, im, twice weekly from 6 weeks to 8 months of age. Similarly, 8 control pups were administered saline solution. At 8 months of age, hip joints were examined by radiography with pups in the standard position; at necropsy, intra-articular tissues were evaluated macroscopically and biochemically. Of 8 treated pups, none had subluxation radiographically, whereas 4 of 8 control dogs had femoral head subluxation. Mean Norberg angle on the radiographs was 109.7° ± 1.6° for the treated group and was 101.5° ± 1.6° for controls, representing a mean improvement in coxofemoral congruity of 8.2° in the treated pups. The radiographic diagnosis (normal vs dysplastic) and the Norberg angle measurements were significantly (P = 0.04 and 0.002, respectively) different for treated and control pups.

At necropsy, 1 of 8 treated pups had cartilage degeneration, whereas 4 of 8 control pups had cartilage degeneration. The mean pathologic score determined for the hip joints of treated pups was 1.6 ± 0.8, whereas for those of controls, the score was 3.3 ± 1.2 (P = 0.09). Normal (disease-free) pups had hip pathologic scores of zero. The mean fibronectin content of femoral head articular cartilage was reduced from 2.19 ± 0.61 μg/mg in nontreated pups to 0.59 ± 0.56 μg/mg for treated pups (P = 0.04).

Fibronectin content was used as a measure of the extent of cartilage degeneration, and the cartilage of disease-free hip joints contained 0.32 ± 0.03 μg/mg. The mean proteoglycan content of the cartilage was unaffected by drug treatment. A trend was evident for lower synovial fluid volume and lower ligament volume (more normal volumes) in treated pups, but the differences were not statistically significant.

Hip joint laxity was assessed by use of a distraction method during radiogaphy of pups in experiments 1 and 2. The differences in laxity determinations between the treated and control pups were not statistically significant.

Taken together, the data indicated that im administration of gycosaminoglycan polysulfates from 6 weeks to 8 months of age in growing pups that were susceptible to hip dysplasia resulted in less subluxation, as determined from the standard radiographic projection. Treated pups had closer coxofemoral congruity when they were 8 months old (P < 0.05); at necropsy, the joint pathologic scores of treated pups indicated a trend toward improvement (P < 0.09), but the differences were not statistically significant. The mechanism of action for this drug effect is unknown.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To isolate mesenchymal stem cells from adult horses and determine specific monolayer culture conditions required to enhance biochemically and phenotypically defined chondrocytic differentiation.

Animals

2 adult horse bone marrow donors without skeletal or hematologic abnormalities.

Procedure

Bone marrow was aspirated from the sternebra, and mesenchymal stem cells were isolated by centrifugation and cultured in monolayers. Subcultures were established in 24-well plates on day 13. Culture medium was harvested every 2 days, and culture of 12 of the 24 wells was terminated on day 6 and of the remaining wells on day 12. Medium proteoglycan content was determined for all samples, and proteoglycan monomeric size was determined for pooled samples from days 2-6 and 8-12. Total nucleated cell numbers were determined at culture termination on days 6 and 12. Histologic, histochemical, and collagen immunohistochemical analyses of multiwell chamber slides harvested on day 6 or 12 were performed.

Results

Mesenchymal cells were an abundant cellular constituent of bone marrow aspirates, and separation of hematopoietic elements was achieved by centrifugation and delayed medium exchange. The remaining mesenchymal stem cells progressed from large, spindyloid, fibroblastic-appearing cells to a rounder shaped cell which formed colony plaques; isolated cells remained more spindyloid. Mesenchymal cell transformation toward a chondrocytic phenotype was verified by a shift in expression from collagen type I to type II, and an increase in quantity and molecular size of proteoglycans synthesized over time.

Conclusions

Mesenchymal stem cells obtained from adult horses have the capacity to undergo chondrogenic differentiation in monolayer cultures and may provide a locally recruitable or transplantable autogenous cell source for articular cartilage repair. (Am J Vet Res 1998;59:1182-1187).

Free access
in American Journal of Veterinary Research

Objective

To determine effect of time of sample collection on serum thyrotropin (canine thyroid-stimulating hormone [cTSH]) concentrations in euthyroid and hypothyroid dogs.

Design

Prospective study.

Animals

6 healthy adult euthyroid dogs, 6 adult Beagles with 131iodine-induced hypothyroidism before and during administration of levothyroxine sodium, and 6 adult dogs with naturally developing hypothyroidism.

