Pet Parasites

Heartworm disease is being reported with increased frequency in San Diego County due to the increased number of mosquitoes resulting from the wet weather. Mosquitoes transmit the heartworm larvae, which grow into adult spaghetti-like strands of worms in the heart and surrounding blood vessels; left untreated, this disease causes heart failure and death. The treatment for heart disease is costly and bears some risk-when the adult worms are killed with treatment, the pet may suffer a major stroke, embolism, or other severe side effects, which may also be fatal. The best measure to take is PREVENTION, which consists of giving a monthly application to prevent any larva from developing into adult worms. Prior to starting heartworm preventative, a simple blood test is run to confirm heartworm infestation is not already present.

Heartworm preventatives available include Interceptor, Heartguard Plus, and Sentinel. These all prevent intestinal parasites-roundworms, hookworms, and whip worms as well. Intestinal worms, if untreated, cause symptoms ranging from weight loss, diarrhea, vomiting and poor coat quality to anemia, severe weakness, and even death. It is recommended that you have a stool sample from your pet checked by your veterinarian at least annually, and when your pet has symptoms of intestinal disease. The feces is examined microscopically for the presence of intestinal parasite eggs. Sentinel, in addition, acts by sterilizing fleas, preventing their eggs from hatching, thus reducing the flea population and associated problems: skin irritation, secondary bacterial infection, allergies, blood loss and anemia, and infestation with tapeworms. Tapeworms, rice-like segments pet owners observe around their pet's bottom and in the stool, result when the pet ingests fleas carrying the tapeworm larva. Thus animals do not contract tapeworms from each other directly; the flea is necessary to complete the life cycle. Your veterinarian has medications to treat tapeworm infestation and in addition will recommend improved flea control. Flea control measures include: bathing, dipping, collars, Sentinel ("flea birth control"-an oral tablet that acts by sterilizing fleas), Capstar (oral tablet offers rapid elimination of adult fleas, usually within 30 minutes), Comfortis (month-long chewable tablet that kills fleas and prevents reinfestations), Advantage topical (kills fleas up to thirty days with monthly application), Frontline topical (kills fleas and ticks), Revolution topical (heartworm preventative and kills fleas and ticks as well), Vectra topical (works by killing adult fleas, preventing development of immature flea stages, and repelling ticks and mosquitoes), Trifexis (monthly chewable tablet for dogs that kills fleas, prevents heartworm disease, and treats/controls adult hookworm, roundworm and whipworm infections), and-very important-treating the environment with carpet powders, foggers, or sprays. It is important to use treatments on a monthly basis due to the flea life cycle. Otherwise, fleas can hatch and develop new infestations.

Our current recommendations include having your pet on heartworm prevention year round with annual testing, flea control year round, and having a stool sample checked once a year, or more often if indicated, for intestinal worms. Our current favorite products include Comfortis, Vectra, and Trifexis.  For heartworm preventatives, we prefer Interceptor, Sentinel, or Heartguard. Heartworm disease is not as commonly diagnosed in cats as in dogs, but we have tests and preventatives available for cats as well. Please refer below  for further information.

Flea Control

Fleas are the most common external parasite of companion animals. Flea allergy dermatitis is the most common skin disease of dogs and cats! Flea control has always been a challenge for veterinarians and pet owners because the adult fleas cause the clinical signs, yet the majority of the flea population (eggs, larvae, and pupae) is to be found off the pet in and around the home. The ideal flea control program utilizes products that target the various stages of the flea life cycle, not only the adult fleas on the pet. In order to help you to select the most appropriate products to achieve a flea-free existence for an allergic pet, we will start by telling you about the life cycle of the flea.

