UK Field Experiences with Orbeseal, a Dry Period Internal Teat
Sealer.
Jon Huxley BVetMed, Cert CHP, MRCVS
and Andrew Bradley MA, VetMB, DCHP,
PhD, MRCVS.
University of Bristol, Division of Animal
Health and Husbandry, Department of
Clinical Veterinary Science, Langford
House, Langford, Bristol, BS40 5DU.
During the non-lactating period the bovine mammary gland is separated from the
environment by the formation of a keratin “plug” which seals the teat sphincter, preventing
the entry of pathogens from the environment. However a functional keratin plug can take up
to two weeks to form, may be compromised during colostrogenesis and in some animals never
adequately seals the teat sphincter even during the mid trimester (steady state phase) of the
dry period.
Many attempts have been made to artificially mimic the function of the keratin plug,
principally to provide protection during the first and last trimester of the dry period, the times
at which the gland is at greatest risk (and the functional integrity of the keratin plug may be
compromised). Anecdotally, a broad range of products has been employed including
Stockholm tar, impervious tapes and spray on “synthetic skins”.
Attempts to provide a functional artificial external seal began during the 1970’s in the
USA with the development of a liquid latex teat dip. More recently a longer lasting polymer
based external sealant has become commercially available (DryFlex, Alfa Laval Agri) in the
UK. It is currently recommended as an adjunct to antibiotic dry cow therapy (DCT). Although
field data from both North America and more recently the UK shows promise, long-term
persistence of the sealant remains a problem and necessitates frequent re-application of the
product.
Internal teat sealers based on bismuth subnitrate in a paraffin base were developed in
Ireland in the early 1970’s. At the time interest in this style of approach to DCT was limited
because of the rapidly expanding interest in and market for long acting antibiotic
formulations. A teat sealer based on this original work used in combination with a short acting
antibiotic has been available in Ireland for well over 20 years (Osmonds Teatseal, Cross
Vetpharm Group, Ireland). In 1996 a reformulation of the original sealer was launched in
New Zealand. In field trials it proved as good as a long acting antibiotic DCT at preventing
new infection during the dry period.
Between September 1999 and May 2000 we carried out a 500 cow study on 16
commercial dairy farms in SW England to compare the teat sealer available in New Zealand
with conventional antibiotic DCT. Farms included in the study ranged from low intensity
grass based systems with cows averaging well under 5000L/year to much higher input
systems with animals producing nearly 9000 L/year. Cows were selected for inclusion in the
study if they had no monthly cow level somatic cell counts (SCC) over 200,000 cells/ml and
no cases of clinical mastitis during the preceding lactation. These criteria were used to select
cows unlikely to be infected with major pathogens at the time of drying off.
Animals were randomly assigned to receive either an internal teat sealer containing
65% w/w bismuth subnitrate in a paraffin base (Orbeseal, Pfizer Animal Health, UK) or a
long acting antibiotic tube containing 250mg cephalonium (Cepravin Dry Cow, ScheringPlough Ltd, UK). All animals on the trial were quarter sampled for bacteriological and SCC
analysis at drying off and at calving. All cases of clinical mastitis were recorded and sampled
for bacteriological analysis for the first 100 days of the next lactation.
Approximately 50% of animals on the 16 farms were suitable for treatment with
Orbeseal. The key finding from the study are outlined below. A more extensive description of
the results can be found elsewhere (Huxley et al. 2002).
Key Study Findings:
 Cows that received Orbeseal acquired significantly fewer new infections during the
dry period caused by E. coli, all Enterobacteriaceae and all major pathogens (Figures
1 & 2).
 Two cases of dry period clinical mastitis occurred in the antibiotic group, compared to
none in the Orbeseal group.
 Cows that received Orbeseal suffered 30 quarter cases of clinical mastitis (during the
first 100 days of lactation) compared to 35 in the antibiotic group.
 Quarters that acquired a new dry period infection were significantly more likely to
suffer a case of clinical mastitis (not necessarily caused by the same pathogen),
compared to those that did not.
 In the antibiotic group, 7 quarters that acquired a new IMI during the dry period
suffered a case of clinical mastitis caused by the same organism, compared to 2
quarters in the Orbeseal group.
 For every 1 litre increase in last recorded yield before drying off there was a 6 percent
increase in the risk of a quarter acquiring a new infection during the dry period.
Key Product Facts:
 Orbeseal is intended for use in cows that are not infected with major pathogens at
drying off.
 Orbeseal prevents infections during the dry period by occluding the internal aspect of
the teat sphincter and preventing the ingress of pathogenic organisms. Radiographs
have demonstrated the presence of the seal in teats 100 days after infusion (Figure 3).
 Orbeseal has a consistency similar to toothpaste (although slightly more dense)
(Figure 4).
 Orbeseal is administered from a tube at drying off in a manner similar to that used for
conventional antibiotic DCT (although Orbeseal is NOT “massaged” up into the
quarter).
 Orbeseal is sucked harmlessly by the calf or stripped manually from the quarter at
calving.
The insertion of a tube through the teat sphincter, for the administration of any intramammary product represents a potential risk to the quarter being treated. Pathogens present
around the teat sphincter or in the environment can be inoculated into the quarter during the
infusion process. Users in the field should be made aware of the potential dangers and
adequately trained to maintain aseptic infusion techniques (Figures 5 & 6). These precautions
will minimise the potential risks of inoculating pathogenic organisms into the quarter, at the
time of dry cow product administration.
Orbeseal is not designed to treat existing infections. The continued use of antibiotic DCT is
vital in cows that are subclinically infected with major mastitis pathogens at drying off. In
these higher SCC animals, antibiotic DCT should be aimed at curing existing infections
(particularly contagious pathogens e.g. S. aureus) by targeting the most prevalent pathogen on
the farm and then selecting an antibiotic DCT with a suitable spectrum of activity and
prolonged duration of action. Veterinarians in the field need to prescribe Orbeseal carefully
by advising clients on the appropriated selection of uninfected cows (based on historical SCC
data) and as part of an overall dry cow therapy and udder health package. DCT is the
singularly most expensive piece of veterinary medicine that the majority of dairy cows in the
UK receive. Careful selection of the most appropriated product for high and low SCC animals
on a farm can significantly impact on the cure rate (high SCC animals) and acquisition of new
infections (low SCC animals) during the dry period.
In summary, Orbeseal was significantly better that the UK’s market leading antibiotic
DCT at preventing the acquisition of new intramammary infections during the dry period, in
cows that were not infected at drying off. Orbeseal represents the first truly novel and
significant advance in DCT, in the UK, for many years. The rationale for the use of high
doses of long acting antibiotic in cows uninfected with major pathogens at drying off will
become increasingly untenable when Orbeseal is commercially available. The advent of
Orbeseal offers an opportunity to significantly reduce the prophylactic usage of antibiotics in
food producing animals without having to compromising the health, welfare, productivity or
commercial viability of UK dairy cattle.
References:
Huxley, J. N., M. J. Green, L. E. Green and A. J. Bradley (2002). “Evaluation of the efficacy
of an internal teat sealer during the dry period.” Journal of Dairy Science 85: 551-561.