Iron robbery by intracellular pathogen via bacterial effector-induced ferritinophagy.

Iron is essential for survival and proliferation of Ehrlichia chaffeensis, an obligatory intracellular bacterium that causes an emerging zoonosis, human monocytic ehrlichiosis. However, how Ehrlichia acquires iron in the host cells is poorly understood. Here, we found that native and recombinant (cloned into the Ehrlichia genome) Ehrlichia translocated factor-3 (Etf-3), a previously predicted effector of the Ehrlichia type IV secretion system (T4SS), is secreted into the host cell cytoplasm. Secreted Etf-3 directly bound ferritin light chain with high affinity and induced ferritinophagy by recruiting NCOA4, a cargo receptor that mediates ferritinophagy, a selective form of autophagy, and LC3, an autophagosome biogenesis protein. Etf-3-induced ferritinophagy caused ferritin degradation and significantly increased the labile cellular iron pool, which feeds Ehrlichia Indeed, an increase in cellular ferritin by ferric ammonium citrate or overexpression of Etf-3 or NCOA4 enhanced Ehrlichia proliferation, whereas knockdown of Etf-3 in Ehrlichia via transfection with a plasmid encoding an Etf-3 antisense peptide nucleic acid inhibited Ehrlichia proliferation. Excessive ferritinophagy induces the generation of toxic reactive oxygen species (ROS), which could presumably kill both Ehrlichia and host cells. However, during Ehrlichia proliferation, we observed concomitant up-regulation of Ehrlichia Fe-superoxide dismutase, which is an integral component of Ehrlichia T4SS operon, and increased mitochondrial Mn-superoxide dismutase by cosecreted T4SS effector Etf-1. Consequently, despite enhanced ferritinophagy, cellular ROS levels were reduced in Ehrlichia-infected cells compared with uninfected cells. Thus, Ehrlichia safely robs host cell iron sequestered in ferritin. Etf-3 is a unique example of a bacterial protein that induces ferritinophagy to facilitate pathogen iron capture.

An intracellular nanobody targeting T4SS effector inhibits Ehrlichia infection.

Infection with obligatory intracellular bacteria is difficult to treat, as intracellular targets and delivery methods of therapeutics are not well known. Ehrlichia translocated factor-1 (Etf-1), a type IV secretion system (T4SS) effector, is a primary virulence factor for an obligatory intracellular bacterium, Ehrlichia chaffeensis In this study, we developed Etf-1-specific nanobodies (Nbs) by immunizing a llama to determine if intracellular Nbs block Etf-1 functions and Ehrlichia infection. Of 24 distinct anti-Etf-1 Nbs, NbD7 blocked mitochondrial localization of Etf-1-GFP in cotransfected cells. NbD7 and control Nb (NbD3) bound to different regions of Etf-1. Size-exclusion chromatography showed that the NbD7 and Etf-1 complex was more stable than the NbD3 and Etf-1 complex. Intracellular expression of NbD7 inhibited three activities of Etf-1 and E. chaffeensis: up-regulation of mitochondrial manganese superoxide dismutase, reduction of intracellular reactive oxygen species, and inhibition of cellular apoptosis. Consequently, intracellular NbD7 inhibited Ehrlichia infection, whereas NbD3 did not. To safely and effectively deliver Nbs into the host cell cytoplasm, NbD7 was conjugated to cyclized cell-permeable peptide 12 (CPP12-NbD7). CPP12-NbD7 effectively entered mammalian cells and abrogated the blockade of cellular apoptosis caused by E. chaffeensis and inhibited infection by E. chaffeensis in cell culture and in a severe combined-immunodeficiency mouse model. Our results demonstrate the development of an Nb that interferes with T4SS effector functions and intracellular pathogen infection, along with an intracellular delivery method for this Nb. This strategy should overcome current barriers to advance mechanistic research and develop therapies complementary or alternative to the current broad-spectrum antibiotic.

Complications and outcomes of swine that underwent cesarean section for resolution of dystocia: 110 cases (2013-2018).