The Life Cycle of the Flea

Ctenocephlides felis
Eggs are laid in the hair coat and are designed to fall of the host. They are resistant to insecticides, but susceptible to various Insect Growth Regulators. Larvae develop in the host's environment and feed on adult flea feces (blood) that fall out of the hair coat of the pet. Larvae are susceptible to traditional insecticides, borates and insect growth regulators. Larvae eventually spin cocoons (often within carpet fibers) for pupation. Pupae are resistant to freezing, desiccation, and insecticides. Pupae can lie dormant for many months; they are stimulated to expupate as emergent adults by vibration, warming and increased carbon dioxide. Normally, expupation occurs when a host is near and the new flea finds the pet within seconds of emergence. Emergent fleas are fairly mobile and can survive a few days without a host, if in a suitable environment. New fleas begin feeding within hours of finding a dog or cat. Once a blood meal has been taken, the flea can survive only a short time if it is dislodged from the host. New fleas experience very high mortality on healthy adult hosts. Most fleas do not survive 72 hours on an animal that is itching and able to groom itself. Unfortunately, limited egg production does occur even on allergic animals. The entire life cycle of C. felis can be completed in as few as 16 days.

Flea Control Recommendations

For the flea allergic patient, 100% flea control is required to remain symptom-free. Even very minimal exposure may be sufficient to perpetuate itching in a hypersensitive patient (one or two bites per week are enough!). Until very recently, veterinarians and pet owners have had to control fleas by treating the environment of the animal for the immature stages of the flea. This approach, although effective when properly instituted, is labor intensive and requires frequent repetitive applications. Application of adulticides on the animal has merely been of palliative value. The safe insecticides previously available to us did not kill fleas instantly or were not long-lasting enough to ensure adequate protection from flea bites. The female flea survived long enough to lay a few eggs and perpetuate the life cycle.

Today's Flea and Parasite Control Products

Recently, some new products have been added to our flea control arsenal. These appear to be highly efficacious, long lasting and have a very low potential of harmful side effects. It may well be that these promising products will revolutionize flea control in the United States.

Trifexis ® (spinosad + milbemycin oxime) from Elanco/Lilly
Trifexis is a once-monthly tablet for dogs that kills fleas, prevents heartworm disease and treats and controls adult hookworm, roundworm and whipworm infections. And since it's beef-flavored, you can offer it as a treat.  Available by prescription through your veterinarian.

Comfortis™ (spinosad) from Elanco/Lilly
Comfortis™ provides month-long flea protection for dogs, and is available in a beef-flavored chewable tablet. Comfortis chewable tablets kill fleas and prevent flea reinfestations. It starts to kill fleas within 30 minutes.

Vectra 3D® from Summit VetPharm (for use in dogs and puppies only)
This is a topical product that is applied monthly. It protects your dog against four species of ticks, three species of mosquitoes, and fleas. It works by killing adult fleas, preventing development of immature flea stages, and repelling ticks and mosquitoes. Vectra 3D® is for use in dogs over the age of 7 weeks.

Vectra 3D® from Summit VetPharm (for use in cats and kittens only)
This is a topical product for cats and kittens that is applied monthly. It kills all fleas and controls the various flea stages. It can be used on kittens as young as 8 weeks of age.

Program® And Sentinel® (Lufenuron) from Novartis
This is available as a once a month pill to be given with a full meal. These are prescription drugs. Adult fleas that feed on animals treated with lufenuron produce sterile eggs. The product does not kill adult fleas. It is a very easy way to break the flea cycle but pets remain fully susceptible to the emergence of any fleas from pupa already present in the environment. Therefore, 4 to 7 months may pass before the flea-free state is reached. In order to stop the life cycle, every animal in the client's environment must receive lufenuron. Pets should be sprayed for fleas with an adulticide during the first few weeks of starting Program® or Sentinel®

Capstar® (Nitenpyram) from Novartis
This is an oral tablet for dogs and cats as young as 4 weeks of age. It offers extremely rapid and complete killing of adult fleas on the pet after administration. It is safe enough that the tablets may be used as needed, as often as once per day, whenever you see fleas on your pet. This product should be used in combination with an insect growth regulator to knock out fleas when these slower products are being used for long-term control. It can also be used when the pet has visited a flea-infested environment for rapid protection.

