SHOULDER LAMENESS IN DOGS

Several of the most common causes of front leg lameness in the dog are problems involving the shoulder joint These problems can be difficult to diagnose and complete recovery can take several months.

SHOULDER JOINT FUNCTION

The shoulder joint of the dog is formed by two bones (the humerus and scapula bones (Figure 1) that must fit together correctly for the joint to function normally. The top of the humerus has a flat ball that fits into the socket of the shallow scapula. The muscles surrounding the joint help to maintain a tight joint. The ball should glide smoothly around the socket without excessive looseness. The biceps muscle attaches to the front edge of the scapula bone and has a long tendon that passes through a groove in the front of the shoulder joint before blending into the muscle itself (Figure 2).

SYMPTOMS

Typically, affected dogs show front leg lameness that can start as young as 5 months of age. The lameness may be intermittent and tends to improve with rest and gets worse with exercise. Some affected dogs will often “warm-up” and don’t show lameness while running. Dogs may also have some pain in their toes and neck due to the alteration in the way they walk. The lameness typically doesn’t get better with anti-inflammatory medication (pain relief). CAUSES OF SHOULDER LAMENESS There are four main forms of shoulder lameness that cause pain and arthritis:
  1. Osteochondritis of the humerus (OCD). A loose flap of cartilage develops on the top of the humerus bone (Figure3)
  2. Biceps tendonitis (BT). The biceps tendon is prone to repetitive strain-type injury especially where it passes through the groove in the humerus bone (Figure4 & 5).
  3. Supraspinatus tendinopathy (ST). This muscle runs along the front of the scapula and can be damaged where its tendon attaches on the front point of the humerus bone.
  4. Medial shoulder instability (MSI). The ligaments and tendons on the inside of the shoulder joint can be injured causing the joint to be unstable.
For a number of years, hip scoring schemes (e.g. PennHIP) have been used to assess breeding dogs for signs of hip dysplasia. X-rays of the hips are taken under anaesthesia or heavy sedation and sent away to be graded by trained veterinarians. These schemes are helping to eradicate this condition but because even normal dogs can produce puppies with hip dysplasia the rate of hip improvement has been slow.   

DIAGNOSIS

A thorough orthopaedic and neurologic examination is performed. The dog is evaluated when walking and by manipulation of all four limbs and the spine, Pain and joint looseness can frequently be felt in the affected joint. To confirm the diagnosis, sedation or anaesthesia are necessary. X-rays are taken of the shoulder to show signs of joint looseness and arthritis. A CT scan or ultrasound is performed on the shoulder to look for defects (Figures 6 & 7), Joint fluid is removed and sent to the laboratory for analysis. The joint is manipulated to determine whether the ligaments are stable (Figures 9 & 10).

MEDICAL TREATMENT

Many dogs with confirmed BT, ST or MSI will improve without surgery. The object of medical treatment is to control the symptoms and to allow the shoulder tendons, muscles, and ligaments to heal properly. The dog should not be allowed to get overweight and exercise should be controlled. Formal physiotherapy is recommended. Cartilage-protecting agents (omega fatty acids, glucosamine, green-lipped mussel, fish oil) may help lubricate the joint and keep cartilage healthy. Generally, lifelong supplementation is necessary. Anti-inflammatory medication (aspirin like drugs or cortisone) can be helpful in reducing pain but should only be necessary occasionally. Medical treatment does not stop arthritis from continuing to develop.

SURGERY

Dogs with OCD of the shoulder benefit from surgical removal of the loose cartilage flap. This is generally performed by passing a small telescope (arthroscope) into the joint. The flap cam then be removed using small forceps (Figure 8). Surgical treatment can benefit dogs with BT, ST or MSI that do not adequately respond to medical treatment. The type of surgery differs between dogs depending on age, degree of arthritis, and shoulder looseness.

RESULTS

Dogs with OCD that have had the flap removed generally show excellent results with minimal progression of arthritis, few complications and normal function. Most dogs with BT, ST or MSI require intensive physical therapy but can return to full activity 3-6 months after diagnosis.

POSTOPERATIVE CARE

EXERCISE CONTROL

To allow the joint to heal following the surgery. complete restriction of exercise is absolutely necessary for the first 4-6 weeks Your dog can be walked on a lead for toileting.

SUTURE REMOVAL

The skin stitches need to be removed 10 14 days following surgery. This can be done by your regular veterinarian. Please call our hospital if there is any swelling, discharge or redness around the stitches.

A bandage is sometimes used for 3-4 weeks as a sling to keep your dog from using the leg This bandage should be assessed at our hospital or by your regular veterinarian weekly to ensure that the foot and skin appear comfortable.

MEDICATION

Most dogs are sent home with medication for additional pain relief. Sometimes, antibiotics are also dispensed. Give the medications as prescribed. Further pain relief can be prescribed if necessary. Please let us know two days before suture removal if you think more medication is required or you may be charged an urgent fee.

PHYSIOTHERAPY

Physiotherapy is an important part of your dog's recovery. We strongly recommend a consultation with a recognised animal physiotherapist. Home-based physiotherapy Should consist of a warm compress applied to the region of the stitches for 15 minutes followed by gentle massage of the muscles. This can be followed by gentle flexing and extending of the leg.

After the bone has healed, your dog can begin more active physiotherapy with regular controlled exercise. Running without leash control is recommended for only short periods. Regular swimming is an excellent way of providing active exercise without joint stress.

LONG-TERM TREATMENT

Some dogs will need long term medication to control the arthritis already present in the shoulder prior to the surgery. Cartilage protecting agents (omega fatty acids, glucosamine, green-lipped mussel, fish oil) may help lubricate the joint and keep cartilage healthy, Generally, lifelong supplementation is necessary.

Anti-inflammatory medication (aspirin-like drugs) can be helpful in reducing pain but should only be necessary occasionally.

DISK FUNCTION

The intervertebral disk of the dog acts as a cushion between the spinal bones (vertebrae) to absorb the shocks and movements of normal activity. The normal disk is like a “jelly doughnut” with a gelatinous centre and an outer ring of stronger fibrous tissue. In certain breeds of dog (Dachshund, Poodle, Beagle, Spaniel, Corgi), the disk degenerates at a very early age. As the dog ages, the jelly like component of the disk becomes more gritty and less resistant to pressure. The disk is then no longer able to cushion the spine and the contents of the centre may forcibly squirt out and bruise the spinal cord. Alternatively, the outer part of the disk may bulge up putting pressure on the spinal cord.

DIAGNOSIS

A thorough neurologic examination is performed evaluating the head, all four limbs, and the spine. Pain can frequently be felt at the site of the affected disk. Anaesthesia and X-rays can help to show signs of narrowed disk spaces and degenerative disks. To confirm the diagnosis, a CT scan is recommended as this provides us with the best information on the spine. A special X-ray test called a myelogram can be helpful, in addition to a CT scan. Some dogs have an associated instability of the vertebrae that has contributed to the disk degenerating.

SURGERY

Dogs that have severe neck pain.or significant spinal cord damage are also candidates for surgery. The most common procedure is a ventral slot, which involves drilling a slot in the base of the vertebrae to relieve the spinal cord pressure and allow the delicate extraction of the disk material. Sometimes, the central portion of adjacent degenerative disks is removed to reduce the chance of further disk

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