This article is intended for general information only. If you suspect your pet may have a tick-borne disease, please consult a veterinarian. There is, as yet, a great deal to be learned about Lyme Disease and other tick-borne diseases in animals.

Because domestic animals are frequently at a higher risk of infection, they play an important role in the surveillance of disease. Infected animals are a sentinel, providing an alert to humans that infected ticks are present where the animals have been. Thus pet/livestock owners must be cautious in caring for their animals. Infection in animals, like humans, has been greatly under recognized. Disease reports from veterinarians are vitally important to the recognition of tick-borne infection danger to humans in a particular given area.

As with other emerging pathogens, tick-borne diseases are spreading due to the ease of travel. Animals are transported over great distances for races or exhibition. An animal carrying undiagnosed or subclinical infection can unwittingly carry new infection back to the animals' home base. This explains why so many disease organisms are rapidly spreading, despite the best of precautions.

Animals that spend most of their time outdoors are more likely to contract Lyme Disease than humans in that they are more exposed to tick habitat. Therefore it is important to minimize the possibility of infection by maintaining yards and pastures, keeping growth in check by mowing or pruning and eradicating debris that may be potential habitats of mice, a primary host for the larval and nymph stages of ticks.

Keeping pastures or lawns shorter is an effective method of control as ticks don't fly or jump onto hosts; there must be direct contact for the tick to attach. Ticks avoid direct sunlight and mowed lawns are not a preferred habitat. Because not all ticks carry the Lyme Disease parasite (Borrelia burgdorferi, or Bb), rates of infected ticks depend on how endemic an area is.

Housepets can bring in ticks which, if not firmly attached, can fall off and infect humans. This emphasizes the need to groom animals as often as possible, preferably on a daily basis. Check haircoats for ticks, being careful not to allow any to attach to you. If grooming a pet that has been at high exposure (such as a hunting dog), it might be wise to use rubber or surgical gloves to minimize the possibility of infection to yourself.

It must be noted that Bb has been isolated from the urine, feces and colustrum of animals; a fact that puncuates the necessity of hygiene when grooming or otherwise working with them.

Animals diagnosed with Lyme disease are treated similarly to humans, with antibiotics. An animal in treatment is going to suffer the effects just as humans do. As the bacteria die off, they release toxins into the blood stream, thereby creating a "Herxheimer" (herx, for short) reaction; this is a temporary worsening of symptoms and should abate in a few days.

Ticks that carry Lyme disease can be co-infected with other pathogens that cause disease in animals, though not all animal species are susceptible to all of the known pathogens. As with humans, there is a small percentage of fatalities if not caught in time.

DOGS

Symptoms of Lyme disease are fever, loss of appetite, fatigue, abnormal development of the lymph nodes, lameness [arthritis], may be sudden, sometimes with severe pain. Lameness occurs two to five months after tick exposure. This symptom may present as shifting from one leg to another. One or more joints may be swollen, hot and painful on manipulation. 90% of infected animals limp (usually one foreleg that may exhibit a swollen lymph node). This lameness progresses over three to four days, going from mild and barely noticeable to complete disuse of the painful limb. Acute or subacute arthritis may be noticed. The acute form may be transient and may recur in some cases. Lyme disease can move from mild discomfort to a phase where a dog will be in such pain it will refuse to move.

It is possible that the heart muscle and nerve tissue may be damaged at this point. Treatment at this stage will prevent permanent joint and nerve damage.

The chronic stage of humans with systemic disease is rare in dogs. However, those reported have involved heart block, kidney failure, liver or eye disorders and neurological changes (seizures, aggression, confusion, overeating) and obsessive/compulisive behaviors such as chewing fur and or licking legs, lack of coordination or palsy. The Erythma Migrans rash is rarely seen in dogs. Symptoms can be subtle or intermittent and vary in intensity from mild to severe and can mimic many other conditions. With pregnant dogs there have been reports of miscarriage, premature births, still births, birth defects and trans-placental infection of the fetus.

Diagnosis is generally the same as for humans, a combination of clinical signs and tests, including ruling out other possible diseases. Absence of any one symptom does not rule out Lyme disease but it must be noted that mis-diagnosis is possible. For example, a diagnosis of a slipped disc, Lupus, Leukemia, Epilepsy, Brucellosis or auto-immune disease, are all conditions that in fact, may actually be Lyme disease.

Prevention of Lyme disease in dogs must bear a cautionary note. There are products available to prevent fleas or ticks; they are capsules applied to the scruff of the neck. However, if you use this product, consult your veterinarian before using a preventative spray on the dog's haircoat before hiking or hunting, to ensure the two products are compatible. Although there is a vaccine available not all veterinarians are enthused; there are concerns the vaccine may cause arthritis in some breeds.

