Parasites

     There are a number of parasites that can affect our pets, (eg. fleas, heartworm, ticks, and intestinal worms), and these parasites can be detrimental to your pet's health. Many parasitic diseases can also be transmitted to humans, so parasite control is always a concern. The veterinary staff are very knowledgeable regarding the many types of parasites and can advise you on how best to protect you and your pet. Click on one of the following links for a brief description:


     When you receive the notice that your pet is due for its annual examination we request that you bring in a fresh faecal sample from your pet. The examination of the faeces is a convenient and easy method to determine whether your pet is harbouring internal parasites. Internal parasites are not only a concern for your pet's health but some are also a concern for you and your family.
     The internal parasites that we most commonly look for are the roundworm, hookworm, whipworm, and tapeworm. The life cycle of these parasites can be quite complicated within their host. We won't go into details of the life cycles here, however, what is important is that eventually the mature adult worms settle in the intestines and produce eggs. These eggs are shed with the faeces and infect the environment. Your pet can acquire a parasitic infection by the ingestion (eating) of faeces or infected prey, and by ingesting grass or dirt that is contaminated with eggs. Your pet can acquire hookworm or whipworm infections by frequenting contaminated areas, as the parasites enter the body through skin contact. Puppies and kittens acquire parasitic infections through ingestion of the mother's milk.
     Senior pets, puppies, and kittens are the most vulnerable for parasitic disease. A worm infection may interfere with normal food absorption and be the cause of lack of weight gain in mild cases. However, in severe infestations it can cause diarrhea, vomiting, intestinal obstruction, and life-threatening anaemia. A healthy adult animal infected by a few worms may not show any signs of disease, however it is a reservoir of infection that sheds eggs into the environment. All ages of pets can harbour parasites so treatment, preventative measures, and/or monitoring should be done on a regular basis.
     Humans can acquire a parasitic infection from their pets. Children and people with compromised immune systems are the most at risk.

     Roundworms: Humans are not the natural host for dog and cat parasites. The accidental ingestion of roundworm eggs results in a condition called Toxocarisasis (visceral larvae migrans). The eggs hatch and the larvae migrate through the visceral and muscle tissue looking for their natural host. This infection can cause fever, coughing, pain, and liver and spleen enlargement.
     Hookworms:  Hookworm infections cause a dermatitis called cutaneous larvae migrans or "creeping eruption". The larvae migrate through tissues searching for its natural host. For humans, the chance of contracting an infection in temperate climates is small. However, infection is common in tropical areas where soils are moist and sanitation is poor. Infection is acquired by walking barefoot in contaminated areas as the larvae penetrate the skin. Hookworm infection can also cause fever, coughing, and abdominal pain as well as presenting a very itchy rash on the skin.
     Tapeworms:  Tapeworm infestation cannot be detected by looking for eggs in the faeces. Tapeworm eggs are shed in small packets called proglottids and look like grains of rice. They can be shed with or without faeces and are found around your pet's anal area. Diagnosis of tapeworm is done by observation (often by the owner) or through consultation with your

Giardia Under the Microscope

veterinarian. Tapeworms have an intermediate host, meaning that the larvae must pass through a different species before it manifests itself and matures in its specific host, in this case the dog or cat. The intermediate host for the dog and cat tapeworms can be a number of other species including the flea, rabbits, mice, and other rodents. Therefore, if your pet is frequently outdoors and ingests mice or rabbit droppings or your pet has contracted fleas, it is assumed that a tapeworm infection follows and the pet will be treated appropriately.  
     Giardia is a common protozoan (single celled) parasite that affects many species but is most common among dogs, cats, humans, and beavers. When the cysts of the giardia are ingested, the cyst walls are digested and the organisms situate themselves in the small intestine. As the organisms increase in number and start to produce cysts, they cause an infection that results in severe diarrhea.
     Diagnosis is determined by a wet mount faecal smear. This smear must be created using a fresh, warm faecal sample. When viewed under a microscope, these motile organisms can be seen swimming about on the slide. Treatment is a course of appropriate antibiotics. 

     The following will assist in preventing parasite infection in your pet(s) and your family:
  • Do not feed raw diets and do provide fresh potable water.
  • Cover sand boxes when not in use and protect yard areas from faecal contamination.
  • Pick up all faeces immediately.
  • Do not allow your pet(s) to roam - keep them on a leash.
  • Practice good personal hygiene and wash hands thoroughly after handling animal waste.
  • Know the risks in the area where you are travelling and treat or prevent infection in your pet(s) accordingly.
  • Take your pet to your veterinarian for regular examinations and discuss parasite treatment or prevention.