Procedure

Healthy euthyroid dogs were identified. Hypothyroidism was induced by administration of 131sodium iodide and confirmed by thyroid-stimulating hormone testing. These dogs then received levothyroxine for 30 days. Naturally developing hypothyroidism was diagnosed on the basis of clinical signs, low serum thyroxine (T 4) concentrations, and high cTSH concentrations or abnormal results on a thyrotropin-releasing hormone response test. Samples for measurement of cTSH and T4 concentrations were obtained at 2-hour intervals from 8 AM to 8 pm.

Results

Mean (± SD) serum cTSH concentrations for healthy dogs, dogs with induced hypothyroidism before and during treatment, and dogs with naturally developing hypothyroidism were 0.11 ± 0.08, 3.31 ± 1.30, 0.08 ± 0.07, and 0.55 ± 0.27 ng/ml, respectively. Diurnal variation in cTSH concentrations was not detected. Clinically important random fluctuations in cTSH concentrations were detected for dogs with naturally developing hypothyroidism.

Clinical Implications

Sample collection time does not appear to predictably influence cTSH concentrations; however, dogs with naturally developing hypothyroidism may have random fluctuations in cTSH concentrations. (J Am Vet Med Assoc 1998; 212:1572–1575)

Free access
in Journal of the American Veterinary Medical Association

Objective—

To determine whether onset of mineralization of the femoral and proximal tibial epiphyses and age at closure of the femoral and acetabular triradiate growth plates was different for Labrador Retrievers that were radiographically normal or that had canine hip dysplasia (CHD).

Design—

Cohort study.

Animals—

36 Labrador Retriever puppies.

Procedure—

Puppies were radiographed every other day from the time they were 8 to 10 days old until ossification of the femoral heads was apparent. Radiographs were then obtained weekly until puppies were 1 month old and then monthly until puppies were 8 to 12 months old. Age at which mineralization was first observed in the proximal and distal femoral and proximal tibial epiphyses and at which the femoral capital, triradiate acetabular, and distal femoral growth plates were no longer radiographically visible were recorded. Fifteen dogs were euthanatized and necropsied to determine whether dogs had CHD.

Results—

There were 26 radiographically normal left and right hip joints and 10 dysplastic left and right hip joints. Onset of mineralization of the proximal femoral epiphyses and of the right proximal tibial epiphysis was significantly later in dysplastic than in radiographically normal puppies. The left femoral capital growth plates closed significantly later in dysplastic than in radiographically normal joints, but other differences in growth plate closure were not detected.

Clinical Implications—

Endochondral ossification may be abnormal in dogs with CHD. The disease appears to affect multiple joints, even though it is most evident clinically in the hip joint. (J Am Vet Med Assoc 1997;210: 1458–1462)

Free access
in Journal of the American Veterinary Medical Association

Summary

A study was initiated to determine whether development of a functional ruminant digestive system was associated with alterations in plasma growth hormone (gh) concentration. Holstein bull calves were fed milk or milk with grain until studied at the age of 1 month (n = 12). Calves placed on pasture with some grain supplementation were studied at the age of 3 months (n = 6) to determine plasma gh concentration in an animal with fully developed ruminant metabolism. Blood samples were taken at 10-minute intervals for 5 hours, followed by administration of bovine gh-releasing factor (0.075 μg/kg of body weight) and subsequent blood sample collection for 1 hour. On the following day, a blood sample was collected via jugular cannula, clonidine (10 μg/kg) was administered, and blood samples were subsequently obtained. Data indicated that milk-fed calves had higher mean plasma gh concentration than did either milk/grain-fed or older calves. The difference in mean plasma gh concentration was related to higher secretory pulse amplitude. Pituitary responses to bovine gh-releasing factor did not differ among the 3 groups, but response to clonidine were greater in milk-fed calves than in calves of the other groups. These data indicate that the change from a nonruminant to a ruminant-type gastrointestinal tract, perhaps attributable to subsequent changes in metabolism, may induce changes in hypothalmic function to decrease gh concentration.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To develop a method for percutaneous collection of fetal fluid from cattle in the late stages of gestation and determine whether bovine viral diarrhea virus (BVDV) can be isolated from such fluids.

Design—Case series.

Animals—169 pregnant beef cattle.

Procedure—Animals were restrained in a squeeze chute, and hair was clipped from a region of the right flank. Pregnancy was confirmed, and fetal fluids were identified by means of abdominal ultrasonography. Fetal fluid was collected with a spinal needle. Virus isolation was performed on fetal fluids, WBC lysates from 160 live calves, and tissues from 12 calves that died or were aborted. Blood samples collected from adult cattle were assayed with an immunoperoxidase monolayer assay.

