Objective-To assess the biological response to recombinant feline interferon-omega (rFeIFN-omega) following ocular or oral administration in cats via estimation of Mx protein expression in conjunctival cells (CCs) and WBCs. Animals-10 specific pathogen-free cats. Procedures-In multiple single-dose drug experiments, each cat received various concentrations of rFeIFN-omega administered topically into both eyes (50 to 10,000 U/eye) and orally (200 to 20,000 units). The same cats received saline (0.9% NaCl) solution topically and orally as control treatments. The CCs and WBCs were collected prior to treatment (day 0), on day 1, and every third or seventh day thereafter until samples yielded negative results for Mx protein. Samples were examined for Mx protein expression via immunohistochemistry and immunoblotting procedures involving murine anti-Mx protein monoclonal antibody M143. Results-After topical application of 10,000 U of rFeIFN-omega/eye, CCs stained for Mx protein for a minimum of 7 days, whereas WBCs were positive for Mx protein for a minimum of 31 days. After topical application of lower concentrations, CCs did not express Mx protein, in contrast to WBCs, which stained for Mx protein at 1,000 units for at least 1 day. Following oral administration, Mx protein was expressed in WBCs at rFeIFN-omega concentrations as low as 200 units, whereas CCs did not stain for Mx protein at any concentration. Conclusions and Clinical Relevance-Results indicate that Mx protein expression (a marker of the biological response to rFeIFN-omega) in CCs and WBCs of rFeIFN-omega-treated cats depends on the dose of rFeIFN-omega, site of administration, and cell type.

Objective-To investigate the effects of exercise on activation of mitogen-activated protein kinase (MAPK) signaling proteins in horses. Animals-6 young trained Standardbred geldings. Procedure-Horses performed a 20-minute bout of exercise on a treadmill at 80% of maximal heart rate. Muscle biopsy specimens were obtained from the vastus lateralis and pectoralis descendens muscles before and after exercise. Amount of expression and intracellular location of phosphospecific MAPK pathway intermediates were determined by use of western blotting and immunofluorescence staining. Results-Exercise resulted in a significant increase in phosphorylation of p38 pathway intermediates, c-Jun NH2 terminal kinase (JNK), and heat shock protein 27 (HSP27) in the vastus lateralis muscle, whereas no significant changes were found in phosphorylation of extracellular regulated kinase. In the pectoralis descendens muscle, phosphorylation of p38 and HSP27 was significantly increased after exercise. Immunohistochemical analysis revealed fiber-type-specific locations of phosphorylated JNK in type 2a/b intermediate and 2b fibers and phosphorylated p38 in type 1 fibers. Phosphorylated HSP27 was strongly increased after exercise in type 1 and 2a fibers. Conclusions and Clinical Relevance-The p38 pathway and JNK are activated in the vastus lateralis muscle after a single 20-minute bout of submaximal exercise in trained horses. Phosphorylation of HSP27 as detected in the study reported here is most likely induced through the p38 signaling pathway.

Objective-To map canine mitochondrial proteins and identify qualitative and quantitative differences in heart mitochondrial protein expression between healthy dogs and dogs with naturally occurring and induced dilated cardiomyopathy (DCM). Sample Population-Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with induced DCM. Procedures-Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by greater than or equal to 2-fold between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. Results-Within narrow pH gradients of control canine heart mitochondrial samples, a total of 1,528 protein spots were revealed. Forty subunits of heart mitochondrial proteins that differ significantly from control tissues were altered in tissue specimens from dogs with naturally occurring and induced forms of DCM. The most affected heart mitochondrial proteins in both groups were those of oxidative phosphorylation (55%). Upregulation of manganese superoxide dismutase was suggestive of heart oxidative injury in tissue specimens from dogs with both forms of DCM. Evidence of apoptosis was associated with overexpression of the heart mitochondrial voltage-dependent anion channel-2 protein and endonuclease G in tissue specimens from dogs with induced DCM. Conclusions and Clinical Relevance-Alterations of heart mitochondrial proteins related to oxidative phosphorylation dysfunction were more prevalent in tissue specimens from dogs with induced or naturally occurring DCM, compared with those of control dogs.

Objective-To evaluate the effect of dietary supplementation with the probiotic strain Lactobacillus acidophilus DSM13241 in healthy adult cats. Animals-15 adult cats. Procedures-Cats were fed a nutritionally complete dry food for 5 weeks. Fecal character was assessed daily, and a single fecal sample and 3-mL blood sample were collected for bacterial enumeration and hematologic analysis, respectively. Cats were then fed the same diet supplemented with L acidophilus DSM13241 (2 X 10(8) CFU/d) for 4.5 weeks. Repeat fecal and hematologic measurements were taken prior to the return to control diet for a 4-week period. Results-The probiotic species was recovered from feces, demonstrating survival through the feline gastrointestinal tract. Probiotic supplementation was associated with increased numbers of beneficial Lactobacillus and L acidophilus groups in feces and decreased numbers of Clostridium spp and Enterococcus faecalis, indicating an altered bacterial balance in the gastrointestinal tract microflora. Fecal pH was also decreased suggesting a colonic environment selective for the beneficial lactic acid bacterial population. Systemic and immunomodulatory effects were associated with administration of L acidophilus DSM13241 including altered cell numbers within WBC subsets and enhanced phagocytic capacity in the peripheral granulocyte population. In addition, plasma endotoxin concentrations were decreased during probiotic feeding, and RBCs had a decreased susceptibility to osmotic pressure. Conclusions and Clinical Relevance-Probiotic strain L acidophilus DSM13241 fed at 2 X 10(8) CFU/d can alter the balance of gastrointestinal microflora in healthy cats. Furthermore, administration of this probiotic results in beneficial systemic and immunomodulatory effects in cats.

