Infectious Disease Screening
Protect Your Pet From Infectious Diseases
Routine screening for various infectious diseases is an important part of keeping your pet happy and healthy for as long as possible. Infectious diseases can be spread animal-to-animal or through insect vectors like ticks and mosquitos. Common infectious disease screening that we may recommend include heartworm and tick-borne diseases for dogs and feline leukemia and feline immunodeficiency virus in cats.
Recommendations for Infectious Disease Screenings
Heartworm/Tick-Borne Disease Screening
For dogs, the American Heartworm Society recommends yearly heartworm screening and the Companion Animal Parasite Council recommends yearly screening for tick-borne diseases. A fast, reliable combination blood test for heartworm and the three most common tick-borne diseases is readily available for in-house use.
Feline Retroviral Disease Screening
For cats, the American Association of Feline Practitioners recommends screening for FELV/FIV in the following situations: all new kittens; all cats entering a new home, especially one with cats; sixty days after being bitten uy an unknown animal; annually if the cat goes outdoors, especially if the cat often fights with other cats; and all sick cats regardless of previous negative results.
Heartworm Screening Details
Why is Yearly Heartworm Testing Important?
Heartworm disease is a serious, progressive disease and the earlier it is detected, the better the chances the pet will recover. There are few, if any, early signs of disease when a dog or cat is infected with heartworms. Detecting the presence of heartworms with a blood test is an important step in allowing for early treatment. Early detection of heartworms also helps prevent spread to other pets in the area.
Why Test for Heartworm if a Dog is on Prevention?
Annual testing is important, even when dogs are on heartworm prevention year-round to ensure that the prevention program is working. Heartworm medications are highly effective but dogs can still become infected. If you miss just one dose of a monthly medication—or give it late—it can leave your dog briefly unprotected. Even if you give the medication as recommended, your dog may spit out or vomit a heartworm pill—or rub off a topical medication. While heartworm preventatives are highly effective, nothing is 100% effective. If you don’t get your dog tested, you won’t know your dog needs treatment.
Why Don't Cats Get Yearly Heartworm Testing?
Heartworm infection in cats is harder to detect than in dogs because cats are much less likely to have the adult female heartworms that are needed for detection with routine in-clinic testing. The preferred method for screening cats includes the use of both an antigen and an antibody testing. The antibody test is used to detect exposure to heartworm larvae while the antigen test looks for the adult female worm. Because the antibody test is not a routine in-house screening test, it is not common practice to test cats for heartworm each year.
Tick-Borne Disease Details
Ticks can carry a wide range of diseases, but only the three most common are tested for using the in-house tick-borne disease screening test. Lyme, Anaplasma and Ehrlichia are all types of bacterial diseases transmitted by ticks. Lyme disease is probably the most well known tick disease but both Anaplasma and Ehrlichia can also be found in Oswego County.
Lyme disease is caused by infection with the bacterium Borrelia burgdorferi. Only 5-10% of dogs that are infected are likely to show clinical signs of Lyme disease. Signs typically occur at the chronic disease stage 2-5 months or longer after infections. The most common symptoms of Lyme disease are lameness, swollen lymph nodes, joint swelling, fatigue, and loss of appetite. In addition, serious kidney complications and death can occur in association with Lyme disease in dogs.
Anaplasma is another type of bacterial disease. There are two types of Anaplasmosis and a dog may be infected with either one or both at the same time.
Granulocytic anaplasmosis is an infection of white blood cells. Many dogs do not develop obvious signs of the disease but when they do, signs may be vague and include lethargy, lack of appetite, and fever. Some dogs may become lame because their joints are painful. Less common signs include vomiting, diarrhea, coughing, and difficulty breathing but most dogs recover well with appropriate treatment.
Infectious cyclic thrombocytopenia is an infection of blood platelets. Signs of disease may include lack of appetite, lethargy, fever, bruising on the gums and stomach, nosebleeds, and weight loss. Most dogs with infectious cyclic thrombocytopenia develop only mild disease and recover quickly with appropriate treatment.
