Effects of implants on daily gains of steers wintered on dormant native tallgrass prairie, subsequent performance, and carcass characteristics

Fall-weaned crossbred steer calves (n = 300; 184 +/- 2.9 kg) received either no implant (Control) or were implanted with Synovex-C (SC = 10 mg estradiol benzoate + 100 mg progesterone), Synovex-S (SS = 20 mg estradiol benzoate + 200 mg progesterone), or Revalor-G (RG = 8 mg estradiol-17beta + 40 mg trenbolone acetate) to determine the effects of implants on weight gain during winter grazing on dormant tallgrass prairie, subsequent grazing and finishing performance, and carcass characteristics. Steers grazed two dormant tallgrass prairie pastures from October 16, 1996, until March 29, 1997 (164 d), and received 1.36 kg/d of a 25% CP supplement that supplied 100 mg of monensin/steer. Following winter grazing, all steers were implanted with Ralgro (36 mg zeranol) and grazed a common tallgrass prairie pasture until July 17 (110 d). After summer grazing, all steers were implanted with Revalor-S (24 mg estradiol-17beta + 120 mg trenbolone acetate), and winter implant treatment groups were equally allotted to four feedlot pens. Steers were harvested November 17, 1997, after a 123-d finishing period. Daily gains during the winter grazing phase averaged .28, .32, .32, or .35 kg/d, respectively, for Control, SC, SS, or RG steers and were greater (P < .01) for implanted steers than for Controls. Summer daily gains were similar (1.05 +/- .016 kg/d; P > or = .61) for all treatment groups. Feedlot daily gains were also similar (1.67 +/- .034 kg/d; P > or = .21), with implanted steers weighing 14 kg more than Control steers (P = .05) at harvest, despite similar management during summer grazing and feedlot phases. Control steers tended (P = .06) to have lower yield grades. There were no differences (P = .99) in marbling between implanted and nonimplanted steers. Steers implanted during the wintering phase had increased skeletal and overall (P < .01) carcass maturities compared with nonimplanted steers, which resulted in more "B" and "C" maturity carcasses. Because carcass maturity score affects quality grade, the increased maturities of implanted steers resulted in a $9.04 decrease in carcass value/100 kg (P < .01) compared with Controls. The results of this study indicate that growth-promoting implants are efficacious for cattle wintered on dormant native range despite low daily gains. This increased weight is maintained through the summer grazing and feedlot phases; however, the benefit of the increased weight may be offset by decreased carcass quality grade and value due to increased carcass maturity.     

A comparison of the bioequivalence of 0.5% fenbendazole top dress pellets or 10% fenbendazole oral suspension against a spectrum of equine parasites.

A controlled test was conducted to assess the efficacy bioequivalence of a single dose of 0.5% fenbendazole (FBZ) top dress pellets to a 10% FBZ suspension formulation (Panacur suspension 10%, Hoechst Roussel Vet). Thirty horses with naturally-acquired parasite infections, in replicates of three, were used. Strongyle egg per gram counts were not significantly different (P>0.1) between groups pretreatment, but FBZ treated groups were significantly different from the control group post-treatment. At necropsy, which occurred seven to nine days post-treatment, two methods of nematode recovery were compared to assess whether a small aliquot can be used in a control test to determine efficacy against large as well as small strongyles. Both post mortem worm recovery techniques revealed similar efficacies of both formulations (>95%) against small and large strongyles, but large differences in the number of worms recovered. Six species of small strongyles comprised 96% of all the small strongyles recovered: Coronocyclus coronatus, Cylicocyclus insigne, Cylicostephanus longibursatus, Cylicocyclus brevicapsulatus, Cylicocyclus nassatus, and Cyathostomum catinatum. The results of this study demonstrated therapeutic bioequivalence between FBZ formulations and also the need to sample at least a 10% aliquot to accurately estimate number of large strongyles. No adverse reactions to treatment were detected.     

Arthroscopic Subchondral Bone Plate Microfracture Technique Augments Healing of Large Chondral Defects in the Radial Carpal Bone and Medial Femoral Condyle of Horses

OBJECTIVE: To evaluate the effect of arthroscopic subchondral bone microfracture on healing of large chondral defects in horses. STUDY DESIGN: Short- (4 months) and long-term (12 months) in vivo experimental chondral defect model. ANIMALS: 10 horses, aged 2 to 5 years. METHODS: Each horse had a 1 cm2 full-thickness chondral defect created in both radial carpal bones and both medial femoral condyles. One carpus and one femoral condyle of each horse had the subchondral bone plate under the defect perforated using an orthopedic awl. All horses were exercised, five horses were evaluated after 4 months and five horses after 12 months. Gross, histologic, and histomorphometric examination of defect sites and repair tissues was performed, as was collagen typing of the repair tissue. RESULTS: On gross observation a greater volume of repair tissue filled treated defects (74%) compared with control defects (45%). Histomorphometry confirmed more repair tissue filling treated defects, but no difference in the relative amounts of different tissue types was observed. There was an increased percentage of type II collagen in treated defects compared with control defects and evidence of earlier bone remodeling as documented by changes in porosity. CONCLUSIONS: In full-thickness chondral defects in exercised horses, treatment with subchondral bone microfracture increased the tissue volume in the defects and the percentage of type II collagen in the tissue filling the defects when compared to nontreated defects. CLINICAL RELEVANCE: No negative effects of the microfracture technique were observed and some of the beneficial effects are the basis for recommending its use in patients cases with exposed subchondral bone.     

