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Parasites are organisms which will cause varying degrees of illness in our pets, ranging from mild symptoms such as diarrhea, to debilitating disease and potentially death.

Some of these organisms are also capable of causing infections in humans, sometimes with disastrous consequences. These parasites are divided into two broad categories: internal and external.
Internal Parasites

The internal parasites include worms and protozoal organisms and are more likely to cause problems for their owners in addition to the pets. Fortunately, with regular exams and the appropriate medical therapy, we can prevent long-term infestations from developing and keep not only the pets healthy, but their families as well.
Roundworms (ascarids, hookworms, and whipworms)

Roundworms are, like their name implies, round worms which can vary in length from a couple of centimeters to several inches long. They attach to the intestines of dogs and cats and feed on blood. In severe infestations they can cause anemia (loss of blood) and if untreated result in death. The worms are often spread from an infected mother to her puppies/kittens either through the placenta during birth or through the milk during nursing. Older dogs and people can be exposed by ingesting the eggs or larva of the worms. Hookworms have the additional ability to infect animals and people by the larva penetrating through the skin. All three types of roundworms are detected by identifying roundworm eggs in the feces.

The implications for humans can be serious. Although these organisms are localized to the intestines in animals, in people the worms will migrate through different organs including the skin, internal organs, and the eye. Every year people go blind because ascarids invade the eyeball and cause permanent loss of vision. Children are most at risk because they run around outside barefoot, and are more likely to put objects, which may contain eggs or larva in their mouths.

The good news is that treatment is safe and effective. Every kitten/puppy we see is dewormed with an effective dewormer during their first visit. Beyond their first visit we recommend all dogs be on monthly heartworm prevention which has the added benefit of treating for roundworms as well. We recommend cats be dewormed yearly at the time of their annual exam.

Tapeworms are flat worms which invade the intestines. Tapeworms attach to the intestine, but unlike roundworms which feed off blood, tapeworms merely absorb digested food around it. An animal infected with multiple tapeworms may have a hard time putting on weight, and in severe cases will lose weight. There are two main sources of infection, eating an infected animal such as a mice and rabbits, or from fleas. People, too, are susceptible to tapeworm infestations, although ingestion of infected meat is much more likely to cause disease than from catching it from our pets. A diagnosis is made by identifying parts of the worm in the feces. These worms look similar to grains of rice and will move around the feces or into the surrounding area.

Treatment is safe and effective. Either a pill is given which will kill the tapeworms or a liquid is placed on the back between the shoulderblades which is absorbed through the skin and kills the tapeworms. All outdoor cats are recommended to be dewormed regularly due to the potential for eating infected organisms. Animals in areas endemic to fleas should be on regular anti-flea medication to prevent the spread of tapeworms from fleas.

Heartworms are a major problem in mesa county. Heartworms are a round worm which, as the name implies, invades into the heart and pulmonary (lung) vessels. Adult worms grow to around 12 inches long and large amounts of worms can fill the right ventricle of the heart. This results in the heart valves malfunctioning and leads to congestive heart failure. Additionally, worms can lead to embolisms in the lungs resulting in sudden death.

Heartworms are mainly a disease of dogs and mosquitos. Infected mosquitos bite a dog and inject larvae. The larvae then spend about six months migrating through the dog until it ends up in heart. The worms then release microfiliaria (essentially eggs) and are ingested by mosquitos and the process starts over again. Although cats can get heartworms, they are not a normal host and the worms cannot reproduce. They will cause severe inflammation in the heart and lungs which can lead to sudden death. People are not susceptible to heartworms.

Diagnosing heartworms in both dogs and cats is done through a blood simple test. Dogs diagnosed with heartworms can be treated successfully if the proper protocol is followed. The medication to kill the adult heartworms is different than the monthly therapy which kills certain larval stages. There is no treatment for cats, but if the worm doesn’t cause a lung embolism, the worm will eventually die and be cleared by the cat’s immune system.

The easiest way to deal with heartworms is to prevent them. A pill is given each month which is designed to kill certain larval stages before they can develop into adult worms. Very rarely, the pill is not effective at killing all the larvae and an animal can become infected with adult worms. Therefore, even though an animal is on preventive therapy year-round, we will test for any adult worms every other year.

Giardia is a protozoal organism found in water, especially ponds, streams, and irrigation ditches. Once ingested, it can wreak havoc on in the gastrointestinal system. Typical symptoms include watery diarrhea which can progress to bloody diarrhea with or without mucus present. Affected animals can also have a loss of appetite and/or mild vomiting. People are susceptible to certain strains of Giardia and can have the same gastrointestinal problems animals have.

