Hematology & Parasitology: A Veterinary Lab Guide

Published on May 2, 2019 by

Veterinary technicians work closely with veterinarians to ensure pets get the best care possible. Two of the most important branches of medicine, hematology and parasitology, are common studies with veterinary technicians who must be knowledgeable about both. These branches of medicine are taught during a medical assistant program offered at many vocational schools.


Hematology is the study of blood, blood disorders, treatment, and prevention of diseases such as: leukemia, anemia, myeloma, and lymphoma. Blood disorders include platelet disorders, vascular disorders, and clotting platelet disorders.


Leukemia refers to several different kinds of cancers in bone marrow. Both dogs and cats can develop blood cell cancers. White blood cells are highly concentrated in bone marrow and they can progress into lymphoid or myeloid cells. Leukemia can be either acute or chronic.

Leukocytes that reproduce too quickly causes acute leukemia. A dog’s red and white blood cell count is too low and cannot fight the disease. It is more commonly found in dogs that are 5-6 years old. Symptoms of this disease can include lethargy, loss of appetite, red or purple spots on the skin, and swollen lymph nodes.

Feline Leukemia

Only cats can contract feline leukemia. It is a virus that impairs their immune system and can cause cancer. It is completely preventable and is caused from cats interacting with other contagious cats. Symptoms are similar to that found in dogs, such as lethargic and loss of appetite. Other symptoms include weight loss, diarrhea, ear infections, fever, weak, and wobbly on their feet.

Diagnosing Leukemia

The most common way to diagnose leukemia is from a blood test. Veterinary technicians perform these blood tests in Wellness exams and if a pet owner suspects they have an ill animal. Veterinary technicians also analyze these blood tests by red blood count and hemoglobin concentration. If the red blood cell count is high, the animal may be diagnosed with polycythemia. A low blood cell count may indicate anemia or bleeding.

In testing white blood cells, veterinary technicians are aware of these five types: neutrophils, basophils, eosinophils, monocytes, and lymphocytes. The most common white blood cell is the neutrophil. These blood cells consume bacteria and will increase if there is an infection, inflammation, or stress. Another white blood cell is the eosinophil, which counts go up if there is an allergy, certain kinds of tumors, and parasites. If the basophils count is high, it’s a sign of inflammation. Monocytes increase in number if there is a sign of a chronic disease, and a high count of lymphocytes may indicate leukemia.


Low red blood count can cause anemia if pets. In taking an animal’s blood, veterinary technicians are able to diagnose this condition. Lab work is needed to identify anemia by performing a packed cell volume (PCV) test. Veterinary technicians then help to determine the cause. Some of the causes of anemia are from a severe injury, an immune-mediated disease, infectious disease, flea infestations poison, certain medications, and chronic diseases (such as kidney disease or certain cancers).

Signs or symptoms of anemia are:


Myeloma is bone marrow cancer derived from a clonal population of plasma cells that are cancerous. It’s an uncommon type of cancer but occurs more in purebred dogs, such as the German shepherd.

Signs or symptoms of myeloma are:


Lymphoma cancer stems from lymphocytes. Most lymphoma cancers are found in spleens, lymph nodes, and bone marrow. While there are over 30 kinds, the four most common are: multicentric, alimentary, mediastinal, and extranodal.

Multicentric is the most common and usually affects the lymph nodes. Symptoms of multicentric are swollen lymph nodes, fever, lethargy, and weakness. They may also be prone to dehydration.

Alimentary is the next most common and affects the intestines. Symptoms of alimentary are diarrhea, weight loss, and vomiting.

Mediastinal is rare and affects the thymus and/or the mediastinal lymph nodes become enlarged in the animal’s chest. Symptoms of mediastinal are difficulty with breathing, swelling in front legs or face, and increased thirst and urination.

Extranodal is a type of cancer that targets a certain organ, with the most common being the skin. Symptoms of extranodal include raised nodules or scaly lesions on the skin. However, if it affects the lungs, then the animal’s respiratory system becomes distressed. If it’s in the nervous system, then the animal may have seizures.

In diagnosing Lymphoma, veterinary technicians take samples of the affected organ by using a fine-needle aspirator. After taking samples, they evaluate the tissue or by a cytology exam. Their studies on hematology are very important in understanding these diseases.


Parasitology is the science dealing with animal parasites or the interactions of a host and the parasites found on or in the host. Veterinary parasitology takes into consideration all aspects of parasites, including the biochemistry, physiology, and morphology. It also includes treating and controlling any diseases or infections caused by parasites and their effect on domestic animals and humans. There are three major groups of parasites: protozoa, helminths, and arthropods.