Potential central nervous system complications of von Willebrand's disease.

Three Doberman pinschers were presented on emergency referral for progressive neurological deficits. All three dogs had a similar onset of clinical signs associated with an apparently minor traumatic event. Each dog progressed to significant neurological dysfunction including paraplegia, tetraplegia, and/or loss of deep pain sensation. None of the animals was apparently affected by cervical vertebral instability ("Wobbler's Syndrome"). All were confirmed to have von Willebrand's disease. In all cases, significant epidural hemorrhage was identified. The etiology of each hemorrhage, however, was different for each animal. The cases presented here demonstrate a potential relationship between neurological deficits and the patient's ability to effectively coagulate blood. Hemostatic abnormalities, such as von Willebrand's disease, should be included as possible differential diagnoses or contributing factors in animals demonstrating neurological deficits. These abnormalities should especially be considered following trauma, intervertebral disk extrusion, or spinal surgery.     

Effects of dietary level of ruminally protected choline on performance and carcass characteristics of finishing beef steers and on growth and serum metabolites in lambs

Ruminally protected choline (RPC) was evaluated in two experiments. In Exp. 1, beef steers (n = 160; average initial BW = 350.9 kg) were fed a 90% concentrate diet with either 0, .25, .5, or 1.0% RPC (DM basis) for 112 to 140 d. Feeding .25% RPC increased ADG 11.6% compared with 0% RPC, but responses diminished with increasing RPC level (cubic response, P < .10). Daily DMI was not affected by RPC level, but feed:gain was improved 6.8% with .25% RPC compared with 0% RPC, and responses diminished with increasing RPC level (cubic response, P < .10). Carcass yield grade increased linearly (P < .10) as RPC level increased, but marbling score was lower for all three RPC-containing diets than for the 0% RPC diet (quadratic response, P < .05). In Exp. 2, 20 Suffolk lambs (initial BW = 29.8 kg) were fed an 80% concentrate diet for 56 d with the same RPC levels as in Exp. 1. Serum triglycerides (TG) and cholesterol (CLSTRL) were measured in weekly blood samples, and intensive blood samples were collected on d 28 and 56 to evaluate serum insulin (INS), GH, and NEFA. For the 56-d feeding period, ADG responded quadratically (P < .10) to RPC level, but DMI and feed:gain were not affected. Serum INS and NEFA concentrations increased linearly (P < .05) and serum GH responded cubically (P < .05) to RPC level on d 28, but no differences were noted on d 56. Serum TG concentrations in weekly samples increased linearly (P < .10) with RPC level, but, averaged over all weeks, serum CLSTRL concentrations did not differ (P > .10) among treatments. Quantities of carcass mesenteric (P < .05) and kidney fat (P < .10) increased linearly, but longissimus muscle and liver fat contents did not differ (P > .10) among RPC levels. Supplementing RPC in high-concentrate diets improved performance, but results were not consistent among RPC levels or between cattle and sheep. Potential effects of RPC might be mediated through alterations in fat metabolism and(or) metabolic hormones related to fat metabolism.     

The immune response and PBMC subsets in canine visceral leishmaniasis before, and after, chemotherapy

Peripheral blood mononuclear cell subsets, in vitro lymphoproliferative response to leishmanial antigen, and Leishmania-specific serum antibody levels were examined in 11 dogs, naturally infected with L. infantum, and 9 healthy control dogs. A decrease in the percentage of CD4+ T-cells and an increase in the proportion of gammadelta T-cells and sIgG+ B-cells were observed during canine visceral leishmaniasis (CVL). These changes may be responsible for the marked humoral response and the absence of in vitro lymphoproliferation to mitogen and specific parasite antigens. This possibility was supported by the analysis of these subsets after treatment with amphotericin B. One month after therapy, a significant increase in the percentage of CD4+ T-cells and a decrease of gammadelta T-cells and sIgG+ B-cells were observed. At the same time, the lymphocyte blastogenesis assay with leishmanial antigen was positive and the levels of specific antibodies to Leishmania were significantly lower than before the treatment. Five months after therapy, lymphocyte proliferative response to LSA disappeared, antibody and lymphocyte subsets levels returned to those observed during CVL. Therapeutic failure in CVL is associated with the inability of antileishmanial drugs to completely revert the profound immunodepression induced by the infection and prevent relapse.     

