Anemia is familiar term to most of us, but one we hope we won't have to become too familiar with. Anemia is a lack of red blood cells, and there are all sorts of anemias and myriads of causes. But the truth remains: the result is always the same. There are particular kinds of anemia that are not uncommon for our dogs and cats. Hemolytic (hemo—blood, lytic—break) anemias are destructive in nature. When your pet has a hemolytic anemia, its red blood cells are being destroyed. Two common types of hemolytic anemia are immune-mediated and non-immune-mediated. This article will focus on the immune-mediated hemolytic anemia type.
Anemia can be caused by a lack of production of red blood cells, usually involving the bone marrow. Accelerated destruction of red blood cells could dwindle their numbers, too. So that is essentially it: You lose them physically, don't make them, or they get destroyed. Either way, your pet is anemic.
In hemolytic anemia, the cells are ‘killed’ by some sort of disease process or by your own body. Immune-mediated hemolytic anemia, or IMHA, is extremely complex and scientifically and physiologically nuanced to the point that it boggles your mind. Doing homework for this month's discussion revealed that some really smart people are working really hard to get to the bottom of the causes of IMHA, and that those causes are many.
For us regular folk, the body sees its own red blood cells as foreign and destroys them. That is the immune-mediated part. That our dog or cat's own self would take such a drastic and harmful step is difficult to understand. Why would your own body take an active roll in wrecking itself? Your body has spent its entire life trying to return to a steady state of normal, or homeostasis, even in the face of all the bad things we torture it with. In IMHA, this is reversed and the consequences can be devastating and even deadly. Face it, ‘Fido’ isn't going far without any blood.
There are two kinds of IMHA: primary and secondary. Differentiating between the two is crucial, so that treatment is directed and targeted for the best response possible. As with all else, killing the head of the dragon takes care of the rest. But here comes the zinger: Upwards of 70 percent of primary IMHA cases are spontaneous events without an underlying etiology. Idiopathic is the medical term for, We don't know what the heck caused it. Idiopathic autoimmune anemia is the most common form. Well, how do we find the head of an idiopathic dragon? Carefully, and with much education and cooperation, as the history, diagnosis, supportive and targeted treatment will take teamwork between hospital and home.
Secondary IMHA is just as daunting, but the dragon's head is usually easier to find. Secondary immune-mediated anemia results from some other cause. Let's say your cat has a parasite haunting its red blood cells, causing destruction and its own form of anemia. That can trigger the immune system to take over and create a worse anemia. It is like the body has an over-reaction to a healing process and goes hog-wild in the wrong direction. If the immune system jumps in with an over-the-top take-over, it is referred to as immune-mediated. Cancers can sometime result in immune-mediated anemia. Sometimes, an infection is the primary problem, or a toxic reaction to a drug, which then winds up causing the secondary anemia.
The specifics are incredibly detailed as to why and how the destruction of red blood cells occurs. There are things lining cells and DNA issues, along with how certain enzymes react with other components like antigens, that define how the red blood cell will meet its demise. But suffice it to say, the body has a hypersensitive reaction, which produces anti red blood cell antibodies. These glom onto your dog or cat's red cells and commence the destruction. The more destruction, the less blood; the more anemic and oxygen-less your pet gets.
Skipping the academics, the symptoms are as such: pale gums, pale whites of the eyes (sclera), pale conjunctiva, weakness, lethargy, labored breathing and exercise intolerance—all of which can be chronic/intermittent, or acute in onset. More severe signs can involve the heart working harder to ship out the remaining oxygen-movers in a desperate attempt to keep all the organs properly fueled.
Diagnosing IMHA can become involved since test results can be falsely negative in many cases. Multiple tests must be run to hash out the most details so that the story can be fully told.
Breed predilections can aid in diagnosis of other forms of non-immune mediated hemolytic anemia, as well. The breed predispositions most often involve the lack of certain enzymes and seem to be inherited, thus affecting some younger dogs and cats. Cocker spaniels and springer spaniels are affected with one type of inherited enzyme deficiency and West Highland white terriers, cairn terriers, and basenjis are the victims of another type. Cats are not immune either, with Somalis and Abyssinians overrepresented. IMHA can pick any breed, though—even mixes—but Irish setters, Old English sheepdogs, and the poor Cocker seem to get this form more than others.
The goal of treatment is to quell the immune system and bring it back in line with a normally functioning one, and it can range from simple to incredibly complex, depending on severity of the disease and concurrent damage/diseases. Your pet's vet will keep you abreast of what it will take to fix your loved one. Many of these cases have favorable outcomes—just keep the teamwork up and work together to affect a cure.