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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To establish and compare the precision of serum total protein (STP) measured by an optical refractometer to the precision of IgG concentrations measured using radial immunodiffusion (RID), the reference test for quantifying IgG in neonatal calves.

SAMPLE

6 sera with previously measured IgG concentration using RID from neonatal beef calves were selected from 3 stratum: low-serum IgG stratum between >5.0 and <15.0g/L(n = 4); moderate-serum IgG stratum between 35.0–45.0g/L(n = 1); high-serum IgG stratum between 60.0–70.0g/L(n = 1).

METHODS

STP was measured 13 times with an optical refractometer. IgG concentrations were measured 28 times with a commercial bovine IgG RID for each sera. The homogeneity of variance within the tests was evaluated with the Levene test (α = 0.10). Unrestricted random sampling bootstrapping (5,000 repetitions) was used to calculate the coefficient of variation (CV) for each serum and test. The homogeneity of variance between simulated test CVs by serum was evaluated (α = 0.10). Differences between simulated test CV by serum were assessed with the Kruskal-Wallis test (α = 0.05).

RESULTS

No difference was observed in the variance for STP between sera (P = .39). The average CV for STP was 4.2%, 10.1% for the low IgG stratum, and 15.5% for the moderate/high IgG stratum. Variance differed in serum IgG concentration (P < .0001). Serum with higher IgG concentrations had more variance. Simulated CV for STP and IgG had homogeneity of variance for only 1 sera (P = .31). STP had a smaller CV compared to IgG for every serum (P < .0001).

CLINICAL RELEVANCE

Estimating IgG concentration directly by RID or indirectly by STP lacks the precision that might affect diagnostic interpretation regarding a calf’s absorption of maternal antibodies.

Open access
in American Journal of Veterinary Research

Abstract

Objective—To assess the effect of dietary potassium citrate supplementation on the urinary pH, relative supersaturation of calcium oxalate and struvite (defined as the activity product/solubility product of the substance), and concentrations of magnesium, ammonium, phosphate, citrate, calcium, and oxalate in dogs.

Animals—12 healthy adult dogs.

Procedure—Canned dog food was fed to dogs for 37 days. Dogs were randomly allocated to 3 groups and fed test diets for a period of 8 days. Study periods were separated by 6-day intervals. During each study period the dogs were fed either standard diet solus (control) or standard diet plus 1 of 2 types of potassium citrate supplements (150 mg potassium citrate/kg of body weight/d) twice daily. Urinary pH, volume and specific gravity, relative supersaturation of calcium oxalate and struvite, and concentrations of magnesium, ammonium, phosphate, calcium, oxalate, and citrate were assessed for each treatment.

Results—Mean urine pH was not significantly affected by dietary potassium citrate supplementation, although urine pH did increase by 0.2 pH units with supplementation. Diets containing potassium citrate maintained a higher urine pH for a longer part of the day than control diet. Three Miniature Schnauzers had a significantly lower urinary relative calcium oxalate supersaturation when fed a diet supplemented with potassium citrate, compared with control diet.

Conclusions and Clinical Relevance—Dietary potassium citrate supplementation has limited effects on urinary variables in most healthy dogs, although supplementation results in maintenance of a higher urine pH later in the day. Consequently, if supplementation is introduced, dogs should be fed twice daily and potassium citrate should be given with both meals or with the evening meal only. (Am J Vet Res 2000;61:430–435)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether kinematic changes induced by heel pressure in horses differ from those induced by toe pressure.

Animals—10 adult Quarter Horses.

Procedure—A shoe that applied pressure on the cuneus ungulae (frog) or on the toe was used. Kinematic analyses were performed before and after 2 levels of frog pressure and after 1 level of toe pressure. Values for stride displacement and time and joint angles were determined from horses trotting on a treadmill.

Results—The first level of frog pressure caused decreases in metacarpophalangeal (fetlock) joint extension during stance and increases in head vertical movement and asymmetry. The second level of frog pressure caused these changes but also caused decreases in stride duration and carpal joint extension during stance as well as increases in relative stance duration. Toe pressure caused changes in these same variables but also caused maximum extension of the fetlock joint to occur before midstance, maximum hoof height to be closer to midswing, and forelimb protraction to increase.

Conclusion and Clinical Relevance—Decreased fetlock joint extension during stance and increased head vertical movement and asymmetry are sensitive indicators of forelimb lameness. Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance are general but insensitive indicators of forelimb lameness. Increased forelimb protraction, hoof flight pattern with maximum hoof height near midswing, and maximum fetlock joint extension in cranial stance may be specific indicators of lameness in the toe region. Observation of forelimb movement may enable clinicians to differentiate lameness of the heel from lameness of the toe. (Am J Vet Res 2000;61:612-619)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of sedation achieved by xylazine (XYL) or acepromazine (ACE) on cardiopulmonary function and uterine blood flow in cows in late gestation.

