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Parasites

Welsh-Terrier

Dog Parasites

Ringworm is the popular name for dermatophytosis, a frequently-identified fungal skin infection seen in dogs. Its name originates from the red, ring-shaped irritation that accompanies infection in human beings. Fungal dermatophyte species identified in canine ringworm infections include Microsporum canis (most commonly identified), Microsporum gypseum, and Trichophyton mentagrophytes. These robust and hardy fungi can live for a very long time in the environment (from months to years) in the form of infective spores (seed-like structures), and take their nutritional supply from the keratin protein in the hair, nails, and skin layers. Different strains can vary in virulence, or disease-causing ability.

How is Ringworm Spread?

Ringworm is transmitted by contact with skin lesions, hair, and scale. The fungus can also be isolated from carriers (infected but asymptomatic dogs) as well as from the soil and surrounding environment. Carriers do not show signs of infection, but can infect surrounding animals. Hairs (which are covered with infectious spores) are continuously shed from the infected dog. The veterinarian should examine the dog’s environment and living style in cases of infection, including close contact with any humans or pets with dermatitis in the household.  Puppies and sick and immunocompromised dogs (as well as those from shelters) are at the greatest risk for infection.

What does Ringworm Look Like?

Ringworm lesions can appear quite variable in dogs, who do not demonstrate the classic human ring-shaped lesion. Dogs typically display bald spots with associated scaly, crusty, irritated and sometimes itchy lesions that mimic other clinical veterinary conditions such as mites, allergy, or bacterial infection. Your veterinarian has the diagnostic tools to differentiate these variable conditions from one another.

How is Ringworm Diagnosed?

Ringworm is diagnosed by fungal culture of hair and scale or crust from lesions, skin biopsy, KOH-DMSO preparation tests, or Wood’s lamp fluorescence (infected hair or scales will fluoresce under the light). Hair from some cases will shine a fluorescent green color if examined under a Wood’s lamp. The Mackenzie toothbrush technique test (rubbing a sterile toothbrush over infected areas) is an effective way to obtain samples for culture, particularly in asymptomatic carrier animals.

How is Ringworm Treated?

Topical and/or oral antifungal medications are used in ringworm treatment. Some of these medications can have serious side effects, and should only be administered under the direction of your veterinarian. Antibiotics are used for secondary skin infections. The flea preventive Program® (lufeneron) may have some utility, but its efficacy is still unclear. Treatment should be continued until hair and skin cultures are negative. Environmental decontamination, though difficult, is essential in effective therapy, and can include vacuuming, steam clean, and bleach de-contamination.

Can Humans Catch Ringworm from and Infected Dog?

Ringworm is a zoonosis, or a shared disease between human beings and animals. Immunosuppressed humans (very young or very old individuals, individuals with chronic diseases such as human immunodeficiency virus or cancer, and individuals undergoing chemotherapy or post-transplant therapy) are most susceptible to ringworm infection and clinical disease.

Please consult your veterinarian if you suspect that your dog has ringworm in order to confirm the diagnosis and start treatment.

Cuterebra Infestations in Dogs

Your pet may become exposed to many parasites in their environment with warmer weather. One of those parasites is the larva of the Cuterebra fly that may cause a wound or sore on your pet’s skin.  Your pet is most likely to be affected in the summer and fall which corresponds to the most active egg-laying time for the adult fly.

What is Cuterebra, how can it infect my dog?

The Cuterebra fly is a large non-biting fly that looks like a bee and lays its eggs on rocks or vegetation located near the openings of rabbit or rodent burrows. Some reports have suggested that eggs can be found in garden mulch that has been obtained near such areas. The rabbit or wild rodent are the normal hosts, and can pick up these eggs on their coats and ingest them during grooming. Cats and dogs may also be exposed in this manner by contacting the eggs as they pass near rabbit or rodent burrows in their environment. Eggs hatch once they are exposed to the warm body temperatures of their cat or dog hosts. The newly hatched larvae invade the host body often through the mouth, nasal passages, or an external wound.

