Dogs and cats often limp for very different reasons, so cats will be addressed in a different article. Dogs limp for a variety of reasons, and it is important to know which warrant a visit to a veterinarian and which do not.
First, there are a few medical definitions for limping that should be addressed. Limps can either be catagorized as acute (sudden onset) or chronic (usually a gradual onset, but not resolving quickly). Chronic can be all the time or intermittent. Second limping can be described as weight bearing or non weight bearing. Non weight bearing is exactly what it sounds like.
As an example, you dog steps on a mesquite thorn. The limp is sudden (acute) and non wieght bearing. The great thing about things like thorns, gum (yes dogs will limp after stepping on gum) and, burrs are that the dog will often attempt to remove the offending item, leading you to the problem quickly. If only all limps were so easily diagnosed.
Last, before you take your limping dog into the vet you have to know several things - which leg is the pet limping on. Nothing is more frustratining to a veterinarain than the family choosing a leg a piece and insisting that that leg is the one fluffy is limping on, because fluffy is now at the vet and amped up on adrenalyn and no longer limping at all. Second, dogs limp because something hurts. People will often discount pursuing limps because they think the dog isn't in pain. Think back on the last time you limped, its doubtfull you did it for any reason besides pain. So, if your pet is limping your pet hurts.
Assuming you didn't see the dog fall off the couch or get hit by a car, there are four very common reasons for limping in dogs.
Back leg lameness could be caused by several factors, one is genetic and found in small dogs, the other has a genetic component, but is compounded by activity, conformation, and weight.
The first cause of lameness in small dogs is called luxating patellas. What this means is that the patellas (knee caps, little disc shaped bones that slide along the top of your knees) slips out of position when the dog moves. This causes the familiar bunny hopping or three legged running seen in poodles, yorkies, and chihuahuas. This lameness is both acute and intermittent. The dog will be non weight bearing until the knee pops back in place, and there will be no residual lameness.
The best way to imagine what is happening in your pet is to think of the patella as a marble running in a groove. When the knee is bent, the marble slides over this groove. In the case of luxating patellas, the groove is too shallow, and the marble slips out sideways, not only can this not be comfortable, but every time the marble jumps the track, so to speak, it loosens the tendons that should be keeping this from happening.
Surgery is the only solution. This does not mean that every one of these dogs need surgery (otherwise veterinarians wouldn't have time to do anything else, as many tiny breed dogs have this genetic condition in one or both knees). Size is a big factor in when to go in and rebuild the groove. Many tiny dogs get along pretty well with mobile knee caps, or do so for much of their lives, other dogs do not and will need surgical intervention to fix the groove. The good news is that the surgery is very successful, the bad news is that often ends up being neccessary for both knees and costs at least $1,000 a knee.
The second most common hind leg cause of lameness is cruciate tears. Cruciate ligaments form a cross (hence the name) connecting the lower leg to to the upper at the knee and provide lateral (sideways) stability. In dogs with poor bone conformation, poor knee conformation, bad luck, or carrying too much weight, this can be a common injury. What happens is that the poor conformation, or a bad move on your dog's part causes a tear in the (usually) anterior (forward) cruciate ligament (ACL). Ligaments do not heal. But they hold the knee together, and can cause excruciating lameness if torn. This is a condition requiring surgery 100% of the time. There are several surgical techniques, and at this writing, though veterinarans suspect that certain techniques may result in better outcomes in certain cases, most cannot agree on what those cases are.
A quick test to see if a dog has a torn, or partially torn ACL is to ask that dog to sit. A dog with a torn ACL will usually be unwilling to fold the affected knee and it will splay out to the side. Certain breeds are predisposed to ACL injuries, Labrador retrivers, Pit bulls (or any dog with a bow-legged appearance), post legged dogs (chows and sharp peis), and any dog carrying too much weight. But, again as this is an injury, any dog can suffer from it, though in most cases only larger breeds can exert the neccessary torque to destroy a ligament. This lameness is often acute, but in some dogs experiencing partial tears, the lamess can be acute and transitory, but ultimately the ligament will tear, and the dog will be largely non weight bearing.
A common cause of shifting leg, or non-specific lameness is lamesness causes are arthritic changes. Shifting leg lamness is caused by the dog finding no comfort on any limb, and therefore weight bearing on one limb until it hurts and then shifting its weight to the rested limb, until it hurts too much to continue bearing weight. This kind of lameness is the kind that sneaks up on people is often dismissed as aging. This lameness often results in that old dog waddle you see so often when dogs are walking down the street. Any lameness, any refusal to do things a dog could formerly do is caused by pain, not sometimes, all the time. And arthritic pain is both quite painful and difficult to target. But these dogs especially need to see a veterinarian and have an assesmant done to help them with the quality of their life.
Lastly, sudden or acute, chronic or intermittent, any lameness in Arizona (especially the Tucson-Phoenix corridor) is Valley Fever until proven otherwise. Even dogs with cruciate tears or other acute lameness could be secretely harboring Valley Fever. Please remember that on x-ray Valley Fever can look just like Osteosarcoma. Any out of town visitors, snow birds, even people traveling through the I-10 corridor need to be aware of this disease, which is little known outside of Tucson or Phoenix, which accounts for 95% of all cases. As an idea of the numbers involved, a recent report states that 100,000 people are affected with Valley Fever every year in the Tucson-Phoenix corridor.
Valley Fever is a fungal spore, it is airborne and is breathed in. Every human and animal in Tucson is exposed. There is no prevention, and in most cases the disease runs its course and leaves in peace, but for many dogs, a cough is the first sign, and in a similar number of dogs, limping is the first sign. This can be a vague intermittent limp, a shifting leg lameness. Valley Fever is insidious, and is found in healthy bone, but it also seems to have a fondness for old fracture or surgical sites, so dogs with histories of old fractures or surgeries should be especially vigilent of limping on the affected leg. Many of these lamenesses are ignored because the owner assumes that the lameness is an age-related degeneration of the old injury, when nothing could be further from the truth. The longer Valley Fever is ignored or left undiagnosed, the more dangerous and difficult to treat it becomes.
In most cases any dog with a Valley Fever lesion visible on radiograph will be treated no less than one year, and often times, quite a bit longer.
There are dozens of reasons a dog can limp, and in most cases, here in the desert the problem is quickly found and removed, in the form of a cactus needle. But needles can break off and cause hard to diagnose lamenessed that take time to resolve, a broken toenail can cause lameness, as can a torn pad. Dogs who roughhouse may be intermittently lame time to time from bashing into one another.
The important thing to always remember about any lameness is that soft tissue injuries, broken thorns, and early Valley Fever do not show up on x-ray. Finding a lameness' cause may be straight forward, or it may take time. Always remember that dogs limp because they hurt. So if limping is severe, or chronic, it should be seen.
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