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Abstract

Objective

To evaluate platelet aggregation responses in calves experimentally infected with a thrombocytopenia-inducing type II bovine viral diarrhea virus (BVDV) isolate (BVDV 890).

Animals

9 neonatal male Holstein calves.

Procedure

5 calves were inoculated with BVDV 890, and 4 were used as controls. Platelet aggregation studies and attempts to isolate BVDV from platelets were performed 2 days before, the day of, and every 2 days for 12 days after inoculation. Platelet function was assessed by means of optical aggregometry, using adenosine diphosphate and platelet-activating factor as agonists. Bovine viral diarrhea virus was isolated from purified platelet preparations by use of an immunoperoxidase monolayer assay.

Results

Maximum percentage aggregation and slope of the aggregation curve decreased over time in calves infected with BVDV. Bovine viral diarrhea virus was not isolated from platelets from control calves, but it was isolated from infected calves from 4 through 12 days after inoculation.

Conclusions and Clinical Relevance

Results suggest that platelet function may be depressed in calves infected with type II BVDV. Although the mechanism for altered platelet function was not determined, it likely involved an increase in the percentage of aged platelets in the circulation, a direct virus-platelet interaction, or an indirect virus-platelet interaction. Platelet dysfunction, in addition to thrombocytopenia, may contribute to the hemorrhagic syndrome associated with acute type II BVDV infection in calves. (Am J Vet Res 1999;60:1396–1401)

Free access
in American Journal of Veterinary Research

Objective

To determine whether intracameral injection of carbachol at the completion of phacoemulsification in dogs would prevent the increase in intraocular pressure (IOP) that can develop during the first 24 hours after surgery.

Design

Randomized controlled trial.

Animals

32 adult dogs undergoing elective unilateral or bilateral phacoemulsification.

Procedure

Dogs were randomly assigned to 1 of 4 groups with 8 dogs/group: phacoemulsification and intracameral administration of 0.5 ml of 0.01 % carbachol at the end of surgery; phacoemulsification, intraocular lens implantation, and intracameral administration of 0.5 ml of 0.01 % carbachol; phacoemulsification and intracameral administration of 0.5 ml of balanced salt solution; and phacoemulsification, intraocular lens implantation, and intracameral administration of 0.5 ml of balanced salt solution. Intraocular pressure was measured at 3 and 6 hours and the morning after surgery. Aqueous flare was also measured 6 hours and the morning after surgery.

Results

None of the dogs treated with carbachol developed postoperative ocular hypertension (ie, IOP > 27 mm of Hg), whereas 12 of 16 control dogs had ocular hypertension 3 hours after surgery. Intraocular pressure 3 hours after surgery was not significantly associated with phacoemulsification time or phacoemulsification power or with whether the dog received an intraocular lens implant. Severity of aqueous flare was similar for treated and control dogs.

Clinical Implications

Results suggested that intracameral administration of 0.01 % carbachol at the end of surgery was a safe and efficacious method of preventing the postoperative increase in IOP associated with phacoemulsification in dogs. (J Am Vet Med Assoc 1998;212:1885–1888)

Free access
in Journal of the American Veterinary Medical Association

Summary

Between October 1986 and September 1988, 37 cats with moderate to severe idiopathic myocardial failure (dilated cardiomyopathy) were evaluated prospectively. Low plasma taurine concentration and diet history including foods that can cause taurine deficiency were documented in most of the cats. Comparison with a retrospectively studied population of 33 cats with dilated cardiomyopathy diagnosed between 1980 and 1986 demonstrated that the clinical and historical findings in the 33 retrospectively studied cats were similar to those in the 37 cats studied prospectively. Clinical findings in the 2 groups were also similar to findings previously reported in the literature. Because clinical findings and diet history were similar in the prospective and retrospective groups, we believe that many cats in the latter group had diet-induced taurine deficiency. These findings support the conclusion that most cases of dilated cardiomyopathy in cats have a common etiopathogenesis related to diet and as such are preventable.

Free access
in Journal of the American Veterinary Medical Association

Summary

Between October 1986 and September 1988, 37 cats with moderate to severe idiopathic myocardial failure (dilated cardiomyopathy) were evaluated. Clinical management of these cats was similar to that described in the literature, except that it also included administration of 500 or 1,000 mg of the sulfur amino acid, taurine per day.

Early death (death within the first 30 days of treatment) occurred in 14 (38%) cats. One cat was lost to follow-up evaluation. Twenty-two cats (59%) had marked clinical and echocardiographic improvement and survived longer than 240 days. In all but 1 cat, the observed improvement in echocardiographic measurements persisted. Hypothermia and thromboembolism were positively associated with an increased risk of early death. Administration of digoxin did not significantly affect survival.

All 22 cats that survived > 30 days remained clinically stable despite withdrawal of all medications except taurine. Administration of taurine was eventually discontinued in 20 of the 22 cats and adequate taurine intake was thereafter provided for in the food.

The clinical response and 1-year survival rate of 58% (21 of 36 cats with a known outcome) in the taurine-treated group represents a marked improvement, compared with a 1-year survival rate of 13% (4 of 31 cats with a known outcome) in a retrospectively evaluated population of 33 cats with dilated cardiomyopathy.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of meloxicam on values of hematologic and plasma biochemical analysis variables and results of histologic examination of tissue specimens of Japanese quail (Coturnix japonica).

Animals—30 adult Japanese quail.

