An evaluation of the relative efficacy of a new formulation of oxytetracycline for the treatment of undifferentiated fever in feedlot calves in western Canada

A field trial was performed under commercial feedlot conditions in western Canada to compare the efficacy of a new formulation of long-acting oxytetracycline (LA 30) to a standard long-acting oxytetracycline formulation (LA 20) and florfenicol (FLOR) for the treatment of undifferentiated fever (UF) in calves that received metaphylactic tilmicosin upon arrival at the feed-lot. Seven hundred and ninety-seven recently weaned, auction market derived, crossbred, beef calves suffering from UF were allocated to 1 of 3 experimental groups as follows: LA 30, which received intramuscular long-acting oxytetracycline (300 mg/mL formulation) at the rate of 30 mg/kg body weight (BW) at the time of allocation; LA 20, which received intramuscular long-acting oxytetracycline (200 mg/mL formulation) at the rate of 20 mg/kg BW at the time of allocation; or FLOR, which received intramuscular florfenicol administered at the rate of 20 mg/kg BW at the time of allocation and again 48 hours later. Two hundred and sixty-six animals were allocated to the LA 30 group, 265 animals were allocated to the LA 20 group, and 266 animals were allocated to the FLOR group. The relative efficacy of the LA 30 group, as compared with the LA 20 and FLOR groups, was assessed by comparing relapse, chronicity, wastage, and mortality rates. The overall mortality (RR = 0.50) rate in the LA 30 group was significantly (P < 0.05) lower than in the LA 20 group. However, the overall chronicity (RR = 2.56) and overall wastage (RR = 6.97) rates of the LA 30 group were significantly (P < 0.05) higher than in the LA 20 group. There were no significant (P > or = 0.05) differences in UF relapse rates or cause specific mortality rates between the LA 30 and LA 20 groups. In the economic analysis, there was an advantage of $28.59 CDN per animal in the LA 30 group compared with the LA 20 group. The overall chronicity (RR = 2.25) and overall wastage (RR = 2.80) rates of the LA 30 group were significantly (P < 0.05) higher than the FLOR group. There were no significant (P > or = 0.05) differences in UF relapse rates, overall mortality rates, or cause specific mortality rates between the LA 30 and FLOR groups. In the economic analysis, there was an advantage of $12.90 CDN per animal in the LA 30 group compared with the FLOR group. In summary, the results of this study indicate that it is more cost-effective to use a new formulation of long-acting oxytetracycline (300 mg/mL formulation administered at a rate of 30 mg/kg BW) than a standard long-acting oxytetracycline formulation (200 mg/mL formulation administered at a rate of 20 mg/kg BW) or florfenicol for the treatment of UF in feedlot calves that have previously received metaphylactic tilmicosin upon arrival at the feedlot.     

Penetrating keratoplasty for treatment of corneal protrusion in a great horned owl (Bubo virginianus)

A young adult great horned owl (Bubo virginianus) was examined following presumed trauma. The owl had soft tissue injury to its left wing as well as corneal protrusion, lens subluxation, and iridodialysis of the right eye. The bird's eye was treated surgically with a large, rectangular penetrating keratoplasty. Following escape from housing, the bird was found with partial wound dehiscence and iris prolapse 12 days post operation. Surgical repair was performed and healing progressed for 14 days, at which time the transplant dehisced and the globe was exenterated. The patient rehabilitated well until escaping from its cage again 4 weeks later, at which time it sustained an open comminuted humeral fracture and was euthanized.     

Efficacy of Fresh-Frozen Plasma and Cryoprecipitate in Dogs with von Willebrand's Disease or Hemophilia A

Here we report the comparative efficacy of fresh-frozen plasma (FFP) and Cryoprecipitate in the treatment of 2 inherited bleeding disorders in dogs. The dogs were divided into 3 groups, consisting of 4 Doberman Pinschers with type I von Willebrand's disease (vWD) (group I), 1 Scottish Terrier with type III vWD (group 2), and 4 German Shepherd Dogs with hemophilia A (group 3). In vWD, therapeutic efficacy was determined by the ability of the products to increase von Willebrand factor antigen (vWf:Ag) concentrations above 35 canine units (CU)/dL and to correct the prolonged buccal mucosal bleeding time. Therapeutic efficacy in hemophilia A was assessed by the ability of the products to increase the factor VIII coagulant (FVIII:C) activity above 30 CU/dL. In both groups 1 and 2, higher increases in vWf:Ag were achieved with Cryoprecipitate than with FFP, despite a significantly smaller total amount of vWf:Ag (in CU) being infused with Cryoprecipitate. The maximum vWf:Ag attained after infusion in group 1 was dependent on both the baseline vWf:Ag concentration and on the type of infusion product. The dogs with vWD in both groups also displayed a delayed increase in FVIII:C activity after infusion of both plasma products, which is characteristic of the disease. In group 3, Cryoprecipitate achieved similar increases in FVIII:C activity compared to FFP, although a significantly lesser amount of FVIII:C (in CU) was delivered with Cryoprecipitate. Six of the 9 dogs treated with FFP experienced adverse effects ranging from mild pruritus to pallor and weakness, whereas none of the 9 dogs treated with Cryoprecipitate had any observable adverse reactions ( P = .009). Based on its efficacy and safety, we recommend Cryoprecipitate over FFP for treatment or prophylaxis of hemorrhagic episodes in dogs with vWD or hemophilia A.     

