Post by huronna on Oct 25, 2008 7:43:50 GMT -5
Enlarged Spleen
Splenomegaly
by Lisa (Tashaferret)
--------------------------------------------------------------------------------
Ferret Splenomegaly (Enlarged Spleen)
Splenomegaly, or the enlargement of the spleen, is one of the biggest question marks in ferret medicine today. It’s not known what causes splenomegaly in the ferret.
The vast majority of enlarged spleens are benign problems that do not threaten your ferret's health, however, about 5% overall can be due to tumors, the most common being lymphosarcoma. 95% of splenic enlargements are due to a massive proliferation of red and white blood cell precursors. This change is due to the presence of a chronic smoldering infection, the most common of which is gastric infection with bacteria called Helicobacter mustelae (which almost every ferret has).
Splenomegaly is a very common finding in the ferret, especially in
those over 3 years of age.
Other possible causes:
Lymphosarcoma, insulinoma, cardiomyopathy, adrenal neoplasia, Aleutian disease, eosinophilic gastroenteritis, systemic mast cell neoplasia, hemangiosarcoma, splenitis, and hypersplenism.
Most times an enlarged spleen is probably just benign changes in the spleen. Very enlarged spleens can cause a variety of weird blood values and cause profound lethargy. Treatment is to remove the spleen.
What does the spleen do?
The spleen actually has several functions. Its most important function is to act as a filter for the blood -- sifting the blood for bacterial agents or evidence of inflammation against which its high population of white blood cells may mount an attack. Additionally, the spleen may act as a storehouse for blood - in some species, the spleen holds as much as 15-20% of the total blood volume in reserve, so that it is immediately available in times of stress.
Additionally, the spleen filters out old red blood cells, which are trapped and subsequently digested by the white blood cells that live there - the iron in these cells is reclaimed and may be used again if necessary, or it may be stored in the spleen against future needs.
Finally, the spleen, in many species and especially in the ferret, is where new blood cells, of both the red and white varieties, may be made, in addition to the bone marrow. Generally, this process occurs only where there is a greater than normal need for these cells, (i.e., after hemorrhage, or during systemic infections.)
By far, the most common cause of splenic enlargement in ferrets is an accumulation of massive numbers of developing red and white blood cells (known as "extramedullary hematopoiesis").
What causes splenic hematopoiesis? (Theories)
1. The virus theory. While several theories feel that a virus causes this change, one has never been isolated, this theory is yet unproven.
2. The hypersplenism theory. Several years ago, a case report was
published on a ferret with a large spleen, who had a progressively
decreasing blood count. When the spleen was removed, the
blood count stabilized. The theory arose that a malfunction of the spleen was responsible for excessive destruction of red blood cells. The term "hypersplenism" was applied to this phenomenon, after a condition in humans that bears some resemblance; however, this was an isolated case.
Theory by Dr. Bruce Williams:
"This is not the result of a formal study- this is simply my opinion,
based on looking at hundreds of cases of splenomegaly with associated clinical data. We know that the extramedullary hematopoiesis arises as a result an increased demand for either red or white blood cells, and there is no reason not to believe that this is the case in ferrets. But relatively few of these animals have evidence of anemia or recent hemorrhage -- this leaves us with the more likely possibility of chronic smoldering infections resulting in an increased demand for blood cells. Well, I certainly see my share of gastroenteritis, and renal infections, but that still leaves a very large portion of animals with enlarged spleens from a yet undetermined cause. However, when you go back and look at the ferrets which had enlarged spleens at autopsy, a large percentage of them have evidence of chronic gastritis due to infection by Helicobacter mustelae. Helicobacter is a very common symptomatic bacterial infection in ferrets which, over time, causes a marked inflammatory response in the stomach and associated lymph nodes. In fact, it is the rare animal over 4 years of age that does not have microscopic evidence of Helicobacter infection. I believe that chronic infection in ferrets due to gastric Helicobacter infection is responsible for a large number (not all) cases of splenomegaly in the ferret. Now let's look at another, probably more important issue - what we should do about enlarged spleens.
Ferrets certainly do not need their spleens to live - they tolerate
splenectomy very well, and it is commonly done. But rather than take out every big spleen we see, we need to set some criteria as to when to remove them and when to leave them in. Ideally, we would like to leave them all in, but for various reasons, we are not always able to."
