If you are nervous your dog has untreated Lyme disease, it should be comforting to know that MOST dogs infected with Lyme disease (95%) and cats ( nearly 100 %) do not get sick from Lyme disease! Your veterinarian can easily test for Lyme disease by a simple blood test that can be performed in the clinic.
Only 5% of dogs develop Lyme disease symptoms. Of the dogs that develop Lyme disease symptoms, the two main diseases they develop are: severe joint inflammation and pain (Lyme arthritis) and more rarely: severe kidney failure (Lyme nephritis).
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Dogs who develop Lyme arthritis can have the following symptoms
- Fever
- Loss of appetite
- Painful joints
- Swollen joints
- Intermittent lameness
- Swollen lymph nodes
- Lethargy
The signature bulls-eye rash seen in people does not occur in dogs with Lyme disease
Dogs who have Lyme nephritis can have the following symptoms
- Lethargy
- Loss of appetite
- Muscle wasting
- Bad breath
- Swollen limbs
- Increased thirst
- Increased urination
- Weakness
Lyme nephritis is an exceptionally rare complication of Lyme infection in dogs and occurs in only about 1% of infected dogs. Lyme nephritis in dogs is rapid kidney failure caused by complexes of antibodies and the lyme bacteria that lodge in the kidneys. These complexes cause severe kidney inflammation and rapid loss of kidney function.
There is an increased incidence in golden retrievers and Labrador retrievers. Sadly, even with aggressive and early treatment, response to therapy is grave and most dogs. Most dogs with lyme nephritis do not survive.
Ticks which carry Lyme
The tick that transmits Lyme disease is the black legged tick (Ixodes Scapularis in the Northeast, Mid Atlantic and north-central US and Ixodes Pacificus on the Pacific coast).
Most humans are infected by tick borne disease in the Spring and Summer months. These months are when ticks are most active and when nymphal (young ticks) are present. In the cooler months, the adult ticks become more active. Ticks don’t jump to attach onto their host. They wait in brush and attach to a host when the host is in contact with the brush
Is your dog going to transmit ticks to you
Ticks on your dog are most commonly attached. Attached ticks are not directly a threat to humans living with that dog. However, if a tick were climbing on the dog’s coat it could attach to a human. Ticks generally remain on their host for a few days until they are engorged (they can expand tremendously in size) and then they will drop off. It’s always a good idea for you to apply a tick preventative to your dog to be safe.
Humans living with dogs are more likely to find ticks on themselves than non pet owners. This may be because pet owners are more likely to be in fields and wooded areas when walking with their dogs.
However, the rate of tick borne illness is no higher in pet owners than non pet owners. There is a higher incidence of tick infection in people who have a garden, wood pile, outdoor play equipment, compost pile, or bird feeders.
Blacklegged Tick which transmits Lyme disease
The CDC shows an image of relative sizes of the various tick stages compared to a dime.
The nymphal ticks feed the most in Spring and Summer months. They are difficult to see as they are less than 2 mm in size. The larvae do not feed on hosts until they have developed into a nymph.
Lyme disease is a bacterial infection with a bacterium called Borrelia transmitted by the bite of a tick. There are at least 52 different Borrelia strains. Some are more commonly detected in dogs, and some are more commonly detected in people.
Ticks can acquire the bacteria by feeding on reservoir hosts, most commonly mice, squirrels, birds and shrews.
In the most lyme endemic areas, as many as 50% of ticks will carry the Lyme bacteria.
A lot of tick bites occur in the warmer months due to increased outdoor recreation by people and their companion animals. Ticks have increased questing behavior to find a blood meal during the warmer months. However, adult ticks can still be very active in fall and winter as well .
Lymes infected ticks have spread across the US primarily because bird migration has allowed Borrelia-infected ticks to establish a new area.
It takes 36 to 48 hours of tick attachment before the tick can transmit Lyme to its host. Other tick borne infections are transmitted more quickly. Frontline takes 24 hours (minimum) to kill an attached tick. In contrast, the newer tick preventatives in the Isoxazoline class (NexGard, Simparica, Bravecto) kill ticks only 4 hours after attachment.
I found a tick on my dog. Did my tick prevention product not work?