OBJECTIVE: To report the surgical survival of dams and piglets and follow-up survival and future breeding potential of swine that underwent cesarean section for correction of dystocia. STUDY DESIGN: Retrospective study. ANIMALS: One hundred ten client-owned, female swine. All swine included in this study were breeding stock for market pigs to be used for exhibition purposes. METHODS: Medical records of swine that underwent cesarean section at The Ohio State University Hospital for Farm Animals for resolution of dystocia between January of 2013 and July of 2018 were reviewed. Signalment, history, number of piglets per litter, treatments, and surgical procedure were recorded. Follow-up information (survival, complications, and additional pregnancies) was obtained via telephone interview. RESULTS: A fetus was not palpable in 77 of 110 (70%) cases at presentation. The median litter size was eight piglets (range, 1-14), with medians of five (range, 0-13) live and one dead (range, 0-11) piglets per litter. Follow-up was available for 52 dams, of which 39 (75%) survived. Complications were recorded in 20 of 52 (38.46%) cases and included incisional seroma formation, lethargy, and anorexia. Twenty-three dams became pregnant and farrowed after the cesarean section, with no reported complication in 13 of these. CONCLUSION: Cesarean section in swine is associated with a good prognosis for recovery from the procedure and a fair to guarded prognosis for future breeding. CLINICAL SIGNIFICANCE: Cesarean section may be considered for resolution of dystocia in swine. However, owners should be advised that nearly half of sows require assistance in subsequent deliveries.

Plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

We hypothesize that some amino acid abnormalities in diarrheic calves are useful for understanding intestinal mucosal damage, as in humans. However, few reports have revealed the relationship between intestinal mucosal damage and plasma amino acids in diarrheic calves. Therefore, the aim of present study was to investigate whether there is a relationship between the amino acid status and plasma diamine oxidase (DAO) activity, which is known to be a biomarker for intestinal mucosal damage in diarrheic calves. Twenty Holstein calves aged 12.6 ± 4.2 days old were enrolled in this study. In the diarrhea group (n = 10), there were yellow loose feces within the rectum and Cryptosporidium parvum (C. parvum) was detected in all fecal samples. These calves were clinically normal except for diarrhea. All calves in the control group (n = 10) appeared to be healthy based on clinical findings with normal feces production and the absence of C. parvum. Plasma amino acid concentrations and DAO activity were measured. The relationships between plasma DAO activity and the concentration of each plasma amino acid were investigated using Spearman's rank test. The plasma DAO activity was significantly lower in the diarrhea group (176.1 ± 60.1 IU mL-1) than in the control group (309.3 ± 74.8 IU mL-1) (p < 0.001). Furthermore, positive correlations were observed when comparing plasma DAO activity with histidine, proline, cystine, arginine, and glutamine concentrations. As a result of relationship between plasma DAO activity and amino acid status, it was concluded that plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

Pharmacokinetics of magnesium and its effects on clinical variables following experimentally induced hypermagnesemia.

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO4 ) to healthy horses. MgSO4 is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO4 at 60 mg/kg of body weight over 5 min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg2+ ). Objective data were analyzed using the Wilcoxon rank-sum test with p < .05 used as a determination for significance. Plasma concentrations of Mg2+ increased nearly fivefold, ionized calcium (Ca2+ ) decreased by nearly 10%, and the Ca2+ to Mg2+ ratio declined more than 3.5-fold and remained different than baseline until 24 hr (p < .05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca2+ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO4 .

Effectiveness of tapentadol hydrochloride for treatment of orthopedic pain in dogs: A pilot study.

This pilot study evaluated the short-term analgesic effect of oral tapentadol hydrochloride (tapentadol) in dogs with unilateral hind limb lameness secondary to naturally occurring cranial cruciate ligament rupture. Baseline data including pharmacodynamic parameters, sedation scores, lameness scores, and objective gait analyses were collected. Tapentadol was administered orally (30 mg/kg body weight). Four hours following administration of tapentadol all data were collected again. Plasma concentrations of tapentadol 4 hours after administration were assessed using high performance liquid chromatography tandem mass spectrometry. No significant side effects were noted. All dogs had measurable plasma concentrations of tapentadol (mean concentration: 18.9 ng/mL). There were no significant differences in pharmacodynamic parameters or sedation over time. Subjective lameness scores were significantly lower than baseline at 4 hours post-drug administration. No significant improvement was seen in objective gait analysis. Further studies are needed to assess dosing regimens which may lead to effective treatment of acute pain and long-term use.