If walking on cleared trails, try to avoid having your animal brush up against foliage. One county in New York found that by cutting back the brush and foliage on the sides of trails by 3 feet substantially reduced the infection in that area. Encouraging your pet to walk firmly on a path is a wise precaution.

CATS

Lyme disease in cats is rare, though cases have been reported. In a limited study, one third of feline blood samples were found to test positive for Lyme disease. It is probable that some cats are able to resist the illness.

Of reported cases, symptoms exhibited were: pain and stiffness in limbs and joints, lameness, fever, loss of appetite, fatigue, possible sudden collapse, a "zombie-like" trance and in cases of heavy infestation, severe anemia. Most cases are diagnosed because the owner has actually found a tick; otherwise symptoms tend to be ambiguous or other illnesses are suspected.

Tick control is the best preventative. Providing an appropriate flea/tick collar is a must in endemic areas as there are presently no vaccines available. Outdoor cats should be checked regularly and thoroughly for the presence of ticks. Check carefully, especially around the ears, skull, feet and anus. Again, remember that pets can bring ticks into the home.

HORSES

Horses most likely have a higher infection rate than humans for Lyme Disease as attached ticks are probably unnoticed for a long period of time. Horses used for equestrian events are no doubt scrutinized more often due to the frequency of grooming. Infection of horses in the northeastern US is widespread with almost 50% of adult horses having been infected at some point.

Adult ticks, which are present in fall and spring, are the stage most likely to feed on horses. As such, the tick is usually large enough to be detected during grooming. Ticks are often found about the head, throatlatch area, belly, and under the tail. Prompt removal minimizes the risk of Lyme disease infection.

The symptoms of Lyme disease in horses are: chronic weight loss, sporadic lameness, laminitis (inflammation of the tissues inside the hoof wall), low grade fever, weight loss, swollen joints, muscle tenderness, eye inflammation, and stiffness. Neurological signs are depression, dysphagia (difficulty swallowing), head tilt and encephalitis, and can be observed in chronic or late stage cases. Behavioral changes are more difficult to determine, but can present as a "changed attitude", unwillingness to work (perhaps due to pain), and irritability. Foal mortality is a possibility.

Equine disease is diagnosed by determining if the animal is living in an endemic area, history of actual tick exposure, elimination of other ailments, tests and consideration of the above symptoms. In 2004 a new test called the Snap 3DX was developed by IDEXX Laboratories in the US. The test requires only a few minutes wait for results. This test may not yet be available in Canada.
Treatment with antibiotics is often required for several weeks. Some animals may experience a "herx", a temporary worsening of symptoms, as the bacteria are killed. If laminitis is suspected, a veterinarian should be consulted to initiate preventative treatment.

Prevention of Lyme disease in horses is dependant on tick control. Daily grooming and removal of ticks is the best method of control. Tick repellants may be applied to the haircoat, especially the head, neck, legs, belly and under the tail. Use these products in spring and fall when adult ticks are most active. Ensuring pastures are reasonably short and removing brush, wood piles, etc., will decrease rodent nesting habitat, diminishing tick populations.As with dogs, when trail riding, if at all possible, try to avoid having your horse brush up against foliage on the sides of trails, thus reducing the chance of infection. Middle of the trail is best.

CATTLE

Lyme disease occurs in cattle but usually presents as a herd problem. A Japanese study showed a positivity difference in different aged animals as well as a seasonal variation. Many cattle do not exhibit outward signs of Lyme disease. When they do so, they may display lameness, with stiff, swollen joints, fever, poor appetite, laminitis (inflammation of the tissues inside the hoof wall), weight loss and decreased milk production. The classic rash may be present on the udder of infected cows. Abortion and other pregnancy difficulties are possible outcomes.

Diagnosis is difficult and as with other animals, is determined by clinical signs, history of tick exposure and positive tests for Bb. Lyme bacteria has been discovered in blood, milk, synovial fluid (from the joints), and aborted fetal tissue. Lyme disease can survive in frozen milk but is killed with pasteurization.

SHEEP, GOATS, LLAMAS & ALPACAS

All species are vulnerable but little information is available. However, it is reasonable to assume that the symptoms for cattle would be the same or similar for these species.

PET RABBITS

In the wild, rabbits are major hosts for Lyme disease and the co-infections. However, a pet rabbit in a raised cage would be at minimal risk. A ground cage would be more exposed to tick habitat but still little risk if the cage were on a sunny lawn.

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Copyright June 2005 Susan Starchuk