Bald Thigh Syndrome
Oct 30, 2011 5:36:23 GMT 10
Post by Tom Meulman on Oct 30, 2011 5:36:23 GMT 10
What causes Bald Thigh Syndrome?
Bald Thigh Syndrome has a number of causes that are interrelated and in many instances depending on the primary cause, do not necessarily adversely affect the performances of the greyhound.
This condition in some instances has a genetic origin, the same as pattern baldness in men runs in families, and could therefore be best described as a genetic predisposition. Greyhounds with a genetic predisposition to hair loss may still finish up with bald thighs even if they were kept as pets with little or no stress in their lives.
In many racing greyhounds the main cause of BTS is a hormone imbalance that narrows the hair follicle structure causing hair loss. This hormone imbalance is primarily caused by an imbalance between the hormones produced by the adrenal cortex which is part of the adrenal glands, and the thyroid gland.
The adrenals glands which sit on top of the kidneys release hormones in response to stress, such as corticosteroids and also control kidney function to a certain extent.
These glands are responsible for stimulating the “fight or flight” response, and in a racing greyhound are for the most part kept in a high state of activity due to the fact that the whole outlook of the greyhound is preoccupied with chasing the lure, or in fact chasing anything that moves.
Even when they are walked or let out for a free run in a yard or paddock, many greyhounds still spend a lot of their focus on looking for something to chase.
The thyroid gland on the other hand is responsible for general body metabolism and stimulating body cell growth, and as such is involved in the injury repair process and in hair growth.
However high levels of adrenal gland stimulation can depress the function of the thyroid gland, and thereby reduce the availability of thyroid hormone.
Often the first sign that the thyroid gland is no longer functioning as required is a general body hair loss, particularly to the outer surfaces of the thighs, and that is why this particular occurrence and the resulting “bald thigh syndrome” is generally blamed on low body thyroid levels.
It should also be kept in mind that extremely low levels of thyroid hormone does affect the general metabolism of the body, and therefore will also affect the rate at which muscle damage heals, and in the long term will affect the on track performance.
Under normal circumstances the production of thyroid hormone is controlled by the hypothalamus of the brain in the following manner:
It is the pituitary gland in the brain that produces TSH (Thyroid Stimulating Hormone) in response to low body thyroid hormone levels.
However the hypothalamus controls the amount of TSH produced by the pituitary gland, by producing a hormone called somatostatin whenever there is too much thyroid hormone in the blood.
This hormone then reduces the output of TSH by the pituitary gland and thus reducing the amount of thyroid hormone being produced by the thyroid gland.
This balancing act is called a Negative Feedback Loop, and it is this same system that controls the levels of various hormones, enzymes, and other body substances such as glucose in the blood.
However it is the disruption of this feedback loop by excessively high levels of substances produced by overstimulated adrenal glands that can cause the hormone imbalance between the adrenal cortex and the thyroid gland which in turn results in damaged hair follicles, causing hair loss and bald thighs in some greyhounds.
Because this system is controlled from the brain, there is little doubt that general hair loss is often worse in highly excitable greyhounds. That is also why in retired greyhounds that are in an environment which encourages a far more relaxed lifestyle and therefore less stimulation of the adrenal glands, the hair loss often corrects itself.
Having said all that, there certainly is no need to be overly concerned if your greyhound has the bald thigh syndrome providing a blood test shows that the Free T4 levels are above 1.5, and while this level may appear low compared to other breeds of dogs, it is normal in greyhounds and does in no way affect their performances or the general metabolism of the greyhound.
In fact I have found during some 40 years of training racing greyhounds that greyhounds with highly stimulated adrenal glands and therefore in most instances with bald thighs, chased harder, had faster reaction times and better speed from the boxes than their more relaxed kennel mates with a full covering of hair on their back legs.
Bald Thigh Syndrome has a number of causes that are interrelated and in many instances depending on the primary cause, do not necessarily adversely affect the performances of the greyhound.
This condition in some instances has a genetic origin, the same as pattern baldness in men runs in families, and could therefore be best described as a genetic predisposition. Greyhounds with a genetic predisposition to hair loss may still finish up with bald thighs even if they were kept as pets with little or no stress in their lives.
In many racing greyhounds the main cause of BTS is a hormone imbalance that narrows the hair follicle structure causing hair loss. This hormone imbalance is primarily caused by an imbalance between the hormones produced by the adrenal cortex which is part of the adrenal glands, and the thyroid gland.
The adrenals glands which sit on top of the kidneys release hormones in response to stress, such as corticosteroids and also control kidney function to a certain extent.
These glands are responsible for stimulating the “fight or flight” response, and in a racing greyhound are for the most part kept in a high state of activity due to the fact that the whole outlook of the greyhound is preoccupied with chasing the lure, or in fact chasing anything that moves.
Even when they are walked or let out for a free run in a yard or paddock, many greyhounds still spend a lot of their focus on looking for something to chase.
The thyroid gland on the other hand is responsible for general body metabolism and stimulating body cell growth, and as such is involved in the injury repair process and in hair growth.
However high levels of adrenal gland stimulation can depress the function of the thyroid gland, and thereby reduce the availability of thyroid hormone.
Often the first sign that the thyroid gland is no longer functioning as required is a general body hair loss, particularly to the outer surfaces of the thighs, and that is why this particular occurrence and the resulting “bald thigh syndrome” is generally blamed on low body thyroid levels.
It should also be kept in mind that extremely low levels of thyroid hormone does affect the general metabolism of the body, and therefore will also affect the rate at which muscle damage heals, and in the long term will affect the on track performance.
Under normal circumstances the production of thyroid hormone is controlled by the hypothalamus of the brain in the following manner:
It is the pituitary gland in the brain that produces TSH (Thyroid Stimulating Hormone) in response to low body thyroid hormone levels.
However the hypothalamus controls the amount of TSH produced by the pituitary gland, by producing a hormone called somatostatin whenever there is too much thyroid hormone in the blood.
This hormone then reduces the output of TSH by the pituitary gland and thus reducing the amount of thyroid hormone being produced by the thyroid gland.
This balancing act is called a Negative Feedback Loop, and it is this same system that controls the levels of various hormones, enzymes, and other body substances such as glucose in the blood.
However it is the disruption of this feedback loop by excessively high levels of substances produced by overstimulated adrenal glands that can cause the hormone imbalance between the adrenal cortex and the thyroid gland which in turn results in damaged hair follicles, causing hair loss and bald thighs in some greyhounds.
Because this system is controlled from the brain, there is little doubt that general hair loss is often worse in highly excitable greyhounds. That is also why in retired greyhounds that are in an environment which encourages a far more relaxed lifestyle and therefore less stimulation of the adrenal glands, the hair loss often corrects itself.
Having said all that, there certainly is no need to be overly concerned if your greyhound has the bald thigh syndrome providing a blood test shows that the Free T4 levels are above 1.5, and while this level may appear low compared to other breeds of dogs, it is normal in greyhounds and does in no way affect their performances or the general metabolism of the greyhound.
In fact I have found during some 40 years of training racing greyhounds that greyhounds with highly stimulated adrenal glands and therefore in most instances with bald thighs, chased harder, had faster reaction times and better speed from the boxes than their more relaxed kennel mates with a full covering of hair on their back legs.