What would you do if you found a tick attached to your dog? What if it was attached to you? If you live in an area where deer ticks and Lyme disease are a concern, you must use year-round tick control on your pets! The Meowing Vet explains how Lyme disease can cause severe illness in both you and your dog. Learn what signs to look out for and how to prevent this tick-borne disease. Keep reading below…
Ixodes deer ticks, or black-legged ticks, transmit Lyme disease to dogs and humans.
What causes Lyme disease?
Lyme disease, also termed Borreliosis, is caused by Borrelia burgdorferi, a spirochete bacteria that is transmitted through the bites of certain ticks belonging to the genus Ixodes. Ixodes scapularis (the deer tick or black-legged tick) is the most common tick species responsible for the spread of Lyme disease (see above image); its relative Ixodes pacificus can also transmit Lyme disease to a lesser extent. In addition to Lyme disease, deer ticks can also transmit some forms of Anaplasmosis, another tick-borne disease that can cause illness in your pets.
Deer ticks are thus named due to their requirement of an intermediate host to complete their life cycle — typically a deer, although small mammals (such as mice, rats, and rabbits) or even birds may also serve as host for the tick. After growing to the adult stage, the deer tick will find its definitive (or final) host (such as a dog, wild canid, or human).
an engorged deer tick after feeding
The adult tick will obtain a blood meal by attaching itself to the host’s skin to begin feeding, engorging itself with blood. If the deer tick previously became infected with the Lyme bacteria when feeding from its last infected host, the tick can then transmit the bacteria to its new host. The Lyme bacteria leaves through the piercing mouth parts of the tick to enter into the punctured skin wound of the host at the site of feeding. This travel of the Borrelia bacteria from the tick to the host takes time; thus, 48 hours or longer is required for an attached tick to be able to transfer Lyme to its host. Therefore, removing a tick from your dog or from yourself as quickly as possible can greatly reduce the risk of Lyme disease transmission. Upon reaching the host, the bacteria multiplies in the skin before entering into the bloodstream, where it may travel to the joints, kidneys, heart, and brain.
For more information on the life cycle of deer ticks and their transmission of Lyme disease, visit the website for the Centers of Disease Control and Prevention (CDC).
So, you’re saying that humans can get Lyme disease too?!
Correct. Borreliosis is a zoonotic disease, meaning that in addition to animals, humans can also be affected. Not only is your dog at risk of acquiring Lyme disease from infected tick bites, but you may also be at risk. Humans do not become infected with Lyme disease directly from infected dogs. However, dogs can harbor the infectious deer tick vector, which can then bite and infect nearby humans. Even if you don’t have a dog, ticks carrying the Lyme bacteria can still attach to you if you encounter them on a walk outdoors.
Where is Lyme disease most prevalent worldwide?
Lyme disease is most prevalent (meaning there are more reported cases) across North America, primarily in the northeast and mid-Atlantic regions of the United States as well as in the states of Wisconsin, Minnesota, Oregon, and California. Certain parts of Canada, South America, and continental Europe also experience a large number of Lyme disease cases. Deer ticks most commonly live in wooded areas or in areas of tall grass, especially in regions where deer, mice, and rabbits inhabit.
View the maps below or consult with your local veterinarian to determine whether a high prevalence of Lyme disease exists in your area of the world.
(The above map images are courtesy of IDEXX Canine Vector-Borne Disease Prevalence Map.)
What are the clinical signs of Lyme disease?
Oftentimes, Lyme disease does not actually cause a disease, meaning that though the bacteria may be spread to a new host, the bacteria may die or be fought off by newly formed antibodies of the host’s immune system before having a chance to cause illness. These cases are termed “exposure” cases. Other dogs and humans that still harbor some Borrelia bacteria may remain asymptomatic and never develop any signs of illness. Other patients are unfortunately not so lucky.
