N‐Terminal Pro‐C‐Natriuretic Peptide and Cytokine Kinetics in Dogs with Endotoxemia

Background

Serum N‐terminal pro‐C‐natriuretic peptide (NT‐proCNP) concentration at hospital admission has sufficient sensitivity and specificity to differentiate naturally occurring sepsis from nonseptic systemic inflammatory response syndrome (SIRS). However, little is known about serum NT‐proCNP concentrations in dogs during the course of sepsis.

Objective

To determine serum NT‐proCNP and cytokine kinetics in dogs with endotoxemia, a model of canine sepsis.

Samples

Eighty canine serum samples.

Methods

Eight healthy adult Beagles were randomized to receive Escherichia coli lipopolysaccharide (LPS, 5 μg/kg) or placebo (0.9% NaCl) as a single IV dose in a randomized crossover study. Serum collected at 0, 1, 2, 4, and 24 hours was stored at −80°C for batch analysis. Serum NT‐proCNP was measured by ELISA and 13 cytokines and chemokines by multiplex magnetic bead‐based assay.

Results

Serum NT‐proCNP concentrations did not differ significantly between LPS‐ and placebo‐treated dogs at any time. When comparing serum cytokine concentrations, LPS‐treated dogs had higher interleukin‐6 (IL‐6), IL‐10, TNF‐α and KC‐like at 1, 2, and 4 hours; higher CCL2 at 1, 2, 4, and 24 hours; and higher IL‐8 and CXCL10 at 4 hours compared to placebo‐treated dogs. There were no differences in serum GM‐CSF, IFN‐γ, IL‐2, IL‐7, IL‐15 or IL‐18 between LPS‐ and placebo‐treated dogs.

Conclusions and Clinical Importance

Serum NT‐proCNP concentration does not change significantly in response to LPS administration in healthy dogs. Certain serum cytokine and chemokine concentrations are significantly increased within 1–4 hours after LPS administration and warrant further investigation as tools for the detection and management of sepsis in dogs.     

Confirmation of vertical transmission of bovine immunodeficiency virus in naturally infected dairy cattle using the polymerase chain reaction.

The purpose of this study was to determine whether bovine immunodeficiency virus (BIV) is vertically transmitted in naturally infected dairy cattle. Twenty-two dam/calf pairs from a Mississippi Agriculture and Forestry Experiment Station dairy were the study group. Blood samples were collected following delivery of calves, the peripheral blood leukocytes were purified from these samples, and the leukocyte DNA was used in polymerase chain reactions targeting the pol gene region of the BIV provirus. Southern blotting and hybridization were used to confirm the BIV specificity of the amplified fragments. BIV provirus was detected in 14 of 22 calves (64%), demonstrating vertical transmission. Eight of the calves were disqualified from the final interpretation of transplacental transfer because they may have nursed their mothers prior to blood collection, allowing the possibility of lactogenic transfer of the virus. Transplacental transmission of BIV was identified in 6 of 22 calves (27%).     

Is AZT/3TC therapy effective against FIV infection or immunopathogenesis?

In vitro and in vivo prophylactic and therapeutic efficacy of AZT/3TC treatment was evaluated against feline immunodeficiency virus (FIV) infection. In vitro studies utilized FIV-infected peripheral blood mononuclear cells (PBMCs) or FIV-infected T-cell lines treated with AZT (azidothymidine) alone, 3TC alone, or AZT/3TC combination and tested for anti-FIV activity and drug toxicity. AZT/3TC combination had additive to synergistic anti-FIV activities in primary PBMC but not in chronically infected cell lines. In vivo studies consisted of four treatment groups (n=15) of SPF cats receiving AZT/3TC combination (5-75 mg/kg/drug PO BID for 8 or 11 weeks) and one control group (n=9) receiving oral placebo. Group I (n=6, 150 mg/kg/drug/day) was treated starting 3 days pre-FIV inoculation, whereas Group II (n=3, 150 mg/kg/drug/day) and Group III (n=3, 100 mg/kg/drug/day) treatments were simultaneous with FIV inoculation. Group IV treatment (n=3, 100 mg/kg/drug/day) was initiated 2 weeks post-FIV inoculation. All cats were monitored for drug toxicity and FIV infection. Eighty-three percent of cats in Group I and 33% of cats in Groups II and III were completely protected from FIV infection. A significant delay in infection and antibody seroconversion was observed in all unprotected cats from Groups I, II and III. Group IV cats had only a slight delay in FIV antibody seroconversion. Adverse drug reactions (anemia and neutropenia) were observed at high doses (100-150 mg/kg/drug/day) were reversible upon lowering the dose (20 mg/kg/drug/day). In contrast, AZT/3TC treatment had no anti-FIV activity in chronically infected cats. Furthermore, severe clinical symptoms caused by adverse drug reactions were observed in some of these cats. Overall, AZT/3TC treatment is effective for prophylaxis but not for therapeutic use in chronically FIV-infected cats.     

