If your dog appears anemic or your vet diagnosed your dog with anemia, you may be tempted to give your anemic dog an over-the-counter iron supplement. After all, the idea makes sense considering that iron supplements along with eating foods rich in iron are commonly part of the plan for treating anemia in humans. In dogs though anemia is quite different than in people, its not a diagnosis nor a disease and it tends to occur secondary to medical conditions that require to be treated in the first place rather than a dietary problem. Before buying that iron supplement, you may want to read on, so to better understand why its important to consult with your vet before trying anything at home.
Dogs are carnivores and their bodies are built differently than in humans. In dogs, anemia caused by a lack of iron in their diet is virtually unheard of considering that their diet contains plenty of iron, explains veterinarian Dr. Fiona.
In dogs instead, iron deficiencies occur mostly secondary to some other medical conditions. What this means is that dogs need to be evaluated for what is causing them to become anemic in the first place in order to be properly treated. So the big question dog owners should ask their veterinarian is: ” Dear doctor, so why is my dog anemic in the first place?”
Anemia is caused by low numbers of red blood cells, the cells that are responsible for carrying oxygen to all the dogs tissues and organs. With less red blood cells carrying oxygen, dogs start getting weak, lethargic, exercise intolerant, and their gums may become pale. Affected dogs will also have a high resting heart rate and increased breathing. So if dogs are likely not suffering from lack of iron in their diet, what could be causing them to become anemic in the first place?
In dogs, anemia may be caused by the dogs body either not making enough red blood cells or making enough quantities but losing them, or the dogs body may be actually destroying them (a catastrophic event called hemolysis). Lets see some brief samples of these happenings.
A possible cause for a dog not making enough red blood cells may occur because of underlying kidney disease. When dogs get older, their kidneys may no longer work as hard as they should. If the kidneys start slacking off in making sufficient amounts of erythropoietin, a special hormone that tells the dogs bone marrow to make enough red blood cells, there are chances that the dog may end up being anemic.
A common cause for a dog losing red blood cells instead is blood loss. When people think blood loss they think seeing their dogs bleeding from their noses or from an obvious wound, but blood loss can often occur silently and insidiously when it takes place internally. The number one place that dogs lose blood chronically is in their intestines, explains veterinarian Dr. Christian K. This can be due to ulcers, inflammation and cancer.
Another cause of internal blood loss is the presence of a hemangiosarcoma, a tumor which may grow on the dogs spleen or heart and that can cause internal bleeding into the dogs abdomen if it happens to rupture. Dog owners wont see any external bleeding, but affected dogs can become weak, wobbly, develop pale gums and an enlarged belly (ascitis).
Finally, destruction of red blood cells may occur as a result of an autoimmune disease where the dogs red blood cells are mistakenly perceived by the immune system as foreign invaders and are consequently destroyed. As one can imagine, this is a very problematic condition.
As seen, the causes for a dog to become anemic can be quite serious and even life threatening! You therefore dont want to delay seeing your vet to identify the underlying cause of your dogs anemia so to initiate proper treatment.
For instance, if the dogs body is not producing red blood cells as it should, there are no supplements that can help the body build those levels back up, other than a transfusion, and if the body is bleeding internally, then the source of bleeding must be found and stopped, explains veterinarian Dr. Bob.
Its therefore important once again finding the reason why a dog is not producing enough red blood cells and/or the source of blood loss so that it can be corrected. However, just because dogs develop anemia secondary to underlying causes and not because of diet, doesnt mean that they do not suffer from iron deficiencies.
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Iron deficiency anemia happens in dogs and the most common cause is chronic blood loss, explain Dr. Heather L. Kvitko-White and Dr. Audrey K. Cook in an article for DVM360.
Once a vet determines the underlying cause of anemia and successfully addresses it, he or she may prescribe an iron supplement such as ferrous sulfate or Pet Tinic/Pet-Tabs Iron-Plus if there is a true iron deficiency. Its important to consult with the vet before giving any over-the-counter iron supplements because overdose can be fatal and dog owners may inadvertently purchase the wrong type. Its important to note that iron is toxic to cells when given in excessive amounts!
The best approach is to therefore to get a supplement through your vet considering that not all types of iron made for humans are absorbed well from dogs. Iron supplements wont treat the anemia, but can help provide affected dogs with all the essentials that their body needs to make more red blood cells, explains veterinarian Dr. Joey.Alternatively, the vet may provide the dog with iron dextran injection, but this can be painful as it must be injected in the muscle.
Generally, it takes several weeks of treatment for supplementation to replenish the normal number of red blood cells and treatment should be continued until their numbers return within normal ranges.