Efficacité de l'hydrochlorure de tapentadol pour le traitement de douleur orthopédique chez des chiens : une étude pilote. La présente étude pilote a évalué l'effet analgésique à court terme d'hydrochlorure de patentadol (tapentadol) chez des chiens avec une boiterie unilatérale d'un membre arrière secondaire à une rupture du ligament croisé antérieur se produisant naturellement. Les données de base obtenues incluaient des paramètres pharmacodynamiques, des pointages de sédation, des pointages de boiterie et des analyses objectives de la posture. Du tapentadol fut administré oralement (30 mg/kg de poids corporel). Quatre heures suivant l'administration de tapentadol toutes les données furent prises à nouveau. Les concentrations plasmatiques de tapentadol 4 heures après l'administration furent déterminées en utilisant la chromatographie à haute performance en phase liquide en tandem avec la spectrométrie de masse. Aucun effet secondaire significatif ne fut noté. Tous les chiens avaient des concentrations plasmatiques mesurables de tapentadol (concentration moyenne : 18,9 ng/mL). Il n'y avait pas de différence significative dans le temps pour les paramètres pharmacodynamiques ou la sédation. Les pointages subjectifs de boiterie 4 heures postadministration du médicament étaient significativement plus faibles que les valeurs de base. Aucune amélioration significative ne fut observée dans l'analyse objective de la posture. Des études supplémentaires sont requises pour évaluer les régimes de dosage qui pourraient mener à un traitement efficace de la douleur aiguë et de l'utilisation à long-terme.(Traduit par Dr Serge Messier).

Short- and long-term success of transfixation pin casts used to stabilize long bone fractures in ruminants.

Transfixation pin casts (TPC) may be useful in management of fractures in ruminants. A retrospective study was conducted to report the uses, complications, and outcomes of TPC in ruminant fracture stabilization. Twenty-five cattle, 7 goats, and 7 sheep with long bone fractures managed with TPC met the inclusion criteria. Long-term outcome was assessed from telephone interviews with owners. Thirty-one animals (79%) survived to removal of external coaptation and return to the farm. Common complications included pin-hole osteitis and disuse osteopenia. Common complications resulting in death or euthanasia included osteomyelitis and non-union and pin tract fracture. Animals with increased body weight had a greater odds of dying or being euthanized. Cattle had a decreased odds of dying or being euthanized compared with goats and sheep. Long-term follow-up was available for 20 patients, 17 of which returned to intended use and 12 of which had no residual lameness.

Succès à court et à long terme des plâtres à broche transfixiante utilisés pour stabiliser les fractures d'os longs chez les ruminants. Les plâtres à broche transfixiante (PBT) peuvent être un outil utile pour la gestion des fractures des ruminants. Une étude rétrospective a été réalisée afin de faire rapport sur les utilisations, les complications et les résultats des PBT pour la stabilisation des fractures des ruminants. Vingt-cinq bovins, 7 chèvres et 7 moutons avec des fractures d'os longs gérée par PBT ont satisfait aux critères d'inclusion. Les résultats à long terme ont été évalués par entrevue téléphonique avec les propriétaires. Trente-et-un (79 %) animaux ont survécu à l'enlèvement de la coaptation externe et sont retournés à la ferme. Les complications communes incluaient l'ostéite du trou de la broche et l'ostéopénie par inaction. Les complications communes se traduisant par la mort ou l'euthanasie incluaient l'ostéomyélite, la non-union et la fracture causée par la broche. Les animaux ayant un poids supérieur présentaient plus de risques de mortalité ou d'euthanasie. Les bovins présentaient des risques réduits de mortalité ou d'euthanasie comparativement aux chèvres et aux moutons. Le suivi à long terme était disponible pour 20 patients et 17 d'entre eux sont retournés à leur usage prévu et 12 n'avaient pas de boiterie résiduelle.(Traduit par Isabelle Vallières).

Characterization of the contributions of Hp-MMP 9 to the serum acute phase protein response of lipopolysaccharide challenged calves.

BACKGROUND: Bovine respiratory disease (BRD) is a costly feature of modern cattle production. Early and accurate detection of BRD may prove useful in the successful management of this disease. The primary objective of the study was to define the time course of covalent complexes of neutrophil, haptoglobin (Hp) and matrix metalloproteinase 9 (Hp-MMP 9) in serum after intravenous lipopolysaccharide (LPS) in comparison to traditional markers. Our hypothesis was that serum concentrations of neutrophil Hp-MMP 9 provides information distinct from traditional acute phase protein markers. To characterize the neutrophil responses to lipopolysaccharide (E. coli; O111:B4; 2.5 µg/kg body weight), nine healthy, Jersey calves (65-82 days of age; 74.5 ± 13.1 kg) were challenged and physiologic parameters, peripheral blood cell counts and serum cortisol (C), Hp-MMP 9, Hp, alpha1-acid glycoprotein (AGP), serum amyloid A (SAA) were obtained starting 24 hours before to 96 hours post-LPS challenge. RESULTS: Physiologic parameters (temperature, pulse, respiratory rate) and attitude assessed at each time point indicated that LPS challenge resulted in rapid onset of depression, tachypnea, leukopenia, neutropenia and lymphopenia within 1 hour. Serum C concentrations were significantly increased by 1 hour post-LPS. Serum Hp-MMP 9 complexes were detectable in serum by 0.5 hours and peaked at 16 h, serum total Hp remained <10 µg/mL until 8 hours post LPS infusion and were significantly greater than baseline by 12 hours post-LPS infusion. Serum amyloid A concentrations increased significantly by 8 hours post LPS. Serum concentrations of AGP increased significantly by 16 hours post LPS. Serum concentrations of Hp, SAA and AGP remained significantly greater than baseline out to 96 hours post-LPS. The total systemic exposure to traditional makers is significantly greater than from Hp-MMP 9 CONCLUSION: Using a well described model for acute phase protein responses, the data demonstrate that serum neutrophil Hp-MMP 9 complexes appear sooner and decline more rapidly than other acute phase proteins (APP). Since Hp-MMP9 is stored pre-formed, it provides information specifically addressing the LPS-induced activation of bovine neutrophils. Contributions of Hp-MMP 9 to the serum acute phase protein response may provide useful information, independent of hepatic responses, in diagnosis of acute inflammation.

