Eliminating chorioptic mange
from a dairy herd without
milk withdrawal
Aurora Villarroel and Megan
Halliburton, Oregon State
University
Many antiparasitic drugs require
lengthy withdrawal times which make
them impractical for use in treating an
entire dairy herd. The authors carried
out a study on the efficacy of
eprinomectin (one of only two such
drugs approved in the US for
treatment of lactating cattle) to tackle
an outbreak of chorioptic mange in a
commercial dairy herd.
All cattle on the farm were treated
on the same day and at dry-off, and
lesion scoring was performed five
times over a 12-month period. Three
months post-treatment there was a
reduction in the proportion of cattle
with lesions but the numbers increased
at 12 months. Factors associated with
the presence of persistent lesions
included older cows, late lactation and
recent treatment. No increase in milk
production was apparent but the
overall welfare of affected cattle was
improved.
The study demonstrated that
chorioptic mange can be controlled in
entire herds although multiple
treatments may be required to
eliminate the parasite. The study also
demonstrates that mange can be
controlled at herd level without
recourse to non-licensed products.
The Veterinary Journal 197 (2): 233-237.
Effectiveness of
interventions to reduce claw
lesions in 40 dairy herds
Zoe Barker and others, University
of Warwick
Various risk factors have been
identified in connection with lameness
in dairy cattle but there is little reliable
data on the impact of management
changes to address those factors.
The authors investigated the
impact of veterinary advice on
reducing such risks on the prevalence
of lameness on 40 dairy units. They
found no significant differences in the
prevalence of lameness or the
incidence of white line disease, sole
ulcers or digital dermatitis between
those farms where recommendations
were provided and the control units
where locomotion was recorded but
no advice given.
The overall uptake of veterinary
recommendations by the farmers was
only 41.3%.
Animal Welfare 21 (4): 563-576.
Impact of an internal teat
sealant on the incidence of
bovine mammary infections
Volker Kroemker and others,
University of Hannover, Germany
Intramammary antimicrobial treatment
has long been the mainstay of
preventive measures to control mastitis
in dairy herds but there is political
pressure to find alternative approaches.
The authors examined the efficacy of a newly introduced product (Orbeseal,
Zoetis) which aims to seal off the teat
canal to prevent invasion by
environmental pathogens.
Rates of
new infections in treated and untreated
quarters in 128 cattle from nine dairy
units was 3.5% and 10.5%,
respectively. Therefore, internal teat
sealants are a viable option for a
drying-off treatment in healthy dairy
cattle.
Journal of Dairy Research 81 (1): 54-58.
Milk flow obstruction caused
by varicose veins in the teats
of dairy cattle
Helene Larde and others,
University of Montreal, Canada
Varicose veins may occur uncommonly
in the teats of dairy cattle but, where
present, they can reduce milk
production and increase the risk of
mastitis. The authors recorded the
clinical features of 22 such incidents
and review the therapeutic options and
eventual outcome for these patients.
The three treatment approaches used
were sclerotherapy, ligation of the vein
associated with sclerotherapy, and
phlebectomy. The overall prognosis
was good with the restoration of
normal milk flow six months post-
treatment in 84% of cases and there
were no discernible differences
between treatment groups. There was
a recurrence of the obstruction in
three cases.
Veterinary Surgery 42 (7): 885-891.
Monitoring body
temperatures in cattle using
infrared thermography
cameras
Gundula Hoffman and others, Free
University of Berlin, Germany
Body temperature measurements using
rectal thermometers provide valuable
information on an animal’s
physiological state but the process is
time-consuming and potentially
disruptive for the animal concerned.
The authors examined the possible
application in herd health monitoring
of infrared thermography cameras.
They compared the results of video
recordings, particularly of the eye and
the back of the ear, in 22 cows and
nine calves with those from
conventional rectal or vaginal
thermometer readings.
An increase in
the maximum temperature recorded
on thermography correlated well with changes measured using conventional
thermometers and the technique
appears to have promise in monitoring
body temperatures in housed cattle.
Veterinary Research Communications 37
(2): 91-99.
Association between
haematological variables and
bovine respiratory disease
risk
John Richeson and others, Texas
A&M University
Bovine respiratory disease complex in
beef calves is the leading cause of
economic losses in the US feedlot
industry. The authors looked at
haematological variables in 1,179 beef
calves arriving at university research
facilities to identify possible risk
factors associated with the later
development of the disease syndrome.
The results indicate that low
eosinophil and high red blood cell
counts in blood samples taken on
arrival may be useful for the
identification of calves with a high risk
of developing BVD. Bull calves also
appeared to be at a higher risk than
those that were castrated before
arrival.
