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Abstract

OBJECTIVE To evaluate the effects of adjunctive treatment with autologous platelet-rich plasma (PRP) on corneal reepithelialization, vascularization, and fibrosis in dogs with spontaneous chronic corneal epithelial defects (SCCEDs).

DESIGN Randomized, controlled, double-masked clinical trial.

ANIMALS 40 client-owned dogs with uncomplicated SCCEDs.

PROCEDURES All dogs were treated with diamond-burr epithelial debridement (DBD) of affected eyes, topical tobramycin solution and atropine sulfate ointment application, and Elizabethan collar placement for 4 weeks. Dogs were randomly assigned to topical ocular administration of autologous PRP (n = 20) or artificial tear solution (control group; 20) 4 times daily for 28 days. Recheck examinations were performed approximately 2 and 4 weeks after treatment began to evaluate SCCEDs for corneal reepithelialization, and semiquantitative corneal vascularization and corneal fibrosis scores were assigned according to affected corneal surface area. Results were compared between groups.

RESULTS All dogs completed the study. The SCCEDs had completely reepithelialized in 11 (55%) control dogs and 12 (60%) PRP-treated dogs by the 2-week reevaluation, and in 15 (75%) control dogs and 18 (90%) PRP-treated dogs by the 4-week reevaluation. No significant differences were identified between groups in these proportions nor in mean differences from pretreatment scores for corneal vascularization and fibrosis.

CONCLUSIONS AND CLINICAL RELEVANCE In this preliminary study involving dogs with uncomplicated SCCEDs, topical PRP administered as an adjunctive treatment following DBD had no significant effect on healing. A larger study is warranted to support or refute these findings and to determine the effects of adjunctive PRP treatment for dogs with complicated SCCEDs.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Case Description—6 alpaca crias from a single farm were examined because of diarrhea (n = 4) or decreased fecal production (n = 2).

Clinical FindingsCryptosporidium parvum was identified by means of fecal flotation in samples from 5 of the 6 crias, and a diagnosis of cryptosporidiosis was made. In the remaining cria, a presumptive diagnosis of cryptosporidiosis was made. Three people involved in caring for the crias from this farm were subsequently confirmed to have cryptosporidiosis, and 3 other people were suspected to have cryptosporidiosis. Sequence analysis of the ssu rDNA gene loci confirmed C parvum as the causative agent in 4 of the 6 crias. Subsequent evaluation of the farm revealed 2 additional crias confirmed to have cryptosporidiosis. Stocking densities on the farm were high, with approximately 20 adults/acre in some pastures.

Treatment and Outcome—All 6 hospitalized crias were given supportive treatment consisting of antimicrobials, gastroprotectants, and fluids. All but 1 survived. Farm owners were advised to decrease stocking density on the farm.

Clinical Relevance—Findings suggested that zoonotic transmission of C parvum from alpacas to humans can occur.

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

The isoflurane-sparing effect of the α2-adrenergic agonist medetomidine (30 μg/kg of body weight, IV) was tested in 7 dogs, using a blinded, randomized-block study design. The baseline minimal alveolar concentration (mac) of isoflurane was 1.18 vol% (95% confidence interval [097,1.39])- Medetomidine significantly (P < 0.003) reduced isoflurane mac by 47.2%. Atipamezolc (0.3 mg/kg, iv), an α2-adrenergic antagonist, completely reversed the effect of mcdetomidine on isoflurane mac. Atipamezole alone did not significantly alter isoflurane mac.

After medetomidine administration, marked bradycardia developed in all dogs and persisted for more than 2 hours Mean arterial blood pressure increased acutely, but later decreased, and hypotension persisted for more than 2 hours. Atipamezole reversed the bradycardic and hypotensive effects of medetomidine.

Results of this study indicate that medetomidine mav be useful in clinical cases in which isoflurane mac-reduction is desirable and that atipamezole might be used to reverse desirable and undesirable effects of medetomidine during isoflurane anesthesia.