Animals—8 cows between 219 and 241 days of gestation.

Procedure—Doses of ACE (0.02 mg/kg) or XYL (0.04 mg/kg) were administered IV. Measurements were obtained to determine cardiopulmonary effects and oxygen delivery to the uterus.

Results—Heart rate was not significantly affected by administration of ACE, but it decreased markedly after administration of XYL. Uterine artery flow was decreased at all times by XYL and was always less than for ACE. Xylazine increased uterine vascular resistance through 30 minutes and caused reduced PaO2 and increased PaCO2 at all time periods. Acepromazine caused a 5% decrease in PaO2 only at 5 minutes. Xylazine reduced oxygen delivery by 59% at 5 minutes and 32% at 45 minutes. In contrast, ACE caused a nonsignificant reduction of oxygen delivery by 16% at 15 minutes and a return to baseline values by 45 minutes

Conclusions and Clinical Relevance—Xylazine markedly reduces flow and availability of oxygenated blood to the uterus, which may critically impair delivery of oxygen to the fetus at a stressful and important time of development or delivery. Acepromazine was associated with slight reductions of much shorter duration. When XYL is used to sedate pregnant cows, it could impose physiologic distress on the fetus and potentially increase fetal morbidity and mortality. When sedation of the dam is desirable, ACE could be an alternative to XYL. (Am J Vet Res 2002;63:1695–1699)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate trends in feedlot cattle mortality ratios over time, by primary body system affected, and by type of animal.

Design—Retrospective cohort study.

Animals—Approximately 21.8 million cattle entering 121 feedlots in the United States during 1994 through 1999.

Procedures—Yearly and monthly mortality ratios were calculated. Numbers of deaths were modeled by use of Poisson regression methods for repeated measures. Relative risks of death over time and by animal type were estimated.

Results—Averaged over time, the mortality ratio was 12.6 deaths/1,000 cattle entering the feedlots. The mortality ratio increased from 10.3 deaths/1,000 cattle in 1994 to 14.2 deaths/1,000 cattle in 1999, but this difference was not statistically significant (P = 0.09). Cattle entering the feedlots during 1999 had a significantly increased risk (relative risk, 1.46) of dying of respiratory tract disorders, compared with cattle that entered during 1994, and respiratory tract disorders accounted for 57.1% of all deaths. Dairy cattle had a significantly increased risk of death of any cause, compared with beef steers. Beef heifers had a significantly increased risk of dying of respiratory tract disorders, compared with beef steers.

Conclusions and Clinical Relevance—Results suggested that although overall yearly mortality ratio did not significantly increase during the study, the risk of death attributable to respiratory tract disorders was increased during most years, compared with risk of death during 1994. The increased rates of fatal respiratory tract disorders may also reflect increased rates of non-fatal respiratory tract disorders, which would be expected to have adverse production effects in surviving animals. (J Am Vet Med Assoc 2001;219:1122–1127)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify, by means of 24-hour ambulatory electrocardiography, electrocardiographic abnormalities in overtly healthy Doberman Pinschers in which results of echocardiography were abnormal.

Design—Clinical case series.

Animals—56 (35 male, 21 female) overtly healthy Doberman Pinschers with echocardiographic evidence of cardiomyopathy on initial examination that subsequently died of cardiomyopathy.

Procedure—Twenty-four-hour ambulatory electrocardiographic (Holter) recordings obtained at the time of initial examination were reviewed. For all dogs, scan quality was > 90%.

Results—Initial Holter recordings of all 56 dogs contained ventricular premature contractions (VPC). Thirty-six (65%) dogs had > 1,000 VPC/24 h, 17 (31%) had > 5,000 VPC/24 h, and 11 (19%) had > 10,000 VPC/24 h. Fifty-four (96%) dogs had couplets of VPC, 37 (66%) had triplets of VPC, and 36 (64%) had episodes of nonsustained (< 30 seconds) ventricular tachycardia. Number of VPC/24 h during the initial Holter recordings was positively correlated with numbers of couplets and triplets of VPC and number of ventricular escape beats and negatively correlated with left ventricular fractional shortening. Twentyeight dogs died suddenly prior to the putative onset of congestive heart failure.

Conclusions and Clinical Relevance—Results suggested that along with echocardiography, 24-hour ambulatory electrocardiography can be used to help identify overtly healthy Doberman Pinschers with cardiomyopathy. (J Am Vet Med Assoc 2000;217: 1328–1332)

Full access
in Journal of the American Veterinary Medical Association