Some lesser-known feline parasites
September 16, 2013
Dorland's Medical Dictionary defines a parasite as "a plant or animal that lives upon or within another living organism at whose expense it obtains some advantage." Insert your white collar professional joke here! We all know about the "big three" parasites that infect our kitties: hookworms, roundworms and tapeworms, but, believe it or not all, parasites are not worms. Organisms such as hemobartonella, coccidia, giardia and even heartworms are all lesser known parasites that deserve some attention.
Feline hemobartonellosis, referred to as "hemobart" as the common name (thank goodness), is also known as feline infectious anemia (FIA) and is an important cat disease. It is a rickettsial organism, which means it's kind of in between a bacteria and a virus. It has been around since 1942, but much about it still remains a mystery. It can be a primary disease itself or a secondary invader riding in on the coattails of such famous diseases as feline leukemia, AIDS viruses and autoimmune diseases.
Hemobart causes a wide range of clinical signs but most of the damage comes from the destruction of red blood cells and anemia. We call these severely anemic cats "Kool-Aid cats" because their thin blood resembles the fruity drink and not the viscous life-sustaining stuff we call blood. Any such cat is automatically a suspect for Hemobart.
Hemobart is transmitted in one of three postulated ways (again we are not positive): 1) Through arthropods like fleas and ticks; 2) Through cat bites in which blood is involved; and 3) From mother to offspring.
Treatment is not a complex thing. First we provide supportive care, including rehydration and blood transfusions, if needed. Then antibiotics like doxycycline or oxy/tetracycline are used. Most veterinarians also use corticosteroids, although the timing as to their administration is controversial. We use it right away if the infection is deemed life threatening. Hemobart can be treated, but often cats remain carriers.
Giardia is a protozoal organism found in the intestinal tract of cats; most often it affects young cats. This suggests an acquired immunity as cats age. The transmission of giardia is fecal-oral thus it is more of a problem in areas where cats are congregated. Some species of giardia are thought to be transmittable to people (i.e. zoonotic), but the jury is still out.
Not all cats with the parasite show clinical symptoms. Diarrhea is the most common, with the feces having a characteristic look and smell. The diarrhea can cause dehydration and weight loss, but rarely causes death. Giardia is diagnosed by seeing the parasite on a fecal smear or by an enzymatic test performed on the feces.
Metronidazole or flagyl is our drug of first choice; panacur or fenbendazole given for five consecutive days will also work. These drugs kill the active form of giardia, the trophozoites, but may not eliminate the dormant state or cysts, so reoccurrences can occur.
Coccidiosis is another common intestinal protozoal disease. It is caused by organisms in the isospora (most common), toxoplasma, sarcocyctis or cryptosporidim genus. Isospora is the most common.
Coccidia has an interesting life cycle, most of what you need to know is that it is a fecal-oral transmission; however mice, cattle, sheep and other herbivores act as an intermediate host. Cryptosporidium can be transmitted to man and immunocompromised people are at greatest risk.
Some researchers say coccidian is a self-limiting disease, but I don't know any vets who don't treat it. Clinical signs include diarrhea, vomiting and abdominal pain. The disease is easily treated with sulfonamide type antibiotics.
I hope you all have learned a little about some different parasites of cats. You should now all be able to ace your next biology exam.
Stephen Sheldon, DVM, practices at Gypsum Animal Hospital. He can be reached by calling 970-524-3647 or by visiting the hospital website at http://www.gypsumah.com. He can also be heard Monday mornings at 8 a.m. on KZYR radio, 97.7 FM, discussing pet topics.