Your dog’s spleen is an organ in the abdomen that has several functions; it’s most vital functions are the production of lymphocytes, a type of white blood cell and also the storage of blood. Therefore it is a very vascular organ, it has a thin capsule and it sits on the left hand side of the abdomen but it is not fixed tightly like the kidneys or the liver allowing it to expand and contract so that it can fulfill its functions.
The spleen is one of those organs that is
commonly forgotten, it sits quietly performing its functions hidden away in the
abdomen. One of the main reasons that the spleen is so mobile is to actually
protect the organ. As it is a very vascular organ with a relatively delicate
capsule it is susceptible to blunt trauma that could result in its rupture. It
sits tucked in the abdominal fat that also provides it with a degree of
protection.
Unfortunately its structure does predispose
it to problems, and more often than not they are veterinary emergencies.
In the older dog, usually from 8 years of
age onwards, the spleen is very susceptible to vascular tumours because of its
highly vascular structure heavily interlaced with immunomodulating regions.
These tumours tend to grow slowly and in my experience tend to be benign at the
start of their development. However as they grow their structure changes and
they become malignant, they become haemangiosarcomas in the majority of cases.
These growths are extremely vascular and grow rapidly. The dog will be totally
asymptomatic during this phase in the majority of cases, clients often
attribute a slightly larger ‘tummy’ to the dog getting fatter as it ages. I
have removed tumours weighing up to four kgs where the owner as been oblivious
to the existence of the mass. This is because of the mobility of the spleen, so
expansion will be into the peritoneal cavity in the abdomen and nobody is none
the wiser that this monster is growing inside your pet.
What happens is the expanding
haemangiosarcoma stretches the thin capsule of the spleen until it ruptures,
often with the most innocuous of traumas e.g. jumping on a sofa. This is
usually the point that the animal is presented to me for examination, the dog
is usually in loads of abdominal pain and it is pale and weak as the animal
bleeds out into its abdominal cavity. As I mentioned previously these tumours
are really vascular so once the mass ruptures the blood loss is rapid.
Unfortunately in most cases the owner is unaware that their dog is bleeding out
as there is no external signs of blood loss.
Early diagnosis and emergency surgery are
necessary for a successful outcome, often there is no time for niceties, no
time for blood tests etc, and aggressive surgical intervention is required to
stop the bleeding. The quicker the diagnosis, the quicker the surgery the
better the chances of your pet’s survival.
Unfortunately once the mass has ruptured
and even after successful surgery the chances of the tumour reemerging in
another part of the abdomen are very high. The rupture releases millions of
cancer cells into the abdomen, so despite abdominal flushing and irrigation it
is very probable that one of these cells will settle on another abdominal organ
and regrow. The time taken for the cancer to reoccur does vary between
different animals and obviously the degree of malignancy of the original
tumour, it can vary from approximately 3 months to a year.
So early diagnosis of a splenic growth is
vital, this can be done using an ultrasound of the spleen, an experienced
veterinary surgeon will be able to detect early changes in the organ’s
structure. I have removed spleens from dogs with early changes, and these
animals live for many more years and pass away from unrelated conditions. If
you have an elderly dog then get that spleen checked, you could save your best
friend’s life .