Journal of the American Veterinary Medical
Association 243 (7): 1,035-1,041.
Diagnosis and management
of Staphylococcus aureus
mastitis in cattle
James Breen and others, University
of Nottingham
Staphylococcus aureus is the most
frequent cause of contagious mastitis
in most UK dairy herds and will often
result in a persistent subclinical
infection. However, the isolation of
this organism from individual cases or
bulk milk tank samples should not
necessarily lead to a herd diagnosis.
The authors explain how systematic
analysis of clinical mastitis and somatic
cell count data is required to
understand the impact of this
pathogen on the herd. They review
procedures for the diagnosis of
infected individuals and herds, and
propose measures for treating infected
animals and identifying control
priorities for infected herds.
Cattle Practice 21 (3): 189-197.
Detection and potential
effects of Ureaplasma
diversum in bull semen
Naomi Hobson and others, Charles Sturt University, New South Wales
Ureaplasma diversum is a common mycoplasmal inhabitant of the vagina
and prepuce of cattle which is known to be an occasional cause of abortion.
The authors investigated the frequency that U. diversum could be identified in semen samples from Australian bulls using direct culture and PCR analysis.
Nine of 29 visually healthy bulls tested positive for the organism. Sperm from infected bulls showed an increased incidence of abnormal gametes with bent or coiled tails, as well as surface abnormalities, such as small protuberances or lumps. These findings suggest a possible association between U. diversum infection and impaired sperm function.
Australian Veterinary Journal 91 (11): 469-473.
Campylobacter foetus isolations from preputialsamples with various preparatory methods
Bonnie Chaban and others, University of Saskatchewan, Canada
Bovine venereal campylobacteriosis is
a venereal disease of cattle causing
infertility and abortion. The causative
organism Campylobacter foetus subsp.
venerealis has reduced viability in
normal atmospheric conditions and so
can be difficult to culture from
preputial scrapings.
The authors
compare the isolation rates from 217
samples from 12 infected bulls with
passive filtration on selective medium
versus non-selective medium, with and
without transport medium. Their
results show that the use of transport
medium and the choice of culture
medium can have significant effects on
C. foetus recovery rates and both
factors should be considered when
animals are tested for this organism.
American Journal of Veterinary Research
74 (8): 1,066-1,069.
Association between MAP
culture results and
tuberculin test responses in
US dairy herds
Barbara Brito and others, University of California, Davis
Bovine tuberculosis has been
eradicated from cattle in most states of
the USA although occasional cases are
identified at slaughter or using the
standard causal fold tuberculin test.
The authors examined the association
between tuberculin test results and the
Mycobacterium avium subsp.
paratuberculosis status of nearly 7,000
cattle on four units in California and
Colorado. They found there was a
strong association between positive
MAP test results and being classified
as a suspect by CFT testing. Within-
herd MAP prevalence may affect the
specificity of CFT testing for bovine
tuberculosis.
Journal of the American Veterinary Medical
Association 244 (5): 582-587.
Comparative efficacy of
gamithromycin and
tulathromycin in treating
BRD
Siddartha Torres and others, Kansas State University
Bovine respiratory disease is a
multifactorial syndrome involving
various bacterial and viral pathogens
along with environmental and
management factors. The authors
examine the relative efficacy of
gamithromycin and tulathromycin in
treating BRD in feedlot calves.
Calves
given a single subcutaneous dose of
6mg/kg gamithromycin needed more
frequent secondary treatment than
those given 2.5mg/kg tulathromycin,
also by subcutaneous injection. Other
parameters such as the mean case
fatality rate, final bodyweight, average
daily weight gain and clinical score 10
days post-treatment did not differ
between the two groups.
American Journal of Veterinary Research 74 (6): 847-853.
Genetic analysis of Mannheimia haemolytica isolates from fatal BRD cases
Jared Taylor and others, Oklahoma State University
Mannheimia haemolytica is the most
common bacterial pathogen isolated
from cases of the bovine respiratory
disease complex in most developed
countries. However, as the bacterium
may be present in the upper
respiratory tract of healthy animals, it
has been suggested that the organism
is an opportunistic infection that only
causes disease in individuals weakened
by other factors.
The authors analysed
ribosomal DNA from bacteria
isolated from fatal BRD cases in the
US and Australia. The findings may
eventually help in assessing whether
the organism is an opportunistic
pathogen or in identifying features
that distinguish commensal isolates
from those more likely to be
associated with disease.
Australian Veterinary Journal 92 (1-2):
15-23.
