Is it really necessary to test your pets for certain diseases at the annual veterinary visit? And what about paying for vaccinations and monthly preventive medications? Dr. Gene Pavlovsky, director of Veterinary Medicine South Clinic, part of the University of Illinois Veterinary Teaching Hospital, asserts that these measures can’t be skipped when it comes to heartworm and Lyme disease. Both are potentially life threatening.
What Is Lyme Disease?
“Lyme disease is a bacterial infection that commonly affects dogs and only rarely cats,” explains Dr. Pavlovsky. “The bacteria, from a genus called Borrelia, are transmitted via a bite from a tick.” For this reason, the Lyme disease vaccination is recommended for dogs that frequently go outdoors where there are ticks.
Lyme disease may not cause noticeable symptoms right away, or ever. However, it may cause chronic illness resulting in arthritis, nephritis (inflammation of the kidneys), or even kidney failure.
“Most dogs infected with Lyme disease do not show any clinical signs. In many cases, one finds out that a dog was infected by seeing a positive result on a routine screening test,” says Dr. Pavlovsky.
“A small proportion of infected dogs, between 5% and 10%, may develop problems several months after infection. The signs usually include fever, reduced appetite, swollen joints, limping, vomiting, increase in thirst and urination, or lethargy.”
Because most pets do not show signs of having Lyme disease, early detection is particularly important. Routine screening can detect Borrelia antibodies in the blood, and when treatment is necessary, it involves a course of antibiotics.
What Are Heartworms?
Heartworm disease results from a parasitic worm, not a bacterial infection.
“Heartworms are blood-borne parasites that infect dogs and cats,” Dr. Pavlovsky states. “When a mosquito bites an infected animal, it will ingest heartworms in the early immature stages of life along with the blood meal. Then that mosquito will transmit the heartworms to other animals via a bite.”
Dogs are more likely than cats to become infected with heartworms. However, no treatment options exist for heartworm disease in cats. Therefore, it’s important to prevent heartworms in our feline friends by administering preventive medications.
In contrast to Lyme, which poses a higher risk for pets that go outside often, heartworm prevention is important for both indoor and outdoor pets.
“Mosquitoes are present in most parts of the country, and they are able to gain access to indoor environments. Even dogs and cats that rarely or never go outside are still susceptible to the disease,” says Dr. Pavlovsky.
After entering the pet’s body through the mosquito bite, the worm grows to maturity within the animal.
“Over a period of several months, heartworms can reach several inches in length. They take up residence in blood vessels around the heart and sometimes in the heart itself,” Dr. Pavlovsky explains.
Heartworm Disease Symptoms and Treatment
“Presence of these worms incites inflammation and subsequent damage to the heart, surrounding blood vessels, and lungs. In severe cases, heartworms can be numerous and large enough to cause obstruction to blood flow and sudden death.”
Symptoms of heartworm disease include coughing, weight loss, and reduced activity levels. Heartworm treatment requires time and can be expensive.
“Treatment of heartworm disease is quite involved and is available only for dogs. There is no effective and safe treatment for cats. Treatment may involve injectable and/or oral and topical medications to kill the various stages of worms and is usually administered over several months or longer,” Dr. Pavlovsky states. In severe circumstances in which the worms completely block one of the heart valves, the surgical removal of heartworms can be done as a last resort due to high risk and the cost of surgery ranging between $1,000 and $3,000.
The Importance of Preventives
Thankfully, preventive products for both Lyme and heartworm disease are available for purchase by pet owners.
Heartworm preventives come as a monthly oral tablet, as a topical liquid, or as an injection that can last between 6 and 12 months. “The goal is to provide consistent prevention during the times of the year when heartworm disease can be transmitted. In most part of the country, this is all year round,” says Dr. Pavlovsky. Mosquito control is also instrumental in preventing heartworm in pets.
Vaccination and various flea and tick protective products, such as collars, topical solutions and oral medications are available for protection against Lyme disease. “Lyme disease does not cause problems in the majority of dogs. However, in those that do get ill, the disease can be serious and potentially life threatening,” Dr. Pavlovsky cautions.
“Vaccination is safe and effective, preventing illness. Tick control is an extra step in prevention but alone isn’t usually sufficient. Dogs and cats bitten by ticks may be infected with other tick-borne illnesses, so Lyme disease is not the sole concern.”
While options such as those listed above are important for preventing illness, they do not guarantee that a pet will never be infected with Lyme or heartworm disease. Annual testing fills that potential gap.
The Importance of Annual Testing
“Heartworm prevention products are not 100% effective, and many pet owners do not use prevention or use it irregularly. Screening for heartworm and Lyme disease allows us to identify animals carrying the diseases so we can treat them during the early, more treatable stages of disease,” Dr. Pavlovsky states. Treating infected pets helps to prevent the spread of these diseases to others.
Screening also makes it possible to determine whether infections in an area are high or low, which allows veterinarians to evaluate the effectiveness of the prevention strategies being used.
Annual testing is especially important in areas where heartworm and Lyme disease are common.
For the year 2024 so far, Champaign County prevalence of canine heartworm disease is 0.25%, feline heartworm disease is 0.51%, and canine Lyme disease is 1.56%. Dr. Pavlovsky recommends the Companion Animal Parasite Council website (capcvet.org) as a reliable resource to discover prevalence of these diseases in your area. (Prevalence is defined as the proportion of a population who have a specific condition in a given time period.) To keep pets safe, veterinarians recommend both preventive measures and annual testing to keep heartworm and Lyme disease at bay.
By Lauren Bryan
The photo featured at the top of this page shows University of Illinois veterinary students caring for pets at an outreach event with the college’s community medicine program.
