The Bovine Practitioner

Risk factors associated with case fatality and treatment success following initial bovine respiratory disease treatment in feedyard cattle

Tue, 14 May 2024 00:00:00 +0000

Bovine respiratory disease (BRD) is an important disease of fed cattle and knowledge gaps exist regarding factors predicting treatment success. The study objective was to identify potential relationships between risk factors known at the time of initial BRD treatment with 3 post-treatment outcomes: first treatment success (FTS), non-cause specific case fatality risk (CFRALL), and cause-specific case fatality risk (CFRBRD). This retrospective analysis used generalized linear mixed models to evaluate relationships between covariates of interest with each outcome. Analysis included 132,521 individual-animal initial BRD treatment records from 14 central U.S. feedyards (May 2017 to Dec 2020) with overall FTS of 67.8%, CFRALL of 10.0%, and CFRBRD of 6.3%. The FTS was associated (P < 0.05) with all covariates except sex, CFRALL was associated with all covariates, and CFRBRD was associated with all covariates except day-of-week treated. Treatments early in the feeding phase (DOF 0-10, 11- 20) resulted in lower (P < 0.05) FTS (49.2% ± 0.8; 55.3% ± 0.8), higher (P < 0.05) CFRALL (12.5% ± 1.3; 12.6% ± 1.4) and higher (P < 0.05) CFRBRD (6.3% ± 1.1; 6.1% ± 1.0) compared to cattle treated on days 21-70. Rectal temperature in the 103.1-104.0 (39.4-40.0 °C) category had higher (P < 0.05) CFRALL (15.3% ± 1.5) and CFRBRD (9.2% ± 1.5) compared to other rectal temperature categories. Specific risk factors including days on feed at treatment, sex and weight at the time of treatment were associated with treatment outcomes. Results can be useful for defining expectations following first treatment for BRD.

Case series: Surgical success and reproductive performance after correction of penile deviations in 10 bulls

Tue, 14 May 2024 00:00:00 +0000

Information regarding expected outcomes such as surgical complications and successful return to natural service after surgery to correct penile deviation of bulls is limited. Therefore, when examining a bull with a penile deviation, making evidence-based recommendations and managing client expectations for return to function is difficult for veterinarians. The objective of the study reported here is to provide documented outcomes of return to reproductive performance for bulls following surgery to correct penile deviation. Medical records at 4 teaching hospitals from 2008 to 2022 were reviewed. Surgical and reproductive outcomes of impotent bulls that underwent surgery to correct spiral or ventral deviation by either fascia graft or synthetic mesh were evaluated. Only 10 cases, from 3 teaching hospitals, had sufficient follow-up information regarding outcome after surgery to be evaluated. None of the bulls experienced surgical complications (e.g., infection, dehiscence, etc.). Surgery sufficiently corrected the deviation to achieve intromission in 6 of the 10 bulls. Five of these 6 bulls sired progeny. Overall, surgical correction of penile deviation in bulls appears to have a low risk for complications, but the success of surgery in returning the bull to reproductive soundness is inconsistent, as only 5 of the 10 total cases sired progeny via natural service.

Case-control study to identify management practices associated with morbidity or mortality due to bovine anaplasmosis in Mississippi cow-calf herds

W. Isaac Jumper, Carla L. Huston, David R. Smith — Sat, 25 May 2024 00:00:00 +0000

Bovine anaplasmosis (BA) is a costly disease affecting the U.S. beef cattle industry. Chlortetracycline (CTC) in feed or mineral supplements is often used to control clinical signs of BA. The objective of this study was to determine if management practices, such as feeding CTC, are associated with illness or death from BA in Mississippi cow-calf herds. Case and control herds were solicited from veterinary practices across Mississippi. Cases were herds with clinical BA diagnosed by a veterinarian within the previous calendar year. Controls were herds under the care of the same practice with no clinical BA diagnosed in the previous year. Blinded interviewers conducted telephone surveys of case and control herd owners. Management and biosecurity factors were tested for association with herd status using a logistic regression generalized linear mixed model with veterinary practice as a random variable. Twenty-two case and 25 control herds from 6 veterinary practices across Mississippi were interviewed, representing 22 counties. The average herd size was 132 for case herds, and 136 for control herds. Twenty case herds and 13 control herds fed CTC medicated mineral or feed. Providing CTC was associated with case herd status (OR = 9.2, 95% C.I. = 1.7-50.7). The association observed between case herds and feeding CTC might be because: 1) herds that had experienced previous BA morbidity and mortality subsequently began feeding CTC, or 2) some individual cattle consume enough CTC to achieve clearance of the persistent carrier state, thereby increasing risk of reinfection and clinical BA.

