Characterization of the Hoof Bacterial Communities of Active Digital Dermatitis Lesions in Feedlot Cattle.

Digital dermatitis (DD) is a costly hoof infection, causing lameness and pain in feedlot cattle. DD lesions can develop nonlinearly through a series of clinical stages, which can be classified by Dopfer's M-stage scoring system. This widely adopted lesion scoring system recognizes five DD stages, where M1 (early lesion), M2 (acute ulcerative lesion), and M4.1 (chronic proliferative lesion with new developing lesion) are considered active but separate stages of the disease. This study assessed the skin surface microbiota of the active DD lesions of feedlot cattle. The DD lesions from three commercial feedlots were swabbed and then scored according to Dopfer's M-stage scoring system. Swab samples were collected from 12 M2- and 15 M4.1-stage lesions. A total of 21 control swab samples from healthy contralateral feet (DD control) were classified as stage M0. An additional six skin swabs (M0) were collected from completely healthy (CH control) cattle with no lesions. The bacterial communities of active DD lesions (M2 and M4.1) and healthy skin (M0) were profiled using 16S amplicon sequencing. Diversity analyses showed that the hoof bacterial communities of M2 and M4.1 lesions were each distinct from those of M0 skin. However, the bacterial communities between the two active lesion stages were not different from each other. A significant increase in the relative abundance of Spirochaetota and Fusobacteriota and an overall decrease in bacterial diversity contributed to the altered bacterial communities in M2 and M4.1 lesions compared to those of healthy skin (M0). Although stages M2 and M4.1 are considered clinically different stages, the lesion-associated bacterial community is similar between the two active stages.

Epidemiology of Digital Dermatitis in Western Canadian Feedlot Cattle.

Digital dermatitis (DD) is an emerging disease in feedlot cattle. Our objective was to identify animal- and feedlot-level risk factors for DD by analyzing individual animal health records (n = 1,209,883) and feedlot-level records from western Canadian feedlots (n = 28) between 2014 and 2018, inclusive. The risk of a DD diagnosis was higher (incidence rate ratio (IRR) = 2.08, 95% CI 1.52 to 2.86) in cattle sourced from confined background operations (CB) versus cattle sourced from auction markets (AM). Conversely, ranch direct (RD) cattle were (IRR = 0.02, 95% CI 0.04 to 0.30) lower risk than AM cattle of being diagnosed with DD. The risk of being diagnosed with DD was higher in females than in males. The magnitude of the risk in females over males was influenced by annual DD incidence in low morbidity years (2014, 2017, and 2018) (IRR = 2.02, 95% CI 1.27 to 3.19), medium morbidity years (2016) (IRR = 2.95, 95% CI 1.64 to 5.33), and high morbidity years (2015) (IRR = 5.41, 95% CI 3.27 to 8.95). At the feedlot-level, the risk of a diagnosis of DD was lower in small capacity (SCF) versus large capacity feedlots (LCF) (IRR = 0.24, 95% CI 0.05 to 0.76). Future research should focus on identifying factors that may propagate disease transmission between cattle of different sexes and from different acquisition sources.

Characterization of the hoof bacterial communities in feedlot cattle affected with digital dermatitis, foot rot or both using a surface swab technique.

BACKGROUND: Lameness is defined as altered or abnormal gait due to dysfunction of the locomotor system, and is a health issue of feedlot cattle, having major economic, labour, and welfare implications. Digital dermatitis (DD-a lesion of the plantar surface of the foot) and foot rot (FR-affects the interdigital cleft) are common infectious causes of lameness in feedlots. These hoof lesions can occur alone or in combination (DD + FR) in the same hoof. A total of 208 hoof swabs were collected from three commercial feedlots located in southern Alberta. Every lesion sample was matched with a corresponding control skin sample taken from a healthy contralateral foot. Control skin samples were also collected from cattle with no lesion on any feet. Bacterial communities of three types of hoof lesions (DD, DD + FR, FR) and healthy skin were profiled using 16S amplicon sequencing. RESULTS: Alpha diversity analysis revealed a lower bacterial diversity on DD and FR lesions compared to control skin. Beta diversity analysis showed that bacterial communities of DD, FR, and DD + FR lesions were distinct from those of the control skin. While the impact of feedlot was minimal, lesion type contributed to 22% of the variation observed among bacterial communities (PERMANOVA-R = 0.22, P < 0.01). Compared to the corresponding control skin, there were 11, 12, and 3 differentially abundant (DA) bacterial genera in DD, DD + FR, and FR lesions, respectively. CONCLUSIONS: The bacterial community description of a DD + FR lesion is a novel finding. Not only did lesions lead to altered bacterial communities when compared to healthy skin, but the composition of those communities also differed depending on the hoof lesion. The 16S amplicon sequencing of surface swabs has significant value as a research tool in separating different hoof lesions and can provide additional insights to the polybacterial etiology of DD and FR in feedlot cattle.

