Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Jan K. Shearer is active.

Publication


Featured researches published by Jan K. Shearer.


Archive | 2006

Manual for treatment and control of lameness in cattle

Sarel R. van Amstel; Jan K. Shearer

Chapter 1: An Introduction to Cattle Lameness. Chapter 2: Horn Formation and Growth. Chapter 3: Nutrition and Claw Health. Chapter 4: Biomechanics of Weight (Load) Bearing and Claw Trimming. Chapter 5: Laminitis. Chapter 6: Pain Management. Chapter 7: Upper Leg Lameness. Chapter 8: Infectious Claw Disease. Chatper 9: Cattle Behavior, Cow-Friendly Facilities and Proper Handling. Chapter 10: Footbaths for the Management of Infectious Skin Disorders of the Foot and Hoof Knife Sharpening. Index.


Infection and Immunity | 2014

Deep Sequencing Analysis Reveals Temporal Microbiota Changes Associated with Development of Bovine Digital Dermatitis

Adam C. Krull; Jan K. Shearer; Patrick J. Gorden; Vickie L. Cooper; Gregory J. Phillips; Paul J. Plummer

ABSTRACT Bovine digital dermatitis (DD) is a leading cause of lameness in dairy cattle throughout the world. Despite 35 years of research, the definitive etiologic agent associated with the disease process is still unknown. Previous studies have demonstrated that multiple bacterial species are associated with lesions, with spirochetes being the most reliably identified organism. This study details the deep sequencing-based metagenomic evaluation of 48 staged DD biopsy specimens collected during a 3-year longitudinal study of disease progression. Over 175 million sequences were evaluated by utilizing both shotgun and 16S metagenomic techniques. Based on the shotgun sequencing results, there was no evidence of a fungal or DNA viral etiology. The bacterial microbiota of biopsy specimens progresses through a systematic series of changes that correlate with the novel morphological lesion scoring system developed as part of this project. This scoring system was validated, as the microbiota of each stage was statistically significantly different from those of other stages (P < 0.001). The microbiota of control biopsy specimens were the most diverse and became less diverse as lesions developed. Although Treponema spp. predominated in the advanced lesions, they were in relatively low abundance in the newly described early lesions that are associated with the initiation of the disease process. The consortium of Treponema spp. identified at the onset of disease changes considerably as the lesions progress through the morphological stages identified. The results of this study support the hypothesis that DD is a polybacterial disease process and provide unique insights into the temporal changes in bacterial populations throughout lesion development.


Veterinary Clinics of North America-food Animal Practice | 2013

Assessment and Management of Pain Associated with Lameness in Cattle

Jan K. Shearer; Matthew L. Stock; Sarel R. van Amstel; Johann F. Coetzee

Lameness impacts the cattle industry in economic losses and welfare considerations. In addition to production deficits, pain and distress associated with lameness have been documented. The evaluation and prevalence of lame cattle is one of the primary factors in third-party welfare audit programs. To improve earlier detection and treatment of lameness, locomotion scoring systems have been developed for routine use by farm employees. Recommendations for pain management typically include the use of a multimodal therapeutic approach. Similarly, in lame cattle, pain can best be alleviated by implementing a multimodal approach including corrective claw trimming and placement of foot blocks combined with additional benefits provided by analgesic compounds.


Veterinary Clinics of North America-food Animal Practice | 2012

Clinical Diagnosis of Foot and Leg Lameness in Cattle

Jan K. Shearer; Sarel R. van Amstel; Bruce W. Brodersen

The causes of lameness in cattle are multifactorial and involve a combination of housing, management, and environmental factors and a variety of infectious agents. Arriving at a cause can often require concerted efforts. Diagnosis of lameness is often based mainly on clinical observations. A detailed record of those observations with time and among several animals within a herd can provide valuable information toward solving lameness problems. Advances in computer hardware and software help facilitate more detailed data collection and analysis.


PLOS ONE | 2016

A Highly Effective Protocol for the Rapid and Consistent Induction of Digital Dermatitis in Holstein Calves.

Adam C. Krull; Vickie L. Cooper; John W. Coatney; Jan K. Shearer; Patrick J. Gorden; Paul J. Plummer

Bovine Digital Dermatitis (DD) is a leading cause of lameness in dairy cattle. DD is reportedly increasing in prevalence in beef cattle feedlots of the US. The exact etiologic agent(s) responsible for the disease have yet to be determined. Multiple studies have demonstrated the presence of a variety of Treponema spp. within lesions. Attempts to reproduce clinically relevant disease using pure cultures of these organisms has failed to result in lesions that mirror the morphology and severity of naturally occurring lesions. This manuscript details the systematic development of an experimental protocol that reliably induces digital dermatitis lesions on a large enough scale to allow experimental evaluation of treatment and prevention measures. In total, 21 protocols from five experiments were evaluated on their effectiveness in inducing DD lesions in 126 Holstein calves (504 feet). The protocols varied in the type and concentration of inoculum, frequency of inoculation, duration the feet were wrapped, and type of experimental controls need to validate a successful induction. Knowledge gained in the first four experiments resulted in a final protocol capable of inducing DD lesions in 42 of 44 (95%) feet over a 28 day period. All induced lesions were macroscopically and microscopically identified as clinical DD lesions by individuals blinded to protocols. Lesions were also located at the site of inoculation in the palmer aspect of the interdigital space, and induced clinically measurable lameness in a significant portion of the calves. Collectively these results validate the model and provide a rapid and reliable means of inducing DD in large groups of calves.


