Dairy Resources - Diseases

January 2021

Abstract:

Experimental downer cows were produced by maintaining healthy cows in sternal recumbency for 6, 9, or 12 hours with the right pelvic limb positioned under the body. Halothane anesthesia was used to create this artificial parturient paresis-like position. In 8 of 16 experiments, cows were able to stand within 3 hours after anesthesia, but the others remained recumbent until death or euthanasia. There was no correlation between duration of the treatment and ability to stand after enforced recumbency. The appearance of the right pelvic limb of downer cows resembled the injured limbs of human patients with compartmental/crush syndrome, as well as the limbs of clinical downer cows. The affected limbs were swollen and held in rigid extension. Some animals which were able to stand also had swollen right pelvic limbs. Systemic signs of crush syndrome included dark yellow or brown urine suggestive of myoglobinuria, and marked elevation of serum creatine kinase enzyme levels. Highest creatine kinase levels were observed at 24 hours in the ambulatory group and at 48 hours in the downer group. Necropsy of downer animals revealed ischemic necrosis of the caudal thigh muscles and inflammation of the sciatic nerve caudal to the proximal end of the femur. Evidence of peroneal nerve damage was observed in at least 9 animals.

American Journal of Veterinary Research, 31 Dec 1981, 43(1):26-31
V. S. Cox, DVM, PhD; C. J. McGrath, DVM; S. E. Jorgensen, PhD

April 2020

ABSTRACT:

Vaccination of adult lactating dairy cattle can have a negative impact on milk production. Decreased milk production may occur from a combination of the cow’s immune response, endotoxin level in the vaccine, and the impact of cattle handling. A randomized clinical trial utilized 3 treatment groups to examine changes in milk production following vaccination with a Mannheimia haemolytica subunit vaccine (MHSV; Nuplura PH, Elanco Animal Health) using 972 lactating dairy cows on a single Midwestern dairy: a vaccinated group (MHSV, n=315); a placebo-treated control (saline, n=342); and a negative control group (no injections, n=315). The decline in milk across a 3 d post-treatment period for the saline group was 0.5 lb (0.2 kg) greater than the negative control cows, but the difference was not significant (P=0.57). The decline in milk during the same time period for cows in the MHSV group was 1.5 lb (0.7 kg) more than the negative control, (P=0.02). The declines between the saline group (0.5 lb; 0.2 kg) and the MHSV group (1.5 lb; 0.7 kg) were not significantly different (P=0.17).

Mark A. Armfelt, Michael W. Overton
DOI: https://doi.org/10.21423/bovine-vol54no1p66-71

September 2020

Abstract:

The objective of this study was to identify associations between herd management practices and the incidence rate of bovine leukemia virus (BLV) infections in Michigan dairy herds. Previous management risk factor studies were of antibody prevalence rather than the rate of recent infections. Milk samples were collected from cohorts of cows on 112 Michigan dairy herds and tested for BLV using an antibody capture ELISA (n = 3849 cows). Cows were subsequently followed for an average of 21 months. Cows negative for anti-BLV antibodies and still present in their respective herds were retested by the same antibody capture ELISA to estimate within-herd incidence rates. The overall crude incidence rate was 1.46 infections per 100 cow-months at risk for the 1314 retested cows in 107 herds. The average within-herd incidence rate was 2.28 infections per 100 cow-months (range: 0 to 9.76 infections per 100 cow-months). A negative binomial regression model was used to identify herd management practices associated with the within-herd incidence rate. Results of the final multivariable model identified higher herd prevalence, milking frequency, needle reuse, as well as housing post-parturient cows separately, to be associated with increased incidence rate. Utilization of sand bedding for the lactating herd was found to be associated with decreased incidence rates. Results of this study suggest potential routes of BLV transmission which should be further investigated as disease control targets in ongoing control programs.

H.C.Hutchinson, B.Norby, R.J.Erskine, K.R.B.Sporer, P.C.Bartlett
https://doi.org/10.1016/j.prevetmed.2020.105084

May 2020

Taylor Leach

Digital Dermatitis ( Lori Hays )

Digital dermatitis, commonly known as hairy heel warts, is an incurable disease caused by an infectious organism called treponeme, a spiral-shaped bacterium commonly found on dairy operations. Clinical signs of this painful disease include raw, red, oval shaped lesions typically found on the back of the cow’s heel and they are prone to animals who consistently have wet, dirty feet.

July 2020

ABSTRACT:

The objective of this study was to determine the utility of single-use hypodermic needles and reproductive examination sleeves in reducing the transmission of bovine leukemia virus (BLV) in dairy herds. Numerous epidemiological studies have identified re-use of needles and exam sleeves as significant risk factors for BLV, therefore adopting a practice of single-use needles and sleeves is a commonly suggested management change for reducing BLV transmission. We conducted a field trial on 3 midwestern commercial dairy herds that had not been employing single use of needles or sleeves as part of their herd health protocol. Additionally, each of the herds had a BLV prevalence among adult cows of at least 20%. BLV milk-ELISA negative cows were randomly assigned to always receive a new single-use needle and new exam sleeve (intervention group). We also monitored and tested BLV milk-ELISA negative cows that received the standard management practice of needles and sleeves that were shared with ELISA-positive herd mates (controls). Cumulative incidence of new infections was determined by semiannual BLV milk-ELISA testing. The cumulative incidence of new BLV infections was not statistically different between the 2 groups. Medical hygiene to prevent bloodborne transmission is still recommended, but in these 3 herds, re-use of needles and sleeves did not appear to be a major route of BLV transmission.