Discovery and comparative genomic analysis of a novel equine anellovirus, representing the first complete Mutorquevirus genome.

The complete genome of a novel torque teno virus species (Torque teno equus virus 2 (TTEqV2) isolate Alberta/2018) was obtained by high-throughput sequencing (HTS) of nucleic acid extracted from the lung and liver tissue of a Quarter Horse gelding that died of nonsuppurative encephalitis in Alberta, Canada. The 2805 nucleotide circular genome is the first complete genome from the Mutorquevirus genus and has been approved as a new species by the International Committee on Taxonomy of Viruses. The genome contains several characteristic features of torque teno virus (TTV) genomes, including an ORF1 encoding a putative 631 aa capsid protein with an arginine-rich N-terminus, several rolling circle replication associated amino acid motifs, and a downstream polyadenylation signal. A smaller overlapping ORF2 encodes a protein with an amino acid motif (WX7HX3CXCX5H) which, in general, is highly conserved in TTVs and anelloviruses. The UTR contains two GC-rich tracts, two highly conserved 15 nucleotide sequences, and what appears to be an atypical TATA-box sequence also observed in two other TTV genera. Codon usage analysis of TTEqV2 and 11 other selected anelloviruses from five host species revealed a bias toward adenine ending (A3) codons in the anelloviruses, while in contrast, A3 codons were observed at a low frequency in horse and the four other associated host species examined. Phylogenetic analysis of TTV ORF1 sequences available to date shows TTEqV2 clusters with the only other currently reported member of the Mutorquevirus genus, Torque teno equus virus 1 (TTEqV1, KR902501). Genome-wide pairwise alignment of TTEqV2 and TTEqV1 shows the absence of several highly conserved TTV features within the UTR of TTEqV1, suggesting it is incomplete and TTEqV2 is the first complete genome within the genus Mutorquevirus.

Economic impact of digital dermatitis, foot rot, and bovine respiratory disease in feedlot cattle.

Digital dermatitis (DD) has emerged in North American feedlots, although production and economic impacts are not fully understood. Objectives of this study were to: (1) estimate the economic impact of a single case of DD, foot rot (FR), and bovine respiratory disease (BRD) in feedlot cattle and (2) determine its impact on average daily gain (ADG). Feedlot cattle health and production records were available from two feedlots for a 3-yr interval. The dataset consisted of 77,115 animal records, with 19.3% (14,900) diagnosed with a disease. Diseased animals were categorized into five groups: DD, FR, BRD, other diseases (OT), and two or more diseases (TM), with a treatment cumulative incidence of 6.0%, 59.1%, 10.7%, 12.7%, and 11.5%, respectively. FR was the disease with the highest cumulative incidence in both heifers and steers (58.8% and 59.6%, respectively). Of all fall-placed cattle diagnosed with any disease, 48.1% of the cases were FR. DD affected the partial budget in five out of the eight groups of cattle, with the highest impact of DD seen in grass yearling heifers and grass yearling steers: $-98 and $-96 CAD, respectively, relative to their healthier counterparts. Healthy cattle had a significantly higher ADG when compared with DD cattle in five of the eight categories, ranging from 0.11 kg/d in winter-placed heifers to 0.17 kg/d in fall-placed steers. In the economic analysis, it was concluded that on an individual animal basis, BRD was the most impactful of all analyzed diseases, whereas DD was second, marking the importance of controlling and mitigating this foot condition. Identifying differential effects of diseases on a partial budget analysis and ADG of the types of cattle stratified by sex enables feedlot producers to focus control and mitigation strategies on specific groups.

Risk factors of digital dermatitis in feedlot cattle.

Digital dermatitis (DD) has been reported in North American feedlots, although risk factors are not well characterized. Our objectives were to analyze: (1) foot and leg conformation and (2) pen hygiene, as potential variables that predispose feedlot cattle to DD. Production parameters in DD-affected cattle were compared with healthy cattle and with those diagnosed with more commonly known infectious lesion foot rot (FR). In total, 2,854 feedlot cattle in 11 pens in 2 feedlots were assessed (bi-weekly pen walks) throughout the feeding cycle. Pen condition was categorized as: "dry," "mud present but has good bedding," "more mud than bedding," and "excessive mud." Gait scoring was competed and cattle with abnormal gait or evident foot lesions (i.e., DD or FR) were restrained in a cattle chute for a close foot inspection (n=280), including scoring of foot angle and claw set and hind and side views of rear feet and legs. Cumulative incidence of DD (present or absent) and FR was 2.5% (71/2,854) and 11.6% (331/2,854), respectively. Foot and leg conformation was not significantly different between left and right sides or between cattle with (n=71) and without DD (n=209). Lameness was diagnosed in only 22% of cattle with DD. Cattle with DD gained 0.27 kg/d less compared with healthy cattle (mean ± SD: 1.29 ± 0.29 vs. 1.56 ± 0.27, P<0.05) and 0.4 kg/d less compared with FR (1.29 ± 0.29 vs. 1.69 ± 0.25). Presence of DD was not significantly different between pens with "dry" and "mud present but has good bedding," but for pens with "more mud than bedding" or "excessive mud," the risk of cattle having DD cases increased significantly [odds ratio (OR)=8.55, confidence interval (CI): 4.0-18.4 and OR=14.1, CI: 5.9-33.8, respectively]. In conclusion, it is important to keep good pen conditions to reduce the risk of DD, which can be managed through proper stocking density and strategic bedding, irrespective of foot and leg conformation.

