Anemia and Pyometra in Dogs

Medical Literature

ANEMIA• Definition

– Anemia is defined as an absolute decrease in the red cell mass as measured by RBC count, hemoglobin concentration, and/or PCV.

• Classifications– Regenerative anemia- the bone marrow responds appropriately

to the decreased number of red blood cells by increasing production of new blood cells.

– Nonregenerative anemia- the bone marrow responds inadequately to the increased need for red blood cells. Anemias due to bleeding or the destruction of existing red blood cells are usually regenerative.

• Clinical signs– Clinical signs in anemic animals depend on the degree

of anemia, the duration (acute or chronic), and the underlying cause.

• Acute anemia can result in shock and even death if more than a third of the blood volume is lost rapidly and not replaced.

In acute blood loss, the animal usually presents with:– tachycardia– pale mucous membranes– bounding or weak peripheral pulses– hypotension

• The cause of the blood loss may be overt, eg, trauma. If no evidence of external bleeding is found, a source of internal or occult blood loss must be sought, eg, a ruptured splenic tumor, other neoplasia, coagulopathy, GI ulceration, or parasites. If hemolysis is present, the animal may be icteric.

• Animals with chronic anemia have had time to accommodate, and their clinical presentation is usually more indolent with vague signs:– Lethargy– Weakness– Anorexia

• These animals may have similar physical examination findings such as pale mucous membranes and weak peripheral pulses. The lack of expected clinical signs may alert the clinician to the time frame involved. Splenomegaly, abdominal distention, and/or heart murmur may be present, depending on the underlying cause of anemia.

• Diagnosis– A complete history is an important part of the

evaluation of an anemic animal. Questions might include duration of clinical signs, history of exposure to toxins (eg, rodenticides, heavy metals, toxic plants), drug treatments, vaccinations, travel history, and any prior illnesses.

– A CBC, including a platelet and a reticulocyte count, will provide information on the severity of anemia and degree of bone marrow response, and also allow for evaluation of other cell lines. A blood smear should be evaluated for abnormalities in RBC morphology or size and for RBC parasites.

Types of Anemia• Hemolytic Anemia

– Hemolytic anemias occur when red blood cells are destroyed. They are usually regenerative. Toxins, red blood cell trauma, infections, immune system defects, and red blood cell membrane defects can all cause hemolytic anemias.

• Immune-mediated Hemolytic Anemia– In dogs, the most common cause of hemolytic anemia is

immune mediated. This type of anemia can occur on its own or as a result of tumors, infection, drugs, or vaccinations. The body no longer recognizes red blood cells as self and develops antibodies to circulating red blood cells, leading to their destruction. Dogs with immune-mediated hemolytic anemia are usually jaundiced, sometimes have a fever, and may have an enlarged spleen. They can show mild, slow--developing signs and not appear to be in any pain, or they can suddenly be in severe crisis.

• Nonregenerative Anemias– Nonregenerative anemias can be caused by nutritional deficiencies,

chronic disease, kidney disease, or bone marrow diseases.• Aplastic anemia

– Anemia in which the ability of bone marrow to generate all blood cells is reduced has been reported in dogs. Most cases have no known cause, but some are caused by infections, drug therapy, toxins, or total body irradiation.

• Myelodysplasia (also called myelodysplastic syndrome) – is a bone marrow disorder in which growth and maturation of blood-

forming cells in the bone marrow is defective. This leads to nonregenerative anemia or shortages of white blood cells or platelets. It is considered a preleukemic syndrome (occurring before leukemia fully develops). Myelodysplasia occurs in dogs, cats, and humans.

• Myelofibrosis – is a progressive disease leading to anemia and enlargement of the spleen

and liver. It brings on bone marrow failure after it causes normal marrow elements to be replaced with fibrous tissue. It can be the initial disease or occur as a result of cancer, immune-mediated hemolytic anemia

Treatment• Transfusion with packed RBCs is usually required. The

goal of therapy is to stop the destruction of RBCs by treating with immunosuppressive drugs; supportive care is also a priority. Prednisone or prednisolone at a dosage of 1–2 mg/kg, bid, is considered first-line therapy, with azathioprine at 2 mg/kg/day (azathioprine is contraindicated in cats and may be replaced by chlorambucil) or cyclosporine at 5–10 mg/kg/day considered as a possible second agent. In one study, low-dose aspirin at 0.5 mg/kg/day improved survival times in dogs treated with azathioprine and prednisone.