Free access
in American Journal of Veterinary Research

SUMMARY

A retrospective study was designed to determine the distribution of equine monocytic ehrlichiosis among the equine population in New York state, and to identify factors associated with risk of disease. Serum samples submitted to the diagnostic laboratory of the university during the period from January 1985 through December 1986 were examined for antibodies to Ehrlichia risticii, using the indirect fluorescent antibody technique. Factors evaluated included geographic origin and date of submission of the sample, and age, breed, and sex of the horse. Logistic regression analysis was used to identify which factors were significantly associated with the risk of seropositivity to E risticii, while simultaneously controlling for other factors.

Of the 2,579 tested samples, 1,950 (76%) had positive results. Factors significantly associated with risk of seropositivity to E risticii were: breed of the horse (Thoroughbreds were 3 times more likely to have been exposed to E risticii, compared with non-Standardbred, non-Thoroughbred breeds); sex (female horses were 2.7 times more likely to have been exposed, compared with male horses); age of the horse (the risk of being exposed to E risticii increased with age, peaked at around 12 years, and decreased thereafter); and month of submission (horses tested during November and December had the highest odds of being seropositive [odds ratio = 2.1], and horses tested during March through April were least likely to be seropositive [odds ratio = 0.5], compared with horses tested during January and February).

Free access
in American Journal of Veterinary Research

Abstract

Objective

To compare chondrocyte proliferation and metabolism in three-dimensional fibrin cultures formed from polymerized autogenous fibrinogen with that of commercially manufactured fractionated fibrinogen.

Animals

Fibrinogen and chondrocytes for in vitro experimentation derived from 2 horses, ages 12 and 14 months, donated for reasons unrelated to skeletal or hematologic abnormalities.

Procedure

Fibrinogen was isolated from whole blood, using plasma cryoprecipitation and centrifugation, and fractionated fibrinogen was purchased. Each was mixed with 10 × 106 chondrocytes/0.5 ml of fibrinogen, and was polymerized by addition of 0.5 ml of calcium-activated thrombin. Thirty 1-ml fibrin-chondrocyte disks were formed from each fibrinogen source and cultured for 0 (n = 6), 7 (n = 12), or 14 (n = 12) days. Chondrocyte metabolism and cell proliferation in each fibrin type were objectively assessed by assays for total proteoglycan content, [35S]proteoglycan accumulation, proteoglycan monomer size, and total DNA. Cell morphology and cartilage-specific cell function was evaluated by routine histologic, alcian blue histochemical, type-II collagen immunohistochemical, and type-II collagen in situ hybridization methods.

Results

Histologic examination indicated better retention of chondrocyte morphology in autogenous composites. Autogenous fibrinogen also stimulated greater chondrocyte proliferation (DNA content increased 1.4-fold on day 14) and supported higher proteoglycan accumulation (increased 1.4-fold on day 14), compared with commercial, fractionated fibrinogen. Abundant intracellular type-II procollagen mRNA was detected in autogenous fibrin cultures by in situ hybridization, and translation was confirmed by extensive pericellular type-II collagen accumulation.

Conclusions

Autogenous fibrinogen has an inherent capacity to maintain chondrocyte phenotypic metabolism that is reduced or absent in commercially prepared fibrinogen. Enhanced, differentiated cell function may be useful for in vivo applications, but represents an added variable that may confound in vitro experiments, and should be considered when designing studies of chondrocyte function. (Am J Vet Res 1998;59:514–520)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine and quantify risk factors associated with exposure of horses to the following serovars of Leptospira interrogans: pomona, autumnalis, and bratislava.

Animals

2,551 horses were randomly selected from a target population during the period of May 1991 to August 1993.

Procedures

Blood was collected from the horses and tested for antibodies to serovars, using the microscopic agglutination test. A titer ≥ 1:100 indicated seropositivity. Information was collected on each horse, its environment, and each farm's management practices. Logistic regression analysis was used to develop a multidimensional indexing system for indices of exposure and to identify factors significantly associated with the risk of seropositivity. These indices were: 1) rodent exposure; 2) wildlife exposure; 3) soil and water; and 4) management.

