Dog and Cat Reproduction and Anatomy PDF

Normals and Reproduction Dog's life span ​ The maximum life span for a dog is estimated to be 27 years ​ However average lifespan for a few animals is 16-18 years of age ​ In general 10-14 years is considered normal for most...

Normals and Reproduction Dog's life span ​ The maximum life span for a dog is estimated to be 27 years ​ However average lifespan for a few animals is 16-18 years of age ​ In general 10-14 years is considered normal for most dogs. However, factors can affect this like body size and breed -​ Small dogs live longer than larger dogs -​ St Bernard's life span is 4.1 years, Irish wolfhound 6.2 years -​ Mixed-breed dogs live longer than purebred dogs -​ Neutered dogs live longer than unneutered because there are diseases prevented by neutering, also less likely to try to roam ​ Ultimately, it depends on what is wrong with the dog in front of you. Vital statistics for a healthy dog and cat Skin and coat ​ Normal shine, growth, and shedding pattern for breed or breed type; skin that is pliable, clean, and free of lesions Mucous membranes ​ Light pink in color (unpigmented areas;) Normal CRT is 1 second Food intake and body weight ​ Normal and consistent appetite; maintenance of ideal (lean) body weight Body Temperature ​ 100.0 -102.5 degrees Fahrenheit Pulse (resting) ​ The dog is 60-140 bpm and the cat is 145=200 bpm Respiration ​ The dog is 10-30 bpm; the cat is 20-14 BMP Skin and hair coat ​ The hair coat forms a physical barrier between the external environment and the skin ​ Some dogs have hair over the fur -​ Fur grows to a pre-determined length and then stops and hair continues to grow ​ All dogs and cats will shed their coat ​ Hair follicles are found in the skin and are responsible for the hair coat production ​ Each follicle is composed of a follicular sheath and a hair bulb -​ The follicular sheath is a tube-like structure through which hairs pass to exit on the skin surface -​ The hair bulb is found in the base of the follicle and is responsible for the production of the hair. ​ Dogs can have compound follicles containing Guard hair and fine secondary hairs -Guard hair is a single, siff primary hair -secondary hairs are thin and small hairs that make up the animal undercoat and can have multiple from the same follicle than primary hairs ​ Variations in the number and type of guard hairs and under hairs are seen between different breeds of dogs ​ The anagen phase is the growth phase of hair. It takes 6-8 weeks. The old hair is shed as the new hair progresses up the hair follicle and forces the old hair out ​ The telogen phase is the rest phase of hair. Variable and can be several weeks to several months depending on genetics, photoperiod, environmental temperature, age, breed, health and reproductive status ​ As longer day lengths for example the spring and summer there would be an increased activity of hair follicle ​ Short day length the hair will have a longer telogen phase hair ​ In spring/ summer as daylight increases, more shedding as more hair follicular activity ​ As many pets are indoors with the artificial light, it affects the photoperiod. For example, they can have year-round shedding and may never develop a “winter coat” ​ The skin is an important mechanical and biochemical protector of the body ​ The skin is also an important sensory structure to convey information about pressure, pain, and environmental temperature ​ The skin is composed of the epidermis and the dermis -​ The epidermis is the top layer. It consists of an avascular layer of epithelial cells firmly attached to the dermis. The epidermis is  thinner in areas with hair and thicker in areas without hair -​ In hairless areas, keratinocytes produce keratin which is the protective outermost layer of the skin -​ Dermis is made up of connective tissue, bloody vessels, and nerve fibers -​ Sebaceous glands are small lobulated glands associated with the hair follicle -​ The sebaceous gland emptys the sebum into the upper lumen of the follicle. The sebum is a lipid compound to covers and protects the hair. It also gives the hairs a lustrous appearance it also lubricates and protects the skin also may have anti-microbial properties. Disorder with abnormal sebum often associated with more bacterial skin infections ​ Dogs have minimal sweat glands in skin ​ Sweat glans perspiration from skin is not effective for heat loss ​ Most sweat glands are in the nose and toe pads so waterly nose means a dog is sweating a dry nose means no sweat ​ Cats will groom self and the saliva deposited in hair will help to dissipate body heat by evaporation ​ Dogs pant to dissipate heat ​ Healthy skin will be clean, pliable and free of dirt, sores, excessive oil or dryness  Mucous Membranes ​ Mucous membranes are lubricating membranes that line body openings such as the mouth, nostrils, eyelids, anus, and