Giardia is diagnosed by looking for cysts in a fecal sample. Treatment is usually successful with a single antibiotic. Occasionally, a combination of medications is needed to resolve the infection.

Coccidia is a protozoal organism which typically infects young animals. It attacks the gastrointestinal system and causes a watery, yellow diarrhea. People are not susceptible to coccidia. An effective antibiotic is available to treat coccidia.
External Parasites

External parasites include mange, lice, fleas, and ringworm. Although they won’t cause the severe debilitating disease like the internal parasites, they can create significant discomfort for our pets, and can require treatment of not only the animal, but the house and yard as well. Medications are available to treat and/or prevent these diseases from becoming a problem.
Demodex (Demodectic Mange)

Demodex is a mite which typically infects young dogs and results in hair loss. Although the hair loss is typically relegated to the legs and head, it can affect the entire body. Older dogs are usually resistant to Demodex infestations, but if they have a compromised immune system, they can develop severe infestations. People are not susceptible to Demodex.

Treatment depends on the extent of the infestation. A few, small spots are usually treated with an ointment for several weeks. More severely affected dogs are given a special medicated bath every 2 weeks until the mites are dead.
Scabies (Sarcoptic Mange)

Scabies is a mite which causes significant itching, especially along the sides of the ears. Dogs and cats will itch constantly resulting in bleeding of the affected areas. Scabies is contagious and is easily transferred to other animals or people.

Diagnosis of Scabies is difficult and sometimes requires several different samples to identify the mite. Due to the amount of trauma that is done with scabies, treatment will be started if the history and physical exam are consistent with the mite, even if it can’t be visualized under the microscope. Treatment consists of a series of injections over several weeks.

Cheyletiella is a mite that infects the skin of animals and can cause itchiness. It is seen more commonly on cats and is sometimes referred to as “walking dandruff” because you can occasionally see white specks moving across the fur. It can be transmitted to other animals, but not to people.

Diagnosis is made by looking at dandruff under the microscope, or identifying the mite in a fecal sample. Treatment is a series of injections given over several weeks.
Otodectes (ear mites)

Ear mites are most commonly seen in cats, but can be spread to dogs as well. They cause severe inflammation of the ears and cause animals to scratch incessantly to the point of bleeding. The mites leave brown debris which can be seen when evaluating the ear. Ear mites will spread to all the animals (but not people) in the household, so when treatment is needed, it is recommended all animals in the household be treated to prevent recurrence.

Diagnosis is by identifying the mite under the microscope. A single dose of medicine put in the ears is very effective at treating ear mites.

Lice are small parasites which suck on blood. They can cause itchiness among animals. Lice are very species specific. Dog lice will not infect cats or people, and vice versa, but will infect other dogs in the household.

Diagnosis is made by identifying the organism on the animal. Treatment is done with a topical medication.

Fleas are small parasites which spend part of their life on an animal and part of it in the animals environment making it very difficult to eradicate once they establish themselves. Fleas bite the animal, mostly on the back toward the base of the tail, but it can be all over. The biting is itchy and animals will scratch and bite themselves incessantly when infected. Fleas are not species specific and will migrate to any animal around.

Diagnosing fleas consists of seeing the fleas, flea eggs, or flea dirt on the animal. Treatment of fleas is more difficult than with other parasites because they spend most of their time off the animal and in the environment. Animals are treated with a medication placed between their shoulderblades that works to kill the fleas. If an animal is severely affected, we will also use a spray to immediately kill some of the fleas. The environment also needs to be treated, which often involves calling an exterminator and having the house “bombed” to kill fleas and the eggs.
Dermatophytosis (ringworm)

Ringworm is caused by a fungal organism which invades the skin and hair follicles resulting in hair loss and dry skin. There is a wide range of affliction for our pets and ourselves. Some animals are essentially immune to ringworm and will never have a problem with it. Other animals, especially cats, can be carries – they show no clinical symptoms of disease, but can spread the fungus to other animals and people. The last group is the susceptible group. They present with round lesions of hair loss and dry skin that may or may not be itchy. The lesions don’t resolve with time, and may continue to spread. Some of the susceptible animals have only one or two localized lesions, while others are affected over their whole body. People are susceptible to ringworm to varying degrees.

Diagnosis of ringworm is based on history, physical examination, and a fungal culture. Treatment is either local with anti-fungal creams or, for severe infections or carrier animals, a pill given every couple of weeks for 3-4 doses.