Category Archives: Parasites

Ear Mites..

Ear Mites
By Dr. Karen Burgess

What exactly are ear mites?
Ear mites are microscopic bugs that physically resemble ticks and reside in the ear canal and skin of cats and dogs.   The adult ear mite may be visible using a magnifying glass as a small moving white dot.  Ear mites produce debris and discharge in the ear canal that can easily be misdiagnosed as a yeast or bacterial ear infection if not looking specifically for ear mites.

What are the signs of ear mite infection?
Ear mites live and breed in the ear canal, specifically on the surface of the skin.  During this process the mites feed on oils and ear wax and subsequently cause inflammation in the ear canal producing a black discharge and general ear inflammation.  Infected pets will often have painful itchy ears, head shaking, crusting on the skin around the ears, and notable ear discharge.  The adult ear mite can travel outside of the ear canal to the surrounding skin and fur making systemic treatment preferable to treating just the ears.

How do dogs and cats get ear mites?
Ear mites are highly contagious and transmitted by direct contact.  Cats contract ear mites more commonly then dogs.  It is not uncommon to diagnose ear mites in pets coming from shelter or group housing situations.

How are ear mites diagnosed?
A microscopic examination of debris from the ear will typically show actual ear mites or their eggs.

How are ear mites treated?
There are a variety of treatments for ear mites.  Topical ear drops have been a common ear mite treatment with some products available even over the counter.  A disadvantage of topical treatment is that they do not kill ear mite eggs and thus involve twice daily ear drops for a minimum of three weeks.  For some pets this can be uncomfortable and difficult to accomplish.  Tresaderm is a prescription topical that does kill eggs and only requires twice daily treatment for two weeks.  Neither topical product addresses mites that have migrated out of the ear canal.  Alternatively the topical product Revolution can be applied twice (one month between doses) to the skin between the shoulder blades.  This treatment effectively kills mites in the ears and on the skin.  Another treatment option is the dewormer ivermectin which can be given as an injection or orally.  This treatment is considered off-label meaning it is not appropriate for all pets.  All pets in the household (including ferrets and rabbits) should be treated simultaneously.  Pet bedding should also be washed. 

Can humans contract ear mites?
Ear mites are not considered contagious to humans.

Heartworm Disease

Heartworm Disease
By Dr. Karen Burgess

What is heartworm?
Heartworm disease is caused by Dirofilaria immitus, an up to foot long spaghetti-like worm that grows to maturity in the heart and pulmonary artery (blood vessel connecting the heart to the lungs).  Dogs become infected with heartworm disease when they are bitten by an infected mosquito that acts as an intermediary host.

What are symptoms of heartworm disease?
Dogs with heartworm disease range in showing no symptoms to experiencing heart failure.  More common symptoms include exercise intolerance or a cough.  The adult heartworm can clog blood vessels and cause dangerous inflammation within the lungs.  Symptoms often do not develop for several years after initial infection, but by this time extensive and permanent damage to the lungs has often already developed.

What is the life cycle of the heartworm?
Heartworms develop through five different life stages.  The adult heartworm resides in an infected dog’s pulmonary artery (blood vessel connecting the heart to the lungs).  After mating, adult female heartworms produce microfilaria, or microscopic larva that travels through the blood stream.  When a mosquito bites an infected dog, they ingest microfilaria along with blood.  The heartworm larva goes through two life stages in the mosquito over a several week timespan before being infectious to another dog via mosquito bite.   After a dog is infected, the heartworm must then go through three more lifestages before becoming an adult in the heart.  Ultimately it takes approximately four months from time of mosquito bite to when a mature heartworm is found in the heart.

How is heartworm disease diagnosed?
There are several blood tests readily available to screen for heartworm disease.  The biggest limitation being that most tests are only able to detect more than three adult female heartworms.  Since it takes four months from time of infection to having an adult heartworm, some dogs may test falsely negative for heartworm disease initially.

How is heartworm disease typically treated?
There are several components to successful treatment for heartworm disease.

The microfiliaria (baby heartworms, L1) and recently injected and developing heartworms (L3 and L4) are killed by ivermectin based heartworm preventatives (Heartgard Plus).  This prevents other dogs from being infected and recently injected larva from growing into adult heartworms in an exposed dog.  Injected heartworms (L3) remain in the skin for three months developing to the larval stage that ultimately migrates to the heart (L5).  Developing larval heartworms (L3, L4) are killed by ivermectin based (Heartgard Plus) heartworm preventatives.