Oxidative stress during acute FIV infection in cats

Oxidative stress is thought to contribute to the pathogenesis of HIV infection in humans. For example, CD4(+) T cells are particularly affected in HIV patients and oxidative stress may also contribute to impairment of neutrophil function in HIV/AIDS patients. Since cats infected with FIV develop many of the same immunological abnormalites as HIV-infected humans, we investigated effects of acute FIV infection on oxidative stress in cats. Cats were infected with a pathogenic strain of FIV and viral load, changes in neutrophil number, total blood glutathione, malondiadehye, antioxidant enzyme concentrations, and reduced glutathione (GSH) concentration in leukocytes were measured sequentially during the first 16 weeks of infection. We found that superoxide dismutase and glutathione peroxidase concentrations in whole blood increased significantly during acute FIV infection. In addition, neutrophil numbers increased significantly during this time period, though their intracellular GSH concentrations did not change. In contrast, the numbers of CD4(+) T cells decreased significantly and their intracellular GSH concentration increased significantly, while intracellular GSH concentrations were unchanged in CD8(+) T cells. However, by 16 weeks of infection, many of the abnormalities in oxidative balance had stabilized or returned to pre-inoculation values. These results suggest that acute infection with FIV causes oxidative stress in cats and that CD4(+) T cells appear to be preferentially affected. Further studies are required to determine whether early treatment with anti-oxidants may help ameliorate the decline in CD4(+) T cell number and function associated with acute FIV infection in cats.     

Efficacy of fluorescent calcein mark retention and identification in endangered Colorado pikeminnow Ptychocheilus lucius

Distinguishing hatchery‐reared fishes from wild conspecifics can be required to quantify the success of augmentation programmes. This study estimated the probability of identifying calcein‐marked, hatchery‐reared Colorado pikeminnow Ptychocheilus lucius Girard from external and internal structures. Both control and marked fish held in the laboratory were correctly identified 80% of the time after 300 days. A fluorometer was more accurate 180 days post‐marking, whereas visual observation was more discriminating at 300 days. There were no differences in detection rates among structures in laboratory fish, and for most structures of fish held outdoors, detection rates were <20%. Overall, a strong negative effect of light on mark persistence was observed. Also, an initial positive effect of fish size on mark fluorescence and a negative effect of fish growth were detected. These results suggest the potential use of calcein as a batch‐marking tool would be aided by future studies that better quantify light exposure and calcein mark persistence in both field and experimental settings.     

Podiatry

Palmar heel pain can be divided into 5 groups, depending on the clinical signs and based on the horse's response to diagnostic analgesia. These groups include navicular pain; solar third phalanx, including the insertion of the deep flexor tendon; distal interphalangeal arthrosis, mixed pain (multiple structures), and palmar pain. Depending on the region of pain, different strategies can be used to treat the horse. Primary among these are reestablishing the biomechanics of the hoof and modifying the pain response of the horse.     

Characterization of growth hormone binding sites in the goldfish,Carassius auratus: effects of hypophysectomy and hormone injection

A recombinant carp growth hormone (rcGH) was used to develop for a GH radioreceptor binding assay in the goldfish (Carassius auratus). Specific binding of¹²⁵I-rcGH to goldfish liver membranes was a pH, time, temperature, and membrane protein dependent process. Scatchard and LIGAND analysis indicated a single class of high affinity and low capacity binding site, with an association constant (Ka) of 1.9×10¹⁰ M^–1 and a maximum binding capacity (B_max) of 9 fmol mg^–1 protein. Liver tissue displayed the highest¹²⁵I-rcGH binding of all the tissues examined. Displacement of¹²⁵I-rcGH with various unlabeled teleost and mammalian GHs and prolactins revealed that the goldfish hepatic binding site was highly specific for teleost GH. Intraperitoneal administration of 0.1, 1.0, and 10 g rcGH g^–1 body weight to hypophysectomized goldfish resulted in a 27, 52, and 68% decrease in total binding sites, respectively. Injection of a high dose of rat prolactin (rPRL) (5 g rPRL g^–1 body weight) also resulted in a 32% decrease in total binding sites. These results suggest that endogenous GH may have a role in the regulation of its own receptors in the goldfish.     