Veterinary Clinics of North America-food Animal Practice | 2017

The Impact of Lameness on Welfare of the Dairy Cow

H R Whay; Jan K. Shearer

The five freedoms offer a framework for discussion of lameness and its impact on the welfare of cows. Altered feeding behavior is a cause of reduced body condition, smaller digital cushion, and lameness. Providing a comfortable environment is critical to recovery and welfare. Pain associated with injury or disease of feet or legs is manifested by lameness. Pain management is an important part of therapy. In cases of severe lameness, euthanasia may be preferred. Lameness interferes with an animals ability to exhibit natural behaviors by altering lying time, social interaction, ovarian activity and estrus intensity, and rumination behavior.


Javma-journal of The American Veterinary Medical Association | 2014

Meta-analysis of the effects of sometribove zinc suspension on the production and health of lactating dairy cows

N.R. St-Pierre; George A. Milliken; Dale E. Bauman; R. J. Collier; Joseph S. Hogan; Jan K. Shearer; K. Larry Smith; W.W. Thatcher

OBJECTIVE To provide an updated evaluation of the efficacy and safety of sometribove zinc suspension (rbST-Zn), a form of recombinant bovine somatotropin, in lactating dairy cows. DESIGN Meta-analysis. SAMPLE 26 studies published in peer-reviewed journals or reviewed by a regulatory agency. PROCEDURES To be included, a study had to involve the use of the rbST-Zn formulation available to US producers in accordance with the label instructions for treatment initiation (57 to 70 days postpartum), dose (500 mg, q 14 d), and route (SC). RESULTS For cows treated with rbST-Zn, mean milk, 3.5% fat-corrected milk, fat, and protein yields were increased by 4.00, 4.04, 0.144, and 0.137 kg/d (8.8, 8.89, 0.32, and 0.30 lb/d), respectively; however, the concentration of milk components did not change. Pregnancy proportion for the first 2 breeding cycles was increased by 5.4%, and pregnancy proportion for the duration of the trial was reduced by 5.5% for rbST-Zn-treated cows, compared with proportions for untreated cows. Mean body condition score (1 to 5 scale) was reduced by 0.06 points during the period of rbST-Zn use for treated cows. Administration of rbST-Zn had no effect on milk somatic cell count, the number of days to pregnancy, or inseminations per pregnancy; rates of fetal loss, twins, cystic ovaries, clinical lameness, lameness lesions, or traumatic lesions of the integumentary system; and odds of clinical mastitis or culling. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that rbST-Zn administration to dairy cows effectively increases milk production with no adverse effects on cow health and well-being.


Veterinary Medicine : Research and Reports | 2015

Perspectives on the treatment of claw lesions in cattle

Jan K. Shearer; Paul J. Plummer; Jennifer A. Schleining

Lameness is a leading cause of welfare and culling issues in cattle, with claw lesions accounting for the majority of these issues. Although the treatment of claw lesions in cattle is a daily activity for hoof trimmers, veterinarians, and livestock producers, there is surprisingly little information in the peer-reviewed literature on which to base strong evidence-based conclusions. As a consequence, many treatment modalities used are empirical and, in some cases, may be counterproductive to rapid lesion healing. Furthermore, many of these empirical treatment modalities fail to fully consider the underlying pathogenesis of the disease process and the implications that it has on lesion healing. For example, sole ulcers are largely a consequence of metabolic disorders and mechanical overloading. Therapeutic interventions that fail to address the weight-bearing issues are unlikely to be successful. Likewise, white line disease is believed to be predisposed by rumen acidosis and laminitis, and interventions need to include in them appropriate measures to prevent further cases through nutritional management. The goal of this review paper is to review the pathogenesis of claw lesions in the context of the published literature and allow the reader to arrive at rational treatment interventions based on the best available information. The use of an orthopedic block applied to the healthy claw of a lame foot, judicious use of bandage or wrap, careful selection of parenteral or topical therapy, and a treatment protocol to manage pain and promote recovery are key components of responsible management of lameness disorders in cattle.


Veterinary Clinics of North America-food Animal Practice | 2017

An Update on the Assessment and Management of Pain Associated with Lameness in Cattle

Johann F. Coetzee; Jan K. Shearer; Matthew L. Stock; M. D. Kleinhenz; Sarel R. van Amstel

Lameness affects the cattle industry via both economic losses and welfare considerations. In addition to production deficits, the pain and distress associated with lameness have been documented. Evaluation and prevalence of lame cattle are among the primary factors in third-party welfare audit programs. Mean lameness prevalence in herds has been reported to be as high as 36.8%, although a less than 10% prevalence of lame cattle was reported by some producers. Note that lameness is usually underreported by producers compared with independent observers, potentially because of a decreased sensitivity in detecting lame cattle.


Journal of Applied Animal Welfare Science | 2015

An Observational Study of the Effects of Therapeutic Hoof Blocks on the Locomotion, Behavior, and Production of Healthy Dairy Cattle

Janet Higginson Cutler; Jan K. Shearer; David F. Kelton; G. Cramer; Pat J. Gorden; Suzanne T. Millman

Therapeutic hoof blocks have been recommended for treatment of sole ulcers in dairy cattle; however, they are underutilized in the industry. Twenty Holstein cows were randomly assigned to receive a wooden hoof block applied to the left hind leg (n = 5), to the right hind leg (n = 5), or no hoof blocks (n = 10). Accelerometers were affixed to both hind legs of 10 blocked cows and 5 control cows. Cows were observed for locomotion scores, and milk production was recorded. Mixed models were constructed to determine effects of block application on behavior, milk production, and locomotion. Activity was altered by day, with cows being most active on Day − 1. The mean number of daily lying bouts and lying bout duration did not differ by treatment. Locomotion scores were higher for blocked cows on Days 1, 2, and 3 compared with baseline; however, milk production did not differ between treatments. In conclusion, although block application affected the appearance of locomotion, it did not appear to adversely affect the behavior or milk production of sound dairy cows.

Collaboration


Dive into the Jan K. Shearer's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge