In vitro dose-dependent effects of enrofloxacin on equine articular cartilage.

OBJECTIVE: To determine whether enrofloxacin has detrimental, dose-dependent effects on equine articular cartilage in vitro. ANIMALS: Cartilage explants were developed from 6 healthy horses between 0 and 96 months old. PROCEDURE: Patellar cartilage explants were incubated in 5 concentrations of enrofloxacin (2 microg/ml, 10 microg/ml, 1,000 microg/ml, 10,000 microg/ml, and 50,000 microg/ml) for 72 hours. Proteoglycan synthesis (Na35SO4 incorporation for 24 hours), proteoglycan degradation (Na35SO4 release for 72 hours), endogenous proteoglycan content (dimethylmethlene blue assay), and total protein content were determined. Cartilage explants were evaluated by use of histomorphologic and histomorphometric techniques (toluidine blue stain) for cytologic and matrix characteristics. Quantitative data were analyzed with a one-way ANOVA to compare results among various enrofloxacin concentration groups and the control group. A general linear model was used to determine whether age had an effect. RESULT: Proteoglycan synthesis was excellent in control specimens and in specimens incubated in low concentrations of enrofloxacin (2 microg/ml and 10 microg/ml). High concentrations of enrofloxacin (> 1,000 microg/ml) effectively eliminated proteoglycan synthesis regardless of horse age. Proteoglycan degradation at low concentrations (2 microg/ml and 10 microg/ml) was not different than control. High concentrations of enrofloxacin (> 1,000 microg/ml) caused significant degradation. Different concentrations of enrofloxacin did not affect endogenous proteoglycan. High concentrations of enrofloxacin were associated with a significant increase in number of pyknotic nuclei. CONCLUSION: Concentrations of enrofloxacin that might be achieved following systemic administration did not suppress chondrocyte metabolism in vitro. High concentrations of enrofloxacin (> 1,000 microg/ml) were toxic to chondrocytes.     

Serotypes of Pasteurella haemolytica and Pasteurella trehalosi isolated from farm animals in Hungary.

The biochemical and serological characteristics of 486 P. haemolytica and 31 P. trehalosi strains (517 in total) isolated from different lesions of cattle, sheep, goats, pigs and poultry were examined. A total of 476 P. haemolytica strains (97.9%) showed the characteristics typical of the former biotype A of P. haemolytica, while 10 isolates (2.1%), all from poultry, could not be biotyped. A total of 481 strains (93.0%) could be assigned to one of the 17 serotypes of P. haemolytica-P. trehalosi and 36 strains (7.0%) could not. The majority (83.6%) of the cattle isolates were serotypes A1 and A2. Among strains isolated from sheep all serotypes of P. haemolytica could be identified with the exception of A14, but serotypes A1, A2, A6, A8 and A5 were the most frequent. The overwhelming majority (94%) of the caprine isolates were A2, other serotypes occurred only sporadically. The pig isolates, which could be isolated only very rarely, represented different serotypes, while none of the 10 strains isolated from poultry could be biotyped or serotyped.     

The efficacy of used engine oil against ticks on cattle

The study was conducted in a peri-urban agricultural system at Botshabelo, a city in the south-eastern Free State. A questionnaire survey revealed that 88.5% of cattle farmers in the area experienced problems related to ticks and tick-borne diseases. Because of the cost of commercial acaricides the Botshabelo farmers use alternative, cheaper methods of tick control, including the application of used engine oil. The specific aim of the study was to determine whether used engine oil can effectively control ticks on cattle. From March to August 1996 the tick burdens of ten control animals and six animals treated by their owner with used engine oil were compared. The total tick burdens for the 6 month period differed significantly between the two experimental groups. The efficacy of the used engine oil on the treated group varied between 15.1% and 64.8% with a mean of 38.1%. Although commercial acaricides can be more cost-effective, the application of used engine oil can be useful to reduce tick numbers on cattle during periods of peak abundance. Another advantage in that the use of the oil will not influence existing endemic stability of Anaplasma marginale and Babesia bigemina infections because of the residual tick burdens after treatment.     

The incidence of caseous lymphadenitis in Alberta sheep and assessment of impact by vaccination with commercial and experimental vaccines.

