Reneé Dewell

Pain and sickness behavior associated with corneal lesions in dairy calves

Infectious bovine keratoconjunctivitis (IBK) is a common corneal disease of calves that adversely affects animal welfare by causing pain and weight loss. Identifying behavioral indicators of pain and sickness in calves with IBK is necessary for designing studies that aim to identify effective means of pain mitigation. Consistent with principles of the 3Rs for animal use in research, data from a randomized blinded challenge study was used to identify and describe variation of behaviors that could serve as reliable indicators of pain and sickness in calves with corneal injuries. Behavioral observations were collected from 29 Holstein calves 8 to 12 weeks of age randomly allocated to one of three treatments: (1) corneal scarification only, (2) corneal scarification with inoculation with Moraxella bovoculi and (3) corneal scarification with inoculation with Moraxella bovis. Behavior was continuously observed between time 1230 - 1730 h on day -1 (baseline time period) and day 0 (scarification time period). Corneal scarification and inoculation occurred between 0800 - 1000 h on day 0. Frequency of head-directed behaviors (head shaking, head rubbing, head scratching) and durations of head rubbing, feeding, standing with head lifted, lying with head lifted and sleeping were compared between study days and groups. Following scarification, the frequency of head-directed behavior significantly increased (p = 0.0001), as did duration of head rubbing (p=0.02). There was no significant effect of trial, trial day, treatment or treatment-day interaction on other behaviors studied. Our study demonstrated that head-directed behavior, such as head shaking, rubbing and scratching, was associated with scarification of eyes using an IBK challenge model, but sickness behavior was not observed.

A survey of reasons why veterinarians leave rural veterinary practice in the United States.

OBJECTIVE To identify factors associated with veterinarians leaving a career in rural veterinary practice (RVP). DESIGN Cross-sectional descriptive study. SAMPLE POPULATION Veterinarians from the United States who no longer worked in RVP. PROCEDURES Veterinarians in any area of practice were solicited to participate in an online survey through invitation letters sent to various veterinary associations. Those who indicated that they had left RVP were asked to rank the importance of various potential factors in their decision to leave RVP. RESULTS 805 responses were obtained from veterinarians who had worked in RVP, of which 246 (30.6%) had left RVP. Most (231/246 [93.9%]) of those who reported leaving RVP had been in practice > 5 years, and 75.2% (185/246) had been in practice > 12 years. Eighty-three (33.7%) who left RVP pursued careers in urban areas, 72 (29.3%) entered academia, and 7 (2.8%) retired. Reasons for leaving RVP ranked by the highest proportions of respondents as being of high importance were emergency duty, time off, salary, practice atmosphere, and family concerns. Women ranked factors such as time off, mentorship, practice atmosphere, conflict with staff, and gender issues as being of high importance more often than men did. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the perceived shortage of veterinarians in RVP may be in part influenced by a lack of retention, particularly among experienced veterinarians. Targeted efforts to tackle issues related to emergency duty, time off, salary, practice atmosphere, and family issues could help alleviate the efflux from RVP.

Evaluating approaches to measuring ocular pain in bovine calves with corneal scarification and infectious bovine keratoconjunctivitis–associated corneal ulcerations