Objective-To determine the pharmacokinetics of marbofloxacin after single IV and orally administered doses in blue and gold macaws. Animals-10 healthy blue and gold macaws. Procedures-In a crossover study, marbofloxacin (2.5 mg/kg) was administered orally (via crop gavage) to 5 birds and IV to 5 birds. Blood samples were obtained at 0, 0.5, 1, 3, 6, 12, 24, 48, 72, and 96 hours after marbofloxacin administration. After a 4-week washout period, the study was repeated, with the first 5 birds receiving the dose IV and the second 5 birds receiving the dose orally. Serum marbofloxacin concentrations were quantitated by use of a validated liquid chromatography-mass spectrometry assay. Results-After oral administration, mean +/- SD area under the curve was 7.94 +/- 2.08 microgram.h/mL, maximum plasma concentration was 1.08 +/- 0.316 microgram/mL, and bioavailability was 90.0 +/- 31%. After IV administration of marbofloxacin, the apparent volume of distribution was 1.3 +/- 0.32 L/kg, plasma clearance was 0.29 +/- 0.078 L/h/kg, area under the curve was 9.41 +/- 2.84 microgram.h/mL, and the harmonic mean terminal half-life was 4.3 hours. Conclusions and Clinical Relevance-Single IV and orally administered doses of marbofloxacin were well tolerated by blue and gold macaws. The orally administered dose was well absorbed. Administration of marbofloxacin at a dosage of 2.5 mg/kg, PO, every 24 hours may be appropriate to control bacterial infections susceptible to marbofloxacin in this species.

Objective-To evaluate the effects of deracoxib and aspirin on serum concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) in healthy dogs. Animals-24 dogs. Procedure-Dogs were allocated to 1 of 3 groups of 8 dogs each. Dogs received the vehicle used for deracoxib tablets (PO, q 8 h; placebo), aspirin (23 to 25 mg/kg, PO, q 8 h), or deracoxib (1.25 to 1.8 mg/kg, PO, q 24 h) and placebo (PO, q 8 h) for 28 days. Measurement of serum concentrations of T4, T3, fT4, and TSH were performed 7 days before treatment (day -7), on days 14 and 28 of treatment, and 14 days after treatment was discontinued. Plasma total protein, albumin, and globulin concentrations were measured on days -7 and 28. Results-Mean serum T4, fT4, and T3 concentrations decreased significantly from baseline on days 14 and 28 of treatment in dogs receiving aspirin, compared with those receiving placebo. Mean plasma total protein, albumin, and globulin concentrations on day 28 decreased significantly in dogs receiving aspirin, compared with those receiving placebo. Fourteen days after administration of aspirin was stopped, differences in hormone concentrations were no longer significant. Differences in serum TSH or the free fraction of T4 were not detected at any time. No significant difference in any of the analytes was detected at any time in dogs treated with deracoxib. Conclusions and Clinical Relevance-Aspirin had substantial suppressive effects on thyroid hormone concentrations in dogs. Treatment with high dosages of aspirin, but not deracoxib, should be discontinued prior to evaluation of thyroid function.

The early release of cytokines by cells involved in innate immunity is an important host response to intracellular pathogens. Gamma interferon (IFN-gamma) is an important cytokine produced during the early stages of an infection by macrophages, natural killer (NK) cells, and other cell types, and it is also a central cytokine mediator for the induction of cellular or Th1 immunity. To better understand innate and adaptive immune responses after infection with Porcine reproductive and respiratory syndrome virus (PRRSV), we investigated serum IFN-gamma concentrations and the duration of viremia. For 2 strains of atypical PRRSV, IFN-gamma was detectable in swine serum soon after infection and lasted for approximately 3 wk. Serum concentrations of IFN-gamma peaked at about 10 d after inoculation and returned to approximately baseline levels by day 22. However, individual pigs manifested short, sporadic increases in the serum concentration of IFN-gamma from 18 to 50 d after inoculation. Prior vaccination blocked the serum IFN-gamma response associated with homologous virus challenge and altered the kinetics of the response after heterologous challenge. Two other respiratory viruses of pigs, Porcine respiratory coronavirus and Swine influenza virus, do not appear to induce serum IFN-gamma. The early production of IFN-gamma in PRRSV-infected pigs might result from activation of NK cells, a response that is more characteristic of immune pathways stimulated by intracellular bacterial and protozoan infections.