In Alberta, caseous lymphadenitis (CLA) is one of the leading causes of lamb and mutton carcass condemnation. In this study, serologic results confirmed a high (50-94%) incidence of exposure to Corynebacterium pseudotuberculosis, the causative agent of CLA, in mature, unvaccinated sheep in southern Alberta. To assess the efficacy and impact of vaccination with 2 commercial (Glanvac-6 and Case-Vac) and 1 experimental (WC+ MDP-GDP) CLA vaccines, a series of 3 field trials in 3249 ewes and lambs was conducted in affected flocks from 1992-1996. Efficacy was assessed from the serological response to vaccination, prevalence and size of injection site reactions by treatment, and the incidence of CLA abscesses. Overall, agglutinating antibody titres to C. pseudotuberculosis in lambs vaccinated with WC+MDP-GDP and Case-Vac remained significantly elevated above nonvaccinated control lambs for the 12 mo period after the initial vaccination. Lambs vaccinated with the WC/MDP-GDP maintained higher titres (P < 0.06) than those vaccinated with Case-Vac for the period from 6 to 12 mo after vaccination. Agglutinating antibody titres for lambs vaccinated with Glanvac did not differ from those of controls at any point during the 12 mo period after vaccination. The number of injection site reactions was elevated in lambs vaccinated with Glanvac as compared to those vaccinated with WC+MDP-GDP but the size of injection site reactions did not significantly differ. Sheep vaccinated with WC+ MDP-GDP also had a reduced incidence of putative CLA abscesses, although confirmation of the presence of C. pseudotuberculosis was only successful in a small number of instances.     

ULTRASONOGRAPHIC DETECTION OF ADRENAL GLAND TUMOR AND URETEROLITHIASIS IN A GUINEA PIG

A 5-year-old guinea pig was presented to the University of Berne Small Animal Radiology Department for an ultrasound examination of the abdomen to confirm a suspected diagnosis of Cushing's syndrome. The patient had bilateral alopecia, was apathic and obese. Ultrasonographically, a tumor of the left adrenal gland, obstruction of the left ureter by an ureterolith, as well as hydronephrosis of the left kidney were detected. During surgery to relieve the ureteral obstruction the adrenal gland tumor was removed. The guinea pig died post-operatively due to blood loss. The left adrenal gland tumor was found histopathologically to be an adenoma and the right adrenal gland also had multiple small adenomas, but grossly appeared normal. The ureterolith was analyzed and found by x-ray diffraction to consist of calcium carbonate.     

Progressive bradycardia,a possible factor in the pathogenesis of ascites in fast growing broiler chickens raised at low altitude

1. The first objective was to evaluate baseline heart rate (HR) responses in fast growing broilers fed ad libitum from 1 to 45d or subjected to a food restriction (85%, 70% and 55% of ad libitum from 7 to 21d) and a refeeding (22 to 45d) regimen in a normal thermal environment. The second was to evaluate HR and haematocrit responses in fast growing broilers reared at a low environmental temperature and fed ad libitum (A-L) from 1 to 42d, subjected to food restriction (70% ad libitum ) between 7 to 21d and refed thereafter (R-R), or subjected to food restriction between 7 to 42d (R), and to follow the changes in normal birds and those prone to ascites. 2. The baseline HR in the normal thermal environment at 21 and 45d in birds fed ad libitum was lower (P < 0.001) than at 7d. The food-restricted groups had higher HRs at 21d than at 7d, with the differences significant (P < 0.01) for the 70% and 55% treatments. At 21d the HRs in restricted groups were significantly higher (P < 0.01) than in ad libitum -fed birds. After returning to ad libitum feeding the HRs in these birds tended to decline, with the differences significant (P < 0.05) for the 70% and 55% treatments. 3. In the birds exposed to cold, each feeding regimen produced distinct patterns of change in HR and haematocrit. Both feeding regimen and age had significant (P < 0.001) effects on the changes of both variables. Relative to 7d, on 14d and 21d the HRs decreased and haematocrits increased in all groups, but the rates of change were highest in the A-L and R-R birds. The first fulminant cases of ascites were observed during the third week in the A-L group and during the fourth week in the R-R group. None of the chickens from the R group developed ascites. Altogether, the incidence of ascites was 48% in the A-L group and 28% in the R-R group. 4. Among the birds exposed to cold, the ascitic birds had significantly (P < 0.001) lower HRs and higher haematocrits than normal birds from the same feeding regimen group. The time trends in the rates of change in HR and haematocrit were distinctly different (P < 0.001) for ascitic and normal birds. The change in feeding regimen from restricted to ad libitum in the R-R group resulted in a significant (P < 0.001) decrease in HR and increase in haematocrit. 5. In view of the evidence presented, it appears that hypoxaemia and tissue hypoxia in broiler chickens may be a result of circulatory insufficiency associated with progressive bradycardia rather than, as commonly believed, pulmonary insufficiency. In this situation the pulmonary hypertension may be a secondary symptom.     