Some dogs develop a plethora of disease complications from Lyme infection, which mainly involves damage to the joints and kidneys. The joints and kidneys are the primary sites of disease due to the formation of immune complexes upon infection with Lyme bacteria (a type III hypersensitivity reaction). The Lyme antigens (or proteins carried by the Borrelia bacteria that the host’s immune system recognize as foreign and potentially dangerous material) bind with antibodies produced by the host’s immune system. Antibodies to the Lyme antigens are formed in an effort to attack the bacteria and clear it from the host’s body before it can cause infection and disease. When the antibodies join with the antigens in the host’s bloodstream in order to flag them as material to be destroyed by the host’s white blood cells, this “fusion” is termed an immune complex. These bulky molecules can become lodged in small blood vessels of the joints and the filtering apparatus (i.e. glomeruli) of the kidneys, leading to painful joint damage and swelling as well as acute renal failure. Acute kidney failure requires prompt detection and treatment in order to save your dog’s life!
SIGNS OF LYME DISEASE
Fever- Lethargy
- Decreased appetite (anorexia)
- Swollen lymph nodes (lymphadenopathy)
- Signs of joint involvement (polyarthritis):
- Reluctance to move or shifting weight from one limb to another
- A slow, stiff, painful gait (as if “walking on eggshells”)
- Joint swelling
- Signs of kidney failure: (rapidly progresses over the course of several days)
- Increased urination and water consumption (polyuria and polydipsia, respectively, or PU/PD)
- Vomiting
- Swollen limbs (peripheral limb edema)
- A distended abdomen or difficulty breathing due to the development of fluid in the abdomen or chest cavity (abdominal or pleural effusion, respectively)
- Weight loss (with chronic disease)
- Less common signs in dogs: (Involvement of the heart and brain are less common in cases of canine Lyme disease whereas disease of these organs is more common in affected humans.)
- Collapse: may be secondary to a cardiac arrhythmia (abnormal heart rhythm) due to myocarditis (inflammation of the heart)
- Seizures
- Behavioral changes
- Bulls-eye skin rash at the site of the tick bite (see image below)
Seek medical advice if you observe a bulls-eye lesion at the site of a tick bite on yourself or your dog.
How is Lyme disease diagnosed?
If you find a tick attached to your dog, especially if it is engorged, you ought to also have your dog tested for tick-borne diseases including Lyme if you are not using a tick preventative on your pet. (Keep in mind that some tick preventatives do not simply repel ticks; a tick has to bite your pet for the product to then kill it before it has time to transmit disease).
And if you live in or travel with your dog to a region where Lyme disease is endemic, your dog should be screened for potential exposure to Lyme annually. The most common screening test, the IDEXX SNAP® 4Dx® Plus Test, is the same simple blood test that also detects heartworm disease as well as certain other tick-borne diseases (Ehrlichia and Anaplasma).
If your pet’s test shows a positive result for Lyme, it does not necessarily mean that your dog has an active Lyme infection that is currently causing disease. This positive result may simply mean that your dog has at some stage been exposed to the Borrelia bacteria after being bitten by an infected deer tick. This exposure prompted the formation of antibodies against Lyme by your dog’s immune system. These antibodies circulating in your dog’s bloodstream are what a positive SNAP® 4Dx® Plus Test is detecting.
If your dog tests positive (a.k.a. seropositive) yet is asymptomatic, your vet may still suggest analyzing a sample of your dog’s urine (i.e. a urinalysis) to ensure that there are no indications of kidney damage that has not yet started causing illness. Many dog owners choose to prophylactically treat with a course of antibiotics (typically doxycycline) even if their dogs are not presently ill… just in case some Lyme bacteria are lingering in their pet’s body with the potential to cause disease later on. Other dog owners wish to perform further testing to decipher between exposure and infection. Other such tests include an ELISA C6 quantitative serology test, multiplex assay, or Western blot test, all of which may further aid your veterinarian in this distinction.