Ehrlichia is another bacterial disease that is similar to Lyme and Anaplasma. There are three phases of illness with Ehrlichiosis. In the acute phase, one to three weeks after the tick bite, Ehrlichia replicates and attaches to white blood cells. During this phase the immune system begins to attack the bodies own platelets. The dog may be lethargic, have a poor appetite, enlarged lymph nodes or a big spleen. They may have a fever or neurologic sypmtoms. Dogs treated during this phase often recover uneventfully. Dogs not treated in the acute phase will move into the subclinical phase where the organism lies dormant for months or years. There may be mild bloodwork changes but overall the dog appears healthy. If the dog moves to the chronic phase of infection, low platelet numbers return and abnormal bleeding is common. Inflammation of the eye (uveitis), neurologic signs and kidney damage may develop. Dogs who reach the chronic phase have a lower chance of recovery.
Feline Retroviral Disease Details
Feline Leukemia Virus (FeLV)
Feline leukemia virus can cause a variety of diseases in cats, including cancers like lymphoma or leukemia. FeLV invades various types of cells within the immune system and bone marrow, leading to cell death or mutation of the cell’s genetic code. The changes in the cell’s code may make the cell cancerous, although this change may not occur for months to years after infection.
Although the development of cancer is one outcome of FeLV infection, moderate to severe immune suppression is also common. Infected cats are less able to defend themselves against infections that are unlikely to cause problems in healthy cats. Affected cats may develop symptoms consistent with any opportunistic infections. FeLV-infected cats may also develop life-threatening anemia, abortions, severe intestinal inflammation, neurologic disease, or eye disease. Most cats tend to experience a progressive deterioration in their health over time. FeLV is almost always fatal within three years of diagnosis. There is currently no treatment for FeLV-infected cats other than symptomatic care.
FeLV spreads by direct contact between cats. The virus is shed in large quantities in the saliva of an infected cat as well as in other bodily fluids such as nasal secretions, urine, and feces. Close contact activities that may spread the diseases include mutual grooming, biting, sharing litter boxes and food bowls, and mating. While the majority of cats exposed to FeLV will become persistently infected, up to 30% may successfully clear the virus. For those cats that do become persistently infected, it may be many months or even years between the initial infection and the onset of clinical disease. During this time, virus particles may be continuously shed in the cat's saliva and infect others.
Feline Immunodeficiency Virus (FIV)
Feline immunodeficiency virus is quite similar to HIV in humans. In infected cats, FIV attacks the immune system, leaving the cat vulnerable to many other infections. Although cats infected with FIV may appear normal for years, they eventually suffer from immune deficiency, which allows normally harmless bacteria, viruses, parasites, and fungi to cause severe disease. Though there is no cure for FIV, recent studies suggest that cats with FIV commonly live average life spans, as long as they are well cared for and not also infected with feline leukemia virus.
The primary mode of transmission for FIV is through bite wounds from an infected cat. Casual, non-aggressive contact, such as sharing water bowls or mutual grooming, does not appear to be an efficient route of spreading the virus. As a result, cats in households with stable social structures where housemates do not fight have less risk of acquiring FIV infections.
There are three phases of infection with FIV. The acute phase of infection generally occurs one to three months after infection. At this time, the virus is carried to lymph nodes, where it reproduces in white blood cells and then spreads to other lymph nodes throughout the body. This leads to temporary lymph node enlargement that is often accompanied by fever, depression, and lack of appetite. This phase of infection may be very mild and is often missed or attributed to other causes of fever.
After the acute phase cats will enter an asymptomatic phase that may last for months or years. During this time, the virus replicates very slowly within the cells of the immune system and cats will not show any outward signs of illness. Some cats will remain in this stage and never progress to more severe disease.
Most cats will eventually enter a progressive immunocompromised state leading to secondary infections which causes the majority of illness related to FIV. In this state, cats may develop chronic or recurrent infections of the skin, eyes, urinary tract, or upper respiratory tract. Inflammation of the gums and severe dental disease, known as gingivostomatitis, is common in cats infected with FIV, and they are significantly more likely to develop cancer and immune-mediated blood disorders than healthy cats. Weight loss, seizures, behavioral changes and neurological disorders are all possible. The severity of these illnesses can vary greatly, but once cats become ill with multiple infections or cancers, survival time is usually no more than a few months. Unfortunately, there is currently no cure for FIV.