SWIMMER PUP SYNDROME
Fred Lanting, TheDogPlace.org - October 2013
An infrequent, puzzling phenomenon is the litter in which many, if not all, of the whelps become strangely deformed sometime in the first two weeks of life. A flattening of the thorax and abdomen, top to bottom, becomes evident about a week after birth from some unknown cause. Swimmer pups happen most often in the dwarf (chondrodystrophic) breeds but swimming has been seen in several other breeds. Instead of the thorax developing normally into a progressively deeper tube from the prosternum/neck area to the diaphragm, it forms more of a flattened cylinder with the height from floor to spine about the same all the way back to the loins, and perhaps even lower midway down the back. The forechest, instead of dropping from the prosternum to the last sternal vertebra, may even be concave, and as time goes on the puppy may become even more flat-chested and pancake-shaped.
Recognizing A Swimmer Pup
There is some variation in swimmer severity and symptoms, but the scenario is usually something like this: As the ribs bow out, the heart and other organs may be pushed into the pleural cavity and displace or decrease the air volume of the lungs; as a result, untreated pups become lethargic, lacking in energy and strength. By the third to fourth week, when normal pups would be running around, surviving swimmers have not yet learned to push themselves up into a standing position. If the extended limbs, especially front legs, are moved at all, it is with a paddling motion to the sides, hence the disorder is often called “Swimming-Puppy Syndrome.” The hind legs typically are extremely weak; they may be tucked under the torso, or less frequently extend behind the pup or laterally (toward the outside), but in any case they have little or no movement. If corrective swimmer therapy is not instigated early, “swimmers” have very poor circulation, respiration, and ability to swallow food or keep milk in their stomachs, and when they are old enough to wean (if they live that long!), are very slow when eating from pans. Stifles may be rotated underneath the belly, patellas are often luxated, and other orthopedic or osteochondral defects may be noted. Many swimming puppies die from inhalation pneumonia (from inspiring regurgitated milk) or other forms of respiratory failure.
If swimmers are not given some sort of therapy, there is a less-than-even chance they will survive to eight weeks. Generally, those that do manage to live, only begin to walk at or after this age. A 1981 Veterinary Medicine/Small Animal Clinician report on a litter of Shepherd pups, five out of six of whom were swimmers, mentions one pup that started walking by nine weeks old, but by six months was still unsteady and slightly undersized (female, 40 pounds). Because she tired rapidly, even after only moderate exercise, she was euthanized. Autopsy showed that her vertebral/rib joints were enlarged, but internal organs seemed normal in appearance.
What Causes Swimmer Pups?
Based on the above evidence, it’s possible to conclude that there might be another cause other than ventro-dorsal compression. Flattening of the chest is more likely an effect than a cause. There may also be permanent damage from the compression early in life that affects viability later, even if swimmer therapy seems to have helped. There may be variability in the severity, based on genetic or environmental factors, or a combination of these.
Many factors have been accused of contributing to the swimmer pup syndrome, both environmental and some of unknown genetic origin. For a while, most people blamed slippery floors, but I’ve raised all my litters on smooth, impervious flooring covered with newspaper and have never had a swimmer in my own operation. The VM/SAC report mentioned above involved excellent footing in the whelping/nursing box: clean, dry, rough surfaced indoor/outdoor carpeting. Until this report, it was generally believed that such a floor would prevent swimmers from developing. I disagree, especially with recommending the use of carpeting, as this surface is notorious for harboring germs and thus causing other health problems. Newspapers are best for lining the nest or exploration areas of the house that has new pups, until they are housebroken.
Helpful Therapy For Swimming Puppies
Some Dachshund breeders told me they were fairly successful in correcting the swimmer syndrome by putting each of the pups in a sling for at least part of each day. This practice encouraged them to make contact with the floor with their pads. Some tied hobbles to the front legs to keep them under the body and the elbows close together. This, they felt, prevented the front legs from becoming spread-eagled. Dish-shaped nests of straw have also been suggested, but not only does that present the danger of filthy conditions if not cleaned often, it also may not be very practical. A modification of the idea has also been proposed: put the whole whelping/nursing area into a sling thus making the “floor” more like a hammock with the canvas or vinyl suspended at the corners and edges and lower in the center. I doubt the efficacy of any of these, but as sailors used to say, “Any port in a storm.”
