Animals, like humans, have secretory glands in the body. They are slightly different in structure and function. For example, both humans and animals have apocrine sweat glands. However, in dogs or cats it is not possible to see sweat protruding. In this article, we will examine the structure, location, and function of the apocrine glands in cats and dogs.
Gland structure
Apocrine glands are sweat glands that perform a secretory function. The appearance of the sweat glands is quite simple, but the contribution made to the body is very large. They are tubular and not branched, at the ends they have secretory sections that go deep into the dermis. The accumulations of those very end sections form dense tangles in the layers of the skin.
The cells that make up the end sections are of two types: cubic (glandular) and process (myoepithelial). It is the process cells that regulate the secretion of secretions from the ducts. They embrace the duct with their processes and, contracting, promote the secret along the duct.
In cats and dogs, the end part of the sweat glands looks different. For the former, it is a tangle, and for the latter, it is tortuous.
Types of sweat glands
It is customary to isolate eccrine (merocrine) and apocrine glands. The former are mainly localized in those areas of the skin where hair and their derivatives are absent. With their help, the secret is released directly on the stratum corneum.
And the apocrine glands, on the contrary, are associated with the hairy areas of the skin. Their ducts exit into the hair follicles, which in turn are located slightly above the sebaceous glands. In addition, the secret of apocrine glands is very rich in proteins.
Human sweat glands
Small eccrine glands predominate in the human body, as the body is not covered with a lot of hair. They produce watery sweat. It is he who plays an important role in thermoregulation. The intensity of the eccrine sweat glands depends on many factors, including environmental temperature and emotional factor.
The sweating system is regulated by the endocrine and nervous system. The main role in regulation is played by the brain and spinal cord. In tetrapods, this type of gland is localized on the paw pads. Due to the fact that dogs do not sweat the way people sweat, it is believed that they lack apocrine sweat glands. However, this opinion is erroneous.
Sweating in dogs
Since the body of most dogs is covered with thick hair, large apocrine glands, which are associated with hair follicles, predominate in them. These glands also prevail in most mammals.
In the secret of animals, the content of organic substances is increased. In particular, the secret of dogs is more dense and odorous. It, in turn, mixes with the secretion of the sebaceous glands and forms a natural fatty lubricant in the skin of animals.
Apocrine glands in dogs are located in certain areas of the body, unlike eccrine glands. Another distinctive feature of this type of glands is that they begin to fulfill their functions only after puberty of the individual. Apocrine glands include glands of the eyelids and excreting earwax.
Despite the fact that dogs and other animals with dense hair have almost no thermoregulation, the excretory system works at full capacity. In particular, perspiration becomes more profuse in the event of an animal disease. In this case, their body is trying to get rid of harmful substances.
The figure shows the skin glands of dogs: 1 - apocrine gland, 2 - eccrine, 3 - sebaceous.
Cat Skin Glands
In cats, the excretory system is very similar to the canine. They have sebaceous, sweat and mammary glands. The former help make the coat water repellent. Perhaps that is why many cats and cats do not like water procedures.
As we already mentioned, the glands that produce liquid sweat, like in humans, in cats are only on the pads of their feet. The function of thermoregulation is performed by the mammary sweat glands. They secrete a liquid similar to milk. However, the cooling of the body is still small. The most important thing that this liquid does is that it smells. Animals use this to mark territory. They just rub about something, leaving an odorous mark on the subject.
Gland disease
These glands have their own diseases. For example, an apocrine cyst. This is a benign tumor-like pathology, which is a cavity filled with contents. Inflammation of the apocrine glands is expressed by adenomas and adenocarcinomas. They can infect the glands themselves or the cells of which they are composed.
Usually these pathologies are not common among young cats and dogs. But older animals, they strike with enviable frequency. For example, German shepherds and golden retrievers are most prone to the appearance of apocrine tumors. Among cats, carcinomas are most likely to occur in Siamese breeds.
Dog Adenomas
Externally, the apocrine cyst is similar to a subcutaneous nodule that rises above the surface of the skin and contains fluid. Its size can vary from 0.5 to 3 cm. Their most frequent localization is on the head of the animal. To the touch, cysts can be firm and dense, and also have a bluish color.
Dogs can also develop carcinomas, which are mostly found in cats. Usually these are single tumors that are very similar to adenomas. That is why the question remains of the correct differential diagnosis, and therefore treatment.
In tetrapods, the most frequent places of localization of adenomas and other inflammations of the sweat glands are the head, neck, trunk and legs.
Carcinomas in cats
In representatives of the Persian and Himalayan breeds, tumor formations of apocrine glands often appear on the eyelids. They are small in size - from 2 to 10 mm. As we already mentioned, adenomas and carcinomas can be very similar in appearance, which in turn makes it difficult to diagnose and select the right treatment. However, it should be borne in mind that carcinomas look harder and inflamed. In addition, they can be mottled with ulcers and suppuration.
Tumors, like dogs, are mostly solitary. Outwardly resemble subcutaneous compacted balls of small size and bluish color. Carcinomas can be located anywhere in the body of the animal. Adenomas can also appear in cats, however, they are localized to a greater extent in the head area.
Apocrine breast metaplasia
Inflammatory diseases of the mammary glands are brought to a separate class. Since it is in cats that they perform an important function of thermoregulation and restriction of their territory, you need to be able to recognize the onset of the disease in time in order to avoid the sad consequences. However, do not forget that dogs are also susceptible to this pathology.
The reasons for the development of breast tumors can be the following factors:
- Age. In dogs, neoplasms appear most often in the period from 7 to 10 years. The older the animal, the less likely it is to have tumors. In cats, the situation is the opposite. In their case, the disease often develops in older animals.
- Castration and sterilization. The earlier these procedures are performed, the less likely the occurrence of tumors. However, it should be borne in mind that previous pregnancies do not affect the frequency and risk of the disease. Moreover, veterinarians argue that periodic delivery and feeding of litter with milk is a kind of prevention of the development of breast tumors in both dogs and cats.
- Suppression of estrus. The use of various hormonal drugs, which are based on progesterone, increase the likelihood of mastopathy. Despite the fact that these tumors are benign, they are still referred to as precancerous conditions and their appearance is best avoided.
- Gender Typically, breast cancer is predominantly a problem in female cats and dogs. However, males can also appear neoplasms. But they will be of a slightly different nature, since males do not have mammary glands, but there is a mammary gland. It also has ducts in its structure that can be prone to the formation of tumors.