Treatment for the adult heartworm (L5) involves a very specific medication called immiticide, a derivative of arsenic.  Prior to treatment, dogs should have their overall health and stage of disease determined.  Blood tests and thoracic (chest) radiographs are recommended at a minimum.  If there is evidence of lung or heart disease on radiographs, a modified treatment regimen or further testing may be necessary in an effort to prevent complications.  Current recommendations for treatment involve an initial one month course of doxycycline.  Research has shown that doxycycline kills a specific bacteria associated with the adult heartworm thus making it more susceptible to immiticide and potentially decreasing side effects of treatment.  After the course of doxycycline, there is a month delay prior to treatment with immiticide.  This allows time for immature heartworms to either be killed by preventative or mature to adulthood allowing immiticide to kill them.  A confirmatory heartworm test should be performed after this eight week delay and prior to immiticide therapy.

Immiticide is administered as an injection in the back muscle.  One month after this first injection, the same injection is given again twice over a two day period.  Each injection of immiticide kills a certain percentage of heartworms.  By dividing the treatment over a two month period, the total number of dead worms a dog is exposed to at any one time is limited.

What is follow-up care after treatment for heartworms?
Dying adult heartworms and the ensuing inflammation they cause in the lungs is a potentially life-threatening problem for dogs undergoing heartworm treatment.  There is no way to completely prevent complications secondary to heartworm treatment.  Anti-inflammatories are often administered immediately after treatment to assist with any local pain at the injection site which can be severe enough to cause a dog to bite.  An estimated 30% of dogs will experience some sort of reaction secondary to the injection.  Strict rest is required for four weeks after each injection; this means short leash walk to go to the bathroom in the yard, no running, walks, playing, or excessive excitement.  The dying adult heartworm can be very dangerous and the more the heart is rested the safer it is for the dog.  It is better to error on the side of caution (crating a pet) than risk a possible complication.  A heartworm test should be performed again six months after treatment.

What are signs of complications from treatment?
Cough (often closely resembling vomiting but with no food present), lethargy, vomiting, difficulty breathing, loss of appetite, or collapse are all possible complications and warrant immediate medical attention.

Can heartworm be prevented?
There are several different products available to prevent heartworm disease.  These are typically a pill that is administered once monthly year round.  Care should be taken to purchase a reliable product from a trusted brand as several product lines have experienced recalls over the years.

Can a dog get heartworm disease while on preventative?
Heartworm treatment is nearly 100% effective.  Reasons for breakthrough include failure of pet to ingest pill, poor owner compliance in giving pill monthly, resistant strains of heartworm (not a current problem in this region), and an animal that had immature worms that were not detected on a previous heartworm test.

Why do dogs need to be tested for heartworm disease prior to giving preventative?
Heartworm preventatives quickly kill off microfilaria.  In rare instances this can lead to a potentially fatal anaphylactic reaction in a dog.  Heartworm positive dogs with microfilaria should be monitored in a hospital setting when first being given preventative.

 

Whipworms

Whipworms
By Dr. Karen Burgess

What exactly is a whipworm?
Whipworm is a parasite or worm found in the large intestine and cecum.  The adult whipworm is only 1/4” in length.  Whipworms cause a great deal of irritation as they attach to the intestinal lining and ingest blood. Whipworm disease is often considered one of the more dangerous worms to a dog’s overall health.

What are the signs of whipworm infection?
Animals that test positive for whipworm may have no symptoms, be critically ill, or present with profuse watery or even bloody diarrhea.  In some cases whipworm disease can lead to electrolyte disorders that resemble another condition called Addison’s Disease.

How do dogs and cats get whipworm?
Whipworm disease is transmitted from dog to dog via eggs passed in the feces.  While it takes ten to sixty days for the fecal eggs to become infective to a dog, they are also very resistant to heat and drying.  For this reason once an area has been exposed to whipworms it is assumed that all future dogs kept in this environment will also be exposed.  Once ingested the whipworm goes through several stages before arriving in the large intestine and embedding itself.

How is whipworm diagnosed?
A microscopic examination of fecal matter will demonstrate whipworm eggs.  Unfortunately whipworm eggs may only be shed intermittently by the female worm.  For this reason, pets showing signs of large intestinal diarrhea may benefit from a preventative deworming in spite of a negative fecal exam.

What is the treatment for whipworm?
Treatment for the adult whipworm involves an oral dewormer while also addressing any clinical disease.  Some monthly heartworm preventative pills also contain dewormer for whipworms.  Whipworm larva that have not yet matured or arrived in the large intestine will not be treated by standard dewormers.  This requires repeated treatments as the whipworm matures to an adult and becomes susceptible to drug therapy.