reproductive tract ​ The presence of blood vessels close to the surface causes the color (light pink to pink) ​ You won't be able to see the color if the mucous membranes are pigmented ​ Color and refill time can indicate the amount and composition of the blood flowing to the extremities ​ Pale mucous membranes can indicate decreased red blood cell (RBCs) blood loss or reduced blood flow. One of the causes is anemia which is the loss or destruction of RBCs or shock ​ Jaundiced or lcteric (Yellow colored) mucous membranes are the result of an accumulation of bilirubin. Bilirubin is a waste product that is produced when hemoglobin is catabolized by the liver. When the liver is unable to metabolize hemoglobin normally or if there is an increased rate of red blood cells, bilirubin can accumulate resulting in jaundice. ​ Bright red mucous membranes can indicate a hyperdynamic state ( early compensated shock) or irritation or it may not mean anything ​ Cyanotic (bluish or purple) mucous membrane means a lack of oxygen in the blood ​ Capillary refill time (CRT) is another way to evaluate blood flow to the extremities -​ To do CRT you lift the upper lip and press the thumb firmly against the gum area above hold for 6-8 seconds. After release, the blanched area should return to normal color in 1-2 seconds. If it is prolonged it can indicate circulatory collapse or shock Body Temperature ​ The normal body temperature of a dog is between 100-102.5 degrees Fahrenheit -​ At the hospital with stress, it can rise to 103 and that can be normal ​ Rectal temperature is more accurate ​ Axillary temp or auricular (ear canal) temperature can also be taken ​ If the fever is pyrexia it is a metabolic cause of an increased temperature -​ When the fever is pyrexia the body has raised the set point higher, they may search out warm areas. You need to treat the underlying problem first before you cool it off because if you cool it off it will just make its temperature go up more -​ Fever environmental cause is an external cause of rising temperature and pets can not dissipate the heat. These patients will appear more stressed and will be trying to dissipate the heat. These patients need to be cooled down Pulse ​ Pulse is the local, rhythmic expansion of an artery that corresponds to each contraction of the left ventricle of the heart ​ Pulse can be taken by either directly palpating the heart or feeling it in the femoral artery of the back leg (proximal inner rear leg). Gently pressing on the lower chest wall immediately behind the dog’s shoulder (in the lower third of the chest cavity) ​ Dog normal 60-140 beats per minute - smaller dogs will be faster beat, and larger dogs will have a slower beat -A cat's normal heartbeat is 120-140 beats per minute ​ The pulse rate and heart rate should be the same Respiration ​ Respiration rate refers to the number of inhalations (or exhalations) per minute ​ Dog normal 10-30 breathes per minute ​ A cat normally 20-40 breathes per minute ​ Count the breaths by watching the movement of the rib cage. The panting does not need to be counted. Panting can be normal in a dog Female anatomy ​ The major organs of the reproductive tract of the female are the oviducts, uterus, vagina, and vulva, and the secondary sex organs, the mammary glands ​ The ovaries are small lima-shaped organs caudal to the kidneys -​ The ovaries produce the egg and certain reproductive hormones ​ Oviducts are small thin tubes connecting the ovaries to the uterus that function to transport the ova (egg) from the ovaries to the uterus. The Ova (egg) will spend about 2 days moving through oviducts to the uterus ​ Fertilization takes place in the oviduct -Fertilization for dogs takes place near the end of the oviduct (closet to the uterus) - the ova (egg) of the cat is ready for fertilization immediately anywhere in the oviduct upon ovulation ​ The uterus is a muscular, hollow, y-shaped organ consisting of 2 long horns and a short body, neck and cervix ​ The cervix is the oval-shaped fibrous/muscular structure that serves as the channel from the uterus to the vagina ​ The vagina (birth canal) is a long narrow muscular/membranous canal extending from the cervix to the vulva  ​ The dog's vagina is lined with stratified, squamous epithelial cells. These cells change in shape and structure during the bitch’s estrous cycle. Can be used as a method for detecting ovulation in the dog ​ The urethra is the canal that carries urine from the bladder and empties into the lower part of the vagina ​ The secondary sex organs of the female are the mammary glands -Most female cats have four functioning pairs of mammary glands, which are located in two parallel rows along the ventral mid-to-caudal abdomen. Dogs have 4-6 pairs in two parallel rows ​ Mammary glands are not developed until puberty ​ Teats or nipples deliver milk to the