Serum concentrations of haptoglobin and haptoglobin-matrix metalloproteinase 9 (Hp-MMP 9) complexes of bovine calves in a bacterial respiratory challenge model.

BACKGROUND: Serum haptoglobin (Hp) and haptoglobin matrix metalloproteinase 9 complexes (Hp-MMP 9) have been identified as biomarkers with diagnostic potential in cattle with conditions resulting in an acute inflammatory response. The purpose of this study was to evaluate potential diagnostic applications of serum Hp and Hp-MMP 9 concentrations in calves with BRD and establish a timeline for their detection in calves experimentally challenged with Bibersteinia trehalosi and Mannheimia haemolytica. Thirty-five cross bred dairy calves were inoculated via tracheal catheterization with either a PCR confirmed leukotoxin negative B. trehalosi isolate, a PCR confirmed leukotoxin positive B. trehalosi isolate, a Mannheimia haemolytica isolate, a combination of leukotoxin negative B. trehalosi and M. haemolytica, or a negative control. Serum samples were collected throughout the study. Calves were euthanized and necropsy performed on day 10 post inoculation. RESULTS: M. haemolytica inoculated calves had increased lung involvement. Serum Hp and Hp- MMP 9 concentrations were elevated compared to the other treatment groups. Increases in serum Hp and Hp-MMP 9 concentrations for the M. haemolytica group were significantly different from other study groups on day 7 of the study. B. trehalosi inoculated calves did not have increased lung involvement compared to control calves, but the leukotoxin positive B. trehalosi group demonstrated increased serum Hp-MMP 9 concentrations from day 3 to the end of the study compared to the pre-inoculation concentrations. CONCLUSION: Serum Hp-MMP 9 concentration is a useful diagnostic tool for detecting early pulmonary inflammation in calves challenged with B. trehalosi and M. haemolytica. Serum Hp-MMP 9 may also be a useful tool in detecting subclinical pulmonary inflammation in challenged calves.

Efficacy of a Haemonchus contortus vaccine under field conditions in young alpacas.

Anthelmintic resistance to Haemonchus contortus creates increasing management challenges with small ruminants and camelids. The commercial vaccine, Barbervax®, contains H11 and H-gal-GP antigens, derived from gut mucosal membrane enzymes of H. contortus involved in digesting blood. Antibody neutralization of these antigens causes failure of H. contortus to digest blood, resulting in parasite death. H11 and H-gal-GP are considered "hidden" antigens, meaning the host immune system does not encounter these proteins under natural infection. Therefore, repeat immunization is required to maintain protective humoral responses. One previous study evaluated the safety of Barbervax® in camelids but the efficacy could not be assessed due to lack of successful infection in the controls. The objective of the current study was to evaluate clinical parameters of anemia, fecal egg counts (FECs), and humoral immune responses of healthy alpacas after immunizing with Barbervax® compared to non-vaccinated controls, all under natural environmental exposure on parasite-laden pastures. A crossover-like study was performed where twenty alpacas (298 ± 66 days of age) were assigned to be initially vaccinated with Barbervax® (n=10) or receive no treatment (n=10). Three doses of Barbervax® were administered at three-week intervals. Feces and blood were collected on Day -10, 0, 21, 43, 64, 85, 106, and 135 to evaluate FECs, packed cell volume (PCV), and antibody titers. Each group was kept on separate adjacent pastures. Tracer sheep (n=2 per study group) were introduced on Day 43 for a three-week period to ensure parasite acquisition. For the crossover-like component on Day 85, the initial non-vaccinated group was administered Barbervax® with dosing repeated on Day 106 and 135. Results indicated all initially vaccinated alpacas produced antibody titers to vaccine antigen that corresponded to lower mean FECs compared to the initially non-vaccinated group. A reduced mean FEC in the vaccinate group was observed 21 days after peak antibody titers. Similarly, when pooled vaccinate antibody titers were noted to wane on Day 106, an increase in FEC was observed at the following time point (Day 135). Conclusions from our study support the use of Barbervax® to reduce H. contortus burdens in alpacas. Furthermore, a less than 30-day lag time between antibody titer and resultant effect in FECs was observed. Additional studies assessing the ability of Barbervax® to reduce H. contortus burdens during subsequent grazing seasons would provide even greater information regarding the use of Barbervax® within alpaca herds to modulate H. contortus infections, refugia, and anthelmintic use.