As seen, in dogs iron deficiencies from diets are virtually unheard of. In the 12 years, working as a vet, Dr. Christian K remarks that he has never seen a diet that causes iron deficiency in dogs, and would never expect to see that. So as long as a dog is on a nutritionally balanced, age-appropriate diet, iron deficiency from diet is close to impossible; however, the only exceptions to the rule are puppies and dogs fed certain fad diets.
Newborn puppies primarily rely on milk when they are young and milk contains very little iron. This is the reason why young puppies who are nursing are particularly vulnerable to parasites like severe flea infestations or hookworms, and can quickly develop an iron deficiency. On top of puppies, dogs fed unconventional diets such as an unbalanced homemade diet or vegan or vegetarian diets risk suffering from an iron deficiency, which is one reason why many veterinary nutritionists frown upon these unconventional diets.
So if a dog is suffering from an iron deficiency and should only be given supplements under the guidance of a vet, can adding any iron-rich foods help? Again, as with iron supplements, the best treatment is having what is causing the dog to lose or destroy his red blood properly addressed. Once the issue is addressed, the dogs body should catch up.
Among foods, since many dogs are losing their appetite, its important to try to feed foods that may entice them to eat. Veterinarians carry several foods and supplements meant to help provide nourishment during illness. And what about feeding cooked liver? It might not really help in certain types of anemia, other than perhaps anemia caused by a nutritional deficiency, which as seen, is very unlikely unless the dog is eating an imbalanced diet. In that case, feeding liver may be an option, but its always worthy asking the vet first!
For a dog with anemia, feeding boiled or baked liver in addition to the regular diet can help, but no more than one or two ounces daily. Its important to note in this case that liver is not a treatment; however, its a source of iron and protein that can help the dogs body build new red blood cells, explains veterinarian Dr. Bob.
The Bottom Line
As seen, anemia is dogs is not a diagnosis nor is it a disease. Anemia in dogs occurs secondary to other medical conditions. Because anemia in dogs is unlikely to be caused by a nutritional deficiency, iron supplements and dietary changes are unlikely to help treat any conditions on their own. It is risky to try to do so, also because the wrong dosage and the wrong type of iron supplement can harm the dog.
Most cases of anemia in dogs are serious and must be treated based on the underlying cause, and that may include blood transfusions, antibiotics, steroids, medications to stimulates the bone marrow and diets for lack or appetite or underlying kidney disease.
Only once the underlying cause is addressed, the vet may decide whether it may be helpful adding an iron supplement or iron-rich foods to the dogs diet. So the bottom line is: dont waste time trying supplements or iron-rich foods until you see the vet and find the underlying cause. Only then, ask your vet whether iron supplements can benefit your dog.
At Angell Animal Medical Center, the majority of cases of iron deficiency anemia are due to chronic hemorrhage from gastrointestinal tumors. Diagnosis of uncomplicated and chronic iron deficiency is based on classic hematologic and biochemical abnormalities such as changes in erythrocyte indices (microcytic, hypochromic anemia) and decreased serum ferritin concentration (table 2). Detection of early iron deficiency, before the appearance of those abnormalities, or iron deficiency in the presence of other diseases (e.g., neoplasia and inflammation) is a diagnostic challenge.4,5 In uncomplicated iron deficiency, the serum iron concentration and ferritin are typically low and the TIBC (total iron binding capacity) is usually high. Because iron is preferentially shunted to hemoglobin (Hb) formation, typical hematologic changes do not occur until late in iron deficiency, long after detrimental effects have occurred. Also, serum ferritin is an acute phase reactant and concentrations may be increased with certain neoplastic and inflammatory diseases, which may make diagnosis of concurrent iron deficiency challenging. Although the immunologic assay for canine serum ferritin has been available for over a decade, its value in detecting iron deficiency anemia (IDA) in chronically ill dogs is not reported. Many clinicians consider the evaluation of bone marrow aspirates or biopsies for the presence or absence of stainable iron as a sensitive and reliable test for iron status assessment in dogs. However, some hematologists consider this invasive procedure to be subjective and imprecise. Thus, the true prevalence of iron deficiency may be unknown, and dogs with early iron deficiency masked by concurrent disease may remain undiagnosed and untreated. Accurate diagnosis of early or complicated iron deficiency is made more difficult by the highly variable results obtained for biochemical markers of iron in serum; including serum iron (Fe) concentration, TIBC, and