Bovine mastitis: a correlation of the pathological changes and bacteria present in the individual quarters of the bovine mammary gland, with the bacteria and other abnormal constituents in the milk from those quarters
l. A study of 87 mastitic quarters from 26 cows has made in order to correlate the results given by seven indirect
tests and the culture test of the milk with those Given by
the cultural and histopathological examinations of the tissue
of the udder from which the milk samples were collected.
2. The accuracy of the chloride test, catalase test,
Whiteside test, and the total cell count
was found to be 50.6%, 46.0%, 49.4% and 45.0% respectively,
when judged on the basis of the culture test as was customary
with previous workers; compared with 875 for the chloride test,
92% for the catalase test, 82% for the Whiteside test and 100%
for the total cell count, when assessment was made on the
results of histopatholosical examination of the udder tissue.
Hotis test and bromthylol blue test were found unreliable.
3. The culture test, even when using both fresh and
incubated milk as well as udder tissue was not able to identify
more than 455 of all mastitic oases, as judged by histopathological examination of the udder tissue.
4. A total cell count of 100,000 per ml. which has been
generally regarded as the borderline for normal milk was
shown to be too high. A figure of 20,000 per ml. is proposed
as the maximum number of cells permissibly present in normal
5. The diagnostic value of the catalase test, total
cell count, and incubated milk smear were stressed; the total
cell count and incubated milk smear being recommended for the
laboratory workers, and the catalase test for field workers.
6. The incidence of bacterial species in specific mastitis in this investigation. was found to be 43.6% for Str. agalactiae, 10.25% for Str. dysgalactiae, 12.805 for Str. uberis
20.5% for Lancefield's Group G Streptococci, 10.25% for pathogenic staphylococci and 2.6% for 0. pyogenes .
7. Tour types of mastitis - :ere distinguished according
to the pathological changes; subacute suppurative, acute catarrhal, subacute catarrhal and chronic; the incidence being 6%,
13%, 37% and 445 respectively.
8. The pathological changes caused by Str. agalactiae
were found to be primarily subacute catarrhal, narked by highly
productive changes in the interstitial tissue and severe leucoeyi:ic infiltration in the alveoli, ;chile those caused by Str.
dysgalactiae, Str. uberis, and pathogenic staphylococci were
much milder. Although quite intensive lesions were also
)roduced by Str. uberis, yet they were much less severe than
those caused by Str. agalactiae. Lesions observed in one case of Coryne. pyo genes infection viere mainly severe subacute
suppurative, characterized by organization of the suppurative
exudate.. The fibrous tissue thus formed remained there with
resulting extensive fibrosis. 24 microphotographs illustrating
normal and a'Anormal udder are included.
9. The ;general belief in the shedding of the epithelial
cells during the later stage of lactation was repudiated.
10. The need for further research into the whole problem
of mastitis was emphasized.