Dog Life Cycle and Growth Stages in Biology

Dogs are carnivore domesticated animals that belong to the family Canidae. Dogs have an average lifespan of 10-15 years. Dogs have accompanied humans for almost 20000 years. Some scientists believe that dogs and wolves share ancestors. But evolution has led the dogs and wolves to develop in their separate ways. The recent wolves are not much related to the wolves that were first domesticated hence, we can arrive at the conclusion that the direct ancestors of the dogs are extinct. 

Dogs are the first species amongst animals that were domesticated. The term dog is coined to the whole of their species. An adult female dog who is capable of bearing pups is termed as a bitch and the adult male dog who is capable of reproducing offspring is known as a stud. The immature offspring are known as puppies before they reach their adulthood. The term litter is coined to a group of puppies that are born out of a single gestational period from the female dog. 

Anatomy of the Dog

Dogs are considered one amongst the ferocious animals. Dogs have highly developed sensory capabilities, unlike humans. According to a scientific study, dogs are capable of seeing the Earth’s magnetic field. Dogs are one among the mammals that are considered predators. They have a strong cardiovascular system that supports speed, pounding, and endurance. They have sharp teeth for hunting and tearing. Dogs have a powerful muscular body and their wrist bones are fused like many other scavenger animals. However, with developed science and technology many varieties of the dogs are bred some of which cannot survive in the wild unlike the nature of their species and are completely considered domesticated. 

Different varieties of dogs measure and weigh differently. A dog can weigh ranging from 20 pounds to 80 pounds depending upon which breed they belong to. Since dogs are warm-blooded creatures and come into the category of mammals, their body comprises organ systems like respiratory, digestive, reproductive, etc as of other mammals. Additionally, they have an integumentary system which is the skin and fur that covers the animal’s body and protects it from various weather conditions. There are two types of coats when it comes to domestic dogs. The first one is the ‘double’ coat variety that is found in dogs that basically belong to the colder climate areas. The double coat is made up of a guard hair on top that protects the animals by preventing the entry of moisture followed by an underfur within that which protects the animals from drastic cold weather. And the other variety is the ‘single’ coat variety which has just the topcoat only. 

Generally, the coat of the dog reveals the health of the animal. And the coat is maintained by proper nutrition. Premature greying of hair is not only found in humans but it is also found in dogs less than 2 years of age. 

The tails of dogs generally describe their emotional state. The dogs have various shapes of tails like a sickle, straight up, docked, curl, etc. This helps them to reveal their emotional state to others. Dogs have a good intellectual capacity which enables them to understand soon and in the case of domestic dogs, it helps them to get trained soon by their master. 

Reproduction in Dogs 

The reproduction in Dogs, wolves, and other canine species is called Canine reproduction. Both female and male dogs attain sexual maturity as early as 10-12 months of age. In a few larger breeds, to attain sexual maturity takes more than 2 years of age. 

When the female begins to develop physiological changes due to the effect of reproductive hormones, they will be physically ready to bear the pups. This is known as the Estrous cycle. This cycle is the way to tell the female dog is ready for copulation. In dogs, the fertilization occurs 3-4 days after ovulation. The embryo if formed attaches to the uterus around 12-15 days post ovulation. Once the embryo attaches to the uterus the heartbeat can be detected 7-9 days after that. In each gestational cycle, the average number of pups vary from 4-6. After fertilization, the female dog will bear the litter for approximately 60-70 days. The length of the gestational period varies in every dog. And the number of pups in each litter also varies when it comes to a different breed of dogs. A much larger variety of dogs who cannot mount the female, artificial insemination is performed to conceive the female.  

Neutering 

In many countries, to control the population of dogs they are sterilized. This process of sterilization is referred to as Neutering. In this process, the testicles are removed in the case of males and in females, the ovaries and uterus are removed. This, in turn, controls their sexual drive and the animals lose their capability to reproduce thus controlling the population. The ASPCA (American Society for the prevention of cruelty to animals) decided to neuter the variety of dogs in which further breeding needs to be controlled rather than killing the animals. Those puppies already born are euthanized (putting the animal to death) to reduce the population. 

Four Stages of a Dog’s Life Cycle

The four stages of the life cycle of the dog include puppy, adolescent, adult, and senior. 