Nutritional considerations for equine rhabdomyolysis syndrome

Exertional rhabdomyolysis represents a syndrome of typically recurrent exercise‐associated muscle damage in horses that arises from a variety of aetiologies. Major advances have been made in recent years in our understanding of the pathophysiology of equine rhabdomyolysis syndrome (ERS), and a few specific causative genetic defects have been identified. Despite the fact that there is no single procedure or set of procedures (including diet and management) that can guarantee against further episodes of ERS, appropriate management of susceptible individuals, including nutrition, may help to reduce the likelihood, severity or frequency of future episodes. Whilst the dietary advice can be more specific and targeted for those with a known intrinsic muscle problem, for all affected individuals, regardless of the underlying cause, a balanced diet (which is suitable for the individual), together with a well‐designed exercise programme, should be the initial management target. This paper will briefly review the condition and give general nutrition and management advice.     

Cover Image,Volume 15, Issue 3

The cover image, by M. E. Gray et al., is based on the Original Article Dual targeting of EGFR and ERBB2 pathways produces a synergistic effect on cancer cell proliferation and migration in vitro, DOI: 10.1111/vco.12230 .

     

Colostral immunoglobulin concentrations in Holstein and Guernsey cows.

OBJECTIVE: To compare the concentration of IgG in colostrum between Holstein and Guernsey cows and among cows of various lactations. DESIGN: Cross-sectional cohort study. SAMPLE POPULATION: Colostrum samples from 77 Holstein and 24 Guernsey cows. PROCEDURE: Colostrum samples were obtained from 101 cows. Colostral IgG concentration was determined, using a radial immunodiffusion assay. Regression analysis was used to determine the effect of breed and lactation number on colostral IgG concentration. Survival analysis and t-tests were used to compare the proportion of colostrum samples that would provide 100 g of IgG for various volumes of colostral intake. RESULTS: Guernsey cows produced 36.4 g of IgG/L of colostrum more than that of Holstein cows. Cows in the third or greater lactation produced 19.5 g of IgG/L of colostrum more than that of first-lactation cows. The IgG concentration of colostrum produced by second-lactation cows did not differ significantly from that produced by first-lactation cows. The colostral IgG concentration of these Holstein and Guernsey cows was higher than values that have been reported elsewhere. CONCLUSIONS AND CLINICAL RELEVANCE: Volume of colostrum needed to meet IgG intake goals is probably lower for Guernsey cows than Holstein cows. Colostrum from first-lactation cows was adequate in IgG content. The practice of discarding colostrum from first-lactation cows on the basis of inadequate IgG content was not justified in this study.     

Control of the weaning-to-estrus interval in sows using gonadotropins and prostaglandins during lactation.

Two experiments were conducted to examine the effectiveness of various strategies using gonadotropins to induce ovulation during lactation as a means of controlling the weaning-to-estrus interval in sows. The objective of Exp. 1 was to examine the efficacy of various gonadotropin regimens for induction of ovulation during lactation. Primiparous (n = 60) and multiparous (n = 83) crossbred sows were assigned, before farrowing, to one of four treatments: no injection (control); 1,000 IU hCG on d 0 (hCG-0; d 0 = day of farrowing); P.G. 600 + 1,000 IU hCG 4 and 7 d after farrowing, respectively (hCG-7); or P.G. 600 + 1,000 IU hCG 11 and 14 d after farrowing, respectively (hCG-14). Sows were weaned on 18 +/- 2 d after farrowing and monitored daily for estrus via exposure to mature boars. The criterion for determining the induction of ovulation was a sustained increase in serum progesterone concentrations above 4.0 ng/mL. The most consistent response to exogenous gonadotropins was on d 0, with an 80% response in primiparous sows (12/15) and a 71% response in multiparous sows (15/21). Weaning-to-estrus intervals for multiparous sows were longer (P = .05) for hCG-14 and hCG-7 than for control and hCG-0 sows. Weaning-to-estrus intervals for primiparous sows were longer (P = .05) for the hCG-14 than for the hCG-0 treatment. The objective of Exp. 2 was to ascertain the effects of postpartum treatment with hCG (1,000 IU) on d 0 and PGF2alpha (10 mg) at d 14 on the weaning-to-estrus interval in multiparous sows weaned at d 14 after birth. Before farrowing, sows (n = 60) were randomly assigned to one of four treatments: positive control, weaning at d 21; negative control, weaning at d 14; hCG within 24 h after farrowing, weaning at d 14; or hCG within 24 h after farrowing and PGF2alpha at weaning, weaning at d 14. Weaning-to-estrus intervals were longer (P = .05) in sows receiving PGF2alpha than in the other treatments. Results indicate that it is possible to induce ovulation immediately after farrowing, using a single injection of hCG, and this strategy can be used to uncouple weaning from the resumption of reproductive activity. However, the administration of PGF2alpha at 14 d after farrowing did not consistently cause regression of the induced corpora lutea.