Results

Rodent exposure index value was associated with the risk of exposure to all 3 serovars. Management index value was positively associated with the risk of exposure to serovars pomona and bratislava, but not with risk of exposure to serovar autumnalis. Soil and water index value had a positive association with risk of exposure to serovars pomona and autumnalis, but not to serovar bratislava. The wildlife index value and the population density of horses turned out together were associated with the risk of exposure to serovar autumnalis. Age of horse in years was associated nonlinearly (years2) and linearly (years) with the risk of exposure to serovars autumnalis and bratislava, and only linearly with the risk of exposure to serovar pomona.

Conclusion

Risk of seropositivity to the 3 serovars of L interrogans varies according to age, management practices, population density of horses turned out together, and the values of the rodent exposure, wildlife exposure, and soil and water indices. (Am J Vet Res 1997;58:1097–1103)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effects of transforming growth factor-β1 (TGF-β1) on the synthesis of DNA, collagen, and proteoglycans (PG) by equine chondrocytes.

Sample Population

Articular cartilage obtained from multiple joints of a 4-month-old foal.

Procedure

Chondrocytes were isolated by collagenase digestion, cultured in monolayer, trypsinized, and implanted at a cellular density of 10 × 106 chondrocytes/ml in a three-dimensional fibrin matrix. Chondrocytes in culture were supplemented with TGF-β1 at concentrations of 0, 1, 5, or 10 ng/ml in serum-free medium or medium containing fetal bovine serum (FBS). Total PG accumulation, [35S]-labeled PG synthesis, PG monomer hydrodynamic size, type II collagen production, total DNA content, and [3H]thymidine incorporation into DNA were determined at 7 and 14 days of culture.

Results

Chondrocytes maintained a rounded phenotype, dedifferentiating slightly to a more fibroblastic appearance only in medium containing FBS and 10 ng of TGF-β1/ml. Type II collagen immunoreaction on day 14 was decreased in the pericellular matrix in cultures containing FBS and 1, 5, and 10 ng of TGF-β1/ml, and in all serum-free culture conditions compared to FBS and 0 ng of TGF-β1/ml. Total proteoglycan accumulation and [35S]-labeled proteoglycan synthesis in cultures on days 7 and 14 were increased by the addition of exogenous TGF-β1 in serum-free conditions and decreased by TGF-β1 in FBS-supplemented conditions. Calculation of the partition coefficients for PG indicated that there was synthesis of low molecular weight PG in serum-free conditions and larger sized proteoglycans in FBS-supplemented conditions. Proteoglycan molecular size was unchanged by the addition of TGF-β1. Total DNA content of chondrocytes increased with the addition of TGF-β1 in FBS-supplemented conditions and decreased in serum-free conditions.

Conclusions

In a solid three-dimensional fibrin matrix, the effects of TGF-β1 on chondrocyte biological activity depend on the culture duration and on the presence of FBS in the medium. Stimulatory effects of TGF-β1 were most pronounced in serum-free culture conditions with high concentration of TGF-β1 (5 and 10 ng/ml) on day 7 and with low concentration of TGF-β1 (1 ng/ml) on day 14.

Clinical Relevance

TGF-β1 may not be a suitable growth factor for enhancement of equine articular grafting in sites exposed to serum. (Am J Vet Res 1997;58:66–70)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether mean annual frequency and destination of equine travel was associated with exposure to Ehrlichia risticii and whether these associations were modified by horses’ place of residence.

Design

Cross-sectional study.

Sample Population

511 equine operations containing 2,587 horses were visited in New York state from a target population of 39,000 operations.

Procedure

Each horse was tested for serum antibodies against E risticii, using indirect fluorescent antibody. Information on the horse's travel history, farm's management practices, and surrounding ecology was obtained by personal interview and resource maps. Statistical analyses were performed on 2 cohorts of animals: all horses enrolled in the study and horses born on the property or that resided at least 4 years on the farm. Three countybased risk regions (RR) were identified by use of cluster analysis.