How can whipworm be prevented?
Whipworm is found frequently in the environment making prompt removal of fecal matter essential to control.  Cleaning hard surfaces with dilute bleach (one cup per gallon of water) is recommended, but whipworms are considered nearly impossible to remove from the environment once exposed.  Avoid taking an infected pet to swim or communal dog areas in an attempt to minimize exposure to others.  Monthly treatment with heartworm preventative as early as possible is also recommended.

 

Can humans contract whipworm?
Humans are not infected by whipworms.

Hookworm

Hookworm
By Dr. Karen Burgess

 

What exactly is a hookworm?
Hookworm is a parasite or worm found in the small intestine.  The adult hookworm is only 1/8” in length but has six teeth and a voracious appetite for the blood it ingests after “hooking” onto the intestinal wall.  There are several different species of hookworms that infect dogs, cats, and humans.

What are the signs of hookworm infection?
Animals that test positive for hookworm may have no symptoms, be critically ill, anemic, or present with profuse diarrhea.  Anemia from blood loss is typically the most dangerous aspect of hookworm infection for puppies and kittens.  For animals infected via the skin itching may be the primary symptom.  In some cases the hookworm migrates through the lung before ending up in the small intestine, thus leading to a cough or respiratory signs.

How do dogs and cats get hookworm?
Hookworm disease can be transmitted in several different ways.  Eggs are shed in fecal matter and become infective larva.  When another dog or cat swallows these eggs they travel to the intestine and after several stages of development attach to the intestinal wall causing disease.  In dogs, hookworms can be transmitted from mother to baby via the placenta during pregnancy or nursing after delivery.  The lifecycle of the hookworm allows it to “hibernate” in the adult female’s muscle tissue.  Pregnancy hormones then awaken the dormant larva releasing them into the bloodstream to be passed on to the fetus or baby.  This is why it is very common for newborns to have parasites in spite of the mother having been dewormed.  Hookworm eggs that have matured into larva in the stool can also infect animals or people by penetrating the skin.  Finally, an animal may ingest another animal (ex. cockroaches, rodents, birds) that have ingested hookworm larva thus becoming infected themselves.

How is hookworm diagnosed?
A microscopic examination of fecal matter will typically demonstrate hookworm eggs as the adult female can produce 20,000 eggs daily.  In the very young however life-threatening disease from the adult hookworm may develop before eggs are seen on a fecal examination.  For this reason multiple deworming treatments are recommended for puppies and kittens regardless of fecal results.

What is the treatment for hookworm?
Treatment for the adult hookworm involves an oral or injectable dewormer while also addressing any clinical disease.  Monthly heartworm preventative pills also typically contain dewormer for hookworms.  Hookworm larva that have not yet matured or arrived in the intestine will not be treated by standard dewormers.  This requires repeated treatments as they mature to adults and become susceptible to drugs.

How can hookworm be prevented?
Hookworm is found frequently in the environment making prompt removal of fecal matter essential to control.  General good hygiene/handwashing and wearing shoes outside can prevent human exposure.  Hookworm eggs do not survive freezing temperatures or hot dry situations.  They are typically are short-lived in the environment dying on their own after several months.  Cleaning hard surfaces with dilute bleach (one cup per gallon of water) is recommended.  Avoid taking an infected pet to swim or communal dog areas in an attempt to minimize exposure to others.  Monthly treatment with heartworm preventative as early as possible along with frequent dewormings of puppies and their mothers helps further prevent disease.

Can humans contract hookworm?
Humans are not infected by adult hookworms however hookworm larva can penetrate skin causing an itchy lesion and a condition called cutaneous larval migrans.  This normally occurs with extended (5-10 minutes) contact between skin and hookworm infested soil.  Sunbathers may be at greater risk from laying on contaminated soil.  Less commonly humans can develop hookworms in their intestine typically after ingesting produce that has not been properly washed.

Giardia

Giardia
By Dr. Karen Burgess

giardia, parasites, feline

What exactly is Giardia?
Giardia is a parasite found in the intestine.   Unlike other intestinal worms, Giardia is a one celled organism better known as protozoa.  Animals coming from communal living situations (breeder, shelter, kennels)  are commonly diagnosed with giardia infection.

What are the signs of Giardia infection?
Animals that test positive for Giardia can range from having no symptoms to being critically ill, dehydrated and with profuse diarrhea.  Giardia found in adult animals showing no symptoms is not typically treated and is considered an insignificant finding.  Essentially the healthy immune system keeps Giardia numbers under control preventing illness.  It is often not even possible to clear Giardia from these pets.  Young animals or immunosuppressed pets testing positive for Giardia are an entirely different situation.  These pets are treated in an attempt to clear infection and avoid illness.