percent saturation of transferrin. Serum Fe concentration is affected by several factors such as time of day, corticosteroid administration, and consumption of meat.4 Reticulocyte indices may be helpful in evaluating for possible causes of anemia. Fry et al demonstrated that reticulocyte indices differed by greater than 3-fold between healthy dogs and dogs with IDA.5 Steinberg et al demonstrated that low mean Hb content of reticulocytes and low reticulocyte MCV are associated with hematologic and serum biochemical abnormalities indicative of iron deficiency.4 Both these indices hold promise as non invasive, cost effective measures of iron status assessment in dogs.4 Further determination of normal reference ranges for reticulocyte indices and comparison between those indices and other causes of regenerative anemias are indicated before it is available for clinical use. Small intestinal malabsorption can also promote IDA. Iron deficiency anemia secondary to inflammatory bowel disease (IBD) has been reported in dogs; therefore, determination of serum iron, ferritin, and TIBC may be worthwhile in anemic dogs with IBD.6 In one study, serum iron concentrations in 3 of 6 dogs and 3 of 7 cats with chronic renal failure (CRF) were below the reference interval (transferrin saturation less than 20%).7 Whether this is related primarily to inadequate intake and absorption of iron or increased losses of iron due to GI blood loss is unclear.7 It is important to distinguish anemia secondary to iron deficiency from anemia of inflammation since only iron deficiency should be supplemented with iron. When erythropoietin (EPO) therapy is used in CRF patients, the demand for iron during stimulated erythropoiesis is high; therefore, iron supplementation is recommended for patients receiving EPO.8
The first line of therapy for iron deficiency anemia is parenteral iron administration. Iron preparations administered intravenously may cause anaphylactic reactions, thus the intramuscularly (IM) route is preferred.13 A small dose should be injected IM to test for hypersensitivity reactions. A maximal dose of 2 mls can be administered daily.14 Large doses of injectable iron may discolor the serum brown which can cause falsely elevated serum bilirubin values and falsely decrease serum calcium values.13 Iron deficiency in dogs is addressed first by administering iron dextran once at 10-20 mg/kg IM and then continuing therapy with oral iron. In cats the dose for prevention of transient iron deficiency anemia in kittens is 50 mg of iron dextran IM at 18 days of age. The dose for adjunctive therapy with EPO treatment is 50 mg of iron dextran IM every 3 to 4 weeks or daily oral supplementation. Oral iron therapy usually follows injectable iron (the first line therapy for patients with IDA) (table 4). Oral iron absorption varies widely based on the type of diet and other factors. Sustained release iron formulations are not recommended as initial therapy because they reduce the amount of iron that is presented for the absorption by the duodenal villi.1 Gastrointestinal absorption of elemental iron is enhanced in the presence of an acidic gastric environment. This can be accomplished through concurrent intake of ascorbic acid (Vitamin C).1, 13 Most common side effects of oral iron supplementation are gastrointestinal upset (mostly vomiting) and constipation. Division of the daily dose may reduce gastrointestinal upset. Although iron absorption occurs more readily when taken on an empty stomach, this increases the likelihood of stomach upset.1 Oral iron may result in black discoloration of feces and cause false positive reactions with the guaiac occult blood test.13 A common product used for iron supplementation is Pet-Tinic (Pfizer Animal Health). It contains 12.5 mg of iron per tablespoon. For adequate iron supplementation at time of iron deficiency, a cat will need to ingest 4 – 8 tablespoons of the liquid per day. Many cats will not tolerate oral supplementation, thus injections of iron dextran may be required in some cases.13
Transfusion of red blood cells (whole blood or packed red blood cells) should be considered for patients with IDA clinical for anemia.1 The patient hematocrit should be raised to 15-20%. The goal of calculating the transfusion volume is avoid reaching a higher hematocrit that will dampen the bone marrow erythrocyte production (table 3).12
Chronic blood loss from bleeding gastrointestinal tumors and intestinal parasitism are the most common causes of iron deficiency. Early recognition and treatment of iron deficiency can prevent life threatening anemia. IDA must be differentiated from anemia of chronic disease so that appropriate treatment can be initiated.
Diagnostic approach to iron deficiency anemia
The diagnostic approach to iron deficiency anemia includes identifying the underlying disease or trigger with a thorough history, physical examination, and diagnostic evaluation ( ). The history should include a thorough review of medications, diet, concurrent medical conditions, fecal characteristics, flea and tick exposure, and careful questioning of the owner for possible sources of blood loss.