Results

Mean seroprevalence for each of the 3 RR was 2.4 (low risk), 8.5 (moderate risk), and 18.5% (high risk) for cohort 1 and 2.5, 8.0, and 18.4% for cohort 2. Among cohorts 1 and 2, pleasure riding and breeding trips were associated with exposure to E risticii, but horse residence (low, moderate, or high RR) was an effect modifier for these associations. Among cohort 1 and stratifying the analysis according to the RR for the travel destination, trail riding at low RR and trail riding at high RR were associated with exposure. Among cohort 2 and stratifying the analysis according to the RR for the travel destination, breeding trips were associated with exposure, and strong effect modification was present for horse residence (low, moderate, or high RR).

Conclusions

Only certain types of travel to specific RR were associated with higher risk of exposure to E risticii. In many instances, travel was not associated, or was associated, with a reduced risk of exposure.(Am J Vet Res 1996; 57: 272-277)

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine the in vitro half maximal effective concentration (EC50) of ganciclovir for canine herpesvirus-1 (CHV-1) and to evaluate the efficacy of ganciclovir ophthalmic gel in dogs with experimentally induced ocular CHV-1 infection.

ANIMALS 10 specific pathogen–free adult Beagles.

PROCEDURES Cytotoxicity and EC50 of ganciclovir for CHV-1 were determined during in vitro experiments. During an in vivo experiment, dogs with experimentally induced ocular CHV-1 infections received 1 drop of 0.15% ganciclovir (ganciclovir group; n = 5) or artificial tear (control group; 5) ophthalmic gel in both eyes 5 times daily for 7 days, then 3 times daily for 7 days. For each dog, ophthalmic and confocal microscopic examinations were performed at predetermined times to determine severity of ocular disease and inflammation. Conjunctival swab specimens were collected at predetermined times for PCR assay analysis to determine CHV-1 shedding.

RESULTS No in vitro cytotoxic effects were observed for ganciclovir concentrations ≤ 500μM. The EC50 of ganciclovir for CHV-1 was 37.7μM. No adverse effects associated with ganciclovir were observed during the in vivo experiment. Mean ocular disease and inflammation scores for the ganciclovir group were significantly lower than those for the control group. Mean duration of CHV-1 shedding for the ganciclovir group (0.4 days) was significantly shorter than that for the control group (6.2 days).

CONCLUSIONS AND CLINICAL RELEVANCE Topical administration of 0.15% ganciclovir ophthalmic gel was well tolerated and effective in decreasing clinical disease scores, ocular tissue inflammation, and duration of viral shedding in dogs with experimentally induced ocular CHV-1 infection.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To describe the in vivo confocal microscopy (IVCM) features of the corneal epithelium and stroma in dogs and cats with herpetic dendritic ulcerative keratitis.

ANIMALS

6 client-owned dogs and 10 client-owned cats with herpetic dendritic ulcerative keratitis (affected group) and 10 dogs and 10 cats from specific-pathogen-free laboratory colonies (nonaffected group).

PROCEDURES

After complete ophthalmic examination, IVCM corneal examination was performed on the clinically diseased eyes of animals in the affected group and on both eyes of animals in the nonaffected group. Results by species were compared between groups.

RESULTS

In the affected group, all 6 dogs had unilateral ocular lesions (total, 6 eyes examined), whereas 7 cats had unilateral lesions and 3 cats had bilateral lesions (total, 13 eyes examined). For the nonaffected group, 20 cat eyes and 20 dog eyes were examined. Corneal epithelial morphological abnormalities were identified in all examined eyes of animals in the affected group and in no examined eyes of the nonaffected group. Hyperreflective punctate opacities and inflammatory cells were present in all epithelial layers in examined eyes of affected animals but were absent in nonaffected animals. Similarly, Langerhans cells and anterior stromal dendritic cells were identified in corneas of eyes examined for animals in the affected group but not in any eye of animals in the nonaffected group. Stromal changes were less consistent in the affected group, but absent in the nonaffected group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that herpetic dendritic ulcerative keratitis in dogs and cats is associated with microanatomic corneal abnormalities that can be detected by IVCM.

Full access
in American Journal of Veterinary Research