Infectious bovine keratoconjunctivitis (IBK) is a common ocular disease in cattle, associated with a 6.8 to 13.6 kg decrease in weaning weight. Antibiotic therapy is available but it is unclear if pain mitigation as an adjunct therapy would reduce the weight loss associated with IBK. Before assessing the impact of pain mitigation therapies, it is first necessary to validate approaches to qualifying ocular pain. The objective of this study was to evaluate approaches to qualifying ocular pain in bovine calves (Bos taurus) with IBK. Our a priori assumption was that scarification or corneal ulcerations consistent with IBK are painful compared to normal eyes. To quantify this difference in pain, we assessed 4 tools: pressure algometry-mechanical nociceptive threshold (PA-MNT), corneal touch thresholds (CTT) obtained with the use of a Cochet-Bonnet aesthesiometer, and assessment for the presence of blepharospasm and photophobia as metrics for pain. Using a 1-eye randomized controlled challenge trial, 31 calves with healthy eyes were randomly allocated to treatment groups, and then a left or right eye was randomly assigned for corneal scarification and inoculation with Moraxella bovoculi or Moraxella bovis. A repeated measures analysis of variance was used for PA-MNT, with significance set at P < 0.05. A log (base 10) transformation was used to stabilize the variance, and Tukeys t tests were used to test differences between assessment days for each landmark. Calves had statistically significantly lower PA-MNT scores (which indicates more pain) the day after scarification relative to baseline measurements (4 d before scarification). For example, at 1 landmark the median PA-MNT (kg/force) prescarification was 4.82 (95% confidence interval [CI]: 3.92-5.93) and 3.43 (95% CI: 2.79-4.22) postscarification. These data suggest PA-MNT may be a tool for quantifying ocular pain in calves. No differences (P < 0.1) in PA-MNT scores between scarified and not-scarified eyes were detected for any landmark on any day. This result suggests that the pain response occurs over the entire face, not just the affected eye. Corneal ulcerations consistent with IBK were not associated with statistically significant differences in PA-MNT or CTT at eye or calf levels. Not surprisingly, scarified eyes were more likely to exhibit blepharospasm and photophobia compared to healthy eyes. Due to blepharospasm, the use of the Cochet-Bonnet to evaluate corneal sensitivity by CTT was of limited value.

Schirmer tear test I and rebound tonometry findings in healthy calves

OBJECTIVE To describe Schirmer tear test I and rebound tonometry findings in healthy bovine calves. ANIMALS STUDIED Thirty-three clinically normal dairy breed calves of mean (SD) 11 (1.1) weeks (range, 9.3-13.3 weeks) of age were evaluated. PROCEDURES A Schirmer tear test I was performed on each eye followed by tonometry, using a TonoVet(®) without topical anesthesia. We report means (SD) and statistical analysis of data for each assay. RESULTS For both Schirmer tear test (STT) I and tonometry, significant differences were not found between fellow eyes (P = 0.1536 and P = 0.83, respectively). The mean (SD) STT I value of all eyes was 20.4 (5.0) mm/min (range, 9-34 mm/min) while the mean (SD) intraocular pressure (IOP) value of all eyes was 15.2 (5.2) mmHg (range, 7-25 mmHg). CONCLUSIONS This study reports normal data for the STT I and rebound tonometry in calves. This data may be useful in complete ophthalmic examinations of cattle, guiding diagnosis of glaucoma, uveitis, and keratoconjunctivitis sicca. However, results of these diagnostic modalities must be interpreted in light of clinical signs, given the wide range of normal values obtained in this study.

Randomized clinical trial to evaluate the pathogenicity of Bibersteinia trehalosi in respiratory disease among calves

BackgroundBibersteinia trehalosi causes respiratory disease in ruminants particularly in wild and domestic sheep. Recently, there has been an increased number of B. trehalosi isolates obtained from diagnostic samples from bovine respiratory disease cases. This study evaluated the role of B. trehalosi in bovine respiratory disease using an intra-tracheal inoculation model in calves. Thirty six cross bred 2–3 month old dairy calves were inoculated intra-tracheally with either leukotoxin negative B. trehalosi, leukotoxin positive B. trehalosi isolate, Mannheimia haemolytica, a combination of leukotoxin negative B. trehalosi and M. haemolytica or negative control. Calves were euthanized and necropsy performed on day 10 of study.ResultsB. trehalosi inoculated calves did not have increased lung involvement compared to control calves. Additionally, B. trehalosi was only cultured once from the lungs of inoculated calves at necropsy.ConclusionsBased on these findings B. trehalosi may not be a primary pathogen of respiratory disease in cattle. Culture of B. trehalosi from diagnostic submissions should not be immediately identified as a primary cause of respiratory disease.

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

BackgroundSerum 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.ResultsM. 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.ConclusionSerum 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.