Advantage® (Imidacloprid) and K9 Advantix® from Bayer
Advantage® is marketed as a drip-on for both dogs and cats. Advantage® seems to be very well tolerated by sensitive cats. It provides flea knockdown in 24 hours. For cats, 100% killing can be maintained for 21 days and for dogs, 90% for 28 days. The pet can remain flea-free even if he/she gets wet. Advantage® is water-resistant, so it kills fleas even after a bath, swimming, or exposure to rain or sunlight. So the pet can enjoy his/her normal activities without worry. Imidacloprid has no efficacy against ticks. K9 Advantix® is effective against ticks, as well as fleas and mosquitos. K9 Advantix® must never be used on cats due to their unique physiology and inability to metabolize certain compounds, and should be used with extreme caution on dogs living in households where cats are present. If applied to a cat, or ingested by a cat actively grooming a recently treated dog, this product may have serious harmful effects.

Frontline Plus® (Fipronil) from Merial
Fipronil is a broad-spectrum insecticide available as a spray or drip-on. Fipronil binds chemically to the hair and is absorbed through the hair follicle by the sebaceous glands. It is labeled for puppies and kittens of 8 weeks and older and bathing does not wash off the product. It is also effective against ticks. The product must be applied no more than once a month. Frontline Plus® contains the insect growth regulator, S-methoprene, and so provides control of eggs and adult fleas.

Revolution® (Selemectin) from Pfizer
This product is topical and designed as a once-a-month heartworm preventative and flea preventative for dogs and cats as young as 6 weeks old. It also kills adult fleas and can be used to treat Sarcoptic mange, ear mites, and ticks. It also helps control roundworms and hookworms in cats. The product is placed on the skin at the back of the neck, but is absorbed in the body to have its effect when female fleas ingest it with a blood meal. Adult fleas will die slowly, but more importantly, any eggs laid prior to death will never develop. It is most useful as a preventative for flea infestation and in the presence of a flea problem in an allergic pet, other insecticide treatment will be recommended at first. It is a prescription drug.

Note: It is recommended that if you bathe your pet or have it bathed, that you allow at least 24 hours afterward before applying a topical flea preventative, such as Advantage, Frontline, Revolution, or Vectra.

Heartguard®Plus (Ivermectin/Pyrantel) from Merial
This product is available as a real-beef chewable that most dogs find palatable and thus can be offered to the dog by hand. This product is a highly effective protection against heartworm disease. Monthly treatment with Heartguard®Plus also provides effective treatment and control of roundworms and hookworms.

Interceptor Flavor Tabs (milbemycin oxime) from Novartis
Interceptor Flavor Tabs are a palatable once-a-month oral tablet, preventing against heartworm disease, as well as aiding in the control of adult hookworm, roundworm, and whipworm in dogs and puppies.

Drontal® (Praziquantel/Pyrantel pamoate) from Bayer
This is a broad-spectrum dewormer for cats and kittens. Drontal® is an oral tablet that aids in the removal of common parasites including tapeworms, hookworms, and large roundworms, all of which are intestinal parasites.

Intestinal parasites are potentially zoonotic, which means they may also cause disease in humans if exposed. Intestinal parasites transmitted from dogs and cats to humans may result in scarring of the skin, or blindness, and are particularly of concern in children.

Drontal® (Praziquantel/Pyrantel pamoate/Febantel) from Bayer
This product is a broad-spectrum anthelmintic for puppies and adult dogs. This is an oral tablet, available in three sizes, that serves for the removal of tapeworms, hookworms, and whipworms. Depending on your vet's recommendation, this product can be used up to every three months.