Reflecting on the past and fast forwarding to present day anthelmintic resistant Ancylostoma caninum-A critical issue we neglected to forecast.

Reports of anthelmintic resistance in Ancylostoma caninum are increasing in frequency in the United States of America (USA). In the last few years in vitro and in vivo studies characterized individual isolates, demonstrating multiple anthelmintic drug resistance (MADR). In 2021, the American Association of Veterinary Parasitologists initiated a hookworm task force to address this issue. The first report of drug resistant A. caninum occurred in 1987 in Australian racing Greyhounds. In the last five years multiple case reports and investigations show drug resistant A. caninum is becoming a much greater problem in the USA and now extends beyond racing Greyhounds into the general companion animal dog population. The literature, regarding drug resistance in livestock and equine nematodes, provides helpful guidance along with diagnostic methods to better understand the evolution and selection of canine MADR hookworms; however, there are limitations and caveats due to A. caninum's unique biology and zoonotic potential. Mass drug administration (MDA) of anthelminthic drugs to humans to reduce morbidity associated with human hookworms (Necator americanus) should consider the factors that contributed to the development of MADR A. caninum. Finally, as Greyhound racing undergoes termination in some regions and the retired dogs undergo subsequent rehoming, drug resistant parasites, if present, are carried with them. Drug resistant A. caninum requires greater recognition by the veterinary community, and small animal practitioners need to be aware of the spread into current pet dog populations. The current understanding of anthelmintic resistance, available treatments, and environmental mitigation for these drug resistant A. caninum isolates must be monitored for horizontal spread. A major goal in this emerging problem is to prevent continued dissemination.

Effect of storage duration on carprofen concentration measurements in dog plasma.

BACKGROUND: Storage of samples may be necessary prior to testing drug levels in certain study designs; however, the effect of storage duration on measured drug levels is not known for all drugs. OBJECTIVES: The objective of this study was to evaluate the stability of carprofen in canine plasma when stored at -80°C for 6 months. METHODS: Six healthy dogs were enrolled (1-10 years old, 17-35 kg) and received compounded carprofen at 2.2 mg/kg orally every 12 h for 2 days. On the third day, blood was collected immediately before the morning dose (trough), then 1 and 6 h after the dose (sampling timepoint). Whole blood was immediately centrifuged, and plasma was stored at -80°C. Plasma carprofen concentration was measured at day 2, week 2 and then monthly for 6 months using reversed-phase high-performance liquid chromatography. The measured carprofen concentrations were analysed statistically using a linear mixed effects model. RESULTS: There was no effect of storage time over 6 months (p = 0.891) on measured carprofen levels. Although there was an effect of sampling timepoint (0, 1 and 6 h) (p < 0.001), the interaction between storage timepoint and sampling timepoint was not statistically significant (p = 1). CONCLUSIONS: Carprofen-laden canine plasma samples can be stored for up to 6 months before analysis with no degradation in carprofen concentrations expected.

Pharmacokinetics and pharmacodynamics of intramuscular dexmedetomidine in dogs.