 Reprinted from “The Pawsitive Express”, Vol 2, Fall 2012 and Vol 1, Spring 2014   




     Heartworm is a parasite spread from any infected canine (coyote, fox, wolf, dog) to your pet by a mosquito. The adult heartworm lives in the heart and large vessels of the heart. They prevent free flow of blood through the heart chambers which eventually leads to heart failure. Unfortunately, by the time you pet exhibits symptoms, the disease will have already caused severe damage to the heart. A dog with heartworm disease will fatigue easily and will not tolerate exercise. They will present with a cough and a poor general appearance.
     There are a number of different heartworm treatments and heartworm/flea treatments available. The medications are based on body weight, so young dogs under seven months of age will have to be weighed before medication can be dispensed. Dogs older than seven months that have not been on heartworm medication before must have a blood test before the medication can be dispensed. This ten-minute blood test can be run at the clinic.
     All heartworm medications are considered a treatment. They do not prevent heartworm disease but will treat any infection acquired over the last 30 days. These products are designed and packaged to treat your animal for the entire heartworm season which is mid-May through to late October. It is imperative that you treat your pet(s) each month until late in the fall, to make sure your pet does not harbour an infection. These products vary in method of application and cost. As well as heartworm, most products also treat intestinal worms.
  


Demodectic Mange:  This tiny worm-like parasite is Demodex canis. It lives in small numbers in the hair follicles of the skin on most dogs. Pups acquire this parasite from their mothers. When this parasite exists in small numbers on the dog, there is generally no issue with the animal's health. However, in young pups with weak immune systems the population of mites can proliferate. Demodex canis will usually appear between the age of three and six months. The pup will be presented with reddened areas with hair loss, around the eyes, the mouth and/or on the limbs. If the lesions remain localized the condition is mild and prognosis is good. Lesions generally resolve upon sexual maturity.  However, in a few cases, the lesions are more wide spread across the entire body. The hair loss covers a wider expanse of the body.  The reddened skin will become course and dry. This condition is very severe and if left untreated can be fatal. Treatment consists of long term treatment with a specific parasiticidal agent. A cure may be impossible to obtain but the animal can enjoy a near normal life by life long management of the condition with the curent therapy.

Fleas: Fleas are normally a problem during warmer months, however, they can also persist during cooler seasons due to their ability to survive indoors.
     The symptoms of fleas on pets are repeated itching, scratching, and chewing. Owners may also see live fleas or flea dirt (feces) on their pets. Constant itching and scratching may lead to patches of hair loss and reddened, irritated skin. Although many pets are very itchy and uncomfortable, some may show no signs at all. In addition to making your pet uncomfortable, fleas can also transmit other parasites, such as tapeworms.
     Treatment of fleas consists of a monthly application of flea medication that is available from the clinic.

Ticks: There has been a lot of media promotion regarding tick prevention. Companies with tick prevention products have been pushing owners to protect their pets.
With spring and summer seasons being warmer and longer, increased tick populations have been noted in Ontario in recent years. Climate change has made it possible for ticks transported by migratory birds to move further north.

    However, not all of Ontario is endemic, as these companies would like you to believe. Certain areas of the province have higher tick populations than others. Ticks do raise health risks to pets and humans. The black legged tick which potentially carries Lyme disease is of great concern for people. (See the articles ‘Ticks” and ‘Lyme Disease” for information on tick borne diseases following this article.) In the past, Dr. Wright saw on average about three tick cases in the clinic per year. Last spring/summer there were perhaps six. Prevalence in the Centre Wellington area has been quite low.  Yet other areas like the Niagara Region or Prince Edward County have shown a greater prevalence of ticks. How do you determine whether you should treat or not treat for ticks? The answer is three fold; education, monitoring, and prevention. There will be a different risk to you and your pet depending upon your

life style and where you travel.

 

Education: The best form of defense in any situation is to know what you are dealing with. The University of Guelph has an information page on ticks and tick borne diseases at http://www.guelphlabservices.com/files/PDC/003Ticks.pdf . Ticks look quite different once they have engorged themselves with blood.  It is important to be able to identify them at any stage of attachment.

Monitoring:  Once you can identify the ticks you can start monitoring for them. Each time your pet returns from the outside you should examine it thoroughly for ticks. Be aware that ticks like to climb onto long grass or bushes so that they can drop onto and attach to an animal. Avoiding areas of this nature can decrease the risk of a tick attaching. If you find a tick on your animal you will want to remove it. Using a special tick removal tool or a pair of tweezers grab the tick by the head, as close to the skin as possible. Pull straight out, firmly and slowly until you have removed it. Put the tick in a small container with a tight lid. It can be submitted to the local Public Health office for species identification.

