Lyme disease is an infectious disease caused by bacteria called Borrelia. The bacteria are most commonly carried by the deer tick, also called a black-legged tick. Infection occurs when a dog is bitten by an infected tick, although the tick must remain attached to the dog for at least two days before it is able to pass the infection onto the dog. The tick itself becomes infected by feeding on infected mice, birds, deer, and other animals.
Pennsylvania has led the nation in Lyme cases since 2011 — more than 12,000 new cases in 2016 — and southeastern Pennsylvania is the hotspot. Since 2015, Lyme disease cases have been recorded in every county in Pennsylvania.
If untreated, Lyme disease can blow up to cause chronic and debilitating arthritis, fatigue, impaired motor functions and senses, an enlarged heart, an even death in rare cases. When caught promptly and treated with antibiotics, full recovery is the norm.
Dogs that spend a lot of time outdoors are more likely to be infected, especially if they visit wooded areas where deer ticks are abundant. The highest risk areas are deciduous (hardwood) forests that have moist sandy or loamy soil and thick vegetation. This includes forested woodlands in the country as well as wooded areas in city parks.
The risk of infection is greatest in the warmer months of the year from spring through autumn when ticks are most active.
The tick should be removed promptly but carefully
so that none of the tick's mouthparts are left in the dog's
skin. If you are not sure how to do this, then take your
dog to a veterinarian to have the tick removed safely.
The tick can be sent to the laboratory to see if it is a
deer tick, and if it is, then it can also be tested to see if it is
infected with Lyme disease.
If the tick is an infected deer tick, then the dog should be monitored signs of infection and your veterinarian may recommend antibiotic treatment. Your veterinarian can also advise you about how to protect your dog against further tick bites using tick control products.
Direct spread of Lyme disease from one dog to another dog has not been reported, even when infected and uninfected dogs have lived together for long periods.
Spread of Lyme disease from dogs to people has not been reported either, but people are equally at risk for Lyme disease if they are bitten by an infected tick.
The most common sign is lameness, but a small percentage of dogs develop severe life-threatening kidney disease. Younger dogs are more likely to show clear signs of illness than mature dogs. In some dogs, the signs may be vague and may not appear for several months after a bite from an infected tick. Many dogs do not show any signs of illness at all.
Lameness: Severely infected dogs may show sudden lameness involving one or more joints. Affected joints are swollen and painful, and the lameness may shift from one leg to another. Joint fluid collected from sore joints shows large numbers of inflammatory cells. Other signs include fever, lethargy, poor appetite, and sometimes enlarged lymph nodes. Routine blood tests from infected dogs are not helpful in diagnosing the disease.
For many dogs, the lameness is mild and passes quickly, so pets may not get proper treatment. Although the lameness resolves, the dog remains infected and may continue to experience episodes of lameness that shifts from leg to leg. This long-term infection can lead to progressive and permanent damage to the joints.
Kidney failure: A less common but more serious consequence of Lyme disease is sudden kidney failure accompanied by protein loss in the urine. In some dogs, kidney involvement appears at the same time as lameness, but in other dogs it appears 3-6 weeks after an episode of lameness. Dogs with kidney involvement show signs of lethargy, poor appetite, vomiting, and weight loss. Routine laboratory tests on these dogs show abnormalities typical of kidney failure, including protein loss in the urine.
There is a simple in-house blood test that will determine if the dog was "exposed" to a tick carrying the disease.
The blood test for diagnosing Lyme disease is the Quant C6 test.
This test determines if the levels of antibody are high enough to justify treatment. If the value of the Quant C6 is higher than 30 IU/mL and signs of illness are present then antibiotic treatment should be considered. If the Quant C6 is less than 30 IU/mL and there are no signs of illness, then treatment may not be necessary.
In addition to doing the Quant C6 test, your veterinarian may want to take samples of blood and urine to assess kidney function and to look for protein in the urine. A positive test for protein in the urine could signal serious underlying kidney disease.
The decision to treat Lyme disease is somewhat controversial since many infected dogs show no signs of illness.
Factors that would support treatment include:
• a moderate to high value of Quant C6
• signs of illness compatible with Lyme disease at the time of testing
• a history of illness compatible with Lyme disease within the past year
• the presence of abnormal levels of protein in the urine.
Several different antibiotics are listed for use in treating Lyme disease, but doxycycline and amoxicillin are two that are commonly used. Most dogs show improvement within 24 to 48 hours of starting treatment. The duration of antibiotic treatment can vary, but most dogs are treated for 30 days.
Dogs that develop kidney failure and/or urinary protein loss will also require additional treatment for the kidney problem. The amount of treatment needed depends on the severity of illness and may include hospitalization with intravenous fluid therapy, antibiotics, and other medications.
A dog's response to therapy can be assessed by repeating the Quant C6 test six months after treatment is complete. Dogs that start with a moderate to high Quant C6 value typically show a 50% reduction or more in the Quant C6 at six months, indicating that treatment has been successful. Dogs that have a lower initial Quant C6 value may not show such dramatic reductions in the Quant C6 at six months, although the value should still be lower than the starting point if treatment has been successful. A persistently high Quant C6 suggests treatment may not have been complete or that the dog became re-infected after treatment was stopped.
There is a vaccine available.
The best way to prevent Lyme disease is to have a good tick control program for your dog. The use of commercial products to prevent tick bites can greatly reduce the risk of Lyme disease. There are a number of effective products available, and your veterinarian can advise you on which one is best for your pet. In addition, if your dog spends a lot of time outdoors, always carefully inspect your dog's skin and hair coat to look for ticks after coming inside; prompt removal of ticks reduces the chances that Lyme disease will be transmitted to your dog. Annual testing is also a good idea for dogs that live in high-risk areas, since early detection and proper treatment of Lyme disease will prevent any long-term damage.