OBJECTIVE: To determine the pharmacokinetics and pharmacodynamics of dexmedetomidine after IM administration in dogs. ANIMALS: 6 healthy adult purpose-bred dogs (3 males, 3 females) with a mean ± SD body weight of 25.2 ± 1.8 kg. PROCEDURES: Each dog received 10 µg/kg dexmedetomidine, IM. Heart rate and respiratory rate were counted via cardiac auscultation and visual assessment of chest excursions. Sedation was assessed utilizing 2 sedation scoring systems. Plasma concentrations were determined using ultra performance liquid chromatography-mass spectrometry. Plasma concentrations versus time data after IM dexmedetomidine were analyzed using noncompartmental analysis for extravascular administration. RESULTS: Over the first 2 hours following IM injection of dexmedetomidine, plasma concentrations fluctuated in each dog. The geometric mean (range) maximum plasma concentration was 109.2 (22.4 to 211.5) ng/mL occurring at 20.5 (5 to 75) minutes, and the mean half-life was 25.5 (11.5 to 41.5) minutes. Heart rate was significantly lower than baseline from 30 minutes to 2 hours postdexmedetomidine administration, and respiratory rate was significantly lower than baseline from 45 minutes to 1.75 hours. Dogs were significantly more sedated from 30 minutes to 1.5 hours postdexmedetomidine administration. Median time to onset of sedation was 7.5 minutes (range, 2 to 10 minutes), and median time to peak sedation was 30 minutes (range, 15 to 60 minutes). CLINICAL RELEVANCE: Variations in plasma concentrations occurred in all dogs for the 2 hours postinjection of dexmedetomidine at 10 µg/kg, IM. This was likely due to alterations in absorption due to dexmedetomidine-induced local vasoconstriction. Despite variable plasma concentrations, all dogs were sedated following IM dexmedetomidine administration.

Measurement and prediction of enteric methane emission.

The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission. While CO(2) receives the most attention as a factor relative to global warming, CH(4), N(2)O and chlorofluorocarbons (CFCs) also cause significant radiative forcing. With the relative global warming potential of 25 compared with CO(2), CH(4) is one of the most important GHGs. This article reviews the prediction models, estimation methodology and strategies for reducing enteric CH(4) emissions. Emission of CH(4) in ruminants differs among developed and developing countries, depending on factors like animal species, breed, pH of rumen fluid, ratio of acetate:propionate, methanogen population, composition of diet and amount of concentrate fed. Among the ruminant animals, cattle contribute the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. The estimated CH(4) emission rate per cattle, buffaloe, sheep and goat in developed countries are 150.7, 137, 21.9 and 13.7 (g/animal/day) respectively. However, the estimated rates in developing countries are significantly lower at 95.9 and 13.7 (g/animal/day) per cattle and sheep, respectively. There exists a strong interest in developing new and improving the existing CH(4) prediction models to identify mitigation strategies for reducing the overall CH(4) emissions. A synthesis of the available literature suggests that the mechanistic models are superior to empirical models in accurately predicting the CH(4) emission from dairy farms. The latest development in prediction model is the integrated farm system model which is a process-based whole-farm simulation technique. Several techniques are used to quantify enteric CH(4) emissions starting from whole animal chambers to sulfur hexafluoride (SF6) tracer techniques. The latest technology developed to estimate CH(4) more accurately is the micrometeorological mass difference technique. Because the conditions under which animals are managed vary greatly by country, CH(4) emissions reduction strategies must be tailored to country-specific circumstances. Strategies that are cost effective, improve productivity, and have limited potential negative effects on livestock production hold a greater chance of being adopted by producers. It is also important to evaluate CH(4) mitigation strategies in terms of the total GHG budget and to consider the economics of various strategies. Although reductions in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises.

Effects of intravenous magnesium sulfate on serum calcium-regulating hormones and plasma and urinary electrolytes in healthy horses.

Intravenous magnesium sulfate (MgSO4) is used in equine practice to treat hypomagnesemia, dysrhythmias, neurological disorders, and calcium dysregulation. MgSO4 is also used as a calming agent in equestrian events. Hypercalcemia affects calcium-regulating hormones, as well as plasma and urinary electrolytes; however, the effect of hypermagnesemia on these variables is unknown. The goal of this study was to investigate the effect of hypermagnesemia on blood parathyroid hormone (PTH), calcitonin (CT), ionized calcium (Ca2+), ionized magnesium (Mg2+), sodium (Na+), potassium (K+), chloride (Cl-) and their urinary fractional excretion (F) after intravenous administration of MgSO4 in healthy horses. Twelve healthy female horses of 4-18 years of age and 432-600 kg of body weight received a single intravenous dose of MgSO4 (60 mg/kg) over 5 minutes, and blood and urine samples were collected at different time points over 360 minutes. Plasma Mg2+ concentrations increased 3.7-fold over baseline values at 5 minutes and remained elevated for 120 minutes (P < 0.05), Ca2+ concentrations decreased from 30-60 minutes (P < 0.05), but Na+, K+ and Cl- concentrations did not change. Serum PTH concentrations dropped initially to rebound and remain elevated from 30 to 60 minutes, while CT concentrations increased at 5 minutes to return to baseline by 10 minutes (P < 0.05). The FMg, FCa, FNa, FK, and FCl increased, while urine osmolality decreased from 30-60 minutes compared baseline (P < 0.05). Short-term experimental hypermagnesemia alters calcium-regulating hormones (PTH, CT), reduces plasma Ca2+ concentrations, and increases the urinary excretion of Mg2+, Ca2+, K+, Na+ and Cl- in healthy horses. This information has clinical implications for the short-term effects of hypermagnesemia on calcium-regulation, electrolytes, and neuromuscular activity, in particular with increasing use of Mg salts to treat horses with various acute and chronic conditions as well as a calming agent in equestrian events.

