Lyme disease is caused by a spirochete bacterium known as Borrelia burgdorferi.  It is transmitted to dogs and to humans (as well as other mammals) through the bite of an infected deer tick.   Lyme disease has been a rapidly growing problem in dogs, as well as humans, in New England for the past 20 years.  It is a very common disease in dogs in our area that will continue to affect our canine friends for the foreseeable future. 

Lyme disease is not contagious between dogs or between humans and dogs.  Therefore, your dog cannot give any other family member Lyme disease.  A tick must bite you or your dog to transmit the disease.  Typically a tick must be attached at least 36 to 48 hours in order to transmit Borrelia to a dog. 

Since the summer of 2007, we at Derry Animal Hospital have been routinely screening dogs at their annual examination.  The same test we do for Heartworm disease also screens for Lyme, as well as two other common tick-borne diseases, Ehrlichia canis and Anaplasma phagocytophila.  This test is called a 4DX test, and it is a very accurate test for each of these organisms.  This is the same test that we use to screen those dogs that present to us with symptoms consistent with Lyme disease.  If your dog should test positive for any of these diseases, your veterinarian will be sure to contact you to discuss this further.

 The trouble with Lyme disease in the dog is that veterinarians do not currently have a method to determine what will happen to an individual dog once they have been infected.  Therefore, even though a test may say that your dog is “positive” for the organism, it does not mean that he/she will develop illness associated with the infection. Less than 10% of Lyme infected dogs will develop clinical signs or be ill.  The majority of dogs we see are healthy, non-symptomatic dogs that test positive for Lyme on our yearly blood test screen. 

 If your dog has exposure to and is bitten by a tick, it takes approximately 2 months for the 4DX test to show that they are positive for Lyme AND for a dog to have clinical symptoms.  However, other diseases that a tick may be carrying may be tested for prior to this (i.e. about a month after the bite).            

The most common clinical symptoms of Lyme disease are as follows:

 Infected dogs can have one of or any combination of these common clinical symptoms.  Unfortunately, all of these symptoms are quite vague, and, therefore, could be caused by any number of other illnesses.   Your dog may test positive on the initial 4DX screening test and have clinical symptoms consistent with Lyme, however it still might not be the Lyme disease causing their illness. 

 We do have a fairly new test available to us, known as a C6 Quantitative test, which is a Lyme-specific test that fairly accurately measures the level of Lyme organism in your individual dog.  If your dog has Lyme disease, your veterinarian may discuss doing this additional test on your dog to help monitor them for Lyme in the future.  This test is especially important in those dogs that are clinically ill and we want to verify that the Lyme organism is causing their symptoms so that we know how to effectively treat them. 

 The organs most commonly affected in the dog are:  the blood system/immune system, the joints, and the kidneys.  Other organs that are more commonly affected in people with Lyme disease but are very rarely affected in dogs are:  muscle, liver, heart, central nervous system (brain), and eyes.

 

Joint Manifestation (Polyarthritis)

The most common manifestation of Lyme disease in the dog is polyarthritis (poly=many, arth=joints, itis=inflammation).  We know that Borrelia starts this inflammation.  It is often seen in dogs as a “shifting leg lameness” where the leg affected may change daily.  Lyme polyarthritis is most commonly treated in both people and dogs with the antibiotic Doxycycline.  Occasionally we may also use corticosteroids to help reduce the joint inflammation. If treated appropriately and in a timely manner, the majority of dogs will feel better in 36-72 hours.  If left untreated, this can lead to more chronic damage of the joints and longer term treatment needs.  Antibiotic treatment typically lasts for about 4 weeks.  Unfortunately, by the time of diagnosis, there is no known treatment that can effectively kill all of the Lyme organism in the body.  The same is true in people who do not seek medical care if they develop the classic “bull’s-eye” skin rash after a tick bite.  Dogs do not develop this rash, and, therefore, are not diagnosed until too far into the disease process.