puppy/kitten Reproductive Anatomy of the Male ​ Testes (testicles) is a paired, sperm production and testosterone synthesis ​ Sperm production occurs throughout the year in dogs and cats that are exposed to natural photoperiod will have decreased spermatogenesis in winter but can mate year-round  ​ The testes are divided into lobules, each of which contains the long, tightly coiled seminiferous tubules -​ Cells lining the seminiferous tubules- the germinal cells- are responsible for spermatogenesis (production of spermatozoa) -​ The Leydig cells, located between the tubules, produce testosterone -​ Testosterone hormone is necessary for normal spermatogenesis, development of secondary sexual characteristics, and sexual performance in the male ​ The seminiferous tubules eventually straighten and empty into collecting ductules that merge to form the epididymis, where sperm maturation takes place ​ Each epididymis empties into its associated vas deferens, which ultimately empty into the urethra -​ The urethra is a hollow tube which originates at the neck of the bladder and runs through the penis ​ The prostate is an accessory sex gland that surrounds the urethra where it joins the bladder ​ The male cat has two accessory sex glands: the prostate and the bulbourethral gland -These glands add secretions to the sperm-containing seminal fluid as it leaves the vas deferens and travels through the urethra Dog penis ​ With the glans of the penis (free portion of the penis) there is a small bone called (the os penis). The Os gives the penis support during the early stages of mating ​ At the end of the os penis is a penile swelling called the bulbous glands -​ This area enlarges to a spherical shape during mating. It's responsible for the “coital tie” which prohibits the male and female from separating immediately. It can last 5 to 80 minutes Cat penis ​ The cat's penis is positioned slightly downward and caudally when erect (rather than cranially, as in other domestic species) which allows intromission when the male mounts a receptive female ​ A unique characteristic is that the external surface of the glans portion of the cat’s penis has barb-like projections. They provide stimulation to the walls of the female's vagina which is necessary for luteinizing hormone surge in the female which leads to ovulation Male anatomy ​ There are several important hormones in reproduction in the male cat. The anterior portion of the pituitary gland produces luteinizing hormone (LH) and follicle-stimulating hormone (FSH)  -​ Luteinizing hormone (LH) will stimulate testosterone secretion by the Leydig cells surrounding the seminiferous tubules. FSH initiates spermatogenesis and the production of androgens Estrous cycle ​ There are 4 stages of the estrous cycle which are anestrous, proestrus, estrus, and diestrus ​ In “heat” or ‘season” is only the estrus stage -the female is receptive to the male at this time and ovulation takes place ​ Dogs are spontaneous ovulators -​ Ovulate even if not mated to a male ​ Cats are induced ovulators -​ Increases chances of successful reproduction when living a solitary life Anestrus ​ This is the period of reproductive rest ​ Ovaries are not active, estrogen and progesterone at baseline levels ​ This will happen after diestrus and before proestrus once the cycle starts again ​ During anestrus the males won't be attracted to the females and the females will not allow breeding at this time ​ In dogs, anestrus starts after whelping (if a dog has gone through a pregnancy after birth). The duration of anestrus varies considerably between females. A range of 2-10 months is seen, with an average anestrus period of 5.5 months which results in an estrous cycle lasting 8 months ​ Cats anestrus usually starts in October and lasts until late December. Anesturs period can be shortened in queens who are kept indoors and exposed to 12 hours or more of artificial light Proestrus ​ Hormonal changes happen during the proestrus period. The anterior pituitary secretes FSH which actives the ovaries to begin follicular development and produce estrogen ​ Estrogen causes the behavioral changes seen as well as preparing the uterus and vagina/vulva for mating and pregnancy​ ​ Estrogen concentration steadily increases as the follicles develop in preparation for ovulation ​ Proestrus ends with the onset of estrus which is when the female will allow the male to mount and breed Dog proestrus ​ During proestrus dogs start to have blood-tinged vaginal discharge and swelling of the vulva ​ At the beginning of proestrus, the vulva is turgid so intromission/breeding is difficult. As proestrus proceeds, the vulva becomes softer and more pliable ​ The blood-tinged vaginal discharge comes from the leaking of red blood cells of vessels lining the uterus into the lumen of the uterus. It can also have some leakage from the wall of the