Minimum diagnostics, such as fecal examination for color and endoparasites, microscopic blood smear evaluation, packed cell volume, and total protein may be sufficient in juvenile anemic animals with suspected ectoparasite and/or endoparasite infestation. However, in many cases, further diagnostic evaluation is necessary, including complete blood (cell) count (CBC) with reticulocyte count, fecal occult blood test, serum iron parameters, coagulation parameters, biochemical profile (including albumin, globulins, and hepatic and renal parameters), urinalysis and abdominal imaging. Animals with chronic blood loss frequently have a marked reactive thrombocytosis which may exceed 1 × 106/μL; the mechanism causing the thrombocytosis is still undetermined (5,9). Furthermore, decreased neutrophil production due to iron deficiency may lead to neutropenia; the mechanism for this is also unknown (21).
If melena or hematochezia is not evident and no blood loss can be identified, fecal occult blood tests should be performed. Various commercial tests are available to detect occult blood in feces that may not be visible on visual inspection. However false positive results are possible with oral iron supplementation, meat diets, and much less likely with commercial animal diets due to the presence of dietary myoglobin, hemoglobin, or plant peroxidases (22,23). Withdrawal of iron supplementation and meat-based diet for 3 d may be required to accurately interpret results. Fecal occult blood test may also be negative if gastrointestinal hemorrhage occurs intermittently. Thus, repeated testing and color assessment by the owner are indicated in cases with elusive iron deficiency anemia. In some cases, the serum total protein values are also low due to the concomittent loss of plasma.
Iron status is further investigated by measuring serum iron parameters. Typically serum iron concentration is very low in animals with iron deficiency anemia. However, mildly low to low normal serum iron values can also be observed with anemia of inflammatory disease ( ) (2,12). Serum iron can be transiently elevated by intravascular red blood cell lysis, recent blood transfusion, and iron supplementation, which can complicate interpretation of laboratory data. Exogenously administered corticosteroids have also been shown to increase serum iron levels by an undetermined mechanism (24). The total iron binding capacity (TIBC) is a measure of the plasma’s ability to carry iron and represents the maximum concentration of iron that can be bound by plasma transferrin. This test is often performed as part of an iron panel, but is of limited clinical value in small animals, as it does not assess serum or tissue iron levels and does not change dramatically in disease. Iron saturation (IS) reflects the amount of iron bound to transferrin and is low (< 20%) in cases of iron deficiency anemia. Finally, the unsaturated iron binding capacity (UIBC) measures transferrin’s open iron binding sites and is elevated in iron deficiency anemia (24).
|Iron deficiency anemia||Anemia of inflammatory disease|
|Hematocrit||↓ to ↓ ↓ ↓||↓ to ↓ ↓|
|MCV||↓ to ↓ ↓ ↓||Normal to ↓|
|Serum iron||↓ to ↓ ↓ ↓||Normal to ↓ ↓|
|Serum TIBC||Normal to ↑||Normal to ↓|
|Serum ferritin||↓ to ↓ ↓||Normal to ↑ ↑|
|Stainable iron in marrow||Absent||Normal to ↑|
|Reticulocytes||Normal to ↓||↓|
Ferritin can be detected in serum and correlates well with body iron stores. However, the assay for ferritin is species- specific and therefore not widely available (26). Ferritin is decreased with iron deficiency anemia and is increased with elevated total body stores of iron (2,12). Ferritin is also an acute phase protein, and hyperferritinemia can occur with underlying disease, such as inflammatory disease, neoplasia, liver disease, or hemolytic disease (2,12). Nevertheless, low serum ferritin concentrations can be helpful in differentiating iron deficiency anemia from anemia of inflammatory disease ( ) (2).
Body iron stores can be qualitatively assessed by staining aspirates, impression smears, or biopsy sections of liver, spleen or bone marrow (or both) with Prussian blue stain. Iron concentration can be quantified in biopsied tissues such as liver and spleen (27). These methods are invasive and usually not performed in cases of known iron deficiency anemia. If iron is visualized in these samples, iron deficiency can be ruled out. It should, however, be noted that healthy, non-anemic cats with adequate iron homeostasis normally lack stainable iron in their bone marrow (2).
Diagnostic imaging may be warranted to further investigate iron deficiency anemia. Abdominal ultrasonography is recommended to visualize abdominal organs and to assess the gastrointestinal tract for evidence of ulceration, wall thickening, or masses. Examples of typical gastrointestinal tumors that can cause ulceration and chronic blood loss include leiomyoma, leiomyosarcoma, carcinoma, and round cell tumors. If primary gastrointestinal disease is suspected, and no abnormalities are noted with abdominal imaging, gastroduodenal or colonic endoscopy (or both), or exploratory laparotomy may be indicated to assess for ulceration and to obtain biopsies (3).
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