Septicemic pasteurellosis causing peracute death and necrotizing myositis in a beef heifer calf (Bos taurus) in Alberta, Canada.

Septicemic pasteurellosis is an acute and fatal bacterial disease of cattle and wild ungulates caused by certain serotypes of Pasteurella multocida. Here we report a single case of septicemic pasteurellosis in a 6-month-old, Red Angus heifer from a cow-calf operation in Alberta, Canada. Postmortem examination revealed necrotizing and hemorrhagic myositis, fibrinous pericarditis and multisystemic bacterial emboli. Pasteurella multocida was isolated from muscle in pure culture, and the capsular antigen group was identified as serogroup B using polymerase chain reaction. To the best of our knowledge, this is the first reported case of septicemic pasteurellosis in beef cattle in Canada. Key clinical message: Veterinary practitioners and diagnosticians should include septicemic pasteurellosis on their list of differential diagnoses when they encounter similar presentations of peracute death and severe necrotizing myositis in cattle in Canada.

Pasteurellose septicémique causant la mort suraiguë et une myosite nécrosante d'une génisse d'embouche ( Bos taurus ) en Alberta, Canada. La pasteurellose septicémique est une maladie bactérienne aiguë et fatale des bovins et des ongulés sauvages causée par certains sérotypes de Pasteurella multocida. Nous rapportons ici un cas unique de pasteurellose septicémique chez une génisse Red Angus âgée de 6 mois provenant d'un élevage vache-veau en Alberta, Canada. L'examen post-mortem a révélé une myosite nécrosante et hémorragique, une péricardite fibrineuse et des embolies bactériennes multi-systémiques. Pasteurella multocida fut isolé du muscle en culture pure, et l'antigène de groupe capsulaire fut identifié comme étant le sérogroupe B à l'aide de la réaction d'amplification en chaîne utilisant la polymérase. À notre connaissance ceci représente le premier cas rapporté de pasteurelle septicémique chez des bovins d'embouche au Canada.Message clinique clé:Les vétérinaires praticiens et les diagnosticiens devraient inclure la pasteurellose septicémique sur leur liste de diagnostic différentiel lorsqu'ils rencontrent des présentations similaires de mortalité suraiguë et de myosite nécrosante sévère chez des bovins au Canada.(Traduit par Dr Serge Messier).

Measuring behavioral and physiological responses to pain mitigation for ovariectomy in Bos taurus yearling beef heifers.

Ovariectomy (spaying) using the trans-vaginal dropped ovary technique (DOT) is performed to prevent pregnancy in cull female beef cattle that are not retained for breeding stock in areas practicing extensive grazing management. There are no reports describing analgesia for this surgical procedure. The objective of this study was to measure behavioral and physiological responses to determine whether an analgesic protocol of BXK [butorphanol (0.01 mg/kg), xylazine (0.02 mg/kg), and ketamine (0.04 mg/kg)] injected intramuscularly (i.m.) before spaying could mitigate procedural and immediate postsurgical pain, and whether oral meloxicam (1 mg/kg) administered at the time of spaying could mitigate postsurgical inflammatory pain. Forty-four red Angus and Angus crossbred yearling heifers (322 ± 27.0 kg BW) were randomly allocated to 1 of 3 groups: PALP (control; palpated but not spayed; n = 14), SPAY (spayed with no analgesia; n = 15), and BXKM (spayed with analgesia; n = 15). Behavioral measurements included visual analog scale (VAS) score, flight speed (FS), stride length (SL), and gait score (GS), as well as activity (lying, standing) and feeding behavior. Physiological measurements included salivary cortisol (SC), haptoglobin (Hp), serum amyloid A (SAA), substance P (SP), complete blood count (CBC), and rectal temperature (RT). Saliva and blood samples were collected, and RT, FS, SL, and GS were measured on day -1, day 0 (time of palpation/spaying), and hours 1, 2, 4, and days 1, 2, 4, and 7 after palpation/spaying. The BXKM heifers had lower SC concentrations than SPAY heifers at 1 h (P = 0.01) and 2 h (P = 0.004). Heifers treated with BXKM had Hp concentrations lower than SPAY heifers at 2 d (P = 0.01), 4 d (P < 0.001), and 7 d (P = 0.008), and lower Hp concentrations than PALP heifers at 4 d (P < 0.001). Concentrations of SAA were greater (P = 0.04) in BXKM heifers than in PALP heifers at 1 h and lower in PALP heifers than in BXKM heifers (P = 0.02) and SPAY heifers (P = 0.05) at 1 d. Heifers in the BXKM group had higher RT than PALP and SPAY heifers at 1 h (P < 0.001) and 2 h (P = 0.004). Results suggest that DOT ovariectomy is acutely stressful and painful and administration of BXK before spaying and meloxicam at the time of spaying mitigated the procedural and postsurgical stress, pain, and inflammation.

