Platelets, and RBC Blood Parasites

Platelets Non nucleated, disk shaped elements released into blood system by cells in bone marrow. Smaller than RBCs, large thromobocytes may indicate disease Platelets are important in hemostasis (blood clotting)

RBC Blood Parasites Drying artifacts Dirofilaria immitis Refractile Dirofilaria immitis Mycoplasma haemofelis – feline Hemobartonellosis or feline infectious anemia Small, coccoid, rod-shaped or ringlike, and dark Periphery of RBCs Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

Mycoplasma hemofelis (formerly Haemobartonella felis) is an epicellular bacterial parasite of feline red cells that can cause hemolytic anemia. In blood smears stained with polychrome stains, the organisms are recognized as small blue cocci, rings, or rods on the edges or across the faces of red cells. Stain precipitate is often mistaken for organisms, resulting in unnecessary tetracycline administration.

Mycoplasma hemofelis cont: The hemolytic anemia caused by M. haemofelis is called feline infectious anemia (FIA) and is usually regenerative in nature (unless underlying disease suppresses the regenerative response, e.g. Feline Leukemia Virus infection). Therefore, a non-regenerative anemia in a cat with H. felis should not be attributed only to M. haemofelis infection and the cat should be further evaluated for another disease process

Parasites (cont.) Cytauxzoon Feline Definitive microscopic diagnosis of C. felis infection relies on identification of piroplasms in circulating erythrocytes on blood smear; identification of large schizonts in splenic, lymph node, or bone marrow aspirates; or identification of large schizonts on impression smears from these organs or from the lung at necropsy. Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

Babesia canis B. canis is endemic in southern Florida, sporadic elsewhere, especially in the southern states; Large, pleomorphic organisms in RBC are typical; classic paired pyriform bodies (below) are rare in this species. B. gibsoni is rarely seen in the USA and is found in dogs from Asian enzootic areas; small, singular annular bodies in RBC are typical

Babesia canis Pups, young dogs are more susceptible than adults, especially kennels Major strain differences in pathogenicity Rhipicephalus sanguineus transmits transovarially, transstadially Incubation period 10 days-3 weeks; transmission possible by ticks, transplacentally or by transfusion Often concurrent with Ehrlichia canis A three week old puppy presented with anemia, icterus after several littermates died in a greyhound kennel Signs and pathogenesis are referable to regenerative hemolytic anemia. In clinical cases, aggregates of parasitized RBC-fibrin  sludging of capillary beds  tissue anoxia, vascular damage, especially brain, heart, kidneys, intestines acidosis, DIC  shock and death

Diagnosis of Babesia Spleen, liver impression smears of a littermate that had died. RBC with organisms become ‘sticky’ and are taken out of circulation. Note multiple parasites in some RBC’s. Organisms were found in <1% RBC at ‘feathered tip’ of thin smears of capillary blood. Giemsa stain is best Coomb’s test is + Serology: IFA of > 1:40 is diagnostic of current or previous clinical disease

Heartworm Disease Heartworm disease or dirofilariasis is a serious and potentially fatal disease. It is caused by a blood-borne parasite known as Dirofilaria immitis. Adult heartworms are found in the heart and adjacent large blood vessels of infected dogs. Rarely, worms may be found in other parts of the circulatory system. The female worm is 6 - 14" long (15 - 36cm) and 1/8" wide (5mm). The male is about half the size of the female. One dog may have as many as 300 worms present when diagnosed.

Heartworm Disease Lifecycle

Transmission Since transmission requires the mosquito as an intermediate host, the disease is not spread directly from dog to dog. Spread of the disease therefore coincides with mosquito season, which can last year-round in many parts of the United States. The number of dogs infected and the length of the mosquito season are directly correlated with the incidence of heartworm disease in any given area. The mosquito usually bites the dog where the hair coat is thinnest. However, having long hair certainly does not prevent a dog from getting heartworms.

Heartworm Disease in Cats Heartworm disease in the cat may involve some or all of the following: Pulmonary arterial, bronchial, and alveolar disease—Heartworm Associated Respiratory Disease (HARD)—is associated with the death of developing juvenile worms. Cats may present with cough, dyspnea, and/or wheezing. Death of adult heartworms (if present) can potentiate HARD signs. Sudden death occurs in approximately 10 to 20% of diagnosed cases. Pathogenesis is unclear, but a condition (similar to acute respiratory distress syndrome [ARDS]) caused by the release of antigenic moieties from injured or dying adult worms is suspected. Vomiting unrelated to eating may be present. Pulmonary thromboemboli (fragments from dead adult worms) may cause acute vascular and interstitial inflammatory events that lead to dyspnea and death. Hematological abnormalities may include anemia, hyperglobulinemia, basophilia, and eosinophilia. Neurological signs may indicate aberrant migration of the worm to the brain, eye, or spinal cord.

Lifecycle in Cats

Summary Quantifying morphologic changes Morphologic abnormalities RBCs Inclusions Parasites Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.