vagina as it changes. Also if a dog is spayed you would still see bloody discharge afterward if an ovarian remnant is left. ​ During proestrus, dogs will act playful or tease males but will not allow mounting by the male. As proestrus progresses, the female will become more passive about the male’s approach ​ Usually, proestrus in dogs lasts 6-11 days with an average of 9 days Cat penis ​ Proestrus in cats is characterized by subtle changes in behavior, which include attention-seeking and restlessness, increased rubbing, and occasional urine spraying. ​ If approached by Tom (male) the female will not allow mating but may allow the male to mount ​ At the end of proestrus, the female's rubbing behavior progresses to rolling, kneading, and stretching. Cats will also start “calling” (howling) which will continue through estrus. A tomcat will respond with a similar call ​ For cats, the proestrus period is short lasting 1-3 days  Estrus ​ Estrus is characterized by a period of sexual receptivity in the female ​ There will be a decline in circulating estrogen and an increase in circulating Dog estrus ​ Estrus starts the first day the female will stand for mounting, and ends when the female will no longer accept the male ​ Behavioral changes in the female including allowing or even initiating interactions with the male, crouching and elevating the rear quarters toward the male, deviating tail to one side tensing rear legs to support the weight of the male during mating ​ The vaginal discharge progresses to a straw color or slightly pink color ​ During estrus, the female dog's vaginal secretion will now contain pheromones which makes the female attractive to the male ​ The average duration of estrus is 5-9 days but can last from a few days to almost 3 weeks ​ Hormonal influences during estrus include a decline in estrogen and an increase in progesterone. The change in estrogen concentration stimulates the release of FH and LH from the pituitary gland, which in turn causes ovulation ​ Ovulation occurs 24-72 hours after the LH surge. Smaller breeds can release 2-10 ova, larger breeds 5-20 ova ​ All of the Ova released over 24-48 hours will have similar stages of development. The Ova will be immature when its been released and it will still have to complete meiosis ​ Capacitation is the process of maturation of the ova for the ova to become capable of being fertilized. This process takes 2-3 days. Once the ova is mature it can be fertilized over 12-72 hours in the distal oviduct Cat Estrus ​ During the estrus period the cat's behavior changes and exhibits lordosis posture. Lordosis posture is when the queen crouches low to the ground with her neck and abdomen touching the floor, rear legs positioned to elevate the perineum, tail deflected to one side, and rear feet will often be mildly lifted back and forth repeatedly. ​ This can be induced by touching or petting the back or neck ​ During estrus, the increased frequency of calling will happen ​ Mating is necessary for ovulation. If no mating, follicles do not ovulate and will regress after several days. If there is a mating, the stimulation of the queen’s vagina causes the anterior pituitary to release LH. Several mating may be necessary to trigger the LH surge. Once triggered within 2 hours, the LH surge will be released and then back to baseline in 8 hours. Ovulation for 24-30 hours will then happen after the LH surge has been released. During ovulation 3-7 ova will be released that have already undergone meiosis and can be fertilized immediately. Fertilization occurs in the upper region of the oviduct. The embryos will then move slowly from the oviduct to the uterus over 5-6 days  Estrus after ovulation ​ After ovulation, the ruptured follicle becomes a corpus luteal ​ The corpus luteal increases the production of progesterone. Corpus luteal is a transient (lasting a short time) hormone but it will last through pregnancy ​ Progesterone stimulates the endometrial lining of the uterus to produce secretions to nurture the embryos in the early stage until implantation and development of the placenta ​ Increases blood flow to the uterus in preparation for pregnancy Detection of ovulation in the dog ​ Females will accept the male several days before ovulation ​ The female dog should be bred on the first day of acceptance of the male and then again, 2 and 4 days until no longer accepting ​ Another way to determine ovulation includes vaginal exfoliation cytology which is commonly used ​ Vaginal cytology provides a rough estimation of the bitch’s estrogen status by checking the thickness and cellular morphology of the vaginal epithelium ​ Estrogen directly affects the thickness and cell morphology of vaginal epithelium ​ Cells become stratified squamous epithelium with rising estrogen levels in proestrus ​ They also become large and flat cells ​ Thickening of the epithelial