Pharmacokinetics of oral and subcutaneous meloxicam: Effect on indicators of pain and inflammation after knife castration in weaned beef calves.

Oral meloxicam is labelled for reducing pain and inflammation associated with castration in cattle in Canada, however, subcutaneous meloxicam is only labelled for pain associated with dis-budding and abdominal surgery. The aim of this project was to determine the pharmacokinetic profile of oral (PO; 1.0 mg/kg BW) and subcutaneous meloxicam (SC; 0.5 mg/kg BW), and to assess the effect of meloxicam on physiological and behavioural indicators of pain associated with knife castration in 7-8 month old calves. Twenty-three Angus crossbred beef calves (328 ± 4.4 kg BW) were randomly assigned to two treatments: PO n = 12 or SC n = 11 administration of meloxicam immediately before knife castration. Physiological parameters included salivary and hair cortisol, substance P, haptoglobin, serum amyloid-A, weight, complete blood count, scrotal and rectal temperature. Behavioural parameters included standing and lying behaviour, pen behaviour and feeding behaviour. Data were analyzed using PROC GLIMMIX (SAS), with repeated measures using mixed procedures including treatment as a fixed effect and animal and pen as a random effect. The pharmacokinetic profile of the drug including area under the curve, volume of distribution and clearance was greater (P < 0.05) in PO than SC calves. After surgery, substance P concentrations, white blood cell counts (WBC), weight and lying duration were greater (P < 0.05) in PO than SC calves, while scrotal circumference was lower (P < 0.05) in PO calves than SC calves. Although statistical differences were observed for pharmacokinetic, physiological and behavioural parameters differences were small and may lack biological relevance.

Effect of meloxicam and lidocaine administered alone or in combination on indicators of pain and distress during and after knife castration in weaned beef calves.

To assess the effect of meloxicam and lidocaine on indicators of pain associated with castration, forty-eight Angus crossbred beef calves (304 ± 40.5 kg of BW, 7-8 months of age) were used in a 28 day experiment. The experiment consisted of a 2 × 2 factorial design where main factors included provision of analgesia and local anaesthesia. Analgesia consisted of: no-meloxicam (N; n = 24) single s.c. administration of lactated ringer's solution and meloxicam (M; n = 24) single dose of 0.5 mg/kg of s.c. meloxicam. Local anesthesia consisted of: no-lidocaine (R; n = 24) ring block administration of lactated ringer's solution or lidociane (L; n = 24) ring block administration of lidocaine. To yield the following treatments: no meloxicam + no lidocaine (N-R; n = 12), no meloxicam + lidocaine (N-L; n = 12), meloxicam + no lidocaine (M-R; n = 12) and meloxicam + lidocaine (M-L; n = 12). Salivary cortisol concentrations were lower (lidocaine × time effect; P < 0.01) in L calves than R calves 0.5 and 1 hours after castration, while concentrations were lower (meloxicam × time effect; P = 0.02) in M calves than N calves at 2, 4 and 48 hours. The serum amyloid-A concentrations were greater (lidocaine × time effect; P < 0.01) in R calves than L calves on days 1, 3, 21 and 28 after castration. Haptoglobin concentrations were greater (meloxicam × time effect; P = 0.01) in N calves than M calves 24 and 48 hours after castration. Lower (lidocaine effect; P < 0.01) visual analog scale (VAS) scores, leg movement frequencies and head movement distance were observed in L calves than R calves at the time of castration. Escape behaviour during castration was lower (lidocaine effect; P < 0.05) in L calves than R calves based on data captured with accelerometer and head gate devices. Scrotal circumference had a triple interaction (lidocaine × meloxicam × time; P = 0.03), where M-R calves had greater scrotal circumference than M-L calves 28 d after castration, but no differences were observed between both groups and N-R and N-L calves. No differences (P > 0.05) were observed for average daily gain (ADG), weights or feeding behaviour. Overall, both lidocaine and meloxicam reduced physiological and behavioural indicators of pain. Although there was only one meloxicam × lidocaine interaction, lidocaine and meloxicam reduced physiological and behavioural parameters at different time points, which could be more effective at mitigating pain than either drug on its own.