The larva migrates to an area under the skin of the pet, typically on the head, neck, or trunk. A cyst or thick capsule is created under the skin as the larva grows; a circular breathing hole may appear as an open wound with matted hair. There is often fluid drainage from the opening and the animal, especially the cat, will groom the area excessively.

What should I expect to see if my pet has been infested by a Cuterebra larva?

Warning:

Do not attempt to remove the larva yourself! Doing so may seriously harm your pet.

Most pets will present to their veterinarian for an open wound or draining sore. If the pet has a long-hair coat, the owner may notice an area of matted hair that appears to irritate the pet causing excessive grooming at the site. Occasionally, the area may appear as a lump or swelling which is also referred to as a warble (the other common name for a Cuterebra cyst). Owners may actually observe the caterpillar-like larvae sticking it’s head from the open hole at times to breathe much like a swimmer periodically coming up for air.

Treatment

Treatment for cuterebriasis should be performed by your veterinarian. It is important not to squeeze the swelling or cyst as it may damage the larva and release harmful chemicals into your pet’s circulation. If the larva is ruptured during removal, it can cause serious complications including allergic reactions and anaphylaxis. Your veterinarian will administer local anesthesia at the site of the cyst or capsule and enlarge the breathing hole so the larvae can be removed in one piece. Your pet can experience repeated and chronic infections if any part of the larva is left behind. Even with complete and appropriate removal, healing may be slower than expected.

Limit your pet’s exposure to areas around rabbit and wild rodent nests or burrows to avoid Cuterebra infection. Cats should be kept indoors to prevent exposure. You should check your pet’s coat or have them brushed or groomed regularly in an effort to remove eggs or larvae early in their development.

How do I know if Cuterebra flies are found where I live?

If you live in the United States, you can be certain that some type of Cuterebra fly lives nearby. Cuterebra flies, also known as New World skin bot flies, are found throughout North and South America. There are over 72 different species of these flies that each target a specific host animal such as rabbits or deer.

Can I catch cuterebriasis from my pet?

Humans can be infested with Cuterebra larvae but not from their pets. You may become exposed to the larvae in the same manner as your pet by contacting soil or mulch that is found near rabbit or rodent burrows. Wounds created by larvae under the skin do occur rarely in people and these follow the same path as infestations in cats and dogs.  These  are considered “accidental” infestations as they are caused by cuterebra that target wild animals for their hosts. There is one specific Cuterebra fly that does target humans as their host, but it is only found in South America.

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 Worms

Worms, or intestinal parasites, can affect all puppies and dogs. Intestinal parasitism is one of the most common conditions in clinical veterinary practice and is frequently identified in all dogs.

Types of Parasites

Many types of parasites infect dogs. The most common canine intestinal parasites in the United States are roundworms (Toxocara cati or Toxascaris leonina), hookworms (Ancylostoma caninum, Ancylostoma braziliense, Uncinaria stenocephala), whipworms (Trichuris vulpis), and tapeworms (Taenia spp., Dipylidium caninum, Echinococcus multilocularis, Echinococcus granulosus). Several intestinal parasites can infect puppies through lactation from an infected mother, and this is why it is important to treat puppies with de-worming medications throughout puppyhood.

How are dogs infected with parasites?

Dogs are infected with roundworms, hookworms, whipworms, and tapeworms after ingestion of infective eggs and larvae from the soil and the environment. They can also become infected by ingesting the tissues and intestines of prey animals or tapeworm proglottids (infectious tapeworm segments full of eggs that look like pieces of rice). Ingestion of infected fleas can result in tapeworm infection in dogs, and all dogs diagnosed with intestinal worms should be treated for flea infestation.

Clinical signs

Infected dogs can demonstrate vomiting, diarrhea, lethargy, weight loss, anemia (low red blood cell counts), respiratory signs (breathing problems, cough) and an enlarged belly. Puppies can become particularly ill. Some dogs may never show symptoms of infection, while others can become very ill. Owners may see worms or proglottids passed in the vomitus or stool or emerging from the anus. Some dogs will exhibit itching in the anal area and drag their rear quarters against rugs and carpets.