Procedures—15 quail underwent laparoscopic examination of the left kidneys, and 15 quail underwent laparoscopic examination and biopsy of the left kidneys. Quail in each of these groups received meloxicam (2.0 mg/kg, IM, q 12 h; n = 10) or a saline (0.9% NaCl) solution (0.05 mL, IM, q 12 h; control birds; 5) for 14 days. A CBC and plasma biochemical analyses were performed at the start of the study and within 3 hours after the last treatment. Birds were euthanized and necropsies were performed.

Results—No adverse effects of treatments were observed, and no significant changes in values of hematologic variables were detected during the study. Plasma uric acid concentrations and creatine kinase or aspartate aminotransferase activities were significantly different before versus after treatment for some groups of birds. Gross lesions identified during necropsy included lesions at renal biopsy sites and adjacent air sacs (attributed to the biopsy procedure) and pectoral muscle hemorrhage and discoloration (at sites of injection). Substantial histopathologic lesions were limited to pectoral muscle necrosis, and severity was greater for meloxicam-treated versus control birds.

Conclusions and Clinical Relevance—Meloxicam (2.0 mg/kg, IM, q 12 h for 14 days) did not cause substantial alterations in function of or histopathologic findings for the kidneys of Japanese quail but did induce muscle necrosis; repeated IM administration of meloxicam to quail may be contraindicated.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the impacts of the introduction of foot-and-mouth disease (FMD) and various FMD control programs in southern Thailand.

Animals—A native population of 562,910 cattle and 33,088 buffalo as well as 89,294 animals legally transported into southern Thailand.

Procedures—A quantitative risk assessment was used to ascertain the probability of FMD introduction, and an intrinsic dynamic model was used to assess impacts. Value for the transmission rate (β) was estimated. Five scenarios created to assess the impacts of nonstructural protein (NSP) testing, mass vaccination, and culling were examined. Impacts were assessed through an examination of the estimated annual cumulative incidence (ACI) of FMD. The ACIs of various scenarios were compared by use of the Tukey Studentized range technique.

Results—β was estimated at 0.115. Approximately 35,000 cases of FMD would be expected from the baseline situation. A 30% reduction of ACI was detected with the introduction of NSP antibody testing. Prophylactic vaccination resulted in an 85% reduction of ACI. Concurrent use of NSP antibody testing and vaccination reduced the ACI by 96%, and the addition of an eradication policy resulted in a slightly greater decrease in the ACI (98%).

Conclusions and Clinical Relevance—The study used epidemiologic models to investigate FMD control interventions. Results suggested that vaccination has more impact than the use of NSP testing. Use of the NSP test reduced ACI during peak seasons, whereas vaccination diminished the underlying incidence. The best mitigation plan was an integrated and strategic use of multiple control techniques.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine titers of serum antibodies against 3 genotypes of bovine parainfluenza 3 virus (BPI3V) in unvaccinated ungulates in Alabama.

ANIMALS 62 cattle, goats, and New World camelids from 5 distinct herds and 21 captured white-tailed deer.

PROCEDURES Serum samples were obtained from all animals for determination of anti-BPI3V antibody titers, which were measured by virus neutralization assays that used indicator (reference) viruses from each of the 3 BPI3V genotypes (BPI3V-A, BPI3V-B, and BPI3V-C). The reference strains were recent clinical isolates from US cattle. Each sample was assayed in triplicate for each genotype. Animals with a mean antibody titer ≤ 2 for a particular genotype were considered seronegative for that genotype.

RESULTS Animals seropositive for antibodies against BPI3V were identified in 2 of 3 groups of cattle and the group of New World camelids. The geometric mean antibody titer against BPI3V-B was significantly greater than that for BPI3V-A and BPI3V-C in all 3 groups. All goats, captive white-tailed deer, and cattle in the third cattle group were seronegative for all 3 genotypes of the virus.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that BPI3V-A may no longer be the predominant genotype circulating among ungulates in Alabama. This may be clinically relevant because BPI3V is frequently involved in the pathogenesis of bovine respiratory disease complex, current vaccines contain antigens against BPI3V-A only, and the extent of cross-protection among antibodies against the various BPI3V genotypes is unknown.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare degree of viremia and disease manifestations in calves with type-I and -II bovine viral diarrhea virus (BVDV) infection.

Animals—16 calves.

Procedure—Colostrum-deprived calves obtained immediately after birth were assigned to 1 control and 3 treatment groups (4 calves/group). Calves in treatment groups were inoculated (day 0) by intranasal instillation of 107 median tissue culture infective dose BVDV 890 (type II), BVDV 7937 (type II), or BVDV TGAN (type I). Blood cell counts and virus isolation from serum and leukocytes were performed daily, whereas degree of viremia was determined immediately before and 4, 6, 8, and 12 days after inoculation. Calves were euthanatized on day 12, and pathologic, virologic, and immunohistochemical examinations were performed.

Results—Type-II BVDV 890 induced the highest degree of viremia, and type-I BVDV TGAN induced the lowest. Virus was isolated more frequently and for a longer duration in calves inoculated with BVDV 890. A parallel relationship between degree of viremia and rectal temperature and an inverse relationship between degree of viremia and blood cell counts was observed. Pathologic and immunohistochemical examinations revealed more pronounced lesions and more extensive distribution of viral antigen in calves inoculated with type-II BVDV.

Conclusions and Clinical Relevance—Degree of viremia induced during BVDV infection is associated with severity of clinical disease. Isolates of BVDV that induce a high degree of viremia may be more capable of inducing clinical signs of disease. Strategies (eg, vaccination) that reduce viremia may control clinical signs of acute infection with BVDV. (Am J Vet Res 2001;62:1095–1103)

Full access
in American Journal of Veterinary Research