4DX Testing
When Spring arrives all vet clinics start calling dog owners to remind them that their seasonal 4DX test is due, but what is this? Simply put, a 4DX is a simple blood test that checks to see if your dog has antigen to heartworm disease or antibodies to one of the five tick-borne diseases (Ehrlichia canis, (Ehrlichia ewingii), Borrelia burgdorferi (Lyme Disease), Anaplasma phagocytophilum (and Anaplasma platys)).
This is a screening test, which gives us a ‘yes’ or ‘no’. If a positive result occurs we need to do further testing. The 4DX test is fast and done in the clinic and should be done every spring if living in Canada. If you and your pet are lucky enough to spend winters elsewhere it should be done twice a year. Detecting these diseases early means that we can treat them early and usually successfully.
These conditions are not that common in our region, but several cases have been diagnosed in the last 5 years. Many of these cases are from rescue foundations coming from other countries. Unfortunately, a few of these cases opted to NOT treat their dogs. This means that we have the potential for more cases in our area as mosquitoes and ticks bite these dogs and then travel to your dog. There are no laws requiring dog owners to treat their dog even if the disease is infectious.
All dogs should be given Preventative medications during the months of June to (and including) October, even November if it is still warm. If you travel to warm areas during the winter with your dog this medication should be continued year round. Often people will comment that their dog spends 90% or more of their time indoors. This does not matter since I’m sure we have all been bitten by a mosquito inside our homes!
The focus is on diagnosis and prevention of these diseases!!
The key point to remember is that these are all preventable vector-borne diseases that can be deadly if left undetected and untreated.
There is more information on these diseases and types of preventatives below. If you have questions regarding the diseases, or the best preventative medication to use for your dog, please don’t hesitate to
Heartworm Disease
Heartworm or Dirofilaria immitis is carried by mosquitoes. The heartworm microfilaria (microscopic worms) is located in the saliva of the mosquito which is then transmitted to the animal by a bite. Once the microfilaria makes its way into the bloodstream it will migrate to the pulmonary artery and ventricle (right generally) of the heart. It will then cause growths and damage to the walls of the heart disrupting the blood flow.
Under ideal conditions, the entire life cycle (microfilaria to mature adult) takes 184 to 210 days. Because only mature adults are capable of reproduction, dogs do not typically become microfilaremic for 6 to 8 months after initial infection. Adult heartworms typically live for up to 5 years in dogs.
Symptoms of heartworm infestation can include a mild persistent cough, decreased appetite, reluctance to exercise, weight loss, as well as fatigue after moderate activity.
A long term issue that can result from Heartworm infestation is hypertension (high blood pressure). This is due to hardened arteries which do not allow the arteries to expand and work when higher levels of oxygen is needed in the tissues.
A diagnosis is based on if the antigen is present on a bloodwork screen. Treatment for heartworm is most commonly Diroban or Immiticide (Melarsomine dihydrochloride), which is an injection given in a series of Intravenous injections, generally 3).
It is important to keep your animal up to date with their dewormer medication in prevention of heartworm for them to stay happy and healthy. The medication we recommend is Interceptor Plus.
Ehrlichia
Ehrlichiosis is a disease spread by ticks’ saliva, caused by the bacteria Ehrlichia. Ehrlichiosis will enter the body once bitten by an infected tick and begin by invading the immune system, specifically a type of cell called a monocyte, and continue to invade different systems of the body. The most common tick that carries Ehrlichia is the Brown dog tick.
The 3 general stages of Ehrlichiosis are the acute stage, subclinical and clinical/chronic stage.
Most animals are seen in the acute stage of the disease and may present with symptoms such as weight loss, respiratory distress, fever, swollen lymph nodes, bleeding/hemorrhaging (due to the low platelet levels in affected dogs) and/or neurological disturbances. This stage may last two to four weeks, and some dogs may eliminate the infection or head into the sub-clinical phase.
The sub-clinical phase represents the stage of infection in which the organism is present but is not causing any outward signs of disease. Sometimes a dog will pass through the acute phase without its owner being aware of the infection. These dogs may become sub-clinical and develop changes observed at the laboratory level yet have no apparent signs of illness. This phase is often considered the worst because there are no clinical signs, and the disease, therefore, goes undetected. The only hint that a dog may be infected during this phase may be when a dog shows prolonged bleeding from the puncture site where a blood sample was drawn. Dogs that are infected sub-clinically may eliminate the organisms or may progress to the next stage, clinical ehrlichiosis.