Surgical aspects
Although splenectomy is an abdominal surgery, it is straightforward.
When isoflurane is used for anesthesia the ferrets wake up quickly after surgery and can usually go home the same night (if surgery is performed early) or the next day. Post-operatively it is recommended that there is limited activity for 7 days (don't encourage playing and separate the ferret that had surgery for at least 2-3 days). When the patient comes home, it is usually best to feed him small amounts 3-4 times a day for the first day or two. Suture removal in 10-14 days. The potential complications include bleeding (usually within the first 24 hrs.) and infection (within first 48-72 hrs.). Warning signs indicating complications include: gums that are pale (rather than pink), poor appetite, lethargy, swelling or inflammation at suture line.
Certainly, all spleens with lymphosarcoma or any other type of neoplasm should come out immediately. Veterinarians can tell when a spleen has a neoplasm in it without taking it out - they can aspirate cells from it with a needle and light anesthesia, or take a small piece of it during exploratory abdominal surgery. Qualified veterinary pathologists with experience with ferrets can then look at the cells in the biopsy to determine whether they are compatible with lymphosarcoma, other neoplasms, or are more consistent with a proliferation of immature blood elements.
In situations where a neoplasm (Cancer) is not present, the pros and cons of splenectomy should be discussed with your veterinarian. If an animal simply has a large spleen, but shows no signs of illness or
discomfort, it is safer for the animal to leave it in. However, if the animal shows signs of discomfort, such as lethargy and a poor appetite, or a decrease in activity, then the spleen may come out.
Finally, if the spleen is especially large, and the animal is very active, there is a risk of splenic rupture, and once again, splenectomy should be considered.
In situations where a neoplasm is not present [this is a common symptom of lymphosarcoma], but the animal shows signs of discomfort, such as lethargy and a poor appetite, or a decrease in activity, the spleen should probably be removed. These animals also need good nursing care to get them back on their food.
--------------------------------------------------------------------------------
SOURCE AND RESEARCH CREDITS:
Written by Dr. Susan Brown, DVM:
Dr. Mike Dutton, DVM,
Written by Dr. Charles Weiss, DVM:
Dr. Bruce Williams, DVM
Splenomegaly
by Lisa (Tashaferret)
--------------------------------------------------------------------------------
Ferret Splenomegaly (Enlarged Spleen)
Splenomegaly, or the enlargement of the spleen, is one of the biggest question marks in ferret medicine today. It’s not known what causes splenomegaly in the ferret.
The vast majority of enlarged spleens are benign problems that do not threaten your ferret's health, however, about 5% overall can be due to tumors, the most common being lymphosarcoma. 95% of splenic enlargements are due to a massive proliferation of red and white blood cell precursors. This change is due to the presence of a chronic smoldering infection, the most common of which is gastric infection with bacteria called Helicobacter mustelae (which almost every ferret has).
Splenomegaly is a very common finding in the ferret, especially in
those over 3 years of age.
Other possible causes:
Lymphosarcoma, insulinoma, cardiomyopathy, adrenal neoplasia, Aleutian disease, eosinophilic gastroenteritis, systemic mast cell neoplasia, hemangiosarcoma, splenitis, and hypersplenism.
Most times an enlarged spleen is probably just benign changes in the spleen. Very enlarged spleens can cause a variety of weird blood values and cause profound lethargy. Treatment is to remove the spleen.
What does the spleen do?
The spleen actually has several functions. Its most important function is to act as a filter for the blood -- sifting the blood for bacterial agents or evidence of inflammation against which its high population of white blood cells may mount an attack. Additionally, the spleen may act as a storehouse for blood - in some species, the spleen holds as much as 15-20% of the total blood volume in reserve, so that it is immediately available in times of stress.
Additionally, the spleen filters out old red blood cells, which are trapped and subsequently digested by the white blood cells that live there - the iron in these cells is reclaimed and may be used again if necessary, or it may be stored in the spleen against future needs.
Finally, the spleen, in many species and especially in the ferret, is where new blood cells, of both the red and white varieties, may be made, in addition to the bone marrow. Generally, this process occurs only where there is a greater than normal need for these cells, (i.e., after hemorrhage, or during systemic infections.)