A longitudinal investigation of an outbreak of toe tip necrosis syndrome in western Canadian feedlot cattle.

This investigation followed a cohort (n = 21) of single-sourced Angus cross yearling heifers diagnosed with toe tip necrosis syndrome (TTNS). The animals were intensively followed for ~7 months, over which time 5 animals were euthanized because of intractable lameness or life-threatening sequelae such as cellulitis and myositis. Treatment consisted of systemic antimicrobial and nonsteroidal anti-inflammatory therapy, removing the necrotic horn tissue to facilitate drainage, and relocating the cattle to an earthen-floor pen. Sixteen of the 21 heifers recovered uneventfully. Upon sectioning the feet after slaughter, all the foot lesions had healed, but in some instances, the 3rd phalangeal bone had undergone bone remodeling, indicative of an earlier pathological process. This study is unique in that it chronicled the clinical and pathological outcomes associated with TTNS over an extended period.

Enquête longitudinale d'une éclosion du syndrome de nécrose de la pince chez les bovins de parcs d'engraissement dans l'Ouest canadien. Cette enquête a suivi une cohorte (n = 21) de génisses de race croisée Angus âgées d'un an provenant d'une seule source qui ont reçu un diagnostic de syndrome de la nécrose de la pince. Les animaux ont fait l'objet d'un suivi intensif de ~7 mois, pendant lequel 5 animaux ont été euthanasiés en raison d'une boiterie intraitable ou de séquelles potentiellement mortelles comme la cellulite et la myosite. Le traitement a consisté d'antimicrobiens systémiques et de traitements anti-inflammatoires non stéroïdiens, de l'enlèvement des tissus nécrosés de la corne afin de faciliter le drainage et du déplacement des bovins dans des enclos dotés d'un plancher de terre battue. Seize des 21 génisses se sont rétablies sans incident. Au moment du sectionnement des pieds après l'abattage, toutes les lésions des pieds avaient guéri mais, dans certaines instances, l'os de la troisième phalange avait subi un remodelage osseux, ce qui indique un processus pathologique antérieur. Cette étude est unique parce qu'elle dresse l'historique des résultats cliniques et pathologiques associés au syndrome de nécrose de la pince pendant une période prolongée.(Traduit par Isabelle Vallières).

Effect of a single dose of subcutaneous meloxicam prior to band or knife castration in 1-wk-old beef calves: II. Inflammatory response and healing.

The aim of this study was to evaluate the effect of a single dose of subcutaneous (s.c.) meloxicam administered at the time of knife and band castration on inflammatory response and wound healing over 56-d post-castration. Seventy-two Angus crossbred calves (47.3 ± 6.70 kg of body weight [BW] and 7 to 8 d of age) were randomly assigned according to a 3 × 2 factorial design assessing castration method: sham (CT), band (BA), and knife (KN) castration, and pain mitigation: non-medicated (NM) and medicated calves (M) injected s.c. with meloxicam (0.5 mg/kg of BW). Calf BW, rectal temperature, swelling ("0": no swelling; "4": swelling needing intervention) and healing score ("1" to "5" with "5" being completely healed), scrotal circumference, and maximum scrotal temperature were measured on d -1, immediately before castration (d 0), and weekly thereafter over a 56-d period. Blood samples for haptoglobin (Hp), serum amyloid-A (SAA), and complete blood cell count were collected according to the same schedule. Hair samples were collected on d -1, 28, and 56 to determine cortisol concentrations. Standing and lying behaviors were measured using accelerometers that were placed on the calves on d -1 until d 35, and visual observations of behaviors related to pain were recorded once a week for 35 d. Knife-castrated calves achieved swelling scores of "3" and "2" between d 7 and 14, which was sooner (Z< 0.05) than in BA calves (from d 14 to 35). In addition, greater (P = 0.03) concentrations of SAA were observed in BA calves (76.9 ± 0.12 g/liter) compared with CT (57.6 ± 0.12 g/liter) and KN (51.6 ± 0.12 g/liter) from d 7 to 35. Healing scores of "2" and "4" tended to be achieved sooner (Z < 0.10) in KN calves than in BA calves, although healing scores of "3" tended to be achieved sooner (Z < 0.10) in BA calves than KN calves. No differences (P > 0.10) were observed among treatments for hair cortisol on d -1 and 28, but on d 56, hair cortisol concentrations in BA-NM calves were greater (P > 0.05) than for CT-NM, BA-M, KN-NM, and KN-M, and tended to be greater (P = 0.08) than for CT-M calves. Lying duration tended (P = 0.10) to be greater and suckling behavior tended (P = 0.08) to be lower in NM than M calves. A single s.c. injection of meloxicam did not reduce long-term inflammatory responses or improve wound healing; however, it may be useful in reducing pain and stress in band castrated calves as evidenced by reduced hair cortisol concentrations up to 56 d post-castration.