Droncit® (Praziquantel)
Droncit® is a cestocide and is available for both cats and dogs as an oral tablet that are sized for easy administration. This product serves for the removal of tapeworms: Dipylidium canium and Taenia taeniaeformis. Droncit® is absorbed, metabolized in the liver, and excreted in the bile.

How Animals (and People!) Get Worms


  • Transferred by ingesting infested soil or feces; eggs can survive in soil for years (10 yrs. +)
  • Roundworms are passed directly from mom to puppies and kittens; for puppies, worms are passed through placenta; for kittens, worms are passed through milk while nursing; nearly 100% of puppies and kittens are born with roundworms.
  • People get roundworms from infested soil and from infested fecal matter from pets or from wild animals - children and immune compromised people are most at risk.

Symptoms: Common signs of roundworm infestation in dogs and cats include diarrhea, vomiting, weight loss, and/or swollen abdomen. In humans, roundworm infestations tend to migrate causing damage to heart, lungs, liver, causing impaired sight or lost vision, and may prove fatal if infestation is at the site of the heart or brain.


  • 2 types; only Ancyclostoma is contagious to people; Sentinel and Interceptor prevent Ancyclostoma infestations
  • Transferred to pets from infested feces, contaminated soil, passed from mom to puppy or kitten by milk
  • Can make pups and kittens very sick - bloody diarrhea, anemia
  • In people causes "cutaneous larval migrants"; larva in infested water/ wet sandy areas and crawl through intact skin; results in rash, irritation

Symptoms: Since hookworms live and feed in intestinal tissue, symptoms typically include blood loss and inflammation, and may lead to anemia, debilitation and even death, especially in puppies. In humans, hookworms usually migrate under the skin; leading to rashes and itching; some may even compromise internal organs, such as the small intestine.


  • Transferred by ingesting infested feces or soil
  • Can survive in soil for years

Symptoms: Signs of anemia, stomach upset, weightloss, diarrhea, and hemorrhaging may occur, although occassionally no visible signs are present.


  • 2 Types:
    1.) Flea tapeworm; pet gets by eating fleas while grooming
    2.) Rodent/Rabbit tapeworm
  • People can get tapeworms by eating fleas, as well; most commonly affects children.

Symptoms: No visible symptoms may occur and usually the first indication of tapeworms is recognized from the passing of segments of tapeworms in the stool. However, some symptoms may include hunger, dizziness, fatigue, loss of appetite, weight loss, and vomiting.


  • Coccidia specific for species of animal (i.e. dogs can't get cat coccidia, etc.)
  • Ingested from infested soil or feces

Symptoms: Some common symptoms include bloody diarrhea, abdominal pain, listlessness, dehydration, and weight loss.


  • Consists of single celled organisms that live in the small intestines of dogs and cats.
  • Some symptoms include diarrhea and weight loss, but most cases are asymptomatic.
  • Transmitted by the consumption of cysts found in fecal matter. Giardia in the feces can contaminate the water and the environment.
  • A routine fecal test can detect Giardia.


  • Affects dogs AND cats
  • Carried by mosquitoes
  • Mosquitoes transfer larva between dogs, larva grow to adult worms in heart and cause congestive heart failure.
  • Need to know animal is heartworm negative when using Sentinel, Interceptor, or Heartguard due to allergic reactions to these medications with heartworm positive dogs
  • Preventatives work by killing larva dog/cat picked up over past month, thereby preventing adult worms from developing in the animal.
  • San Diego's weather allows for heartworm disease to be a concern all year - dogs should be on YEAR-ROUND prevention!

Symptoms: Some common symptoms include coughing, difficulty breathing, loss of appetite, sluggish behavior, vomiting and even sudden death.

→Heartworm prevention also protect against intestinal parasitism on a monthly basis; this is another important reason to give your dog oral heartworm preventative, as our dogs are continuously exposed to intestinal parasites in the environment and from other dogs.

Call Morena Pet Hospital at 619-275-0888.

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