A comparison of two multivalent modified live viral/bacterial combination vaccines in feedlot calves at ultra-high risk of developing undifferentiated fever/bovine respiratory disease

Fri, 07 Jun 2024 00:00:00 +0000

Vaccine 1 (VAC1 group) and Vaccine 2 (VAC2 group) are commercially available vaccines labeled for the control of bovine respiratory disease (BRD) in beef cattle. There are limited data from large-scale commercial feedlot trials comparing VAC1 and VAC2 arrival processing vaccination programs. The objective of this study was to evaluate the relative effects of VAC1 and VAC2 arrival processing vaccination programs on animal health, feedlot performance and carcass characteristic outcomes in feedlot calves at ultra-high risk of developing undifferentiated fever/BRD under large-scale commercial production conditions. Animals were randomly allocated at feedlot arrival to 1 of 2 experimental groups: VAC1 or VAC2. Animals in the VAC1 group (6 multi-pen lots; 3,001 animals) received a bovine rhinotracheitis-virus diarrhea-parainfluenza 3-respiratory syncytial virus-Mannheimia haemolytica-Pasteurella multocida vaccine per animal once at allocation. Animals in the VAC2 group (6 multi-pen lots; 3,005 animals) received a bovine rhinotracheitis-virus diarrhea-parainfluenza 3-respiratory syncytial virus vaccine with a Mannheimia haemolytica toxoid per animal once at allocation. Vaccines differed regarding viral strains, bacterial protection, means for providing bacterial immunity, and adjuvant use. Animals were housed by experimental group in commercial feedlot pens and followed from allocation until slaughter. Although histophilosis mortality was higher in the VAC1 group compared to the VAC2 group (P = 0.040), no statistical differences were detected in overall mortality or any of the other outcome variables (P ≥ 0.050). The relative cost effectiveness of each arrival processing vaccination program in the study population is therefore dependent on relative program cost.

Distribution trends of bovine Anaplasma marginale in Iowa, based upon veterinary diagnostic lab submissions from 2017-2022

Fri, 21 Jun 2024 00:00:00 +0000

Anaplasma marginale is the common etiological agent of bovine anaplasmosis. Infection results in erythrocyte destruction leading to the clinical signs of anemia, hypoxia, abortion, jaundice and sudden death. Cattle that survive this acute phase or have lower levels of initial bacteremia become chronic, persistent carriers. Carrier animals serve as reservoirs for the organism and allow infection to spread via mechanical or biological vectors, to susceptible herdmates. The objective of this study was to report the distribution trends of A. marginale positive test results during a 5-year period in Iowa. This study evaluated Iowa State University Veterinary Diagnostic Lab (ISU VDL) testing results from bovine cases submitted from January 1, 2017 to January 1, 2022, for molecular and serological detection of all stages of anaplasmosis. Cattle residing in Iowa with positive results for PCR or competitive ELISA were included in the analysis. The state was divided into 4 geographical districts (1 = northeast, 2 = southeast, 3 = southwest, and 4 = northwest) and the number of positive tests in each district was determined. Total positive tests by district included: northeast 282; southeast 277; southwest 223; northwest 281. Disease spatial analysis mapping, based upon geographic longitude and latitude location of herds with positive diagnostic tests, illustrate progressive disease expansion from the southern counties of Iowa, near the Missouri border, into the northern parts of Iowa. These results suggest that A. marginale has developed a widespread distribution across the state of Iowa.

A randomized trial comparing the effects of tulathromycin, tildipirosin and gamithromycin used as first treatment for clinical bovine respiratory disease in commercial feedlot steers

Lucas M. Horton, Isaac Hardee, Nathan F. Meyer, David G. Renter — Fri, 21 Jun 2024 00:00:00 +0000

Our objective was to compare effects of 3 macrolide antibiotics used as first-time bovine respiratory disease (BRD) treatment on primary health outcomes (retreatment, removal and mortality) in feedlot steers. Secondary outcomes included days-on-feed, rectal temperature and weight at the time of event occurrences. Crossbred beef steers (n = 978; average body weight [± SD] 655 ± 84.0 lb [297 ± 38.1 kg]) were enrolled across 2 commercial feedlots in the U.S. High Plains in a randomized complete block design. Steers were eligible for inclusion if they were exhibiting clinical BRD symptoms from natural exposure and had not been previously treated with an antimicrobial drug for any reason including metaphylaxis. Treatment was administration of tulathromycin, tildipirosin or gamithromycin, at the time of first BRD diagnosis. Linear and generalized linear mixed models were used for statistical analyses with significance threshold α = 0.05. At enrollment, animal weight (P = 0.98), rectal temperature (P = 0.58), and days-on-feed (P = 0.28) did not differ significantly between treatments. There was no evidence of differences for any health outcome (P ≥ 0.30), nor for any cattle characteristics at the time of retreatment, removal, or mortality (P ≥ 0.15). Treatment success (steers that were never retreated, removed, and/or were a BRD case fatality) ranged from 62.7 to 64.8% between treatments (P = 0.87). There was no evidence to reject the null hypothesis of similar effectiveness between these macrolides when administered to similar steer populations as first-time clinical BRD treatments.