Effect of subcutaneous meloxicam on indicators of acute pain and distress after castration and branding in 2-mo-old beef calves1,2.

The aim of this study was to assess knife castration and knife castration + branding in 2-mo-old calves, and the effect of a single dose of s.c. meloxicam at mitigating pain indicators. Seventy-one Angus crossbred bull calves (128 ± 18.5 kg of BW) were used in a 3 × 2 factorial design where main factors included procedure: sham (control calves, CT; n = 23), knife (KN; n = 24) or knife + branding (BK; n = 24), and medication: single s.c. administration of lactated ringer solution (NM; n = 35) or a single dose of 0.5 mg/kg of s.c. meloxicam (M; n = 36). Physiological samples were collected at T0, 60, 90, 120, and 180 min and on days 1, 2, 3, and 7 after procedure, whereas behavioral observations were evaluated at 2 to 4 h and 1, 2, 3, and 7 days after procedure. A procedure × time effect (P < 0.01) was observed for cortisol, where KN and BK calves had greater (P ≤ 0.01) cortisol concentrations than CT calves 60 min after the procedure, whereas BK calves had the greatest (P < 0.05) cortisol concentrations, followed by KN calves and by CT calves 90, 120, and 180 min after the procedure. A procedure × time effect (P = 0.01) was observed for tail flicks, where KN and BK calves had a greater (P < 0.05) number of tail flicks than CT calves on days 1 and 3, whereas BK calves had the greatest number of tail flicks, followed by KN calves, and then by CT calves on day 2. Haptoglobin had a procedure × medication × time interaction (P = 0.05), where BK-NM calves had greater haptoglobin concentrations than BK-M, KN-M, and CT calves on days 1 and 3, whereas BK-NM and KN-NM calves had greater haptoglobin concentrations than BK-M, KN-M, and CT calves on day 2 after the procedure. Lying duration and tail flicks had a medication effect (P = 0.04; P < 0.01) where M calves had greater (P < 0.05) lying duration and lower (P < 0.05) number of tail flicks than NM calves 2 to 4 h after procedure. No medication effects (P > 0.10) were observed for salivary cortisol, substance P, and scrotal temperature minutes after the procedure or for cortisol, substance P, serum amyloid-A, stride length, or behavioral observations days after the procedure. Overall, BK calves presented greater physiological and behavioral indicators of acute pain than KN calves, suggesting that the combination of knife castration + branding was more painful. Meloxicam administered s.c. was effective at reducing physiological and behavioral indicators of acute pain associated with knife castration and knife castration + branding.

Use of topical healing agents on scrotal wounds after surgical castration in weaned beef calves.

Angus bulls (n = 48) were randomly assigned to control (castrated without the application of a postoperative healing agent) or surgical castration followed by either the application of a topical germicide, aluminum powder spray, or liquid bandage. The objective of this study was to determine the efficacy of commercial topical healing agents in improving wound healing and reducing inflammation and secondary infection after surgical castration. Indicators of wound healing included scrotal area temperature (determined by infrared thermography), scrotal circumference, clinical state of the scrotum score, and the wound healing score. Pain sensitivity was measured using a Von Frey anesthesiometer. The healing agents used in this study did not improve indicators of healing such as swelling and healing rate scores or indicators of inflammation including scrotal temperature and circumference of surgical castration lesions. Pain sensation associated with surgical castration was found to last 35 d after the procedure.

Usage d'agents cicatrisants topiques sur des blessures scrotales après la castration chirurgicale chez des veaux de boucherie sevrés. Quarante-huit taureaux Angus ont été assignés au hasard à la castration témoin (castration sans l'application d'un agent cicatrisant postopératoire) ou à la castration chirurgicale suivie soit de l'application d'un germicide topique, d'un poudre à l'aluminium en vaporisateur ou d'un pansement liquide dans le but de déterminer l'efficacité des agents cicatrisants topiques commerciaux pour l'amélioration de la guérison des plaies et la réduction de l'inflammation et de l'infection secondaire après la castration chirurgicale. Les indicateurs de cicatrisation des plaies incluaient la température de la région scrotale déterminée par thermographie infrarouge, la circonférence scrotale, le pointage de l'état clinique du scrotum et le pointage de la cicatrisation de la plaie; et la sensibilité à la douleur mesurée à l'aide d'un anesthésiomètre Von Frey. Les agents cicatrisants utilisés dans cette étude n'ont pas amélioré les indicateurs de cicatrisation comme l'enflure et les notes de la rapidité de cicatrisation ou des indicateurs de l'inflammation qui incluaient la température scrotale et la circonférence des lésions de castration chirurgicale. Il a été constaté que la sensation de douleur associée à la castration chirurgicale durait 35 jours après l'intervention.(Traduit par Isabelle Vallières).