A protozoa is a single-celled organisms with a nucleus and a nuclear membrane. Veterinarians and veterinary technicians make calculated assumptions that an animal has a protozoal parasite and will prescribe a medication to treat it. This is actually called diagnostic therapeutics because the diagnosis isn’t easy. They tend to be more prevalent in puppies and kittens. Coccidia and Giardia are the most common intestinal parasites.


These parasites infect the cells of the small intestines. Although there are numerous types that infect both dogs and cats, Isospora is the most common. Coccidia will spread from an animal eating an infected fecal material, such as a rodent or an infected host. These infections are usually harmless and are eliminated through natural body defense. If treatment is necessary, the veterinary technician may treat the animal with sulfa drugs and make sure its surroundings are clean and well kept.


These are also one cell-organisms that are pear-shaped and infect the small intestines of cats and dogs. Common symptoms of Giardia include watery diarrhea, dehydration, and weight loss. Adult animals may have the parasite but show no outward sign. It’s most often found in beavers and is thought they are the primary reservoir for the infection. Domestic animals usually come down with giardia by drinking contaminated stream or pond water. Veterinary technicians may treat giardia with a drug called metronidazole. Prevention of giardia occurs by keeping the home sanitized and insuring your pet has clean water.


Helminths, or worms are often prescribed with broad-spectrum parasite control. Dog’s gastrointestinal systems are still affected. Veterinary technicians often perform annual fecal exams for signs of worms like hookworms, whipworms, tapeworms, and roundworms.


Hookworms are usually found in puppies and causes severe anemia. They actually hook onto their intestine’s lining and feed off the small blood vessels. Dogs get hookworms from their mother’s milk, oral ingestion, skin contact, and in utero. Catching hookworms early can prevent pets from having discomfort and becoming very sick. Symptoms to watch for include anemia, pale gums, bloody diarrhea, itchy paws, and weight loss. To check to see if your dog has hookworms, veterinary technicians may perform a test called a fecal float to search for eggs. There are drugs or de-wormers available to kill hookworms. On occasion, a veterinary technician may need to perform a transfusion.


Whipworms live in the colon and cecum, where the large and small intestines meet and attach themselves to the mucosal lining. Since it’s not easy to detect them, watch out for the following symptoms: bloody diarrhea, weight loss, and anemia. Veterinary technicians take stool samples and then examine them under microscopes.

Veterinarians may have their veterinary technicians give the dog an anti-worm medication to treat the whipworms. Prevention occurs from the use of heartworm medication. It is important to properly clean a pet’s home or kennel and that the area is moisture free.


An adult flea transmits tapeworms to dogs. The flea settles in their small intestines and can also be transmitted to humans. Therefore, it’s critical to destroy the tapeworm before it gets to that point. If you notice dried, cream or white colored pieces broken off in feces or in the fur under the tail, this could be a sign of tapeworms. Also, if a dog drags their hind quarters over the ground, it’s likely due to itching, which is another possible sign. Veterinary technicians analyze stool samples for signs of tapeworms. Oral medication or an injection may be given for treatment.


Roundworms are also found in a dog’s intestines. Sometimes you may notice them in the pet’s poop or vomit. Puppies may get roundworms from their mother’s milk, eating a roundworm’s eggs, or from eating mice. Some symptoms you may notice are vomiting, diarrhea, weight loss, or a pot-belly. A veterinary technician may treat roundworms with deworming drugs after giving them a fecal exam.


Arthropods are invertebrate animals comprising of three major types: Insects (beetles and ants), Crustacea (crabs), and Arachnids (spiders, ticks, and fleas). Pets get fleas from other infested animals, such as dogs, cats, raccoons, and opossums are some of the main carriers. The pet can get ticks from tall grass or walking through the woods. Fleas can cause allergies, but are killed with sprays or spot on treatments.

By studying hematology and parasitology, veterinary technicians, along with Veterinarians, can advise pet owners the best ways to treat diseases and infections. They can also provide excellent advice on prevention and care.

Did learning about Hematology and Parasitology interest you? Ready to start a program to become a veterinary technician? With an associate degree in veterinary technology, you’ll gain the knowledge and skills you need to start an entry-level career as a veterinary technician. Broadview University has been part of the community for more than 40 years, so we’ve developed connections that can help move your career forward. After completing our accredited degree program, you’ll be eligible to sit for the Veterinary Technician National Exam (VTNE). Passing the VTNE allows you to become a Certified Veterinary Technician (CVT), a designation that will give you a competitive advantage when you enter the job market.

Contact us today to learn more about becoming a veterinary technician and working in veterinary technology.

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