MASTITIS BASICS Categories of Mastitis Mastitis can be divided into different categories: clinical and subclinical contagious and environmental
Definitions
Clinical mastitis is when there are obvious changes to the udder tissue and / or the
milk. The milk may appear watery or full of clots, but will have an abnormal secretion.
The udder may appear normal or may be hot and swollen. Depending on the severity of
the infection, the cow may appear normal and behave accordingly or toxic mastitis can
Subclinical mastitis is when there are no visible changes to the milk. A milker will be
unable to identify subclinical mastitis unless he carries out tests, such as individual cow cell counts, or the California mastitis test. The cell count of quarters with subclinical
mastitis will always be elevated above 200,000.
Contagious mastitis: the udder and teats are the reservoir of infection. Transmission occurs during the milking process from udder preparation by contaminated hands,
udder cloths and liners. Infection establishes on the teat and teat canal. Bacteria may
then penetrate the mammary gland. Most infections are subclinical and result in raised
cell counts. Control measures include post milking teat disinfection, dry cow therapy and
culling. Contagious bacteria include Staphylococcus aureus, Streptococcus agalactiae and
dysgalactiae. If your herd cell count is over 200,000 then this indicates that there is a
problem with contagious mastitis.
Environmental mastitis: the environment is a reservoir of infection. Infection is transmitted on to the teats between milkings or during udder preparation.
Organisms are forced up through the teat canal during the milking process or after milking
if cows are allowed to lie down immediately following milking. Most infections cause
clinical mastitis. Subclinical infections are less common. Environmental mastitis is
controlled by provision of a clean environment, adequate accommodation for cows,
milking through a correctly functioning machine, good udder preparation and pre- milking
teat disinfection. Environmental organisms include E coli, Streptococcus uberis (straw
bedding), Klebsiella (sawdust and shavings) and Bacillus.
THE THREE STAGES TO REDUCE HERD CELL COUNTS: 1.
Identify the high cell count cows and the bacteria responsible for the high cell count
Take specific action for high cell count cows, this will depend on your herd SCC, milk
price penalties and your youngstock availability
OPTIONS FOR HIGH CELL COUNT COWS a) Cull ~ Cost is about $800 – 1,200
Permanent solution and irreversible Take into account full mastitis history (SCC and clinical mastitis records and
bacteriology) and also consider other factors lameness, production, other problems Costly decision Is it really necessary?
b) Dry off the cow ~ $8 - 12 Retains cow in the herd Allows treatment with dry cow therapy You can check the cows cell count at next lactation and keep the calf You may still need to cull cow, but allows this option later You could dry off the cow early or stop milking her and put a calf with her to suck out
c) Antibiotic treatment during lactation ~ $125 +
Treatment success is poor, treat three cows and cure one Not recommended
d) UdderMint treatment during lactation ~ $5-8
Massage UdderMint into the udder for a five to seven day period This helps to improve circulation and the number of white blood cells and can help
e) Separate and milk last
Put your problem high cell count cows into a separate group and always milk last. You can always disinfect clusters between uses as an additional measure
Shepton Veterinary Group, Allyn Saxon Drive, Shepton Mallet, BA4 5QH
Not to be reproduced without written permission.
HIGH SCC MASTITIS ORGANISMS Staph aureus
Micro-abscesses within the udder tissue
Treatment success during lactation varies between 10 and 25% with intramammary
Treatment success decreases with increasing age of the animal
Many strains of Staph aureus are resistant to Penicillin
Response with dry cow therapy can be up to 70%, or as low as 5-10% in older and
Can be difficult to isolate from bacteriology as there is intermittent shedding
Cell counts highly variable in infected cows
Treatment success for cows in lactation 4 and above are very poor indeed
Infection associated with poor teat skin and / or teat injuries
Very difficult to eliminate from a dairy herd
Strep uberis
Bacteria is environmental in origin and associated with straw bedding and yards
Outbreaks at pasture and also in dry period
Subclinical infections are common and may be associated with poor mastitis
identification and/or poor treatment regimes
Response to treatment during lactation may be 60% or less
Response to dry cow therapy is generally good
This organism lives both in the udder and the environment
Control measures will involve reducing the level of contagious and environmental
Shepton Veterinary Group, Allyn Saxon Drive, Shepton Mallet, BA4 5QH
Not to be reproduced without written permission.
Strep dysgalactiae
Associated with poor teat condition due to milking machine problems and/or poor
A less common cause of high cell counts
4. Strep agalactiae
Causes cell counts up to 20,000,000 with no changes to the milk
Highly contagious, and up to 100,000,000 bugs per cc of milk
Can cause fluctuating Bactoscan or TBC
Responds very well to treatment during lactation
Treatment success in old cows is very good
Can be eradicated from a dairy herd using dry cow therapy, treatment during lactation
CAUSES OF CLINICAL MASTITIS Coliforms and E coli
70% cases eliminated by the cow without signs of clinical mastitis
Clinical cases often have a watery secretion
Subclinical E coli is uncommon and is very unlikely to cause a high herd cell count
Vaccine available to reduce severity and incidence
Strep uberis
Shepton Veterinary Group, Allyn Saxon Drive, Shepton Mallet, BA4 5QH
Not to be reproduced without written permission.
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