Prospective case-control study of toe tip necrosis syndrome (TTNS) in western Canadian feedlot cattle.

A case-control study was conducted to investigate potential risk factors for toe tip necrosis syndrome (TTNS) in western Canadian feedlot cattle. Feedlot veterinarians provided hooves from 222 animals that died of either TTNS ("cases") or from all other causes ("controls"). The claws were sectioned by researchers to confirm the diagnoses; there was very good agreement between the practitioners' field diagnosis and that of the researchers (Cohen's kappa = 0.81; P < 0.001). The sole thickness of the apical white line region was thinner (P < 0.001) in the cases (3.74 mm) than the controls (4.72 mm). Claws from cases were 5.0 [95% confidence interval (CI): 1.5 to 8.6; P < 0.001] and 7.3 times (95% CI: 1.5 to 69.3; P < 0.01) more likely than those of controls to yield a heavy growth of Escherichia coli and Trueperella pyogenes, respectively. Cases were 4.4 times (95% CI: 4.4 to 22.9; P < 0.001) more likely to be acutely/transiently infected with bovine viral diarrhea virus than were controls. The findings support the hypothesis that TTNS is initiated by excessive wear along the white line, leading to separation and bacterial colonization of the 3rd phalangeal bone (P3) and associated soft tissues.

Étude prospective de cas-témoins du syndrome de la nécrose du bout des orteils dans un parc d'engraissement de l'Ouest canadien. Une étude de cas-témoins a été réalisée pour investiguer les facteurs de risques potentiels pour le syndrome de la nécrose du bout des orteils (SNBO) chez le bétail des parcs d'engraissement de l'Ouest canadien. Les vétérinaires des parcs d'engraissement ont fourni des sabots provenant de 222 animaux qui sont morts soit du SNBO («cas¼) ou d'autres causes («témoins¼). Les ongles ont été sectionnés par les chercheurs pour confirmer les diagnostics; il y avait une très bonne concordance entre le diagnostic sur le terrain des praticiens et celui des chercheurs (Kappa de Cohen = 0,81; P < 0,001). L'épaisseur de la sole dans la région de la ligne blanche atypique était plus mince (P < 0,001) dans les cas (3,74 mm) que dans les témoins (4,72 mm). Il était 5,0 fois (IC de 95 % de 1,5 à 8,6; P < 0,001) et 7,3 fois (IC de 95 % de 1,5 à 69,3; P < 0,01) plus probable que les ongles des cas donnent une croissance importante d'Escherichia coli et de Trueperella pyogenes, respectivement. Il était 4,4 fois (IC de 95 % de 4,4 à 22,9; P < 0,001) plus probable que les cas soient infectés de manière aiguë ou transitoire par le virus de la diarrhée virale des bovins comparativement aux témoins. Les résultats appuient l'hypothèse que le SNBO est amorcé par une usure excessive le long de la ligne blanche, ce qui entraîne une séparation et la colonisation bactérienne de l'os de la troisième phalange (P3) et des tissus mous connexes.(Traduit par Isabelle Vallières).

A retrospective study of non-suppurative encephalitis in beef cattle from western Canada.

Non-suppurative encephalitis occurs sporadically in beef cattle in western Canada, leading to loss of animals. This retrospective study investigated the presence of viral, bacterial, and protozoal antigens or DNA in 37 western Canadian feedlot cattle with non-suppurative encephalitis for which a cause had not been identified. Cases were selected based on the age of the animal (> 7 months), and clinical history of recumbency and depression. The identification of rabies in 1 case stresses the importance of including this viral disease in the list of differential diagnoses. Because there was variation in the severity, distribution, and type of lesions, it is possible that there may be more than 1 cause, but failure to identify an infectious agent might also suggest that non-infectious agents could play a role.