Association of milk yield and infection status at dry-off with intramammary infections at subsequent calving.

The dry period plays an important role in maintenance of udder health. Cows are most susceptible to intramammary infections (IMI) after dry-off and near parturition and drying-off procedures may affect the likelihood of IMI at calving. The objective of this study was to evaluate the association of milk yield and infection status at dry-off with the likelihood of IMI at calving by examining different drying-off methods. Cows (n=112) at the Ohio State University Waterman Dairy Teaching and Research Herd were randomly assigned to either an intermittent or a standard, twice-daily milking group 1 week prior to dry-off. All quarters of all cows in the herd were treated with an antibiotic dry-cow product after the last milking. Milk samples were collected 1 week prior to dry-off (pre-dry), on the day of dry-off, and within 3 d of parturition to determine infection status of the quarters. Association between IMI at calving and cumulative milk yield for the final week of lactation and drying-off method was examined using generalized estimation equations with logic link, accounting for potential confounders, such as pre-dry and dry-off infection status, and for the correlated data structure due to quarters clustered within cows. Intermittent milking significantly reduced milk yield at the end of lactation. Increasing cumulative milk yield during the last week of lactation was significantly associated with a greater probability of IMI at calving for quarters that were uninfected prior to dry-off: uninfected quarters of cows producing more than 115 kg during the last week of lactation were 7.1-times more likely to be infected at calving (P=0.0081) than uninfected quarters of cows producing less than 75 kg. Even though the overall cure rate over the dry period was relatively high at 84%, the odds of a quarter being infected at calving was 7.6- and 3.3-times higher if it was infected at dry-off with major pathogens (P<0.0001) or minor pathogens (P=0.028), respectively, compared with an uninfected quarter at dry-off. The results suggest that decreasing milk yield prior to dry-off may serve as an effective means to maintain good udder health in a herd.

Plasma histidine concentrations as a specific biomarker for intestinal mucosal damage in calves with cryptosporidiosis.

Specific alterations in plasma histidine concentrations and diamine oxidase (DAO) activity were recently reported as a potential biomarker for intestinal mucosal damage in diarrheic calves. However, there are no data on the comparison of precision between histidine concentration and DAO activity in bovine plasma. The aim of the present study was to compare precision of histidine concentrations and DAO activities in plasma as a biomarker for the Cryptosporidium parvum (C. parvum)-associated intestinal mucosal damage in diarrheic calves. Thirty-two Holstein calves aged 12.2 ± 4.1 days old were enrolled in the present study; they were divided into C. parvum (n = 9), diarrhea (n = 11), and control (n = 12) groups based on the presence or absence of diarrhea and with or without C. parvum infection. Receiver operating characteristic (ROC) curves were used to characterize the sensitivity and specificity of each parameter for the C. parvum-associated intestinal mucosal damage. The proposed cut-off points for plasma histidine concentrations and plasma DAO activities for cryptosporidiosis in calves based on ROC analyses were < 55.8 nM and < 246.0 IU/ml, respectively. The sensitivities and specificities of the proposed diagnostic cut-offs were 88.9% and 82.6% for plasma histidine concentrations and 100.0% and 34.8% for plasma DAO activities, respectively. It was concluded that plasma histidine concentrations may be superior to plasma DAO activities as a specific biomarker for the C. parvum-associated intestinal mucosal damage in diarrheic calves.

Sequential changes in hepatic mRNA abundance and serum concentration of serum amyloid A in cattle with acute inflammation caused by endotoxin.