Prevention: The need to use a tick prevention product is determined by the level of risk to your pet. If you live in or you will be vacationing in an area that is endemic for ticks you may want to consider prevention. There are four products on the market currently. Discuss your concerns with Dr. Wright or a staff member and they will help determine which product is best for your situation.

Lyme disease: If you are considering spending time in areas where Lyme disease is prevalent, then you may want to take the added precaution and have your pet vaccinated for Lyme disease. The Public Health website has a good map showing the areas prevalent for Lyme disease in Ontario at http://www.publichealthontario.ca/en/eRepository/Lyme_Disease_Risk_Areas_Map_2015.pdf .  Discuss your concerns with the veterinary staff.

Reprinted from "The Pawsitive Express" Spring 2016



Ticks - A pest most commonly seen in spring and fall are ticks. An encounter with a tick or ticks causes many a client to make a frantic call to the clinic. Ticks vary in their abundance and distribution across Canada.
     In Ontario one may encounter the American Dog tick (Dermancentor variabilis), Blacklegged tick or Deer tick (Ixodes scapularis), Brown Dog tick (Rhipcephalus samguineus), and occasionally the Lone Star tick (Amblyomma americanum). The real concern with ticks for us and our pets is the possibility of acquiring a vector-borne disease.  “Vector borne diseases are those transmitted by fleas or ticks among other parasites that infest dogs and cats. They can affect pets and people. Ticks can transmit a large number of diseases in North America including ehrlichiosis, Lyme disease, relapsing fever, Rocky Mountain spotted fever and tularemia.” (1)
     Dogs can acquire Ehrliciiosis, Lyme disease, and a condition called Tick Paralysis from tick bites. The Blacklegged tick (Ixodes scapularis) is well known for the transmission of Lyme disease. 
     Ticks prefer cool environments and are most prolific in the spring and fall. You and your pet will encounter them in wooded areas, scrub brush, grassy meadows, and pastures. 
     To protect your pet(s) avoid areas where ticks may be prevalent. A tick must feed for a minimum of 24 hours before disease transmission can occur. If your dog(s) frequents areas where there are likely to be ticks, it is advised you do a tick check on your pet(s) twice daily. Remove any ticks found with tweezers, ensuring to remove the entire head. You can also protect your dog(s) by using products that will prevent the tick from attaching to or staying attached to your dog(s). 
     “Revolution” from Zoetis has been a popular product with veterinarians and clients. “K9 Advantix” by Bayer has also been on the market for several years. Both these products are labelled for flea and tick control for dogs and are applied to the skin at the back of the neck on a monthly basis. This spring, two additional products will be available to guard against fleas and ticks in dogs. “Nexgard” produced by Merial is a chewable tablet to be administered monthly and Merck Animal Health has launched “Bravecto”, a chewable tablet to be administered once every three months.
     If you have a concern with regard to ticks and your dog(s) speak to a veterinarian about the risks in your area and what product would be best suited to protect your dog(s).

References:(1) Pets, Parasites and People, information flyer, companion Animal Parasite Council, 2007.
Infectious and Parasitic Dermatoses, Bayer Animal Health, Fifth World Congress of Veterinary Dermatology, Vienna, Austria, 2004, p. 33 - 37.
No Bite” Tick Control, Animal Health Today, Bayer Inc., Spring  2013 Volume 1, Issue 8. P 3 - 11
Grognet, J. D.V.M., Parasites Lost, Dogs in Canada, March 2010. P 24 - 27

Reprinted from "The Pawsitive Express" Spring 2015


Lyme Disease - 
Lyme disease is not actually a disease, but a syndrome with clinical signs associated with infection from the bacteria Borrelia burgdorferi. It is transmitted by ticks to host species such as dogs. Only one species of tick, Ixodes scapularis, (black legged tick), transmits the disease in Ontario. 

     Even if your animal has a tick sitting on them, it does not mean that they are going to get sick from Lyme disease. In Ontario it is very uncommon for an animal to get sick with Lyme disease, even after       a tick encounter. 

     There are many criteria that your veterinarian will use to evaluate if your animal truly has been         infected with this bacteria and needs to be treated with specific antibiotics(1). The four main questions   are:

·      Are the clinical signs consistent with Lyme disease?

·      Are specific antibodies against B. burgdorferi detectable?