By far, the most common cause of splenic enlargement in ferrets is an accumulation of massive numbers of developing red and white blood cells (known as "extramedullary hematopoiesis").
What causes splenic hematopoiesis? (Theories)
1. The virus theory. While several theories feel that a virus causes this change, one has never been isolated, this theory is yet unproven.
2. The hypersplenism theory. Several years ago, a case report was
published on a ferret with a large spleen, who had a progressively
decreasing blood count. When the spleen was removed, the
blood count stabilized. The theory arose that a malfunction of the spleen was responsible for excessive destruction of red blood cells. The term "hypersplenism" was applied to this phenomenon, after a condition in humans that bears some resemblance; however, this was an isolated case.
Theory by Dr. Bruce Williams:
"This is not the result of a formal study- this is simply my opinion,
based on looking at hundreds of cases of splenomegaly with associated clinical data. We know that the extramedullary hematopoiesis arises as a result an increased demand for either red or white blood cells, and there is no reason not to believe that this is the case in ferrets. But relatively few of these animals have evidence of anemia or recent hemorrhage -- this leaves us with the more likely possibility of chronic smoldering infections resulting in an increased demand for blood cells. Well, I certainly see my share of gastroenteritis, and renal infections, but that still leaves a very large portion of animals with enlarged spleens from a yet undetermined cause. However, when you go back and look at the ferrets which had enlarged spleens at autopsy, a large percentage of them have evidence of chronic gastritis due to infection by Helicobacter mustelae. Helicobacter is a very common symptomatic bacterial infection in ferrets which, over time, causes a marked inflammatory response in the stomach and associated lymph nodes. In fact, it is the rare animal over 4 years of age that does not have microscopic evidence of Helicobacter infection. I believe that chronic infection in ferrets due to gastric Helicobacter infection is responsible for a large number (not all) cases of splenomegaly in the ferret. Now let's look at another, probably more important issue - what we should do about enlarged spleens.
Ferrets certainly do not need their spleens to live - they tolerate
splenectomy very well, and it is commonly done. But rather than take out every big spleen we see, we need to set some criteria as to when to remove them and when to leave them in. Ideally, we would like to leave them all in, but for various reasons, we are not always able to."
Surgical aspects
Although splenectomy is an abdominal surgery, it is straightforward.
When isoflurane is used for anesthesia the ferrets wake up quickly after surgery and can usually go home the same night (if surgery is performed early) or the next day. Post-operatively it is recommended that there is limited activity for 7 days (don't encourage playing and separate the ferret that had surgery for at least 2-3 days). When the patient comes home, it is usually best to feed him small amounts 3-4 times a day for the first day or two. Suture removal in 10-14 days. The potential complications include bleeding (usually within the first 24 hrs.) and infection (within first 48-72 hrs.). Warning signs indicating complications include: gums that are pale (rather than pink), poor appetite, lethargy, swelling or inflammation at suture line.
Certainly, all spleens with lymphosarcoma or any other type of neoplasm should come out immediately. Veterinarians can tell when a spleen has a neoplasm in it without taking it out - they can aspirate cells from it with a needle and light anesthesia, or take a small piece of it during exploratory abdominal surgery. Qualified veterinary pathologists with experience with ferrets can then look at the cells in the biopsy to determine whether they are compatible with lymphosarcoma, other neoplasms, or are more consistent with a proliferation of immature blood elements.
In situations where a neoplasm (Cancer) is not present, the pros and cons of splenectomy should be discussed with your veterinarian. If an animal simply has a large spleen, but shows no signs of illness or
discomfort, it is safer for the animal to leave it in. However, if the animal shows signs of discomfort, such as lethargy and a poor appetite, or a decrease in activity, then the spleen may come out.
Finally, if the spleen is especially large, and the animal is very active, there is a risk of splenic rupture, and once again, splenectomy should be considered.
In situations where a neoplasm is not present [this is a common symptom of lymphosarcoma], but the animal shows signs of discomfort, such as lethargy and a poor appetite, or a decrease in activity, the spleen should probably be removed. These animals also need good nursing care to get them back on their food.
--------------------------------------------------------------------------------
SOURCE AND RESEARCH CREDITS:
Written by Dr. Susan Brown, DVM:
Dr. Mike Dutton, DVM,
Written by Dr. Charles Weiss, DVM:
Dr. Bruce Williams, DVM