Other swimmer therapies that may be beneficial, although tiresome and time-demanding of the breeder, include massage (passive exercise), administration of vitamin E (possibly with selenium added if they’re not getting solid food yet; but have your vet research and advise, as it’s easy to overdose selenium, which is then toxic), taping or tying hobbles to prevent splaying, and suspension in warm water. The last-named swimmer therapy is promising if either active or passive movement can be induced. Thus, swimming (the real kind, in water) may help correct the “swimmer” syndrome. Whirlpool baths are beneficial for partially paralyzed or weak adults such as those suffering from coonhound paralysis, but of course the waves in such a tub would overwhelm a 3- to 6-week old puppy. Therefore, hold him in your hand or a sling, with support to keep his head up out of the water, and let him paddle for a while in warm water (probably around 80 degrees F to prevent chilling), but take him out and dry him thoroughly when he tires. As many of these sessions as you can manage should help the swimming pup to develop coordination, muscle development, and better circulation while putting much less weight on his body. Your hand or makeshift sling plus the buoyancy of the water will take the weight off the chest. Finger manipulation of his limbs might be a good idea, too, while he’s in the water, but also when he’s out.
Genetic and Ethics Of Flat-Chested Puppies
Starting in 1999, after much of the above was printed in my book “The Total German Shepherd Dog” (2nd edition), some e-mail correspondence on the subject started coming to me. A French Bulldog breeder expressed the belief that a dam that produced this defect should not be spayed or eliminated from the breeding program. At first I disagreed with her because I am a hereditarian, but later came to feel that breeding her again might not be all that much of a risk. This lady had two swimmers, each 12 oz at birth, never left on flat surface. She said she put them on blankets, “facing upwards and they stayed in an upright position,” and claimed they were both fine within weeks.
The syndrome of swimmer puppies is sometimes referred to as Pectus Excavatum, and described by many as “a condition of so-called flat-chested puppies.” Without intervention, and often despite best efforts, they usually die anywhere from two days to four weeks after diagnosis or symptoms. More often it is sooner than later, according to the Bulldog people I have heard from.
When nursing (if it is able to get to the teat at all), the swimmer puppy may arch its back extremely in a backward movement to compensate for an apparent inability to flex at the neck.
Some breeders prefer not to assign any blame to genetics. They disagree with those who hold that the puppy inherits most problems from the parents, and a pair that produces a swimmer puppy should be removed from one’s breeding program. These people often postulate that the bitch was fed inadequately or that she did not utilize the necessary dietary nutrients (i.e., vitamins, proteins, fats, or minerals) to give the puppy the “skeletal components needed.” This may be stretching credulity, as swimmers also happen in households of experienced breeders, and to bitches whose diets are normal. In this age of commercial dog food, it is nearly impossible to blame it on such a drastic dietary deficiency. Others who refuse to acknowledge the major part that genes play in determining characteristics and deformities tend to blame environments such as too flat or too hard or too slick a surface, bacteria, viruses, etc.
A breeder of Lhasa Apsos and American Cocker Spaniels corresponded with me after reading the section on swimmers in my “Total GSD” book. She made some very interesting observations that may give us a clue to the primary genetic defect: She had become frustrated with the feeble answers from “experts such as vets and breeders [who]… all knew what it was and all had answers, none of which were very successful… none of which had real solutions.” She started to see a pattern emerge. The incidence of swimmers appeared to be “random.” Type of food or use of supplements “didn’t decrease or increase the occurrence of swimmers.” What she did observe was “the swimmer syndrome began to show up at anywhere from one hour to a couple of days after birth, beginning with a slight flattening of the chest or an actual bend in the ribs.” I believe that by careful observation, she hit upon a method of early identification of afflicted pups and possibly, therefore, carriers of the defect. By following her techniques, one may prevent the development of the symptoms, but will not eliminate any genes that cause the untreated neonate to become a swimmer. I am enough of a eugenicist to want to remove carriers of a defect from a gene pool, but enough of a “compassionate conservative” (as a famous politician’s speech writer coined the term) to want to save any pup that could possibly live a useful life and bring someone happiness. However, such pups, while saved from death or uncomfortable existence, perhaps should be neutered. You might not eliminate all the genes from these lines, but the “worst” ones, those causing obvious cases.
