Canine hip dysplasia, or CHD, is a common, genetically-induced joint disease. As the name suggests, the problem occurs in the dog's hip joint.
A dog's hip joint consists of two parts, the acetabulum and the femoral head. The femoral head at the top of the thigh bone fits into the acetabulum, and there is a strong ligament and cartilage layer between the two parts to ensure a tight fit, allowing the joint to bear a lot of weight while still being able to move flexibly. When these structures fail, they cause poor union, and the femoral head and acetabulum can't interact properly, and CHD occurs.
The root cause of this poor union is the ligaments and cartilage between the acetabulum and the femoral head. When these two fail, the tight fit of the hip joint is no longer there, and daily activities will cause wear and tear. It's like a gear that breaks down without lubrication. Over time, the hip joint will undergo structural changes, and osteoarthritis caused by CHD may occur, and inflammation and pain will begin to plague the dog.
In dogs with CHD, the cartilage is broken and eroded, and the joint is no longer working cartilage against cartilage, but bone against bone. Bones also react to hard contact and grow accordingly to deal with this wear and tear, just like people get calluses. This reaction adds fuel to the fire. The femoral head, which was originally smooth and round, is now either worn flat or covered with bone growths like cauliflower. The acetabulum, which was originally just enough to accommodate the femoral head, also changes, becoming rougher and shallower. Over time, all of this works together to make the entire hip joint become weirdly distorted.
What dog breeds are most likely to get CHD?
Dogs of any breed and physique may suffer from CHD, and large dogs are the hardest hit. The reason why large dogs are more susceptible to CHD is simpler than you might think: they are heavier. In addition to large dogs, bulldogs are also prone to CHD. Bulldogs have a unique bone structure and are very susceptible to CHD.
As mentioned earlier, CHD is a disease that involves genes. You may wonder why CHD is still torturing dogs after years of breeding, and there is no significant reduction? First, there is not a single gene involved in the production of CHD, but it is caused by the combined effects of multiple genes; second, in addition to genes, the production of CHD is also affected by the environment, growth rate and nutrition; not to mention that CHD can be inherited from generation to generation, and the offspring of healthy dogs may suddenly have a puppy prone to CHD. It is difficult to simply eliminate CHD through breeding.
The severity of CHD varies. Some dogs do not have severe degeneration of joint cartilage and ligaments, so they are unlikely to have obvious lameness. On the contrary, some dogs have their entire joint structure rotten when they are found. One of the major factors that determines the severity is weight. Breeds with a normal weight of more than 27kg are more likely to suffer from CHD and have a higher severity.
Among common dog breeds, Golden Retrievers and German Shepherds are the most commonly associated with CHD. The reason is that these two breeds are very popular and the CHD-prone genes are also easy to match.
Clinical symptoms of CHD
The clinical symptoms of CHD generally appear between 4 and 12 months of age, but a few dogs may appear between 12 and 36 months of age. Some dogs have CHD but do not show any symptoms in the short term. The clinical symptoms of CHD vary greatly, because the pain in the hip joint ranges from very mild discomfort to severe lameness.
The main manifestations are:
1) Like to lie down and unwilling to exercise; especially unwilling to go up and down stairs
2) Difficult to stand up after lying down
3) Jumping on three legs when running, like a little rabbit
4) Violent twisting of the hip when walking
5) Abnormal sensitivity of the hip joint when palpated
If you want to confirm the diagnosis, take the dog to the hospital for further examination and take X-rays.
The pathological characteristics of CHD are discomfort between the femoral head and acetabulum; shallow acetabulum, small or enlarged neck-shaft angle, and joint laxity. Due to joint laxity, excessive friction between the femoral head and the dorsal margin of the acetabulum causes the dorsal margin of the acetabulum to be subjected to multiple forces, so that the dorsal margin of the acetabulum is aggravated, and femoral head cartilage necrosis and acetabular bone hyperplasia are caused. At the same time, the synovial fluid in the joint increases, etc. In many cases, the hip joint is in a subluxated state.
How to determine if a dog is in pain
There is not necessarily a direct correlation between how much pain a dog has and what the X-ray shows. Sometimes the joints don't look too bad on an X-ray, but the dog is in a lot of pain, and this is not uncommon. In the same way, some dogs look very bad on an X-ray, but they don't seem to be in pain or itchy. How to determine whether a dog has joint pain depends on your observation. These can help you decide whether to use medication for pain relief, or observe how effective the medication is!
1. Reduced activity
The most common manifestation of joint pain. It is true that dogs will not like to move when they get old, but if this happens at a very young age, it is abnormal. Your dog should not be significantly less active at 4 or 5 years old than at 1 year old.
2. Difficulty getting up and lying down
When getting up and lying down, the joints are under greater force, and dogs with joint pain will be hesitant and indecisive about this. As mentioned earlier, joint pain is most obvious in the morning, so you can observe at this time.
3. Abnormal climbing and stairs
The dog will hesitate or even refuse to climb stairs, even if it has never had this problem before. It may actually be joint pain.
4. Frequent and excessive licking
Because of joint pain, dogs can't exercise properly, so they naturally feel bored. What do they do when they are bored? Licking their fur. Some dogs are lazy and always lick their fur, licking their thighs, legs and abdomen, and even licking their fur until they are bald.
5. Calluses and bedsores
Dogs who lie still for a long time may develop bedsores and calluses in the most heavy-bearing and least protected areas, with the elbows and hips of the forelimbs being the most serious.
6. Weird gait
The most critical step in CHD care: weight control!
If a dog grows too fast, its bones will not keep up, and the chance of joint problems in adulthood will rise sharply. Limiting the food intake of puppies, controlling their weight, and slowing down their growth rate can significantly reduce the incidence of CHD and arthritis in adulthood. How much? Nearly 50%.
Weight control
The pressure of weight on the hip joint is the first thing we need to solve. Dogs with CHD especially need to lose weight. The higher the weight, the faster the CHD worsens. For dogs that have been neutered, calorie restriction should be paid attention to.
About exercise
Exercise is not the more the better.
In order to make you happy, dogs will do anything, and they will still cooperate with you to play even if their physical strength is at its limit. Dogs have well-developed muscles at 12-16 months old, but their bones are not fully mature. Appropriate exercise is OK, but don't let dogs exercise too much.
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