Lyme disease is a significant concern for dog owners, particularly in regions like Minnesota where ticks are prevalent. Ticks, including the black-legged tick (also known as the deer tick) which transmits Lyme disease, can remain active even in cold weather. Understanding how ticks find hosts, the bacteria causing Lyme disease, and its effects on dogs is crucial for prevention and timely treatment. This article delves into the complexities of Lyme disease in dogs, offering insights for concerned pet owners.
How Ticks Transmit Lyme Disease
Ticks are persistent parasites that can live for years, often entering a dormant stage during winter. They become active when ground temperatures reach approximately 45 degrees Fahrenheit, meaning they can be present even with snow on the ground. Ticks locate their hosts by detecting breath, body odors, heat, moisture, vibrations, and even shadows. While they cannot jump or fly, ticks are adept at attaching to unsuspecting hosts. They often adopt a “questing” posture on the tips of grasses or shrubs, extending their front legs in anticipation of a host brushing past. The black-legged tick, a common species in Minnesota, is the primary vector for Lyme disease, as well as other tick-borne illnesses like anaplasmosis and babesiosis.
Lyme disease is caused by a spiral-shaped bacterium called Borrelia burgdorferi. In humans, infection can lead to serious health issues, including a characteristic bull’s-eye rash and flu-like symptoms, and in some cases, chronic debilitating illness. However, the impact on dogs differs significantly. It is estimated that only about 5-10% of dogs exposed to the Lyme bacteria actually develop the disease. When symptoms do manifest, they typically appear around two months after infection.
Symptoms and Diagnosis of Lyme Disease in Dogs
The clinical signs of Lyme disease in dogs can include:
- Lameness: This may present as limping or an abnormal gait.
- Arthritis: Inflammation and pain in one or multiple joints.
- Enlarged lymph nodes: Swollen glands, particularly in the neck and rear quarters.
- Lethargy: A general feeling of weakness or fatigue.
- Fever: An elevated body temperature.
Skin lesions are notably rare in dogs affected by Lyme disease.
Diagnosing Lyme disease in dogs involves antibody testing, often performed concurrently with screenings for heartworm and other tick-borne diseases. A positive antibody test indicates that the dog has been exposed to the Borrelia burgdorferi bacteria and has developed an immune response by producing antibodies. It’s important to understand that a positive test does not necessarily confirm an active infection, but rather past exposure. Previous vaccination against Lyme disease does not affect test results; a vaccinated dog will not test positive solely due to the vaccine. Antibodies typically develop within a few weeks of exposure.
Managing a Positive Lyme Test Result
Many dogs that test positive for Lyme antibodies will never exhibit any clinical symptoms. Therefore, a positive test result alone does not equate to a diagnosis of Lyme disease. A collaborative decision between the pet owner and veterinarian is essential to determine the appropriate course of action, if any, for a dog that tests positive but shows no clinical signs. There is not a universal consensus within the veterinary community on how to manage such cases. However, for my patients who test positive and are otherwise healthy, I recommend the following:
1. Screening for Kidney Problems
The Lyme bacteria can cause direct infection or trigger autoimmune responses. A severe autoimmune complication is known as “Lyme Nephritis.” In this condition, the glomeruli – the kidney’s filtering units – become compromised. Healthy glomeruli effectively sieve waste products from the blood while retaining essential proteins. In Lyme Nephritis, the “sieve” develops holes that are too large, allowing vital proteins to be lost in the urine. This protein loss can overwhelm the body’s ability to compensate, leading to severe illness and potentially death. To screen for this, a Urine Protein Creatinine ratio (UPC) test is recommended for dogs newly diagnosed as positive on a Lyme test. A positive UPC warrants further investigation and treatment. If the UPC test is negative, proceed to the next recommendations.
2. Tick Prevention
Year-round tick prevention is strongly advised for all dogs exposed to Lyme bacteria. In Minnesota, this typically means using a preventative from the first thaw until the first hard freeze. For dogs that travel to milder climates, year-round application is even more critical. Several effective tick preventative medications are available. Popular options include topical treatments like Frontline and oral medications such as Nexgard, which offer convenient once-monthly protection.
3. Family Tick Safety Review
It’s crucial for the entire family to be aware of tick-borne disease prevention. While Lyme bacteria cannot be transmitted directly from dogs to humans, a positive test in your dog suggests that your family has also likely been in an area endemic for Lyme disease. Protecting your dog with tick preventatives indirectly helps safeguard your family, as ticks do not die after feeding and can move to new hosts. After outdoor activities, especially in wooded areas, perform thorough tick checks on all family members. Remember, it takes at least 36 hours for Lyme bacteria to be transmitted from an infected tick to a host. Prompt removal of ticks before this window can prevent transmission. To remove a tick, use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible and pull upward with steady, even pressure.
Lyme Disease Vaccine for Dogs
A highly effective vaccine is available to prevent Lyme disease in dogs. However, there is some debate within the veterinary community regarding vaccination for dogs that have already been naturally exposed to Lyme bacteria. Discussing the pros and cons of vaccination with your veterinarian is recommended to make the best decision for your individual pet.