layers pushes the cells lining the lumen further away from the blood supply which causes the cells to become cornified and slough ​ Vaginal smears should be obtained in a series from beginning or middle of proestrus ​ 100% cornified cells can be seen for 10-14 days ​ On average, 100% cornified cells for 6 days when ovulates ​ Female should be bred 4-5 days after 100% cornified cells and then bred daily to every other day for 3-4 breedings ​ Another way to detect ovulation is progesterone levels in the blood. You will need to get a series of blood levels to know when the progesterone level is increasing ​ The rising progesterone levels are highly correlated with the LH surge peak in dogs ​ Ovulation happens 2 days after LH peak and takes 2-3 days for ova to mature, then viable for 12-72 hours ​ A very fertile period for dogs is 4-7 days after LH peaks ​ Breed dogs 2 days after progesterone level increasing and then every other day for several matings Cat Diestrus ​ Diestrus period happens in cats after mating and successful ovulation ​ This is the period of the reproductive cycle in which the cat’s reproductive tract is under the influence of progesterone by corpus lutea (CL) ​ In a pregnant queen, diestrus ends abruptly at the time of parturition, approximately 65 days after fertilization (range 60-68 days). If Ova are not fertilized, the CL will regress in 36-44 days and ir can then go back into proestrus if still breeding season. ​ Interestrous happens if no ovulation/mating, the follicle regresses and enters a short period of interestrous. It will last an average of 8 days but can be 3-15 days ​ Then can go back into proestrus and estrus (and your female cat calling again) Dog diestrus ​ Dog will go through diestrus 2 months following estrus with reproductive organs under influence of progesterone from the CL ​ Diestrus in dogs begins with cessation (pause) of sexula receptivity by female until the CL regresses (less) ​ Diestrus in dogs will last for 60-66 days if pregnant or not pregnant ​ All the changes to reproductive organs are the same in pregnant and non-pregnant female ​ Non-pregnant females can produce milk and have a pseudoregnancy ​ During pseudoregnancy varies by individual, can also have increased appetite, decreased activity and increased material behavior. It will also decide an object as their puppy and protect it from everyone (even is she would have let you touch her puppy) ​ Eventually returns to anestrus (at parurition if was pregnant) Breeding management  ​ The shelters have many pets which are euthanized and that should be taken into consideration before breeding ​ The welfare and heath of the mother and her offspring as well as availability of a good and permanent home should be considered ​ If going to breed, should have medical records will all past breeding and estrus history/sperm viability, vaccination history, brucellosis testing in dogs and any testing for genetic diseases before breeding Dog breeding management ​ The female is usually brought to the male for breeding ​ Courtship usually initiated by the male and the female can reject the male ​ Once breeding, initial portion of ejaculate its sperm free prostatic fluis ​ Becomes locked or tiedand then the sperm-rich fraction is ejaculated during the first 1-5 minutes of the tie ​ Tie can last 5-60 minutes ​ Male and female should be allowed to separate naturally once the bulbis glandie has reduced in size sufficiently Breeding management artificial insemination ​ Artificial insemination is manually collecting semen from the male and subsequently depositing it (inseminating) into an ovulating receptive female ​ Eliminates need to transport dogs ​ Can reduce risk of injury to the male and female dogs ​ Reduced stress to dog ​ Reduced risk of transmitting diseases ​ Sperm can be preserved with freezing and transported ​ Is being used more commonly Cat breeding management ​ Timing of breeding best determined by queen’s behavior. That is when going into coital crouch ​ Mating can occur rapidly lasing 30 seconds to 5 minutes ​ The tomcat mounts female and clasps the female with his legs and grasps her dorsal neck with his teeth- usually does not penetrate the skin ​ Inteomission is almost immediately followed by ejaculation. The tomcat will dismount and hide/run away. Queen will have a postcopulatory cry and will turn aggressive. Most mating areas will have a place fot he tomcat to hide during this period. Queens will have vigorous rolling, rubbing and grooming lasting 30 seconds to several minutes ​ Cats will repeat mating in 15-30 minutes ​ Estimated that 4 matings in a 24 hour period is needed to induce the LH surge and ovulation ​ Estrus ends 24-36 hours after initial onset of mating ​ If the cat or dog is bred by multiple males in the same estrus, it is possible to have offspring from multiple males in the same litter