Basic reproduction of the cat


Basic reproduction of the cat

Lecture Notes

In this lecture we discuss basic reproduction of the cat.


Anatomy of the male cat

Lecture Notes

Starting with the male - take a moment and orient yourself, starting at the left side of this diagram, locating the cat's kidneys and bladder, which are important parts of the cat's urinary tract.

As for the reproductive tract then, if you start at the bladder and move your way back toward the cat's tail, you will see the prostate and the bulbourethral glands; these are what we call accessory sex glands, and their primary function is to produce some of the fluids that make up semen.

Next, locate the penis and its tip, or glans penis. Note that the cat's penis is positioned so that it is deflected slightly downward and caudally (or towards the rear of the animal) when it is erect. The penis in most other domestic species deflects cranially (or toward the head).

Finally, locate the scrotum, inside which you will find the paired testes; the testes or testicles are the site of sperm formation and much of the cat's testosterone production.


Glans Penis

Lecture Notes

An additional distinguishing feature of the male cat's reproductive tract is that the glans penis is covered with hundreds of tiny spines or barbs. The function of these spines is to aid in tactile stimulation of the female's reproductive tract during mating. These barbs are dependent on testosterone and will disappear within weeks of a male being castrated.


Anatomy of the female cat

Lecture Notes

Here we see a picture of a portion of the reproductive tract of a female cat, or queen. You see the paired ovaries, which produce the oocytes, and the long uterine horns. This uterine structure is typical of animals who bear multiple young, or litters.

The uterus and ovaries in this picture had been removed from a cat during a spay surgery; you can see where the tissues were cut at the base of the uterus. Imagining for a moment that the uterus was still inside the cat, if we were to continue to follow the tract past the cut mark, we would encounter the cat's vagina and then the external opening, the vulva.


Estrous cycle of the queen

Lecture Notes

Now let's discuss some key aspects of the female's reproductive, or estrous cycle. The cat's estrous cycle can begin as early as four to five months of age, depending on conditions.

The cat is what we call seasonally polyestrous. Let's break that down into its two parts. Seasonally because the female's reproductive system is active only during the breeding season. Cats are long-day breeders, which means that increasing day length triggers an increase in reproductive hormone activity. In the Northern Hemisphere, under normal conditions, female cats will normally cycle from spring until late fall. However, strictly indoor cats under artificial lighting conditions may cycle year-round because they do not feel the natural photoperiod.

The prefix poly means many, so polyestrous means many, or multiple estrous cycles. To define the cat as seasonally polyestrous explains that she can have many, or multiple estrous cycles with her breeding season.

Finally, the cat is what we can an induced ovulator. Unlike many mammals (including humans and dogs), in which ovulation spontaneously occurs during the sexual cycle, ovulation in the female cat must be induced through the process of mating. That's where the penis spines come into the picture. The tactile stimulation from the spines triggers the increase in reproductive hormones necessary for ovulation. This is an incredibly efficient system of reproduction by pairing ovulation with mating, thus ensuring that the oocytes and the sperm are present in the reproductive tract at the same time.


Superfecundity

Lecture Notes

The induced ovulation model is also why cats are capable of what we call superfecundity. This occurs when multiple fathers are represented within one litter.


Litter size

Lecture Notes

A litter size of four to five kittens is normal, but anywhere from one to nine kittens is not uncommon.


Estrous cycle of the queen

Lecture Notes

A bit more about the queen's estrus cycle. It is quite complex and has five different stages, or phases: proestrus, estrus, interestrus, diestrus (or metestrus), and anestrus. Each stage involves significant changes in hormones and behavior.

We will not discuss the details of each stage here but will point out the period of sexual receptivity - or estrus. Estrus begins when the queen allows the male to mount her and breed. Since ovulation is paired with mating, this is therefore also the stage of the cycle during which the queen will ovulate.

Many people also refer to estrus as heat.


This female is exhibiting lordosis.

Lecture Notes

During estrus, the queen will display behaviors to attract males; she will be extremely active and restless and will make loud calling sounds. She will also exhibit the lordosis posture. Lordosis, also sometimes called the coital crouch, is shown in this picture. The queen crouches low to the ground with her rear quarters elevated and her tail deflected to one side.

During estrus, the queen will not only allow mating to occur, but she will often actively seek out males.

This drive can be severe in many cases, and it's not uncommon to hear of indoor cats breaking out of their houses during estrus, in active pursuit of breeding males.


Gestation

Lecture Notes

Gestation, or pregnancy, in the cat lasts approximately 63 to 65 days. The first sign that a queen is pregnant can usually be detected at around four weeks and is observed in her nipples. They will change from pale, soft structures to ones that are pink, enlarged, and firm.


Approaching parturition

Lecture Notes

The queen will also gradually gain weight over the course of gestation and her abdomen will swell. The cat you see here is within just a few days of parturition, or giving birth. Her mammary glands will further enlarge during these last few days in preparation for feeding the newborn kittens.

When delivery time is near, the queen's body temperature will start to drop slightly. She will start to exhibit nesting behaviors and will become increasingly restless as parturition approaches.


Parturition

Lecture Notes

Parturition begins with a series of uterine contractions that lead to expulsion of the first fetus. The placenta for each fetus will often pass shortly thereafter. As you see here, the mother licks away the membranes to clean the kitten, and she also may eat the placenta. The kitten will be encouraged by the mother to nurse.

The process will continue until all of the kittens have been born. At that time the contractions will cease, and the mother will continue to clean and nurse her young.

 


Credits

Lecture Notes