Diagnosis

Intestinal parasites can also be diagnosed by identification of eggs in the fecal samples. This is why your veterinarian requests a yearly fecal sample for evaluation.

Treatment

Several medications are available which effectively treat these parasites. Treatment usually includes a single treatment followed by several follow-up treatments to kill all immature worms in the body. There are many different de-worming medications available throughout the United States (pyrantel pamoate, fenbendazole, praziquantel). Each medication treats different worm(s). It is therefore imperative that you immediately contact your veterinarian if you suspect that your dog has worms. The veterinarian will identify the worm species and prescribe appropriate treatment. Over-the-counter wormers are usually not helpful.

Prevention

The best way to decrease the likelihood of intestinal parasites in your dog is the use of regular heartworm preventative medications. Most (but not all) of these medications de-worm your dog for common intestinal worms as well as protect against heartworms. Dogs should also be treated with flea preventative medication. These medications are all available from your veterinarian. Please consult your veterinarian to determine the most effective protocol for your dog’s parasite prevention. Some of these parasites can infect humans, and this is another reason to emphasize parasite prevention, particularly in families with young children and immunocompromised family members.

Note: Before beginning heartworm medication, dogs have to be tested first to ensure they are not already infected as administering heartworm meds to an already infected can result in serious illness and even death.

Fleas and Ticks

Ticks can transmit a number of diseases, including Lyme, Ehrlichia, Babesiosis, Rocky Mountain Spotted Fever, and Anaplasmosis.  Some of these are potentially lethal.

Flea infestation can lead to skin infections, tapeworms, hair loss from scratching, and anemia.  This anemia can be life-threatening, especially in puppies and geriatric animals.  Flea Allergic Dermatitis (FAD) is quite common, in which even a single bite can cause a severe rash.

Signs of Infection

Ticks bury their head under the skin and stay in one spot. When they first attach they may be as small as a pinhead, but they enlarge when they become engorged with blood. They often attach in warm areas, such as the neck or head.

Flea infection usually leads to itching, although some animals are not allergic to the bites and do not develop a severe rash.  While you may see actual fleas on your dog, the most common sign is flea dirt, pepper-like granules in the coat, especially on the rump and groin.  These are found by either parting the coat or using a special “flea comb” with narrow-spaced teeth.  To determine if what you find is flea dirt, which is actually digested blood, place the granules on a moistened white paper towel.  Rub them gently; if the paper towel turns orange or red, your pet has flea dirt.  It is not necessary to find actual fleas to confirm an infection.

Control

Ticks are not affected by cold weather, and animals with exposure to woods, brush, or tall grassy areas should be treated year-round.  Options for prevention include collars and spot-on treatment. All dogs should be checked for ticks regularly, but because the ticks are so small before they attach they are easy to miss.  To remove a tick, grasp it tightly with tweezers at the point where the head is imbedded into the skin and pull gently.  If mouthparts remain, do not dig after them!  If they do not work their way out, contact your veterinarian for removal. Never use fire to remove a tick; it is dangerous and will not work.

The most common flea in the U.S. is the cat flea, which can infect any mammal (including humans).  While the adult fleas live on their animal host, the eggs, pupae, and larvae do not.  For this reason, once there is an infestation, it is often necessary to treat the animal and the house.  Many of the newer preventatives address multiple stages of the flea life cycle; for example, even if a flea is not killed by a given preventative, the eggs it lays will have actually been affected by the preventative and will not hatch.  Washing bedding, thorough vacuuming, and, if necessary, environmental sprays can all help remove non-adult stages of fleas from the indoor environment.

While flea powders and collars still exist, there are many newer, more effective, and less toxic flea control products available.  Some are given by mouth, others as a monthly spot-on treatment. Shampoos and dips have a more immediate effect than some of the other treatments, but this effect does not last as long.  Some treatments are waterproof or water-resistant, some safe in pregnant and nursing animals, and some are combined with other products to prevent other infections such as tick, mosquito, heartworm, roundworms, and hookworms.  Resistance to flea preventative has been noted, especially in over-the-counter products, and every dog is different in their exposure level.  For this reason, we suggest that you contact your local veterinarian for their recommendation on what solutions would be best for your dog.  A very important consideration is that some products are safe in dogs but not in cats. It is critical to use cat-specific products in cats or death can occur.

