Dwarfism is the lack of growth hormone production, a disease that can occur in dogs. It is a process that is diagnosed when the dog is growing and it is observed as a growth that is not what it should be according to its age and breed. In addition, deficits of other hormones can occur at the same time that lead to other endocrine processes, such as hypothyroidism or heat problems in females, as well as testicular atrophy in males; in addition to dermatological problems and secondary infections. Diagnosis is made with the help of laboratory measurements and treatment is with progestogens, in order to increase growth hormone.
If you have never seen a dog with dwarfism, here is a picture of a German shepherd with dwarfism. Right at this furry one, another of the same age as him appears, but he althy. In fact, both dogs are brothers from the same litter. Keep reading this article on our site about dwarfism in dogs, causes, symptoms and treatments to learn more about this endocrine problem that can affect our dogs.
What is canine dwarfism?
Dwarfism or pituitary dwarfism in dogs is an endocrine disease in which there is a deficiency of growth hormone (GH) that sometimes appears together with deficits of hormones generated in the hypothalamus, such as TSH and prolactin.
This results in dwarfism or lack of normal growth as the months go by.
Causes of dwarfism in dogs
This is a congenital disease: puppies inherit it from their parents under an autosomal recessive inheritance pattern.
The most predisposed breed seems to be the German Shepherd, although it can also be seen in the Weimaraner, Pinscher and Spitz.
Canine dwarfism symptoms
The symptoms of pituitary dwarfism appear when dogs reach two or three months of age, before they look like normal puppies. However, from this moment they still have puppy hair, then they begin to lose it causing bilateral alopecia on the trunk and present a reduced but proportionate size In addition in a dog with pituitary dwarfism it can be observed:
- Longening of the closure of the epiphyses of long bones.
- Fontanelles open longer than in a normal puppy.
- Calcification of the penile bone.
- Delayed appearance of teeth.
- Hyperpigmentation.
- Thin and hypotonic skin.
- Progressive peeling of the skin.
- Comedones and papules on the skin.
- Secondary bacterial infections of the skin or respiratory system.
- Hypothyroidism at 2-3 years of life.
- Reproductive disorders: anestrus (lack of heat) in bitches and testicular atrophy in dogs.
Although dwarfism is not fatal in itself, it does reduce life expectancy to less than 10 years. However, if your dog is not growing, it may be due to other reasons, as we explain in this other article on Why is my dog not growing?
Diagnosis of dwarfism in dogs
The diagnosis of pituitary dwarfism is based on clinical signs and laboratory diagnosis.
Differential Diagnosis
The differential diagnosis of dwarfism in dogs includes the following diseases:
- Juvenile hypothyroidism.
- Hypoadrenocorticism.
- Iatrogenic hyperadrenocorticism.
- Juvenile diabetes.
- Malnutrition.
- Portosystemic shunt.
- Gonadal dysgenesis.
- Bone disease.
- Renal disease.
Clinical Diagnosis
The clinical diagnosis is mainly based on the observation of a proportionate reduction in the size of the dog according to the characteristics of its breed and age, which commonly comes together with other clinical signs that we have mentioned, such as problems of skin.
Laboratory analysis
The laboratory analysis will be based on a blood test with measurement of certain factors and hormones:
- Cell count and biochemistry: The blood count and biochemistry in these dogs are usually normal, although there is hypophosphatemia, mild hypoalbuminemia, and in In some cases, there may be azotemia (increased creatinine or urea), since growth hormone deficiency can affect the development of the renal glomeruli, which are responsible for filtering urine.
- Hormone Test: Thyroid hormone tests usually reflect an increase in free and total T4 but unlike the expected in hypothyroidism which is an increase in TSH, in dogs with dwarfism there is a decrease in TSH due to the lack of release by the hypothalamus in this disorder.
- Insulin-like growth factor assay-Insulin-like growth factor-1 (IGF-1) assay is the best way to indirectly reflect growth hormone values. In dogs with dwarfism this factor is significantly reduced, being less than 50 ng/ml.
Other forms of diagnosis
Another way to reach a definitive diagnosis is by stimulating growth hormone release using xylazine or GNRH In an animal he althy, growth hormone will increase after this administration, however, in dwarfism this effect does not occur.
Treatment of canine dwarfism
Canine dwarfism is treated with the administration of progestogens, such as medroxyprogesterone, at a dose of 2.5-5 mg /kg every three weeks in 6 doses. Subsequently, if necessary, it is repeated every 6 weeks. This drug induces the production of growth hormone in the mammary gland. Dogs should be checked and checked every week, as it can cause acromegaly or diabetes. Generally, clinical skin signs improve, adult hair grows, and weight gain.
Today the treatment that was carried out with bovine, porcine or human growth hormone is discouraged, since in addition to having a high price, insulin resistance or hypersensitivity may appear. The administration of thyroid hormones or glucocorticoids should also be considered, if necessary.