Clinical ehrlichiosis occurs if the immune system is not able to eliminate the organism. Dogs are likely to develop a host of problems such as anemia, bleeding episodes, lameness, eye problems (including hemorrhage or blindness), neurological problems, and swollen limbs. If the bone marrow (site of blood cell production) fails, the dog becomes unable to manufacture any of the blood cells necessary to sustain life.
To diagnose Ehrlichiosis blood work may be done to detect antibodies (4DX), other tests including PCR (polymerase chain reaction test) can be done as well. Once an infection is confirmed antibiotics may begin to treat the infection, depending on the severity of infection additional treatment may be required for the symptoms caused by Ehrlichiosis.
The best way you can keep your pet happy and healthy away from Ehrlichiosis is to keep them updated on their parasite prevention as well as test them if there is a suspected infection.
Humans can get canine ehrlichiosis from tick bites but cannot get the disease directly from their dog. The disease is only transmitted through the bites of ticks. Therefore, even though the disease is not transmitted directly from dogs to humans, infected dogs serve as sentinels or warnings to indicate the presence of infected ticks in the area.
Lyme Disease
Borrelia burgdorferi is the bacteria that causes Lyme Disease, which is spread by the bite from a tick. The most common tick which can spread this disease is the Deer tick (also known as the Black- legged tick or the Western Black-legged tick).
When the tick bites the bacteria enters through the skin and travels to circulate through the bloodstream to disrupt many internal systems, tending to localize in the renal system and joints.
Animals can remain asymptomatic after being bitten however, symptoms that they may show are fever, swollen joints, stiffness, lack of appetite, depression, sensitivity to touch, lameness, and lethargy to name a few. Antibodies that are created when Borrelia burgdorferi is in the body are generally not detectable until 4-6 weeks after the infection occurs, therefore is generally not diagnosable until 4 - 6 weeks after infection.
To diagnose Lyme Disease special tests may be used to detect the antibodies in the blood.
The best way to keep your pet safe from Lyme disease is to limit their exposure to ticks such as walking on paths when on hikes and limiting the long grass, as well as most importantly keeping them up to date on their parasite prevention medications such as Bravecto or Nexgard.
Anaplasmosis
Anaplasma Phagocytophilum is the gram-negative bacterium that causes Anaplasmosis, which is like Lyme disease however it can be slightly more difficult to detect, and both are spread by ticks, most commonly the Deer Tick (also known as the Black- legged tick or the Western Black-legged tick). Once the tick has made its bite, the bacterium spreads to the bone marrow as well as spleen giving access to many host cells, commonly presenting in neutrophils (white blood cells) in peripheral tissues as well as showing symptoms in severe cases of anemia, leukopenia, and thrombocytopenia. The replication occurs in the cytoplasm of the host cell then bursts free.
The incubation period for this bacterium is approximately 1 - 2 weeks. Symptoms include lethargy, vomiting, diarrhea, fever, and loss of appetite; however, it is common to be asymptomatic. Generally, Anaplasmosis can be detected by the antibodies that will be present in bloodwork, however if symptoms are not present, these antibodies may suggest a previous infection of Anaplasmosis.
The most common treatment for Anaplasmosis is the antibiotic, Doxycycline. This antibiotic inhibits/blocks the protein synthesis of Anaplasma Phagocytophilum preventing replication and protein living conditions for the bacteria. Other supportive care such as fluid therapy, or additional medications and monitoring may be required depending on the severity.
The most common areas to find this species of tick is southern British Columbia, southeastern and south-central Manitoba, southern, eastern, and northwestern Ontario, southern Quebec, southern New Brunswick and Grand Manan Island, and parts of Nova Scotia.
The best way to prevent an infection of Anaplasmosis is to keep your animals updated on their tick and flea medications year round! The ones we recommend are Bravecto (chewable or Topical) or Nexgard(chewable).
Treatment is the best policy!!
These medications are prescription and requires being seen by a veterinarian, within 365 days, at our facility to be prescribed.
