Neoplastic Anemia in Dogsby Rebecca Bragg
Anemia can be a symptom of some forms of neoplasia, or cancer.
Anemic dogs, like their human counterparts, may feel tired and listless because their tissues and organs are being deprived of oxygen, which is distributed throughout the body by circulating red blood cells. Some causes of anemia in dogs, such as internal bleeding or heavy infestations of internal or external parasites, are more straightforward for veterinarians to treat than "neoplastic," or cancer-related, causes. If you suspect your pup is anemic, see your vet right away. If the underlying cause turns out to be a malignant disease process, early diagnosis offers the best chance for a positive outcome.
Signs of Anemia in Dogs
If your buddy seems unusually lethargic, check the color of his gums. In healthy dogs, gums are dark pink to red. If he's anemic, the shortfall in circulating red blood cells produces faded pink gums. Your vet will order blood tests to check his red blood cell count. If your buddy's red blood cell count is so low that his brain is being deprived of oxygen, he may experience fainting spells and appear disoriented. Panting and a pounding heartbeat may reflect his body's efforts to oxygenate his bloodstream. Most types of cancer don't show up in blood tests but canine leukemia does, says veterinary oncologist Robyn Elmslie of Veterinary Cancer Specialists in Denver. Detailed blood work plays an important role in diagnosing neoplastic anemia and evolving an appropriate course of treatment.
Fast-Moving Acute Lymphoid Leukemia
The acute form of lymphoid leukemia tends to come on more suddenly, progress more quickly and be more resistant to treatment than the chronic form. This cancer originates in the bone marrow or lymphatic system and from there, often spreads to other organ systems. The National Canine Cancer Foundation, describing the disease process, says that neoplastic white blood cells called lymphocytes crowd out production of other types of blood cells, including red blood cells and others that combat infections. Typically, this form of leukemia responds poorly to chemotherapy, notes the "The Merck Manual for Pet Health." Even when dogs do seem to come around, "remission times are usually short." The NCCF notes that German shepherds and males appear to be more susceptible to lymphoid leukemia than other breeds, with the average age of onset being 5.5 years.
Chronic Lymphoid Leukemia: Slower Progression
The chronic form of lymphoid leukemia tends to be more of a challenge for vets to diagnose because symptoms are often milder and evidence of the disease in blood work less conclusive. On the positive side, by the time dogs suffering from this disease are diagnosed, they've probably been living with it for some time, says the NCCF. Chances are good that they'll respond well to therapy. Even though it's not curable, it usually can be managed for quite a while, suggests Elmslie. In fact, with appropriate treatment, dog owners can expect "a median survival time of 2.5 years" for their pets -- with one caveat. Research suggests that early diagnosis and intervention, ideally even before the onset of anemia, significantly prolong survival times, she says.
Autoimmune Hemolytic Anemia: A Secondary Disease
Cancers that don't affect red blood cell production in dogs can sometimes trigger a condition that does -- autoimmune hemolytic anemia. Most of the time, autoimmune hemolytic anemia is primary, meaning it exists alone, but according to VCA Animal Hospitals, about a quarter of diagnosed cases are secondary to other illnesses, usually neoplasias. In addition to the usual signs of severe anemia, as autoimmune hemolytic anemia advances, the diseases cause the pigment bilirubin, a byproduct of decomposing red blood cells, to build up, turning a dog's urine dark and tinting his skin, gums and mucous membranes yellow. Breeds most susceptible to autoimmune hemolytic anemia include cocker spaniels, poodles, shih tzus, Lhasas, old English sheepdogs, border collies and springer spaniels, according to L. Ari Jutkowitz, associate professor at Michigan State University's College of Veterinary Medicine. In the August 2008 issue of "DVM 360" magazine, he Jutkowitz wrote that this "devastating" disease has a mortality rate ranging between 29 and 70 percent with spayed female dogs accounting for about 75 percent of cases seen at MSU over a four-year period.
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