Vickie J. Ruggiero
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824
Paul C. Bartlett
    Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824
DOI:
    https://doi.org/10.21423/bovine-vol53no2p128-133

November 2019

UK - Scientists at the University of Surrey have developed a novel vaccine and complementary skin test to protect cattle against bovine tuberculosis (bovine TB).

Publishing their findings in the journal Scientific Reports, researchers reveal they have for the first time created a vaccine that is compatible with a synthetic form of the tuberculin skin test (PPD), a legally required test used for the surveillance of TB in cattle throughout the UK.

Bovine TB is an infectious disease in cattle affecting their lungs, and those that test positive for the disease are culled. The BCG vaccine, which is currently used to protect humans against TB and is effective in cattle, is incompatible with the PPD test.

Cattle that are vaccinated with the BCG vaccine, which contains a harmless strain of the bovine TB pathogen Mycobacterium bovis, produce a positive PPD test for TB making it impossible to distinguish, with the PPD skin test, if the animal has TB or has simply been vaccinated.

November 2019

Abstract:
Background: Bovine digital dermatitis (BDD) is a painful infectious foot disease of cattle, and much evidence implicates a pathogenic role for treponemes. This study measured the survival of BDD treponemes on hoof knife blades and tested the efficacy of relevant disinfectants under laboratory conditions.

Methods: Two strains of BDD treponemes were applied to hoof knife blades under aerobic conditions. Swabs were taken at different time points (10 minutes, one hour, two hours, four hours and 18 hours) and again after 20-second disinfection time with one of five disinfectants. Swabs were used directly for nested PCR to detect treponemes or inoculated for anaerobic growth, and subsequently examined using phase contrast microscopy and PCR.

Results: BDD treponeme DNA was detectable by nested PCR at all survival time points, and these organisms were culturable from hoof knives for two hours after exposure under aerobic conditions in the laboratory. Three of the five disinfectants—1 per cent volume per volume (v/v) FAM30®, 2 per cent weight per volume (w/v) Virkon® or 2 per cent (v/v) sodium hypochlorite—were effective at preventing visible growth of treponemes following 20-seconds contact, and 1 per cent (v/v) FAM30® also prevented detection of treponemes by PCR.

Conclusion: Treponeme viability of two hours under aerobic conditions suggests BDD treponemes could be transmitted between cows on hoof knives. It is therefore important to apply a disinfection protocol during foot-trimming; the authors have identified three common disinfectants that may be suitable.

Amy Gillespie, Stuart D. Carter, Roger W. Blowey and Nicholas Evans
http://dx.doi.org/10.1136/vr.105406

June 2019

Bovine leukemia virus (BLV) infection has worldwide distribution in both dairy and beef herds. Our study was initiated in order to encourage control of BLV infection by using milk samples, in lieu of serum samples, to readily test lactating animals prior to dry-off and calving. Two Holstein dairy herds (A and B), with known status of BLV infection as determined by serology, were sampled by the collection of serum and fresh milk samples. Selected samples were tested using a USDA-licensed BLV antibody ELISA kit (Bovine leukemia virus antibody test kit; VMRD, Pullman, WA) for serum. Forty-one lactating cows from each herd were sampled. Herd A was confirmed to have endemic BLV infection; herd B was confirmed to be free of BLV infection. The milk ELISA results demonstrated 100% identification of positive and negative animals compared with the serum results. The correlation of the ELISA values between serum and milk samples was 97%, which supports the use of this BLV ELISA on milk samples.

James F. Evermann1, David M. DeAvila, Steven M. Parish, Catherine H. Merritt, Katherine C. Noble, Sampath Srikanth, Amanda L. E. Bronowski
Research Article https://doi.org/10.1177/1040638719860487

June 2019

A cow naturally infected with M. avium subspecies paratuberculosis.

A team of Agricultural Research Service (ARS) and university scientists is investigating a new “ingredient” for use in vaccinating cattle against Johne’s disease, a chronic wasting affliction that costs the U.S. dairy industry more than $200 million per year.

November 2018

Research gets closer to identifying susceptible animals. ( Farm Journal Media )

Johne’s disease, also called mycobacterium avium subspecies paratuberculosis, results in inflammation and damage to the intestinal wall and negatively affects absorption of nutrients and overall cattle performance. The disease is present on dairies around the world, causing significant economic and animal welfare losses. A 2007 USDA study showed 68% of U.S. dairy herds have at least 8% of animals affected by the disease.