·      Does the patient improve with therapy?

·      Does the patient live in or travel to an area endemic for I. scapularis?(1,2)

     The signs of Lyme disease are non‑specific and are often transient or only present shortly after initial infection. There are a variety of preventive and therapeutic options for Lyme disease including tick control, vaccination and drug therapy.In North America there are only two species of tick that can transmit Borrelia burgdorferi: Ixodes scapularis (3) and Ixodes pacificus.(4,5) 

     There are many factors that influence the prevalence of Lyme disease in a particular area. These include; the tick’s ability to survive and propagate in an area; the presence of a Borrelia burgdorferi reservoir species in that same area; the likelihood of the tick finding a susceptible host and the likelihood of an encounter with a tick.(3) The areas in Ontario that have established populations of ticks infected with B. burgdorferi are all located along the northern shores of Lake Ontario and Lake Erie.(6) The spring and fall are the times of year when there is a higher chance of a host having a tick bite.(7) It is very difficult to diagnose Lyme disease because only about 5‑10% of dogs exposed to Lyme disease develop clinical signs which are often non‑specific and variable.(3)

     There are many methods available both in veterinary clinics and laboratories to detect Borrelia burgdorferi spirochetes. Even when using these methods, the antibody is not detectable for the first three to four weeks after infection and will stay in the blood for years after the infection is cleared.(1) One of the most common in‑clinic tests used is the IDEXX SNAP test. A blood sample is taken from your dog and the Snap test will diagnose the presence of antibodies to heartworm, Lyme disease and Ehrlichia canis.

     Canine Lyme vaccines provide protection by inducing antibodies that kill B. burgdoferi when the bacteria are transmitted from the infected ticks to the vaccinated host.(9) Once a tick bites a vaccinated host, the antibodies prevent infection.

     In Canada, protection from B. burgdorferi via ticks has been shown to be effective through the use of K9 Advantix. This topical spot‑on product should be applied at least 7 days before suspected exposure to I. scapularis.(6) The use of  collars impregnated with amitraz have been shown to be more effective in interrupting the tick life cycle and be longer acting than topical applications of fipronil.(1)

     Prevention includes limiting the opportunity for contact with ticks by keeping dogs on leash and limiting contact with uncultivated grasses and bushes where ticks may reside. For humans, wearing long sleeved shirts and pants will help to prevent skin attachment.(1) The vaccines available for canine Lyme disease are not fully protective, but are recommended as part of the tick control program for dogs. Attached ticks should be removed as soon as possible and tick‑infested areas should be avoided whenever possible to reduce risk of infection.

References:

1. Krupka I, Straubinger RK. Lyme borreliosis in dogs and cats: Background, diagnosis, treatment and prevention of infections with Borrelia burgdorferi sensu stricto. Vet Clin Small Anim 2010;40:1103‑1119.

2.Littman MP, Goldstein RE, Labato MA, Lappin MR, Moore GE. ACVIM small animal consensus statement on Lyme disease in dogs: Diagnosis, treatment, and prevention. J Vet Intern Med 2006;20:422‑434

3.Fritz CL. Emerging tick‑borne diseases. Vet Clin Small Animal, 2009;39:265‑278.

4.Gary AT, Webb JA, Hegarty BC, Breitschwerdt EB. The low seroprevalence of tick‑transmitted agents of disease in dogs from southern Ontario and Quebec. Can Vet J 2006;47:1194–1200.

5.Ogden NH, Lindsay LR, Morshed M, Sockett PN, Artsob H. The emergence of Lyme Disease in Canada. Can Med Assoc J 2009:180(12);1221‑1224.

6.Ogden NH, Trudel L, Artsob H, Barker IK, Beauchamp G, Charron DF, Drebot MA, Galloway TD, O’Handley R, Thompson RA, Lindsay LR. Ixodes scapularis ticks collected by passive surveillance in Canada: Analysis of geographic distribution and infection with Lyme borreliosis agent Borrelia burgdorferi. J Med Entomol 2006:43;600–609.

7.Morshed MG, Scott JD, Fernando K, Geddes G, McNabb A, Mak S, Durden LA. Distribution and characterization of Borrelia burgdorferi isolates from Ixodes scapularis and presence in mammalian hosts in Ontario, Canada. J Med Entomol 2006;43:762‑773.

8.Leschnik et al.  Humoral immune response in dogs naturally infected with borrelia burgdorferi sensu lato and in dogs after immunization with a borrelia vaccine.  2010; Clin. Vaccine Immunol.17(5): 828

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