How do dogs and cats get Giardia?
Giardia is shed in fecal matter in the form of cysts.  When another dog swallows these cysts they travel to the intestine and after several stages of development become infective.

How is Giardia diagnosed?
A microscopic examination of fecal matter will typically demonstrate Giardia cysts.  Cell proteins of Giardia can also be tested for in the blood or feces via ELISA.  Giardia cysts are very small and can be difficult to visualize; submission of specimens to a reference laboratory is often the most reliable testing method.  Giardia cysts can be shed intermittently.  If diarrhea persists in a patient retesting for Giardia via ELISA of fecal may be recommended.

What is the treatment for Giardia?
Treatment for Giardia usually involves metronidazole, fenbendazole, or in more resistant situations a combination of the two.

How can Giardia be prevented?
Giardia is found frequently in the environment making prompt removal of fecal matter essential to control.  Cleaning surfaces with dilute bleach (one cup per gallon of water) and drying will also kill cysts that are highly resistant that can survive for years in cold moist environments.  Bathing at least once during treatment is also recommended to remove any cyst stuck to the fur.  Avoid taking an infected pet to swim or communal dog areas in an attempt to minimize exposure to others.

Can humans contract Giardia?
Humans do contract Giardia, but a different strain than animals.  There have been cases where pets have contracted human strain Giardia thus making it a zoonotic disease.  The risk of human infection from animal strain Giardia is considered rare if not impossible having never been reported.  This would be more of a risk for those that are immunocompromised.  Drinking contaminated water (fresh or tap) is a common source of exposure for people to human strain Giardia.  Care should be taken to avoid handling of fecal matter from infected pets.  Contact your physician with any specific questions regarding Giardia in humans.

 

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Praziquantel (Drontal Plus)

Praziquantel
Antiparasitic
(Droncit, Drontal Plus, Sentinel Spectrum)
By Dr. Karen Burgess

 

Brand name and formulations

  • Praziquantel (generic formula)
  • Droncit, Drontal Plus, Sentinel Spectrum (brand name animal formula)
  • Tablet, Flavor Tablet, Injectable

What is praziquantel?
Praziquantel is an antiparasitic known for its efficacy against the tapeworm class of parasites.  The drug damages the parasites skin leading to disintegration.  Worms are not commonly seen in the feces in response to treatment.

How is praziquantel given and what if a dose is missed?
Praziquantel is typically prescribed as a single dose medication.

How should praziquantel be stored?
Store at room temperature and protected from light.

What side effects are associated with praziquantel?
Gastrointestinal signs including appetite loss, vomiting, and diarrhea occur in approximately 5% of patients taking praziquantel.  The oral formulation may taste bitter to pets.

What drugs should not be given with praziquantel?
There are no specific drug interactions of major concern.

What follow up is necessary with praziquantel use?
Prevention of future re-exposure is recommended via flea and rodent control.  Follow up fecal examination is recommended a week after treatment is completed.

Pyrantel Pamoate (Strongid)

Pyrantel Pamoate
Antiparasitic
(Strongid, Nemex)
By Dr. Karen Burgess

   Brand name and formulations

  • Pyrantel pamoate (generic formula)
  • Strongid, Nemex, Virbantel (brand name animal formula)
  • Tablet, Liquid

What is pyrantel?
Pyrantel is an antiparasitic known for its efficacy against roundworms, hookworms, and stomach worm.  The drug paralyzes the parasite thereby causing it to release from a pet’s intestine and be passed naturally with fecal matter.

How is pyrantel given?
Pyrantel is typically prescribed as a single dose medication.

How should pyrantel be stored?
Store at room temperature and protected from light.

What side effects are associated with pyrantel?
Vomiting may occur after treatment with pyrantel.  Worms may be seen visually passing in stool or in vomitus.

What drugs should not be given with pyrantel?
There are no specific drug interactions of major concern.

What follow up is necessary with pyrantel use?
Pyrantel only treats adult worms leaving immature migrating worms behind.  Follow up dosing is recommended at two week intervals for a total of two to three doses.  Prevention of future re-exposure is recommended via monthly heartworm preventative administration.  Follow up fecal examination is recommended a week after treatment is completed.

 

Fenbendazole (Panacur)

Fenbendazole
Antiparasitic
(Panacur)
By Dr. Karen Burgess

Brand name and formulations

  • Fenbendazole (generic formula)
  • Panacur (brand name animal formula)
  • Powder, Liquid

What is Panacur?
Fenbendazole is an antiparasitic known for its efficacy against roundworms, hookworms, lungworm, flukes, Giardia, and tapeworm.