 

Kidney Manifestations

In those dogs that develop symptomatic Lyme disease, a few can occasionally result in kidney damage.  This comes in 2 forms:  1) severe and acute; and 2) more mild and chronic.  The severe form is referred to as “Lyme Nephritis,” and it is, thankfully, much less common than the milder form.  “Nephritis” simply means “kidney inflammation”.  The veterinary community is investigating why this happens in some dogs. IT DOES NOT HAPPEN IN ALL DOGS.  At this time, we know only that extensive damage is done to the kidney and the cells start to die.  Dogs that develop this have a very poor prognosis.  They start to lose protein into the urine and then they lose weight and overall muscle mass.  Often they develop fluid in their abdomens and/or chest cavities as well as under their skin (edema) secondary to this protein loss from their kidneys.  There are no medications that appear to help these patients, and most dogs succumb to their disease within 2 months of the diagnosis.  Definitive diagnosis is made through a biopsy of the kidney, but often these dogs are too sick to perform that procedure.  Mainly, the diagnosis is made on a variety of laboratory and physical exam findings, including a Lyme positive status.  While we may diagnose about 100 to 200 new cases of Lyme disease a year at Derry Animal Hospital, we have seen only 1 to 2 severe cases like this each year.

The second form is called “glomerulonephritis secondary to Lyme disease”.  This is also kidney inflammation and damage but it seems to be limited to the filters that are built into the kidney.  These are called glomeruli.  Most of the damage is actually done by the dog's own immune system in this case.  We think that Borrelia stimulates the immune system initially, and then the immune system develops a self-perpetuating process of inflammation.  Once again, protein is lost through the kidneys with this, but the kidney cells do not die as rapidly.  With proper therapy, the protein loss often can be slowed down.  The prognosis with this manifestation is still guarded, but it is much better than with the severe form, as dogs with this can live for many months or even years.  Treatment can involve: Doxycycline (or similar antibiotics), prescription kidney diets, medications to decrease blood pressure in the body, anti-inflammatory therapies (not steroids), aspirin, and/or drugs to suppress the immune system.  To know which combination of the above therapies would be best, a biopsy of the kidney is recommended.  Kidney biopsy is not right for every patient, but it is encouraged in those who are strong enough to undergo anesthesia.  It is a rapid procedure, only lasting 15-20 minutes, but the patient must be anesthetized for it. 

If a dog with the second form of the disease has both protein loss and has elevated kidney values on their bloodwork, then the prognosis is very poor.  Most of those patients succumb to their disease in less than 6 months.  If the kidney values are normal, then the prognosis depends on how the dog responds to the medications (i.e. Can we slow down the protein loss significantly). 

Common sequelae to protein losing kidney diseases (see “Protein Losing Nephropathy” handout) are muscle wasting and hypertension (high blood pressure).  Special diets will be used to help your dog try to maintain the muscle mass (i.e. we do not want to protein restrict their diets too much), while also trying not to over-work the kidneys with too much protein.  We will also monitor for hypertension routinely by checking blood pressure routinely.  If hypertension is identified, then your dog will be on medications to lower the blood pressure.  Hypertension can cause even more damage to the kidney and to other organs over time.

Due to the potential for kidney disease, it is recommended that a urinalysis is performed on dogs with lyme disease to screen for protein-loss.  This should be done first near the time of diagnosis (to obtain a baseline value) and then yearly so that this form of the disease can be caught early.

  

Preventative Care

Preventative medicine is incredibly important, regardless of whether or not your dog has Lyme disease.  The two components of this are: 

 The first three medications are very safe topical medications that you apply to your dog once a month, year-round.  Our current recommendation is for either Vectra-3D or Advantix, as they both have repelling action against ticks (and fleas), as well as a fast killing effect.  Frontline is also a good alternative, however, it does not have any repelling action.  The Preventic collar is felt to be the most effective tick preventative.  However, it does not treat against fleas, so you will need to use another product in addition to this collar to prevent fleas.  Also, it should not be used on any dogs where there is a chance that it could be chewed off and swallowed by another dog, as ingestion is toxic.  External, topical use of a Preventic collar is very safe in dogs.

 The particular lyme vaccination we use here has been used in dogs for over 6 years, both safely and effectively.  There are always chances in any patient, both canine and human, for vaccine reactions to any vaccination; however, this particular lyme vaccine has been proven to be one of the least reactive of any of the vaccinations that we currently give to our canine patients.  While it is not 100% effective in stopping Lyme infection from occurring in vaccinated dogs, it has certainly helped to reduce the number of cases of Lyme disease we have seen in dogs in the past 5 years we have been using it.

 Our goal is to try to prevent ticks from actually attaching to the dog to bite and to protect the dog from further infection with more Borrelia organisms.  This is important to reduce regardless of whether your dog has Lyme disease or not.  For those with the disease, the more Borrelia that is put into their bodies with subsequent tick exposure, the more likely they are to develop clinical Lyme disease down the road.