Objective-To validate a radioimmunoassay for measurement of procollagen type III amino terminal propeptide (PIIINP) concentrations in canine serum and bronchoalveolar lavage fluid (BALF) and investigate the effects of physiologic and pathologic conditions on PIIINP concentrations. Sample Population-Sera from healthy adult (n = 70) and growing dogs (20) and dogs with chronic renal failure (CRF; 10), cardiomyopathy (CMP; 12), or degenerative valve disease (DVD; 26); and sera and BALF from dogs with chronic bronchopneumopathy (CBP; 15) and healthy control dogs (10 growing and 9 adult dogs). Procedure-A radioimmunoassay was validated, and a reference range for serum PIIINP (S-PIIINP) concentration was established. Effects of growth, age, sex, weight, CRF, and heart failure on S-PIIINP concentration were analyzed. In CBP-affected dogs, S-PIIINP and BALF-PIIINP concentrations were evaluated. Results-The radioimmunoassay had good sensitivity, linearity, precision, and reproducibility and reasonable accuracy for measurement of S-PIIINP and BALF-PIIINP concentrations. The S-PIIINP concentration reference range in adult dogs was 8.86 to 11.48 microgram/L. Serum PIIINP concentration correlated with weight and age. Growing dogs had significantly higher S-PIIINP concentrations than adults, but concentrations in CRF-, CMP-, DVD-, or CBP-affected dogs were not significantly different from control values. Mean BALF-PIIINP concentration was significantly higher in CBP-affected dogs than in healthy adults. Conclusions and Clinical Relevance-In dogs, renal or cardiac disease or CBP did not significantly affect S-PIIINP concentration; dogs with CBP had high BALF-PIIINP concentrations. Data suggest that the use of PIIINP as a marker of pathologic fibrosis might be limited in growing dogs.

Objective-To determine whether inflammation of the jejunum of horses decreases the number of motilin receptors and amounts of motilin receptor mRNA and alters erythromycin lactobionate binding affinity to the motilin receptor in jejunal tissues. Sample Population-Jejunal segments in 6 adult horses. Procedure-Each horse was anesthetized, and a ventral median celiotomy was performed; 2 segments of jejunum underwent a sham operation, 2 segments underwent ischemic strangulation obstruction (ISO), and 2 segments underwent intraluminal distension (ILD). Treatments were maintained for 120 minutes. From each segment, full-thickness biopsy samples were collected and smooth-muscle homogenates were prepared. Affinity and distribution of motilin binding to these preparations were determined by use of iodine 125 (125I)-labeled synthetic porcine motilin. Via displacement experiments, competition between 125I-labeled motilin and erythromycin lactobionate for binding to motilin receptors in the different segments was investigated. A quantitative real-time PCR technique was used to assess motilin receptor mRNA content in the muscle preparations. Results-Compared with the ISO or ILD segments, the number of motilin receptors was significantly higher in the sham-operated segments; ILD segments contained the lowest number of motilin receptors. The expression of motilin receptor mRNA was significantly decreased in ILD segments but not in ISO segments. Erythromycin lactobionate displacement of 125I-labeled motilin from motilin receptors did not differ significantly among the jejunal segments. Conclusions and Clinical Relevance-Results suggest that downregulation and decreased production of motilin receptors in inflamed jejunal tissue contribute to the altered prokinetic response to erythromycin in horses with gastrointestinal disease.

Objective-To study the pharmacokinetics of difloxacin (5 mg/kg) following IV, IM, and intragastric (IG) administration to healthy horses. Animals-6 healthy mature horses. Procedures-A crossover study design with 3 phases was used (15-day washout periods between treatments). An injectable formulation of difloxacin (5%) was administered IV and IM in single doses (5 mg/kg); for IG administration, an oral solution was prepared and administered via nasogastric tube. Blood samples were collected before and at intervals after each administration. A high-performance liquid chromatography assay with fluorescence detection was used to determine plasma difloxacin concentrations. Pharmacokinetic parameters of difloxacin were analyzed. Plasma creatine kinase activity was monitored to assess tissue damage. Results-Difloxacin plasma concentration versus time data after IV administration were best described by a 2-compartment open model. The disposition of difloxacin following IM or IG administration was best described by a 1-compartment model. Mean half-life for difloxacin administered IV, IM, and IG was 2.66, 5.72, and 10.75 hours, respectively. Clearance after IV administration was 0.28 L/kg.h. After IM administration, the absolute mean +/- SD bioavailability was 95.81 +/- 3.11% and maximum plasma concentration (C(max)) was 1.48 +/- 0.12 mg/L. After IG administration, the absolute bioavailability was 68.62 +/- 10.60% and C(max) was 0.732 +/- 0.05 mg/L. At 12 hours after IM administration, plasma creatine kinase activity had increased 7-fold, compared with the preinjection value. Conclusions and Clinical Relevance-Data suggest that difloxacin is likely to be effective for treating susceptible bacterial infections in horses.