Implant sequence effects in intact male Holstein veal calves: live and slaughter traits

Seven sequences of growth promotant implants were used in special-fed intact male Holstein veal calves (n = 443). Calves received implants 4 d after arrival at the veal barn, 42, and 84. The following implants were used: placebo (0), Z (36 mg zeranol), ET (20 mg estradiol, 200 mg testosterone), EP/2 (10 mg estradiol, 100 mg progesterone), EP (20 mg estradiol, 200 mg progesterone), and EBA (24 mg estradiol, 120 mg trenbolone acetate). The following sequences were compared: 0-0-0 (negative control), 0-ET-ET, Z-ET-ET, 0-EP-EP, Z-EP-EP, 0-EP/2-EBA, and Z-0-EBA. From 0 to 42 d, Z implants increased (P<.05) ADG by 3.4% compared to placebo. However, implant schemes without an initial Z implant (0-ET-ET and 0-EP-EP) had higher (P<.05) mean ADG for the period from d 42 to 84. From 84 d to the end of the experiment, only the 0-EP/2-EBA treatment increased (P<.05) ADG compared to 0-0-0. Over the entire trial 0-ET-ET, 0-EP-EP, Z-EP-EP, and 0-EP/2-EBA implant sequences increased (P<.05) ADG by 3.2, 3.2, 2.4, and 4.7%, respectively, compared to the 0-0-0 sequence. Blood traits measured within 2 wk before slaughter were not affected by implant sequence, except that sequences with EP had higher (P<.05) leukocyte counts than were observed for the other sequences. Testicular weight was less (P<.01) for all of the implant sequences than for the negative control and less (P<.05) for Z-ET-ET than for 0-ET-ET, 0-EP-EP, 0-EP/2-EBA, and Z-0-EBA. The type and frequency of medical treatments did not differ among implant sequences for any of the 42-d phases, or over the entire trial. Generally, the growth promotant implants currently approved for beef cattle resulted in approximately 50% of the increase in growth rate in Holstein intact bull calves, as has been observed in beef-type steers or heifers.     

The analgesic and sedative effects of GV20 pharmacopuncture with low-dose hydromorphone in healthy dogs undergoing ovariohysterectomy

This study evaluates the analgesic efficacy of low-dose hydromorphone administered via pharmacopuncture at Governing Vessel 20 (GV20) for postoperative pain management following canine ovariohysterectomy. Fifty clinically healthy female dogs undergoing ovariohysterectomy were allocated to receive hydromorphone [0.1 mg/kg body weight (BW)] intramuscularly (IM, n = 25) or hydromorphone (0.01 mg/kg BW) pharmacopuncture at GV20 (GV, n = 25) following extubation. This was a prospective, blinded, randomized clinical trial. Pain and sedation scores were evaluated using the Glasgow Composite Measure Pain Scale Short Form (CMPS-SF) at 1, 2, 3, 4, and 12 hours following study treatment. Time of treatment failure (CMPS-SF ≥ 6/24) was recorded and analyzed using Kaplan-Meier survival analysis. Patient demographics and duration of surgery and anesthesia were analyzed using the appropriate unpaired Student’s t-test. The Glasgow CMPS-SF and sedation score were analyzed using a repeated measures 2-way analysis of variance (ANOVA) followed by Bonferroni post-test where appropriate. Significance was set a P < 0.05. There were no significant differences in patient demographics, anesthesia and surgery duration, and study treatment failure. The Glasgow CMPS-SF scores were significantly higher for IM compared with GV [2 (0 to 8) versus 1 (0 to 6), respectively; P = 0.044] at 4 hours. Sedation scores were significantly higher for IM compared with GV at 2 [2 (1 to 3) and 1 (1 to 3), respectively; P = 0.0004] and 4 [1 (1 to 3) and 1 (1 to 2), respectively; P = 0.03] hours. Pharmacopuncture with low-dose hydromorphone provided adequate postoperative analgesia in dogs undergoing ovariohysterectomy with reduced sedative effects. Pharmacopuncture is a good alternative in dogs when reduced dosing of opioids is recommended.     

Cystic echinococcosis in the Falkland Islands

From 1991 to 1993, an investigation into the epidemiology of cystic echinococcosis (CE) was carried out in the Falkland Islands to evaluate the progress of the hydatid eradication campaign. The prevalence of CE in sheep was assessed using abattoir and farm slaughter data, and the exposure of dogs to the parasite was estimated using immunological techniques. A total of 59 466 sheep was examined at slaughter for E. granulosus and T. hydatigena cysts and the entire dog population of the Falkland Islands (n = 908) was examined by ELISA for the presence of specific serum antibodies to E. granulosus (IgG, IgA and IgE). In addition, a subsample of dogs (n = 464) was tested for the presence of E. granulosus antigens in faeces (copro-antigens). The prevalence of CE in sheep increased significantly during the period of the study from 0.11% in 1991 to 0.47% in 1993. Nineteen (2.1%) of 908 dog sera tested were seropositive, and eight dogs (1.7%) of 464 tested were positive in the copro-antigen assay. The combined use of abattoir surveillance, specific antibody and copro-antigen assay suggested that there were several locations in the Falkland Islands where the life cycle of E. granulosus may still perpetuate. Specific deficiencies in the eradication effort in those locations could be identified through follow-up questionnaires.