Results—Fourteen animals aborted or delivered premature calves within 3 weeks after fetal fluid collection; however, it could not be determined whether this was a complication of the procedure or attributable to other factors. Results of BVDV isolation from fetal fluid samples were negative for 168 animals. However, a noncytopathic BVDV was isolated from fetal fluid obtained from a 2-year-old heifer; results of the immunoperoxidase assay of serum from this heifer were also positive, and a noncytopathic BVDV was isolated from tissue specimens from a stillborn calf produced by this heifer.

Conclusions and Clinical Relevance—Results suggest that fetal fluids can be collected percutaneously from cattle in the late stages of gestation and that virus isolation performed on fetal fluids can be used to identify fetuses infected with BVDV in utero. However, safety of the procedure could not be evaluated. (J Am Vet Med Assoc 2002;220:1348–1352).

Full access
in Journal of the American Veterinary Medical Association

Objective—

To validate a new immunoradiometric assay for canine thyroid-stimulating hormone (cTSH) and to document changes in serum cTSH concentration during induction of hypothyroidism in dogs.

Animals—

Six healthy adult male Beagles.

Procedure—

Sensitivity, specificity, precision, and accuracy of the cTSH assay were evaluated in vitro. Hypothyroidism was induced in dogs by IV administration of sodium iodide I 131 solution. Subsequently, l-thyroxine was administered orally to normalize serum thyroxine concentrations.

Results—

The cTSH assay appeared to be specific and was sufficiently sensitive to detect cTSH in the serum of these dogs prior to induction of hypothyroidism. There was a 35-fold increase in mean serum cTSH concentration following induction of hypothyroidism, and 35 days after initiation of thyroid replacement therapy, mean serum cTSH concentration was not significantly greater than mean baseline value.

Clinical Implications—

Assay of serum cTSH is likely to prove helpful in the differential diagnosis of primary, secondary, and tertiary hypothyroidism in dogs, and in monitoring response to thyroid hormone replacement treatment. (J Am Vet Med Assoc 1996;209:1730–1732)

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Summary

A study was done to determine whether radiographic-distraction measurement of coxofemoral joint (hip) laxity at 4 and 8 months of age can serve as a predictor of hip dysplasia in older Labrador Retrievers. The method of Smith, Biery, and Gregor was used for radiologic examination of hips and for evaluation of radiographs. Mean (± sem) distraction laxity (ie, distraction index) for 10 adult disease-free dogs was 0.29 ± 0.05, whereas a group of 8 dogs with dysplastic hips had mean distraction index of 0.60 ± 0.10 (P < 0.05). Mean distraction index at 4 months of age for 11 pups of 4 litters from matings between dogs with normal hips was 0.39 ± 0.07, and was 0.54 ± 0.04 for 31 pups of 7 litters from matings between dogs with hip dysplasia. The distraction index and, thus, joint laxity at that age was significantly (P = 0.0351) different for the 2 groups. The distraction index at 4 months correlated positively with the distraction index at a later age at necropsy (r = 0.43; P = 0.0289). Distraction index < 0.4 at 4 months of age predicted normal hips in 88% of cases and distraction index ≥ 0.4 predicted hip dysplasia in 57% of the dogs. Logistic regression modeling indicated that the odds of a hip being normal decreased with increasing distraction index, and thus, with increasing joint laxity. The logistic regression models provided a reasonable mathematical description of the data. Based on the logistic model of the data, distraction indexes between 0.4 and 0.7 at either 4 or 8 months of age were not associated strongly enough with evidence of disease to be clinically reliable in predicting, on an individual basis, the outcome for dysplastic hip conformation when dogs were older. Index > 0.7 was associated with high probability for developing dysplastic joints and distraction index < 0.4 predicted normal hips with high probability.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effect of vitamin E supplementation on the immune system of dairy cows.

Design

The following immune parameters were followed: production of chemotactic factors and superoxide by mammary macrophages and chemotactic responsiveness of blood neutrophils.

Animals

16 healthy Holstein dairy cows.

Procedure

Dairy cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and vitamin E supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition, and included oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. In addition, the same group of cows received 1 injection of vitamin E (5,000 IU) 1 week prior to the expected date of parturition. Blood samples were collected weekly throughout the experimental period.

Results

Vitamin E supplementation enhanced by 30 to 83% (P < 0.05) chemotactic responsiveness of blood neutrophils beginning 2 weeks before to 4 weeks after parturition, compared with controls. There were no differences in production of superoxide or chemotactic factors by mammary macrophages between control and vitamin E-supplemented cows.

Conclusions

Vitamin E supplementation prevents the periparturient inhibition of neutrophil Chemotaxis. It is unlikely that vitamin E affects directly the function of mammary macrophages. (Am J Vet Res 1996;57:468–471)

Free access
in American Journal of Veterinary Research