If you reside in an area with a higher prevalence of Lyme disease and your dog is experiencing the signs of Lyme as discussed above, your vet is likely already suspicious of Lyme disease and will begin with an orthopedic exam, SNAP® 4Dx® Plus Test, urinalysis, and bloodwork. If your pet has swollen joints (i.e. joint effusion) your vet may also obtain a sample of joint fluid for analysis. If kidney damage (a.k.a. glomerulonephritis) has already occurred based on your dog’s excessive thirst and urination, your pet’s labwork results will show the following:
- Azotemia (increased levels of BUN and creatinine in the bloodstream): These waste products are normally excreted by the body in urine, but since the kidneys are not functioning properly, these toxins build-up in the blood, making your dog feel ill.
- Electrolyte and mineral imbalances: high potassium (hyperkalemia) and high phosphorus (hyperphosphatemia)
- Low levels of blood proteins (hypoproteinemia): These proteins are leaking through faulty “holes” in the kidneys into urine. This renal damage is caused by immune complexes lodging in the kidneys; Low levels of blood proteins can lead to spontaneous fluid build-up in the chest or abdomen.
- Poorly concentrated urine (a.k.a. low USG or isosthenuria) because the injured kidneys are not appropriately concentrating waste products to be eliminated by the body
- Excessive amounts of protein in the urine (proteinuria)
Some vets may also recommend a renal biopsy to be sent to a special lab for analysis.
Learn how to interpret your pet’s bloodwork and urinalysis results.
In the face of financial difficulties, some pet owners may decline diagnostic tests (though not advised) and elect only for antibiotics to see if their ill dog responds to treatment. If the dog improves within 72 hours, Lyme disease was most likely the cause of illness. If the dog does not improve or continues to decline, either another disease is responsible or else the dog’s Lyme infection has already caused severe kidney failure.
Wondering how the IDEXX SNAP® 4Dx® Plus Test works? See the informative video below.
How is canine Lyme disease treated?
Borrelia burgdorferi is killed by treating your dog with an appropriate antibiotic choice for a strict 30 day period. Doxycyline is the most common and best choice. However, if your dog does not tolerate the potential side effects of doxycycline well (ex. bitter taste and possible vomiting), another option may be administered another antibiotic instead (such as amoxicillin, azithromycin, or cefitriaxone). Alternatively, coating the doxycycline tablet with a tasteless empty gel capsule may mask the poor taste.
It is vital to give your dog his or her antibiotic exactly as directed for the full 30 day treatment cycle in order to kill the Lyme bacteria. Sick dogs typically begin feeling better within the first 3 days of treatment, feeling less painful and regaining appetite. Your vet may also prescribe anti-inflammatory medications to reduce joint pain and swelling.
If your dog has already sustained renal damage, hospitalization to administer IV fluids to correct dehydration and electrolyte imbalances is typically required. Your vet may switch your pet to a specialized renal diet (low in protein and phosphorus) as well as administer other medications to offset secondary consequences of kidney disease: phosphate binders to decrease high levels of phosphorus in the blood and anti-hypertensives (such as benazepril) to reduce high blood pressure.
Sadly, some dogs die of acute kidney failure despite treatment. Others may survive yet face chronic kidney disease for the remainder of their lives, which is shortened significantly due to this kidney damage. These dogs will need to receive frequent subcutaneous fluid administration, eat solely a prescription kidney diet, and take a daily medication to regulate blood pressure.
Click here for our article on Chronic Kidney Disease (CKD).
How can I protect my dog against Lyme disease?
I tell my clients to think of protection against Lyme disease like an army in hand-to-hand combat: The first and most important line of defense is year-round tick control (i.e. an oral, topical, or collar option)… yes, even during the winter months! The second line of defense is an annual vaccine.
When choosing an appropriate flea and tick prevention for your pet, you need to know what types of parasites the product you’re using controls. For instance, many pet owners choose Revolution® or Stronghold®, thinking it offers heartworm, flea, and tick prevention properties. This is mostly true, and I enjoy this product in most areas of the world…but with one exception: Both of these products are in fact labeled for protection against the American dog tick (Dermacentor variabilis), which transmits Rocky Mountain Spotted Fever and some forms of Ehrlichia. However, Revolution® and Stronghold® are not labeled for efficacy against deer ticks, meaning they do not protect your dog against Lyme disease. Therefore, I recommend that another product for tick prevention is used for dogs in Lyme-heavy areas.