Most tick preventatives do not prevent attachment but will kill the tick within a few hours of attachment. Products that contain permethrin (Vectra 3D, Advantix II) prevent attachment because they have repellant properties. Collars that contain permethrins or amitraz also act to prevent tick attachment (Preventic collar, Seresto collar). Tick collars should always be placed so that they do contact the skin in order to be effective.
Topical permethrins should never be applied near cats as they can cause seizures in cats.
How to remove a tick
A tool most everybody owns is a pair of tweezers. While these work well to remove ticks, there are good tools specifically designed to help make tick removal easy. The diagram below shows how a tool called a tick twister works.
If you leave the mouth parts behind when removing a tick, can it still transmit disease?
Ticks no longer can transmit disease if you remove the main body of the tick. It can sometimes be hard to remove the entire tick . Mouthparts or the tick head may still remain attached to the skin. The Lyme organism, Borrelia, lives in the midgut of the tick. A tick can no longer transmit infection if the head or mouthparts are all that is attached to the skin. Sometimes, leaving the head or mouthparts behind can cause a secondary irritation, swelling or infection on the skin. If it requires digging into the skin to remove these parts, it’s best to leave it alone . It will naturally fall out/be rejected by the body of the dog.
Which tick prevention product works best to prevent lymes disease?
The fastest tick preventatives which are in the isoxazoline family have the fastest tick tickle. Furalaner in Nexgard killed 90% of ticks by 4 hours of attachment and 98% by 8 hours. Fipronil products in comparison take about 24 hours to kill ticks (frontline). This is why the isoxazoline class of tick preventatives are now favored. The chance of tick borne illness decreases dramatically if you can remove the tick quickly (within 24 hours ideally). Although Lyme transmission irequires 36-48 hours of tick attachment, there are some other tick borne illnesses that can be transferred after only a few hours.
Comparing tick prevention products for dogs
Tick products that prevent tick attachment/repel ticks:
Topical: Advantix, Vectra 3D Ingredient: Permethrin
Collars: Seresto Collar Ingredient Permethrin
Preventic Collar Ingredient Amitraz
Oral: no products on the market currently
Tick products that kill ticks once attached
Oral: isoxazolines (NexGard, Simparica, Bravecto)- FAST kill – about 4 hours
Topical: Fipronil (Frontline)- SLOW kill- about 24 hours
Collars: Seresto and Preventic collars
If a dog is going to spend a lot of time outdoors in heavily tick infested areas, your veterinarian may recommend doubling up on tick protection. This can be done with two different classes of drugs. Most commonly, a tick repellent collar like Seresto or Preventic, combined with an oral or a topical tick preventative is chosen.
Areas of the country where Lyme disease is highest
The total rate of Lyme disease found in dogs varies a lot depending on the state. A 2017 seroprevalence table showed the highest seroprevalence in dogs in Connecticut who had a 16.34% rate of positivity, the lowest states were under 1% positivity . The Companion Animal Parasite Council has a parasite prevalence map.
Why some dogs develop symptoms of Lyme disease and other dogs do not
Why some dogs develop symptoms of Lyme and others do not is not entirely clear. Based on the increased prevalence of Lyme nephritis in Golden and Labrador Retrievers, there is some breed predisposition. Repeated infection or infection with several tick borne parasites may increase the chance of adverse clinical signs. Any tick that stays on a pet longer than 24 hours is more likely to transmit a tick borne disease.
Dogs are most likely to develop acute joint inflammation and pain in the joints closest to the tick bite. The median time to development of symptoms of lymes disease is 68 days after the tick bite. A general rule is it takes 2-5 months for symptoms to develop after a tick bite.
How is Lyme disease treated in dogs?
Four out of six expert panelists who drafted a Consensus statement on Lymes disease in Dogs and Cats did not believe asymptomatic dogs positive for Lyme should be treated with antibiotics.
Dogs with Lyme arthritis symptoms are recommended to be treated with a 4 week course of doxycycline. Doxycycline is the favored drug because it has efficacy against possible other tick borne co infections (such as Anaplasma, Ehrlichia).
Treatment beyond 1 month has not been recommended as chronic lyme arthritis is not well- documented.
Thankfully, the response to treatment is rapid, with a superb response seen within 1-3 days.
If there is no response to treatment after 3 days in a dog with suspected Lyme arthritis, the diagnosis may need to be reconsidered.
