Larger Puppies … Bigger Bone Problems?

Damian* couldn’t contain his excitement when his dad came home with Bongo*, a Great Dane puppy.  This was his ‘new best friend’, the 7 year-old was told.  Bongo lived up to his name – went exploring everywhere with Damian – over rocks, down to the river running through their plot, and almost half way up the trees Damian climbed!  When Bongo came home with a pronounced limp one afternoon, off to the vet the family went.  Hopefully Bongo hadn’t been over eager at pleasing his energetic master?

When you consider the vast variation in size between the different dog breeds, (think Chihuahua and then, think Great Dane), and the fact that large- and giant-breed dogs reach their adult weights at the age of 12 – 18 months, you realise that the factors affecting their growth must differ greatly.  Large- and giant-breed puppies are predisposed to skeletal development disorders, and a persistent or recurrent lameness, even if mild, in any young puppy should be properly investigated and not just assumed to be because of rough play.

Rapid Growth, Knobbly Knees

The most rapid growth phase occurs between 3 and 6 months of age. At this stage your puppy will often have big knobbly joints, and look all gangly. Bones grow from each end towards the middle. The end of the bone that forms the joints is called the epiphysis (‘head’) then there is a region called the metaphysis (‘neck’) and the long bone shaft connecting the two epiphyses, is called the diaphysis. All growth, both into the head and into the shaft of the bone, occurs at the metaphysis. This is an area of very active bone formation and the bone-forming tissue is quite soft and sensitive to damage caused by trauma and inadequate blood supply. On an x-ray, this area of the bone does not show up white , but rather as a dark line , as the developing bone is not yet mineralised. This line is called a growth plate.It is these active areas of bone growth that give your puppy those knobbly joints.  Maturation of these growth plates occurs at different times in the various bones and breeds. Once the growth plate is mature, no further growth in the length of the bone will occur and the area will mineralise andbecome white on the radiograph like the rest of the bone.

The Correct Nutrition Is Vital

In the majority of our dogs today, malnutrition refers to an excess or imbalance of nutritional factors rather than a deficiency. Strong evidence supports the role of excess energy, calcium, phosphorous and vitamin D in the developmental skeletal disorders. Excess energy calories and calcium in the diet stimulate rapid bone growth, but the subsequent strengthening of that new bone by mineralisation, and also the development of a good blood supply, cannot  keep pace and the bone develops areas with poor blood supply and is weaker. Once growth slows down after 6 months, some of these changes can be corrected by remodelling (Is this correct? never heard of it please check alled remodelling). This allows bone to grow longer and wider during growth and is also how it heals. Many of these changes will however have a permanent effect in bone remodelling (should this not be t-bone remodelling Joints have to be very smooth and are created to fit exactly with each other’s conformation. Any changes in this structure will cause abnormal pressures within the joints.   Joint incongruency will eventually result in degenerative osteoarthritis.

A Not-So-Hip Disease To Have …

Conditions commonly occurring in large and giant breeds include hip dysplasia, where the hip joint is loose and the socket part of the joint is not deep enough for the ball part of the joint to fit properly into. This causes partial dislocation and rubbing of the hip joint , eventually wearing away the soft cartilage and causing bone-on-bone contact.

Elbow dysplasia is a combination of any number of four elbow abnormalities, where small pieces of the bones have not fused properly with the main bone, due to abnormal forces inside the joint, and these ’loose’ pieces then causearthritis. The smaller bones in the elbow should fuse together by 22 weeks. These conditions are called fragmented medial coronoid process and ununited anconeal process.

Osteochonditis dissecans is a defect that occurs in the cartilage of the joint surface of the bone. There is a weakness in the cartilage , probably due to inadequate blood supply during development , and a flap forms, which can eventually break off into the joint. This responds well to surgery. There may be several causes for these conditions, including  genetics , calcium over-supplementation, trauma and rapid growth.

The above conditions may become evident from 6 months of age onwards in your dog , even though he isn’t displaying any lameness, or only mild, intermittent signs. Over time, however, lameness could develop due to secondary arthritis changes in the joint. Secondary changes within a joint and the development of arthritis is a permanent condition and will require life-long management. The only successful surgical cure, in some cases, is early diagnosis and surgery to correct the abnormal forces on the joint, while there is still growth potential left in the bone.

Before You Buy …

Ensure that puppies come from parents who are certified free of hip dysplasia and elbow dysplasia. This doesn’t mean that it is impossible for the puppies to develop hip dysplasia, as the parents may still carry some genes which may contribute to joint problems , but their expression in an asymptomatic dog  is obviously not as strong as if the parent were actually showing clinical symptoms.

Feed The Correct Food

The aim in young large-breed puppies is to have them grow ‘slower but stronger’. A good quality large-breed puppy food in the first 15 months may save you a lot of trouble later on in the dog’s life. Large-breed puppy diets are formulated with less energy than normal puppy food to reduce the rate of growth. It is thus also important not to allow free access to the food , but to feed the required daily allowance in frequent meals (2 – 3 times per day). Even a large-breed puppy formulation , fed “ad lib”, may cause nutritional imbalances. Each dog is different and the quantity of food should be adjusted as required. The body condition score of a puppy younger than 6 months should be on the thin side of normal. They should look like gangly teenagers.

Calcium Concerns …

The calcium content is extremely important,  as is the ratio of calcium to phosphorous, which usually balance each other in the body. Puppies younger than 6 months of age absorb calcium passively through the intestine wall as a fixed ratio of what is taken in, thus they cannot control what gets absorbed. A vitamin D-controlled intestinal transport absorption process, correlated to the level of calcium in the bloodstream becomes mature and functional at 6 months. Thus in the rapid growth phase at 3 – 5 months ,excess dietary calcium will be absorbed and will affect bone growth in a negative manner. Large-breed puppy diets have a decreased calcium content which slows down the growth rate due to its effect on various hormones and minerals. Feeding a poor quality diet in general , although often providing a low calcium component , usually also has a low-energy density , requiring that the dog must eat a lot of food before feeling full, and thus actually resulting in a high calcium uptake.

No Over-The-Top Exercise Please

Do not over-exercise your puppy. Heavy training, jumping and running long distances will cause trauma to the developing joints. Wait until your dog is skeletally mature before taking him running with you on marathon runs.

No Lame Excuses!

In the first year, take any lameness, recurrent or persistent, however mild …  seriously, and visit your vet. Early diagnosis of developmental skeletal disorders allows the best long-term outcome as interventions, surgical or medical, can be instituted while the bone is still growing and may result in greater ‘normalisation’ of the forces acting within the joint. Sometimes specialist veterinarians will need to be consulted in this process.


© Pet’s Health

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