Fleas cannot survive outside in freezing temperatures. However, they can easily be carried on clothing between houses, and hop between apartments.  Year-round control may still be necessary, especially in animals with FAD.  Flea eggs can also stay dormant for several years in the environment, hatching when they sense a warm body in the house.

In summary, fleas and ticks are very common parasites. They are associated with diseases and avoidance of infection is strongly recommended.  Luckily, there are many safe, new products available for prevention.

How To Remove Ticks

Summer is here, the days are longer, and we are spending more time outside. Our dogs are outdoors more often and for longer periods of time. And the ticks are waiting!

Even your indoor kitty is at risk of tick bites or infestation. Ticks are accomplished hitchhikers and can be transferred into the home on clothing, tools, furniture, and any other item that enters your home from the outside. Once inside they will lie in wait for a warm mammal to brush by them, then attach themselves and be on their way to a warm blood meal.

Besides being just plain icky, ticks are a health hazard to humans and pets. They are known to transmit tick-borne disease (TBD). Lyme disease, Rocky Mountain Spotted Fever, Rickettsiosis, Babesiosis, Tickborn Relapsing Fever, are just a few. TBD can range from simply annoying, to serious or fatal for you and your pets.

Regular use of a high-quality flea and tick prevention product like Frontline is a recommended measure. Daily inspection of your pets while grooming is an excellent way to discover a tick.

If you find a tick that has attached itself, engorged with blood or not, you can remove it safely if you follow these guidelines. It’s a good idea to keep removal supplies on hand so they are readily available if and when you might need them.

Items needed:

  • sharp tweezers or Ticked Off tick removal tool
  • gloves
  • soap
  • water
  • alcohol

Do not use oils, matches, nail polish or other techniques to remove ticks, as they are not only ineffective but dangerous. If the tick is traumatized the substances in their guts may be disgorged.  The potentially infectious organisms in their guts may then be transferred to the tick’s host.

  1. While wearing gloves, use your tweezers or Ticked Off tool to grasp the body of the tick as close to the tick’s head as possible.
  2. Hold the tweezers firmly on the body and pull the tick straight out without wrenching or yanking.  Take care not to puncture the tick’s body. You may have to apply quite a bit of pressure in order to withdraw the tick.
  3. When the tick is removed, dispose of it in alcohol, which will kill it. Do not crush the tick as the gut contents can be dangerous to you if the tick contains infectious organisms and they get on your skin. Do not flush it in the toilet or wash it down a drain as ticks can survive such attempts at permanent disposal.
  4. It is best to transfer the withdrawn tick to a dated bottle or a zipper lock plastic bag that has a bit of alcohol in it. If you or your pet does develop TBD symptoms* then the tick can be inspected at a laboratory and the appropriate treatment started.  If there are no symptoms after 40 days you may throw the bag or bottle away.
  5. If it appears that some of the tick did not come out of your pet’s skin you can use an alcohol sterilized needle to take out the leftover pieces.
  6. Clean the wound site with soap and water. Then wipe the site with alcohol. Keep the wound clean and disinfected in order to reduce the risk of secondary infection.

*Several of the many, many common symptoms of TBD (tick- borne disease)

  • Lack of appetite
  • Weight loss
  • Lethargy
  • Depression
  • Discharge from the eyes or nose
  • Diarrhea
  • Nosebleeds
  • Vomiting
  • Swelling of the extremities
  • Lightening of the color of the nose
  • Continuing skin and ear infections
  • Weakness
  • Muscle wasting
  • Pallor
  • Kidney failure
  • Liver failure
  • Uveitis—inflamation of the uvea of the eye
  • Increased thirst
  • Increased urination
  • Dilated pupils
  • Enlarged lymph nodes
  • Arthritis
  • Incontinence
  • Anemia

Only one or two of these symptoms may be present with a tick-borne illness and any of these symptoms may be indicative of many other diseases, so please consult your veterinarian should you notice any change in your pet.

 

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