Effect of hemolysis on nonesterified fatty acid and beta-hydroxybutyrate concentrations in bovine blood.

Nonesterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) assays are used for evaluating dairy herds for negative energy balance and subclinical ketosis, respectively. Hemolysis is a common artifact in samples submitted to diagnostic laboratories. The effect of hemolysis on NEFA and BHB in bovine serum was determined. Hemolysis was introduced into 26 serum samples by adding serial dilutions of a red cell hemolysate, prepared by repeated freeze-thawing of EDTA-anticoagulated bovine blood. NEFA, BHB, and degree of hemolysis (hemolytic index) were measured by an automated chemistry analyzer. Two endpoint assays that differed by inclusion of a sample blank were used for NEFA measurement. A kinetic enzymatic assay with 2 reagent sources was used for BHB measurement. The assessed methods yielded similar NEFA or BHB results in baseline, nonhemolyzed samples (median NEFA: 0.25 mEq/L, median BHB: 3 mg/dL, median hemolytic index: 8 units). NEFA results were adversely affected by hemolysis, with values increasing significantly with higher degrees of hemolysis. Median values increased above a critical medical decision limit (0.40 mEq/L) at a hemolytic index of 506 units (marked hemolysis). This increase was prevented by inclusion of a sample blank. Result interpretation was affected in individual animals when samples were moderately hemolyzed (median hemolytic index: 258 units). In contrast, BHB results were unaffected by hemolysis with either reagent source. Thus, assays for measuring NEFAs should include a sample blank and NEFA results should not be interpreted in moderately to markedly hemolyzed bovine samples, because result accuracy cannot be assured.     

The avian neurologic examination and ancillary neurodiagnostic techniques: a review update.

The purpose of this article is to guide the avian clinician in the assessment of neurologic function in birds. Physical and neurologic examinations that evaluate cranial nerves, postural reactions, and spinal reflexes identify neurologic dysfunction and the corresponding anatomic location of the lesion. Ancillary diagnostic tests, such as cerebrospinal fluid analysis, diagnostic imaging, muscle and nerve histology, and electrodiagnostics, are tools to confirm and clarify conclusions from the neurologic examination and to identify the cause of disease. Once the disease location and pathologic process have been identified, appropriate treatment and prognosis may be provided.     

Clinical efficacy and safety of recombinant canine erythropoietin in dogs with anemia of chronic renal failure and dogs with recombinant human erythropoietin-induced red cell aplasia

The efficacy and safety of recombinant canine erythropoietin (rcEPO) therapy was evaluated in 19 dogs with anemia of chronic renal failure (group 1) and 6 dogs with chronic renal failure and recombinant human erythropoietin (rhEPO)-induced red cell aplasia (group 2). Hematocrit (Hct) and absolute reticulocyte count (ARC) were monitored weekly for the first 8 weeks, CBC (including ARC) and serum iron profiles were evaluated monthly, and serum biochemical analyses were performed every 2 months for 6 (group 2) to 12 (group 1) months. For group 1 dogs, median Hct and ARC increased significantly during the 1st week of rcEPO treatment, and median Hct was sustained at >35% after week 5. In contrast, median Hct and ARC for group 2 did not change significantly with rcEPO treatment, even with doses greater than those used in group 1. Nevertheless, 2 (33%) of the 6 dogs in group 2 developed erythroid hyperplasia, reticulocytosis, and increases in Hct with rcEPO treatment. Although median systolic blood pressure did not change significantly in either group, 5 dogs developed systolic blood pressures > or = 180 mm Hg during the study. Appetite and energy level improved in most group 1 dogs with increases in Hct. Recombinant cEPO stimulated erythrocyte production in dogs with nonregenerative anemia secondary to chronic renal failure without causing the profound erythroid hypoplasia that can occur in rhEPO-treated dogs. Unfortunately, rcEPO was not as effective in restoring erythrocyte production in dogs that had previously developed rhEPO-induced red cell aplasia.