How to diagnose Lyme disease in dogs
To diagnose exposure to Lyme disease, there is a simple beside test that uses only a few drops of blood. If your dog has had several ticks removed,an immediate Lyme test will not indicate if the disease has been transmitted. It takes a few weeks for the body to mount an immune response (create antibodies) to the infection. So, it’s advised to wait at least 30 days after a bite to check.
Should every dog that is positive for Lyme be treated?
Treatment of non symptomatic Lyme positive dogs is not currently recommended. A majority of internal medicine specialists (panelists) who crafted a Consensus statement about Lyme disease in dogs did not recommend treatment for all dogs with Lyme disease.
The panelists who do not advocate routine treatment of asymptomatic Lyme positive dogs believe doing so promotes overuse of antibiotics. They also cite lack of evidence that treatment decreases the risk of subsequent illness. Furthermore, the Lyme organism, Borrelia, is not reliably cleared from the tissues with treatment and many dogs will commonly become reinfected at another point as well.
It is recommended to treat asymptomatic, Lyme infected dogs if a urine screen shows abnormal protein levels.
This indicates proteins are being lost through the filter unit of the kidney secondary to kidney damage. Protein loss from the kidneys is a sign of possible Lyme nephritis.
Specialists who do recommend treatment for asymptomatic Lyme positive dogs base their recommendation on the quantitative results of a Lyme c6 test. This is a test that gives a value for the amount of circulating immune complexes . Immune complexes that lodge into the kidney are responsible for the kidney damage incurred with Lyme nephritis. A higher value for Lyme c6 is sometimes used as a determinant for whether to treat asymptomatic dogs. There is no proof, however, that treatment will prevent immune complex disease in dogs
The efficacy of tick control products are very good. They have proven to prevent tick infection in experimental studies with tick exposure challenges.
How should you monitor a dog that is positive for Lyme disease?
Although routine treatment for asymptomatic dogs that are positive for Lyme is not routinely recommended, routine monitoring is recommended. A urinalysis with a urine protein quantification is recommended. Urine protein loss indicates damage in the kidneys and concern for development of Lyme nephritis. Luckily less than 2% of Lyme positive dogs develop urine protein loss (proteinuria).
Should I give my dog the Lyme vaccine?
Recommendations for use of the Lyme vaccine is debated. The duration of vaccine immunity is not clear. Some vaccine failures were noted before 6 months had elapsed with the OspA subunit or bacterin vaccine. The newest vaccine, the Vanguard crLyme vaccine, was shown to prevent infection in 44% of vaccinated dogs versus 88% of unvaccinated dogs.
Half of the expert panelists who created the Consensus Statement on Lymes disease in dogs and cats recommend the use of a Lyme vaccine.
The panelists that recommend the vaccine cite that dogs do not create immunity from natural infection . The dissenting panelists cite that the efficacy of the vaccine is inconsistent and there is an inconsistent duration of immunity. There still remains a need to provide tick control and because most Lyme positive dogs remain asymptomatic. Finally, they cite concern about sensitizing a dog to developing vaccinal antigen-antibody complexes. However, there is no known negative impact of circulating immune complexes after Lyme vaccination. Of dogs studied with Lyme nephritis, fewer than 10% were previously vaccinated for Lyme.
It is not recommended to give the vaccine without also providing tick prevention.
Can Lyme disease go away on its own in dogs
It takes a certain amount of bacteria from a tick bite to enter the host to cause a true infection. Some dogs that will test positive for exposure to the organism (measured by antibodies against the organism). Many of these dogs will later test negative for Lyme (within months to years). This means that their antibodies are no longer present. This may be due to the dog’s immune system clearing the infection or because the organism has “hidden” within the dog.
Conclusion for Lyme disease in dogs
Depending on where you live in the US, as many as 16% of dogs may test positive for Lyme disease. However, only 5% of those dogs will show any signs of illness. Of those dogs that do get sick, most will have joint pain. This responds quickly (1-3 days) to a course of antibiotics. There is a fatal form of Lyme related illness that occurs in only about 1% of Lyme infected dogs. This disease swiftly attacks the kidneys and the hallmark sign is protein loss detected in a urine screen. It is very important to provide tick prevention. If ticks can be killed within 24 hours of attachment, Lyme disease will not be transmitted.
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