Explanation of facts

Adopted at 8 months from the humane society-No family history of the dog available.  Questionable nutritional quality as a puppy

Current on vaccinations and deworming-Dog is looked after at least relatively well.  Neurologic problems from rabies or distemper unlikely.

No history about parents-Don't know if there is any predilection of stifle disease in family history

Spayed at six months of age-may need less calories to maintain weight

6-year-old-Makes it less likely to be a disease of young dogs.  Trauma, neoplasia, DJD, infection etc. are possible etiologies

Labrador retriever-More likely to get cancer.  Large sporting breed dog is more likely to have traumatic lameness?  Breed predisposed to many orthopedic problems.

Indoor dog while owner is at work-Less likely to sustain a traumatic injury while owner is at work.  Less likely to contract infectious diseases while roaming.

First time dog has been hurt-No history of lameness makes this less likely to be  chronic type lameness.  Dog is healthy other than current problem.   

Fed 4 cups Hill's adult maintenance daily-This is an excessive quantity for a lab of her age, especially since she is over weight.  Should recommend weight reduction diet or a reduction of amount of food for her.  High quality diet, so nutritional causes would be limited to excessive nutritional diseases, but less likely overall to be suffering from a nutritional disease besides obesity.

Markedly overweight-It is important to maintain optimal weight for the patients well being especially in patients with lameness.  Obesity may slow recovery, exacerbate a lameness, or increase the chances for traumatic injury.

30-60 minute walks twice daily-Unlikely to cause lameness, but may exacerbate a lameness that is present. 

Runs 3 miles couple times a week with owner-concussion of running may cause lameness to a predisposed patient as this one, especially since she is overweight.  

Plays fetch and takes hikes whenever owner has time-Exposes patient to possible traumatic injury, by twisting of limbs, or abnormal stress on limbs, especially if playing with other dogs.

Chases cats and dogs when given opportunity-May increase chances of being hit by a car, bite wounds, other traumatic events that lead to lameness.  May increase chances of contracting disease from unfamiliar animals.

Difficulty getting up-Indicates weakness or pain associated with the lameness.  May be musculoskeletal, neurological,  infectious, degenerative, etc

Walks well after she gets up-Indicates more pain from flexing and extending with weight on leg (as in getting up) rather than from walking (most weight carried on front legs).   May indicate lessening pain with use of leg as in osteoarthritis.

Difficulty moving up and down stairs-Again, weight having to be placed on the affected leg causes more pain, and hind legs are the ones used for propulsion so stairs may increase the need for propulsive force.

Lame less than a week-Probably an acute disease, but may be an emergent chronic disease.  Important to diagnose in case of disease that will have a worse prognosis with time.

Lame left hind leg-Important because it localizes the lameness, but can't rule out lameness in other legs, or other affected organs whether it is trauma, infectious, or other etiology.  If one leg only is truly  affected, will help to eliminate diseases that are usually bilateral.

Partial weight bearing on left hind limb-Indicates that there is not complete paralysis, and the dog is able to support some weight with the limb.  

Pain upon manipulation of left stifle-Many neoplasms are not associated with pain, so can help to rule them out (like synovial cell sarcoma).  Further localizes problem to stifle joint on left hind leg.   Can't rule out problems on other areas of leg or body.

Barely toe touches left hind limb when standing-Indicates pain on standing only, without weight on the limb.  May help approximate the amount of pain the dog is in, or judge the progression of disease, i.e. was toe touching and now is supporting weight.

Left stifle joint effusion and joint capsule distension-Can rule in diseases that cause joint effusion.  Examination of fluid can help in diagnosis.  May be the cause of some of the dog's pain.

Joint capsule distension around both sides of patellar ligament-Does it involve the patellar ligament?  Is it intra- or extra-capsular?  

Joint tap performed-Will help rule in/out infectious and immune-mediated diseases when examined.

No cranial drawer on either stifle while awake-Examination under sedation is indicated for further evaluation.

4-5 mm cranial drawer of left stifle under sedation-Most likely indicates a complete cranial cruciate ligament tear.  Important for diagnosis and prognosis since dogs that tear one are likely to tear the other.

Less than 2 mm cranial drawer on right stifle under sedation-Normal for dogs under sedation.

Patellae in correct anatomical position and normally mobile-Makes luxation less likely, but must be manipulated

Hip joints normal-Less likely to be a problem with the hips.

No other limb abnormalities found-Probably limited to the left stifle, but keep an open mind if nothing is found with further examination of the stifle.

Left hind limb appears rotated laterally on gait observation-May be a pain resonse, but can have a valgus deformity which can lead to lameness.