Puzzled over which flea, tick, or heartworm prevention is right for your pet? Download The Meowing Vet’s product comparison charts to find the right preventative for your dog or cat.
Vaccinating against Lyme disease is a second line of defense in case your dog’s monthly tick prevention fails for some reason. Although the Lyme vaccine is optional (unlike vaccines against Rabies and DHPP, which are core for canines), I recommend that dogs receive annual Lyme vaccines if they are in areas of heavy infestations. The initial vaccine can be started in puppyhood and should be followed by a single booster 2 weeks later and then boosted annually thereafter. You must keep your dog up-to-date on his or her Lyme vaccine in order to provide protection; just one vaccine administered by your vet several years ago is not protective enough. Follow through with the proper annual vaccination schedule to optimize protection.
Older Lyme vaccines were thought to potentially worsen immune complex formation in previously infected dogs, amplifying kidney damage. However, newer vaccines are much safer and are deemed safe to administer to exposed dogs or those previously treated for Lyme disease. They should not be administered to ill dogs and should be reserved until after your dog is treated for Lyme disease appropriately. Some modern day vaccines prevent infection in the canine host once the Borrelia bacteria enters through the skin; other vaccines work by also preventing the Borrelia bacteria from moving from the deer tick vector’s mouth parts to your dog in the first place.
Although vaccination is a good option in most cases, I reiterate that the first line of defense against Lyme disease is consistent year-round application with a good quality tick prevention, many of which also control flea infestations.
Learn about other vaccines recommended by your vet to preserve the health of your dog or cat.
If Lyme disease is not a concern to cats, why should I use tick prevention on my kitty?
For two big reasons!!!:
- To reduce the risk of an infected deer tick moving from your cat to you or to your dog
- To prevent other tick-borne illnesses in cats, such as potentially lethal Cytauxzoonosis
What is the prognosis of Lyme disease in dogs?
Ensuring the survival of your dog after he or she begins showing signs of Lyme disease relies largely on prompt detection and necessary treatment. If diagnosed and treated before the development of signs of kidney involvement, the prognosis is overall guarded to good. However, some cases (including those which were not treated appropriately) may result in chronic illness manifesting as relapsing joint pain, heart abnormalities, or chronic kidney disease. Some cases of chronic or relapsing disease may also occur due to persistence of the Lyme bacteria in host tissues despite proper treatment.
If kidney damage has already occurred, the prognosis is unfortunately very poor, even with appropriate treatment in most cases. Younger dogs as well as Labrador retrievers and golden retrievers tend to have worse kidney involvement. Therefore, preventing Lyme disease before it ever affects your dog is the key to success.
How can I protect myself against Lyme disease?
No human vaccine against Lyme disease is currently on the U.S. market, but researchers are actively working on one with hopes that one shall be developed for the general public soon. In the meantime, protect yourselves against tick bites and Lyme disease by adhering to the following tips:
- Use appropriate year-round tick control in your dogs and cats in order to reduce your own exposure to ticks in your household.
- When walking outdoors in wooded areas or in areas of tall grass, wear long sleeves and long trousers to reduce exposure of your skin to ticks. If possible, wear shirts and trousers with either banded ends, or tuck your trouser bottoms into your socks to keep ticks from crawling up your body.
- After coming indoors, check your body and especially your hair and scalp for ticks.
- If you do find a tick attached to your skin, remove it in full safely in order to reduce the risk of transmission of the Lyme bacteria from the tick to you.
- Consult your personal physician if you are bitten by a deer tick, especially if you discover it embedded in your skin, engorged, or that it has caused a bulls-eye rash. Ask for doxycycline or another appropriate antibiotic choice, and take it as directed for an entire 30 days.
- If you feel lethargic, suffer from joint aches, or discover swollen glands, seek medical attention without delay.
– Maranda Elswick, DVM
The Meowing Vet urges you to have your dog screened for Lyme disease and other tick-borne illnesses if you live in an endemic area. And please speak with your veterinarian today about year-round flea, tick, and heartworm prevention for your dog or cat.