The objective of the present study was to elucidate sequential changes in mRNA abundance of serum amyloid A (SAA) isotypes in endotoxin (ETX) challenge model cattle. Ten healthy cattle were separated to 2 groups: control and ETX groups. Cattle in the ETX group were challenged by 2.5 µg/kg of O111:B4 lipopolysaccharide in 4 ml of autologous serum. Blood samples were withdrawn at pre, 0.5, 1, 2, 4, 8, 12, 24, 48, 72 and 96 hr after ETX challenge. Plasma ETX activity, serum SAA concentrations, mRNA abundance of interleukin (IL)-6, SAA2 and SAA4 in the liver and polymorphonuclear leukocytes were measured. The plasma ETX activity in the ETX group increased at 0.5 hr after the ETX challenge. The serum SAA value remained higher between 12 and 72 hr after the ETX challenge than that of the control group. Hepatic IL-6 mRNA abundance in the ETX group increased at 2 hr after the ETX challenge. Hepatic SAA2 and SAA4 mRNA abundance significantly increased from 4 hr after administration, and remained significantly higher than those pre-values up to 12 and 24 hr, respectively. The abundance ratio of hepatic SAA2 was much higher than that of SAA4. The major isotype was SAA2 in liver tissue, and it is indicating systemic inflammation in cattle.

Pharmacokinetics of an intravenous constant rate infusion of a morphine-lidocaine-ketamine combination in Holstein calves undergoing umbilical herniorrhaphy.

OBJECTIVE: To describe the pharmacokinetics of morphine, lidocaine, and ketamine associated with IV administration of a constant rate infusion (CRI) of a morphine-lidocaine-ketamine (MLK) combination to calves undergoing umbilical herniorrhaphy. ANIMALS: 20 weaned Holstein calves with umbilical hernias. PROCEDURES: Calves were randomly assigned to receive a CRI of an MLK solution (0.11 mL/kg/h; morphine, 4.8 µg/kg/h; lidocaine, 2.1 mg/kg/h; and ketamine, 0.42 mg/kg/h) for 24 hours (MLK group) or 2 doses of flunixin meglumine (1.1 mg/kg, IV, q 24 h) and a CRI of saline (0.9% NaCl) solution (0.11 mL/kg/h) for 24 hours (control group). For all calves, the CRI was begun after anesthesia induction. Blood samples were obtained immediately before and at predetermined times for 120 hours after initiation of the assigned treatment. Noncompartmental analysis was used to estimate pharmacokinetic parameters for the MLK group. RESULTS: During the CRI, steady-state serum concentrations were achieved for lidocaine and ketamine, but not morphine. Mean terminal half-life was 4.1, 0.98, and 1.55 hours and area under the concentration-time curve was 41, 14,494, and 7,426 h•µg/mL for morphine, lidocaine, and ketamine, respectively. After the CRI, the mean serum drug concentration at steady state was 6.3, 616.7, and 328 ng/mL for morphine, lidocaine, and ketamine, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: During the CRI of the MLK solution, steady-state serum concentrations were achieved for lidocaine and ketamine, but not morphine, likely owing to the fairly long half-life of morphine. Kinetic analyses of MLK infusions in cattle are necessary to establish optimal dosing protocols.

Analgesic efficacy of an intravenous constant rate infusion of a morphine-lidocaine-ketamine combination in Holstein calves undergoing umbilical herniorrhaphy.

OBJECTIVE: To assess the analgesic efficacy of an IV constant rate infusion (CRI) of a morphine-lidocaine-ketamine (MLK) combination in calves undergoing umbilical herniorrhaphy. ANIMALS: 20 weaned Holstein calves with umbilical hernias. PROCEDURES: Calves were randomly assigned to receive a CRI of an MLK solution (0.11 mL/kg/h; morphine, 4.8 µg/kg/h; lidocaine, 2.1 mg/kg/h; and ketamine, 0.42 mg/kg/h) for 24 hours (MLK group) or 2 doses of flunixin meglumine (1.1 mg/kg, IV, q 24 h) and a CRI of saline (0.9% NaCl) solution (0.11 mL/kg/h) for 24 hours (control group). The assigned CRI was begun after anesthesia induction. A pain-scoring system and incisional algometry were used to assess pain, and blood samples were obtained to measure serum cortisol concentration at predetermined times for 120 hours after CRI initiation. RESULTS: Mean pain scores did not differ significantly between the MLK and control groups at any time. Mean algometry score for the MLK group was significantly greater (calves were less responsive to pressure) than that for the control group at 4 hours after CRI initiation. Mean cortisol concentration decreased over time for both groups and was significantly greater for the MLK group than the control group at 1, 4, and 18 hours after CRI initiation. CONCLUSIONS AND CLINICAL RELEVANCE: A CRI of MLK provided adequate postoperative analgesia to calves that underwent umbilical herniorrhaphy. However, the technical support required for CRI administration limits its use to hospital settings. Kinetic analyses of MLK infusions in cattle are necessary to establish optimal dosing protocols and withdrawal intervals.