Effects of dietary ingredients on manure characteristics and odorous emissions from swine

Two feeding studies were conducted to examine the impact of dietary inclusion of specific feed ingredients on manure characteristics and manure odor. In one study, 72 finishing pigs were used to evaluate the effects of distillers dried grains with solubles (DDGS) on pig performance, manure characteristics, and odorous emissions. Three diets containing 0, 5, and 10% DDGS were fed during six 4-wk feeding periods. Week 1 served as a dietary adjustment period. Animals were housed in two feeding rooms (six pigs/room) with one treatment/room. A new group of animals (average initial BW = 85.8 kg) was used for each feeding period. Diets were replicated four times. Rooms were equipped with individual shallow manure storage pits that were cleaned once weekly (d 7). On d 4 and 7 of each week, manure pit samples, for chemical analyses, and air samples, for olfactometry analysis, were collected from each room. Odor dilution threshold was greater on d 7 than on d 4 of manure storage across all treatments (P < 0.01). No treatment differences in manure composition were noted. In the second study, weaned pigs (approximately 5 wk old) were fed isonitrogenous diets containing 0, 1.5, or 3% bloodmeal. Pigs were housed by diet (three pigs/diet) in one of four individual feeding rooms. A new group of pigs was used for each of the two, 4-wk feeding periods. During period 1, the 3% bloodmeal diet was fed in two of the four rooms; the 0% bloodmeal diet was fed in two rooms during period 2. Manure samples, for chemical analyses, and air samples, for olfactometry analysis, were collected 2 d per week (d 4 and d 6) from each room during wk 2 through 4. No significant treatment differences were observed for odor dilution threshold (P = 0.30). Longer manure storage time, 6 d vs 4 d, resulted in a larger odor dilution ratio (P < 0.01). Manure composition was unaltered by storage time. Results suggest that odor intensifies during storage.     

Udder cleft dermatitis and sarcoptic mange in a dairy herd

OBJECTIVE: To determine prevalence of udder cleft dermatitis in a dairy herd that was experiencing an outbreak of sarcoptic mange. DESIGN: Clinical survey. ANIMALS: 1,597 Holstein cows and late-gestation heifers. PROCEDURE: Animals were examined for udder cleft dermatitis and for skin lesions consistent with sarcoptic or chorioptic mange. Skin scrapings were collected from 56 cows and examined for ectoparasites. The herd was revisited 1 year later, and prevalences of udder cleft dermatitis and lesions consistent with mange were determined in 506 cows. RESULTS: Of the 1,597 cattle examined, 280 (18%) had udder cleft dermatitis, and 1,397 (87.5%) had lesions consistent with mange. In 43 of 56 (77%) cows, skin scrapings revealed Sarcoptes mites. Udder cleft dermatitis was significantly more common in older than in younger cows. In first-lactation cows, udder cleft dermatitis was less common during the first 4 months of lactation than in the later stages of lactation, but udder cleft dermatitis was identified in cows in all stages of lactation and in cows that were not lactating. The herd was treated with eprinomectin to control mites, and prevalence of lesions consistent with mange 1 year later was only 2.8%. However, prevalence of udder cleft dermatitis was still 12%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cows in any stage of lactation and cows that are not lactating can have udder cleft dermatitis but that lesions are more common in older cows. Control of sarcoptic mange was accompanied by a moderate reduction in the prevalence of udder cleft dermatitis but did not eliminate the condition.     

Plasma and urine electrolyte and mineral concentrations in Thoroughbred horses with recurrent exertional rhabdomyolysis after consumption of diets varying in cation-anion balance

OBJECTIVE: To determine whether plasma, urine, and fecal electrolyte and mineral concentrations differ between clinically normal horses and Thoroughbreds with recurrent exertional rhabdomyolysis (RER) after consumption of diets varying in cation-anion balance. ANIMALS: 5 Thoroughbred mares with RER and 6 clinically normal mixed-breed mares. PROCEDURE: Each of 3 isocaloric diets designated as low, medium, and high on the basis of dietary cation-anion balance (DCAB) values of 85, 190, and 380, respectively, were fed to horses for 14 days. During the last 72 hours, 3 horses with RER and 3 control horses had daily urine and fecal samples obtained by total 24-hour collection. Remaining horses had urine samples collected daily by single catheterization. RESULTS: For each diet, no differences existed between horses with RER and control horses in plasma pH, electrolyte concentrations, and creatine kinase activity or in urine pH and renal fractional excretion (FE) values. Plasma pH, strong ion difference, bicarbonate and total carbon dioxide concentrations, and base excess decreased and plasma chloride and ionized calcium concentrations increased with decreasing DCAB. Urine pH decreased with decreasing DCAB. The FE of chloride and phosphorus were greatest for horses fed the low diet. The FE values for all electrolytes exept magnesium did not differ between urine samples obtained by single catheterization and total 24-hour collection. Daily balance of calcium, phosphorus, sodium, chloride, and potassium did not differ significantly among horses fed the various diets. CONCLUSIONS: In clinically normal horses and in horses with RER, the DCAB strongly affects plasma and urine pH and the FE of sodium, potassium, chloride, and phosphorus.     