Corneal sensitivity in healthy bovine calves

OBJECTIVE To evaluate corneal sensitivity as measured by the corneal touch threshold in healthy bovine calves. ANIMALS STUDIED Twelve clinically normal male calves with predominantly Holstein genetics and a median age of 76.5 days (range, 67-92 days). PROCEDURES Corneal touch threshold (CTT) of the central cornea was measured in both eyes of each calf using a Cochet-Bonnet aesthesiometer. RESULTS The mean ± standard deviation corneal touch threshold of all eyes was 1.33 ± 1.1 g/mm(2) (range, 0.62-66.15 g/mm(2) ), corresponding to a filament length of 34.56 ± 8.02 mm (range, 14-47.5 mm). There was no significant difference between fellow eyes. CONCLUSIONS Cochet-Bonnet aesthesiometry was well tolerated in all 12 calves using a modified head restraint. Calves in this study may have a relatively sensitive central cornea compared to adult cattle and some other species; however, wide variation among individuals and eyes may be possible. Studies utilizing larger calf populations are necessary to establish reference ranges.

Validation of a portable pneumatic captive bolt device as a one-step method of euthanasia for use in depopulation of feedlot cattle

OBJECTIVE To validate the effectiveness of a penetrating captive bolt device with a built-in low-pressure air channel pithing mechanism (PCBD) as a 1-step method for euthanasia of cattle. DESIGN Clinical trial. ANIMALS 66 feedlot steers and heifers (weight, 227 to 500 kg [500 to 1,100 lb]) that were not expected to survive or finish the feeding period with their cohorts. PROCEDURES Cattle were transported to a university facility and euthanized with the PCBD. For each calf, clinical variables were monitored and recorded immediately before and for at least 10 minutes after application of the PCBD. Following euthanasia, the head of each calf was removed and trauma to the brain and skull was assessed and scored. RESULTS Death was successfully achieved with the PCBD without application of an ancillary technique in all 66 cattle; however, 4 (6%) cattle required a second or third shot from the PCBD because of technical errors in its placement. All shots from the PCBD that entered the cranial vault successfully rendered cattle unconscious without a return to sensibility. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the PCBD was an effective 1-step method of euthanasia for use in mass depopulation of feedlot cattle.

Cattle Assessment On-Site During Emergencies

Veterinary assessment of the condition and needs of livestock and their owners in an emergency is an essential element of the disaster response. The emergency response for livestock has 4 critical components: assessing the need for and attending to the immediate medical needs of injured or affected livestock, determining the resources available to meet the needs, including feed and facilities, identifying any ongoing threats or potential hazards to livestock health and welfare, and appropriate documentation of damages and actions by responders. Information gathered from cattle assessments by veterinarians is used to prioritize resources and plan for anticipated needs.

On-site veterinary medical evaluation and care of working dogs and horses at the 2012 Republican National Convention

OBJECTIVE To describe on-site veterinary medical care for working dogs and horses deployed for the 2012 Republican National Convention (RNC) in Tampa, Fla, August 24 to 30, 2012. DESIGN Retrospective case series. SAMPLE 130 dogs and 45 horses. PROCEDURES Data collected included breed, age, history, task assignment, reason for evaluation, and physical examination findings. A patient encounter report was recorded each time an animal was seen by veterinary staff for a physical evaluation. RESULTS 46 of the 130 (35%) dogs and all 45 (100%) horses underwent at least 1 on-site veterinary evaluation, for a total of 478 patient encounters. The most common reason for an on-site veterinary evaluation was a wellness check (446 patient encounters). On the basis of veterinary recommendations, 1 dog and 4 horses were removed from continued service for the duration of the event. In addition, 1 dog and 1 horse were removed from active service for 12 to 24 hours but allowed to return to service for the duration of the event following a veterinary reevaluation. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that working dogs and horses deployed for large planned events face different health concerns, compared with concerns previously reported for animals deployed following disasters. Pre-event planning and training of handlers and riders may have helped reduce the number of health concerns, particularly health concerns related to high heat.