ducts which typically stain dark blue (basophilic) in H&E
sections and black with von Kossa stain.
10.2 Vaccination Side-Effects
With the exception of Tasmania, virtually all salt-water
farmed salmonids are vaccinated. Most vaccines in current
use are multivalent, i.e. they contain antigens from several
different bacteria and/or viruses. In order to enhance and
extend the duration and/or directing the nature of the
immune response, an oil based adjuvant is mixed with the
antigens. The composition of the vaccines may vary
depending on the zoosanitary situation. After a few days of
starvation fish are typically immunized prior to
smoltification and sea-water transfer. The fish are
anesthetized and the vaccine is given intraperitoneally,
either by vaccination teams or automated machines. The
injection site is typically in the ventral midline, 1.5 fin
lengths cranial to the base of the pelvic fins, and the injection
volume ranges from 0.05 to 0.1 ml.
The combination of antigens and adjuvant provokes a
strong localized inflammatory response. This chronic
inflammation is macroscopically visible as fibrinous strands
between the peritoneal wall and internal organs (Fig. 10.6).
Typically, the caudal parts of the pyloric caeca and spleen
are involved in the lesions. Thrombosis and granulomatous
inflammation is also reported in the liver. Moderate lesions
are considered acceptable, both from an animal welfare and
from the consumers’ points of view.
Histologically, the affected region between the wall of the
pyloric caeca and pancreatic tissue and around the spleen,
show clear, empty spaces within the granulomatous
response. These correspond to the oil droplets in the vaccine
which are dissolved during the tissue processing. The
inflammatory response is dominated by macrophages,
lymphocytes, fibroblasts and multinucleated giant cells.
Eosinophilic granular cells and melanomacrophages are
Fig. 10.6 Vaccinated Atlantic salmon showing. (a) Mild adhesions between visceral organs and body wall near the injection site. (b) Moderate
adhesions between visceral organs and body wall; and (c–d). Severe melanisation of internal organs and peritoneal surface
10.2 Vaccination Side-Effects
155
sections and black with von Kossa stain.
10.2 Vaccination Side-Effects
With the exception of Tasmania, virtually all salt-water
farmed salmonids are vaccinated. Most vaccines in current
use are multivalent, i.e. they contain antigens from several
different bacteria and/or viruses. In order to enhance and
extend the duration and/or directing the nature of the
immune response, an oil based adjuvant is mixed with the
antigens. The composition of the vaccines may vary
depending on the zoosanitary situation. After a few days of
starvation fish are typically immunized prior to
smoltification and sea-water transfer. The fish are
anesthetized and the vaccine is given intraperitoneally,
either by vaccination teams or automated machines. The
injection site is typically in the ventral midline, 1.5 fin
lengths cranial to the base of the pelvic fins, and the injection
volume ranges from 0.05 to 0.1 ml.
The combination of antigens and adjuvant provokes a
strong localized inflammatory response. This chronic
inflammation is macroscopically visible as fibrinous strands
between the peritoneal wall and internal organs (Fig. 10.6).
Typically, the caudal parts of the pyloric caeca and spleen
are involved in the lesions. Thrombosis and granulomatous
inflammation is also reported in the liver. Moderate lesions
are considered acceptable, both from an animal welfare and
from the consumers’ points of view.
Histologically, the affected region between the wall of the
pyloric caeca and pancreatic tissue and around the spleen,
show clear, empty spaces within the granulomatous
response. These correspond to the oil droplets in the vaccine
which are dissolved during the tissue processing. The
inflammatory response is dominated by macrophages,
lymphocytes, fibroblasts and multinucleated giant cells.
Eosinophilic granular cells and melanomacrophages are
Fig. 10.6 Vaccinated Atlantic salmon showing. (a) Mild adhesions between visceral organs and body wall near the injection site. (b) Moderate
adhesions between visceral organs and body wall; and (c–d). Severe melanisation of internal organs and peritoneal surface
10.2 Vaccination Side-Effects
155