Identification of immunoreactive polypeptides of Babesia equi parasite during immunization

This study was carried out to identify immunoreactive polypeptides in Babesia equi merozoite antigen. Three fractions of killed B. equi merozoite antigen viz.; whole merozoite (WM), cell membrane (CM) and high speed supernatant (HSS) antigens were prepared from the parasite infected erythrocytes. These antigenic preparations along with ghost antigen from non-infected erythrocytes were fractionated on 12% sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotted with sera showing high antibody titres. On SDS-PAGE, 16 polypeptides with molecular weight (Mr) in the range of 112-17kDa were obtained from the WM and CM antigens. But only six polypeptides were detected (96.5-28kDa) in the HSS antigen. On immunoblotting with high titred serum collected from donkeys following two immunizations with a killed B. equi merozoite immunogen, 11 polypeptides were observed in the WM and CM antigens (Mr 112-18kDa). Of these, four polypeptides (Mr 112, 45, 33 and 18kDa) were identified as most immunoreactive. Besides these, a 28kDa was observed as strong immunoreactive protein in WM and CM antigens. The HSS antigen showed only six polypeptides and one peptide (28kDa) was identified as immunoreactive. When high titred serum collected from immunized donkeys following challenge with B. equi infected blood and was used for immunoblotting, the protein profile of WM and CM antigens remained the same. However, three additional polypeptides (Mr 81, 54.5 and 39kDa) were detected in HSS antigen.     

Hosts,seasonal occurrence and life cycle of Rhipicentor nuttalli (Acari: Ixodidae)

There are only two species worldwide within the genus Rhipicentor, namely Rhipicentor bicornis and Rhipicentor nuttalli and both occur only in Africa. Rhipicentor nuttali has a widespread distribution in South Africa and the present investigation was initiated to elucidate its host preference, seasonality and life cycle. Rock elephant shrews, Elephantulus myurus were examined for ticks at four localities in the Free State Province, one in Gauteng Province and two in Limpopo Province, South Africa. Cape elephant shrews, Elephantulus edwardii were examined at two places in the Western Cape Province, and a single specimen of the bushveld elephant shrew, Elephantulus intufi was examined in central Namibia. Small mammals of other species were also examined at two of these localities. The majority of E. myurus at two sites in the Free State, at the locality in Gauteng and both sites in Limpopo Province were infested with larvae and/or nymphs of R. nuttalli, while the single E. edwardii examined at one site in the Western Cape Province and the single E. intufi examined in Namibia were infested with nymphs of this tick. Not one of the other small animals was infested. Although larvae and nymphs of R. nuttalli were present on E. myurus throughout the year, the former were generally most numerous during the period March to September, and the latter during May to October. The preferred hosts of the adults are domestic dogs, leopards, Panthera pardus and South African hedgehogs, Atelerix frontalis. Adult females engorged on Atelerix frontalis in 16-32 days and, after a preoviposition period of 2-4 days, produced approximately 170,00 eggs during the following 60-70 days. The average incubation period of the eggs was 59 days. Larvae engorged on E. myurus in 4-10 days and moulted to nymphs 12-20 days later. Nymphs required 11-15 days to engorge on E. myurus and moulted to adults 32-47 days later. Allowing 14 days for the exoskeletons and mouthparts of each of the three parasitic stages to harden before they can attach to a host, the life cycle took approximately 214 days to complete in the laboratory. The length of this period, considered in conjunction with the times of maximum seasonal occurrence of the immature stages, indicates that the life cycle probably takes a year to complete in the field.     

The gamma-interferon test: its usefulness in a bovine tuberculosis survey in African buffaloes (Syncerus caffer) in the Kruger National Park

A survey to determine the bovine tuberculosis status of buffalo herds north of the Olifants River in the Kruger National Park was conducted, using a new diagnostic approach. Diagnosis of Mycobacterium bovis infection was accomplished using the gamma-interferon assay technique in 608 adult buffaloes out of a total of 29 discreet herds. The animals were immobilized in groups of 10-15, bled, individually marked and then revived and released on site. As soon as test results were available (after 26-36 h), the same buffalo herd was relocated by tracking the frequency of a radio-collar previously fitted to one adult cow per group during the initial operation. Bovine reactors were identified, darted and euthanased from the helicopter. Necropsy and culture findings of all culled buffaloes showed excellent correlation with the results of the ante-mortem gamma-interferon test. The survey revealed that over and above the two positive herds that had been identified during a previous survey carried out in 1996, there were three additional, but previously unidentified, infected herds in the region north of the Olifants River.