Étude rétrospective de l'encéphalite non suppurative chez les bovins de boucherie de l'Ouest canadien. L'encéphalite non suppurative se produit sporadiquement chez les bovins de boucherie de l'Ouest canadien, ce qui cause une perte d'animaux. Cette étude rétrospective a fait enquête sur la présence d'antigènes viraux, bactériens et protozoaires ou d'ADN dans 37 parcs d'engraissement de l'Ouest canadien atteints de l'encéphalite non suppurative dont la cause n'avait pas été identifiée. Les cas ont été choisis en fonction de l'âge de l'animal (> 7 mois) et de l'anamnèse clinique de décubitus et de dépression. L'identification de la rage dans 1 cas met en lumière l'importance d'inclure cette maladie virale dans la liste des diagnostics différentiels. Parce qu'il y avait une variation au niveau de la gravité, de la répartition et du type de lésions, il est possible qu'il y ait plus d'une cause, mais la non-identification d'un agent infectieux pourrait aussi suggérer que des agents non infectieux pourraient jouer un rôle.(Traduit par Isabelle Vallières).

Associations between antimicrobial use and the prevalence of antimicrobial resistance in fecal Escherichia coli from feedlot cattle in western Canada.

A randomized, controlled, blinded clinical trial was performed at a research feedlot in western Canada. Auction-market-derived steers (n = 288) were randomly assigned to 1 of 3 treatments: 1) no antimicrobials on arrival; 2) oxytetracycline in the starter ration for 14 d; and 3) long-acting oxytetracycline subcutaneously on day 0. Minimal inhibitory concentrations of 7 antimicrobials were determined for 3 generic fecal E. coli isolates per animal on arrival and throughout the feeding period. There was a low prevalence of antimicrobial resistance in generic E. coli isolates from calves on arrival. There were increased proportions of cattle with resistant E. coli isolates early in the feeding period among calves in groups 2 and 3. Individual animal treatments were not associated with increased proportions of cattle with resistant E. coli isolates preslaughter. There was no difference in the proportion of animals with E. coli isolates resistant to tetracycline between the treatment groups preslaughter. However, there were significantly more animals with tetracycline resistant isolates of E. coli preslaughter than at arrival.

Microbiological and histopathological findings in cases of fatal bovine respiratory disease of feedlot cattle in Western Canada.

The aim of this study was to describe the microbiologic agents and pathologic processes in fatal bovine respiratory disease (BRD) of feedlot cattle and to investigate associations between agents and pathologic processes. Ninety feedlot calves diagnosed at necropsy with BRD and 9 control calves without BRD were examined, using immunohistochemical (IHC) staining and histopathologic studies. Mannheimia haemolytica (MH) (peracute, acute, and subacute cases) and Mycoplasma bovis (MB) (subacute, bronchiolar, and chronic cases) were the most common agents identified in fatal BRD cases. Significant associations (P < 0.10) were detected between microbiologic agents and between agents and pathologic processes. When IHC staining was used, 25/26 (96%) of animals that were positive for bovine viral diarrhea virus (BVDV) were also positive for MH; 12/15 (80 %) of animals that were positive for Histophilus somni (HS) were also positive for MB; and all of the animals that were positive for HS were negative for MH and BVDV. This quantitative pathological study demonstrates that several etiologic agents and pathologic processes are involved in fatal BRD of feedlot cattle.

Antimicrobial resistance in generic fecal Escherichia coil obtained from beef cattle on arrival at the feedlot and prior to slaughter, and associations with volume of total individual cattle antimicrobial treatments in one western Canadian feedlot.

A prospective observational study was carried out to examine antimicrobial resistance patterns of fecal Escherichia coli isolates of calves on arrival at the feedlot, and then evaluate the associations between the total volume of antimicrobial used for disease treatment and changes in antimicrobial resistance, during the feeding period. No macrolides or tetracyclines were administered in the feed during this study. On arrival, at the animal level, all 3 isolates obtained from 36.6% [95% confidence interval (CI): 29.0 to 44.8] of all cattle sampled (n = 153), were susceptible to all antimicrobials, while 5.9% (95% CI: 2.7 to 10.9) of cattle had at least 1 isolate that was resistant to--3 antimicrobials out of the 7 antimicrobials tested. The most frequent antimicrobials for which resistance was observed were sulphamethoxazole, ampicillin, and tetracycline where, of all cattle, 44.4% (95% CI: 36.4 to 52.7), 20.3% (95% CI: 14.2 to 27.5), and 17.7% (95% CI: 12.0 to 24.6), respectively had at least 1 resistant isolate. All cattle received antimicrobial metaphylaxis on arrival at the feedlot. Antimicrobial use was described for a cohort of 95 cattle. Antimicrobials were given to 42 of the 95 cattle during the feeding period, to treat disease. Amongst the 42 treated cattle, there were a total of 133 animal daily doses (ADD(Feedlot)), where 1 ADD(Feedlot) represented 1 day of antimicrobial treatment received by a feedlot animal at the approved dose. Only 1 ADD(Feedlot) was given in the 100 days immediately prior to slaughter. There were no associations found between antimicrobial use and antimicrobial resistance in this study.