• Puppy: This stage begins soon after birth until the first 6-15 months. During the initial weeks of life, the puppy cannot see or hear, neither are they capable of regulating their body temperature. The puppy solely relies on the mother for survival. Once the puppy completes 3-4 weeks of life their sensory power increases and the puppy then starts to see and hear. They begin to move around little. The initial 2 months after their birth it is necessary for the puppy to live with their mother and siblings until they learn to accommodate in the new surroundings. When it comes to bred dogs, once they complete the initial few weeks of life the breeder of the dog will start training the pup to socialize. This way the pup will learn to adjust with new people apart from its family which will help it in adjusting to its new master. 

• Adolescent: This stage of a dog’s life begins somewhere between 8-18 months depending upon the breed of the dog. This is the stage when the initial reproductive hormones begin to bring changes in the physical and mental behavior of the dog. If the dogs are not neutered or sprayed, they start to show up signs like how teenagers are in humans. This is the phase when the female dogs enter into heat and male dogs are more interested in sniffing the urine to mate with females. In some large breeds, this stage can continue until 36 months of their life cycle. 

• Adulthood: This stage in dogs is easy to manage when compared to the adolescent stage. The dogs if trained well behave as per the command. They enjoy spending time and going out for walks. Sexual behaviors are also controlled and the agitation in the dogs is less. In most of the breeds, the adult stage begins after 20 months of their lifecycle.

• Senior Stage: This stage of dogs are more like the senior stage in humans. The stage begins after the completion of 6 to 8 years of their life. The dogs are tired easily with runs. They are found sleeping often and do have dental issues. Urine incontinence is one of the major problems to be dealt with when the dogs enter into this stage of life. Though the average lifecycle of the dogs is between 8-15 years, some dogs are capable of living beyond 20 years depending upon the nourishment and also if they don’t have any serious illness. 

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Diseases in Dogs

Diseases in dogs are acquired through contact with the surroundings when they are taken for a walk to the park or if they come in contact with dogs who suffer from illnesses. It is required to take them to the veterinary doctors if any unusual signs or symptoms are noticed. The type of diseases that are considered as deadly in dogs are:

1. Canine Distemper: This is a contagious viral disease that can spread easily. The dogs develop fever, coughs, vomiting, and even paralysis. This can be considered airborne and can spread even if the food bowl is shared with other dogs who suffer from these diseases. The dogs often behave angry and irritated. Plenty of rest and fluid is advised by the doctors. A vaccine is the best method to prevent this disease and the dogs must be kept away from stray dogs.

2. Heartworm:  As the name suggests, this refers to the parasite that lives in the dog’s heart leading to infection in the lungs, heart, and blood vessels. The symptoms include respiratory issues, coughing, weight loss. The dogs suffering from this problem require rigorous treatment with steroids and antibiotics. The only way to prevent this disease is to give them a clean atmosphere and taking the dogs to the veterinary doctors frequently for health checkups. 

3. Canine Parvovirus: This disease occurs when the healthy dog comes in contact with the feces of a sick dog. This is highly contagious and difficult to treat if the infection spreads to the internal organs of the dog’s body. Symptoms include weakness, fever, cough, severe weight loss. The treatment protocol includes the administration of plenty of fluids and prevention of secondary infection by early treatment. Timely vaccination is necessary to prevent the disease in the first place.

4. Lyme Disease: This disease occurs when the dog suffers from a tick bite. The bacterium is spread through a tick bite and is carried through the bloodstream. Once the spread begins the pup or dog starts feeling pain in the joints. The dogs suffer from loss of appetite, fever, and often start to limp because of the pain. The disease can be serious if it is left untreated. Treatment includes the administration of antibiotics and proper vaccination. Following a healthy diet and keeping the dogs clean is necessary. 

5. Rabies: This is one among the fatal diseases that is spread through the saliva or bites from an infected animal. It can easily spread even to humans through a bite. There is no treatment for the rabies virus. The only way is prevention from being in contact with the infected animal and timely vaccination for the rabies virus. 

6. Leptospirosis: There is a presence of Leptospira bacteria in natural soil and water sources like rivers, lakes, etc. Exposure of this bacteria causes the disease in dogs and symptoms include fever, vomiting, jaundice, dehydration, etc. 

7. Kidney Disease: This usually takes place in dogs who are older in age when the kidneys stop working normally. This cannot be cured. Only further progression is controlled through medication. 

8. Kennel Cough: This is a highly contagious respiratory disorder in dogs caused due to inflammation in the airways. Exposure to the infected animal is the main cause. This can spread to dogs of all ages. However, proper vaccination helps in the prevention of the disease.