How is fenbendazole given?
Fenbendazole is typically prescribed daily for three to five consecutive days.

How should fenbendazole be stored?
Store at room temperature.

What side effects are associated with fenbendazole?
Vomiting, diarrhea, and excessive salivation may be associated with the use of fenbendazole.

What drugs should not be given with fenbendazole?
There are no specific drug interactions of major concern.

What follow up is necessary with fenbendazole use?
Follow up dosing may be recommended.  Prevention of future re-exposure is recommended via monthly heartworm preventative administration.  Follow up fecal examination is recommended a week after treatment is completed.

 

Sulfadimethoxine (Albon)

Sulfadimethoxine
Anticoccidial, Antibiotic
(Albon)
By Dr. Karen Burgess

 

Brand name and formulations

  • Albon (brand name)
  • Liquid

What is albon?
Albon is an antibiotic in the sulfonamide family and as a bacteriostatic agent inhibits bacterial replication.  Management of coccidial overgrowth, a common cause of diarrhea in young animals, is the primary use for albon in small animals.

How is albon given and what if a dose is missed?
Albon is typically prescribed for once daily dosing and for a total of ten days.  The first dose is twice the volume of the subsequent nine doses.   If a dose is missed give the missed dose and alter future dosing times accordingly.

How should albon be stored?
Store at room temperature and protected from light.

What is albon’s background?
The sulfonamide class of antibiotics was the first developed in 1932 and saved numerous lives during World War II.  When used in combination with other antibiotics the effects of sulfadimehoxine is improved.  As a sole agent, sulfadithoxine is exclusively used to treat coccidia.

What side effects are associated with albon?
The sulfonamide class of antibiotics including albon is not recommended in pets with severe kidney or liver disease.  Use should be avoided in Dobermans.  Rare side effects include joint pain, generalized inflammation, rashes, decreased tear production, and blood cell abnormalities.

What drugs should not be given with albon?
There are no specific drug interactions of major concern.

What follow up is necessary with albon use?
Medication should be used for a full ten day course.  Follow up fecal examination is recommended a week after treatment is completed.

Roundworm, Canine

Roundworms
By Dr. Karen Burgess

Roundworms are an intestinal parasite that lives in the small intestine of the dog and live off of partially digested food.

 Where do roundworms come from?
There are several ways that dogs become infected by Toxocara canis, or the common roundworm.

  • Eating microscopic worm eggs from the environment (example-infected dog defecates, another dog steps on soil containing roundworm eggs and then licks paws thereby ingesting the eggs)
  • Puppies that nurse from an infected mother’s milk
  • Eating an infected prey animal (usually rodent), these animals are carriers and themselves do not become sick but merely pass the worm on
  • While in utero from an infected mother

The life cycle of the roundworm is multistep and complicated, but ultimately adult roundworms are found in the intestine.

During development the immature worm migrates through the body and can encyst (essentially allowing it to “hibernate”) in a variety of tissues.  When female dogs become pregnant the encysted worms are reactivated, released into the bloodstream and eventually pass on to the puppies through the placenta, milk, and mother’s feces.  Puppies less than two weeks old can have dangerous roundworm infections.

What problems do roundworms cause?
Infection with roundworms can cause vomiting, diarrhea, weight loss, and potential death in the very young or weak.  The adult roundworm is very long (up to seven inches) and can lead to intestinal obstruction.  Migrating worms can cause respiratory signs including pneumonia.

How is roundworm infection diagnosed?
It should be assumed that all puppies are infected with roundworms and intestinal dewormings should start as early as two weeks of age; ideally mother dogs are dewormed even during pregnancy.  A microscopic examination of a stool sample can also reveal roundworm eggs.

Are humans at risk from roundworms?
Oral consumption of roundworm eggs by humans can lead to major medical problems related worms migrating through the body.  This is of particular concern with young children who are more likely to be exposed to fecal oral contact while playing outside or in sandboxes.  In particular, human roundworm infections can cause serious liver disease and even blindness (ocular larval migrans).

How is my pet treated for roundworms?
Several very safe oral medications are available to treat roundworm infection.  These treatments temporarily anesthetize the adult worm causing it to “let go” of the gut and then pass with stool.  It is not uncommon to see worms in the stool after treatment that may even be moving.  Repeated dewormings are necessary to create worms that are not yet adults in the intestine.

How is roundworm disease prevented?
Roundworm eggs are not immediately infective, so picking up pet feces immediately is the best prevention.  Once in the environment, eggs can last for weeks to months and are quite resistant.  Monthly heartworm preventative typically also contains a dose of intestinal dewormer providing added protection from environmental exposure.  Control of rodents in the environment is also recommended.