PYOMETRA• Definition– Pyometra is a hormonally mediated diestrual disorder

characterized by cystic endometrial hyperplasia with secondary bacterial infection. Pyometra is reported primarily in older bitches (>5 yr old), 4–6 wk after estrus.

• EtiologyPyometra is a hormonally mediated diestrual disorder characterized by cystic endometrial hyperplasia with secondary bacterial infection. Pyometra is reported primarily in older bitches (>5 yr old), 4–6 wk after estrus.

• Etiology– Factors associated with occurrence of pyometra include administration of

longlasting progestational compounds to delay or suppress estrus, administration of estrogens to mismated bitches, and postinsemination or postcopulation infections. Progesterone promotes endometrial growth and glandular secretion while decreasing myometrial activity. Cystic endometrial hyperplasia and accumulation of uterine secretions ultimately develop and provide an excellent environment for bacterial growth. Progesterone may also inhibit the WBC response to bacterial infection. Bacteria from the normal vaginal flora or subclinical urinary tract infections are the most likely sources of uterine contamination .Escherichia coli is the most common bacterium isolated in cases of pyometra, although Staphylococcus,Streptococcus, Pseudomonas, Proteus spp, and other bacteria also have been recovered. By itself, estrogen does not contribute to the development of cystic endometrial hyperplasia or pyometra. However, it does increase the stimulatory effects of progesterone on the uterus. Administration of exogenous estrogens to prevent pregnancy (ie, “mismate shots”) during diestrus greatly increases the risk of developing pyometra and should be discouraged.

Clinical Findings• Clinical signs are seen during diestrus (usually 4–8 wk after estrus) or

after administration of exogenous progestins. The signs are variable and include:– Lethargy– Anorexia– Polyuria– Polydipsia– Vomiting.

• When the cervix is open, a purulent vulvar discharge, often containing blood, is present. When the cervix is closed, there is no discharge and the large uterus may cause abdominal distention. Signs can progress rapidly to shock and death.

• Physical examination reveals lethargy, dehydration, uterine enlargement, and if the cervix is patent, a sanguineous to mucopurulent vaginal discharge. Only 20% of affected animals have a fever. Shock may be present.

• Diagnosis– Pyometra should be suspected in any ill, diestrual bitch or queen, especially if

polydipsia, polyuria, or vomiting is present. The diagnosis can be established from the history, physical examination, abdominal radiography, and ultrasonography. Vaginal cytology often helps determine the nature of the vulvar discharge. A CBC, biochemical profile, and urinalysis help exclude other causes of polydipsia, polyuria, and vomiting; they also evaluate renal function, acid-base status, and septicemia. The uterine exudate should be cultured and sensitivity tests performed. Differential diagnoses include pregnancy and other causes of vulvar discharge, polyuria and polydipsia, and vomiting.

• Treatment– Ovariohysterectomy is the treatment of choice for pyometra. Medical

management could be considered if preserving the reproductive potential of the bitch or queen is desired. Fluids (IV) and broad-spectrum, bactericidal antibiotics should be administered. Fluid, electrolyte, and acid-base imbalances should be corrected as quickly as possible, before ovariohysterectomy is performed. The bacterial infection is responsible for the illness and will not resolve until the uterine exudate is removed. Oral antibiotics (based on the results of the culture and sensitivity) should be continued for 7–10 days after surgery.

Actual Case

Medical History

•The animal is diagnosed with Pyometra prior to the anemia and is scheduled for operation but the client was not able to pursue with the operation.

Clinical signs • The animal refuses food and water intake for 2 days

prior hospital visit. • The animal is lethargic and unilateral epistaxis is

present.• Temperature upon arrival to the hospital is below

reference index.• The animal cannot stand firmly there is weakness of the

hindlegs • The mucuous membrane is severely pale and the

dehydration is prominent since the nose of the animal is already flaking.

Diagnosis• Blood sample was obtained from the patient

for CBC, the Attending Vet suggested blood chemistry but the client refused.

CBC results

Treatment

Control/ Prophylaxis• The animal is subjected for confinement

because critical care is required since the animal’s CBC count results are not good and since the animal’s anemic stage is severe replacement doses of fluid should be administered.