Swimming Puppies and Righting Reflex
The Lhasa-and-Cocker lady became adept at determining if a pup has a problem by picking up each pup and testing its “righting reflex.” She correctly stated, “What you will notice about these swimmers is that they are always lying flat on the belly. If you lay them on their side, they will immediately return to lying on their bellies. This is what is known as the righting reflex. You can observe this by disturbing [waking] a sleeping litter of very young puppies and watching all of them right themselves. They immediately [turn to lie on] their stomachs and begin to look for a nipple. The righting reflex is the first response to nursing and the cause of swimmer puppies.” While that last phrase may sound a bit awkward, it is true that the normal neonate has an instinct to get onto its belly and crawl or drag itself to a teat. Once there, it may just as easily and happily again flop over on its side a little, as long as it does not twist too far in the direction of having its belly-side up. After nursing, the normal newborn pup will lie on its side to sleep. As they get a little older, they will be just as comfortable draped over each other, and as they are old enough for the ribcage to have developed strength, they may sleep belly-down for a while, but by then it is not abnormal.
Occasionally a puppy seems to indicate that it doesn’t want to or cannot “return to a normal relaxed state on its side and insists or remains [on its belly] causing the flattening of the chest, which, if left undisturbed, leads to swimmer syndrome and probable death.” This is possibly not a defect in the righting reflex, per se, but a genetic defect in proprioception, the instinctive knowledge of position. It may well originate in a genetic defect in the embryonic development of the inner ear. Perhaps the swimmer has inherited poor proprioception and therefore its body “doesn’t know to roll over on its side.” Once in the righted position used for finding the nipple, it has no way of knowing that there is a more comfortable and normal resting position.
The ear is divided into three parts: outer, middle, and inner. The outer part helps funnel sound to the eardrum, a membrane on the other side of which is the middle ear. There, three bones hinged together relay eardrum vibrations to the inner ear, which is separated by more membranous tissue. The inner ear includes not only the nerve endings that transform mechanical movement into electrical impulses and carry auditory messages to the brain, but it also includes the organ of balance. The rear part of the membranous labyrinth has three semicircular canals that look like three bicycle tubes joined together in one bulbous end. Each of the three canals is oriented 90 degrees to the other two, and all are filled with fluid and nerve endings. The tiniest movement of the body tells these moving-fluid-activated nerves what direction the head is turning, and thus informs the brain as to what muscles must contract in order to change or return to a given position. It is my hypothesis that in swimmers, the message is not being relayed or interpreted somewhere along the chain of events. We also see similar interruptions in these messages in older dogs, caused by infections, poisoning, or late-developing genetic factors. It may be that the messages coming from the legs are not getting to the brain or spinal cord, nor going in the return direction.
The “cure,” if you want to call it that, will only be for the individual itself. If it is indeed a genetic problem, correcting the condition in the individual does not erase the cause, so cannot be considered a cure in the strict semantic and population sense. If your breed has been known to have swimmers, or you are slightly paranoid by nature, steps to identify and correct could be taken as soon as possible and can be quite simple, according to that Lhasa breeder: “Check all the pups right after birth and every hour or so for the next couple of days.” [I don’t know about you, but I have to sleep sometimes, and don’t have shift workers in my kennel to do this!] “If you notice a pup that is always on its belly or beginning to show signs of a flat chest, what you do is lay mom down and put this pup on a good nipple. After it’s on, turn it on its side, holding its entire body and … making sure it stays on its side. If the pup lets loose… start over. Do this several times a day until the pup returns to normal… on its side; when that happens, you have just cured swimmer puppy syndrome.”
You will have to determine for yourself if it is worth it, realizing that not everyone is able to save every defective puppy. And, if you want to prevent it from happening again, perhaps the surest and safest approach is not to breed either parent again. That is, play the odds and assume a genetic cause unless you are convinced a problem is purely or mostly environmental and at the same time not very important to the breed population. The longer I live, the more evidence I see that nearly everything has a bigger genetic component than you would initially think, but probably there are more urgent matters to attack first.
Surviving Swimming Pup Syndrome
A friend and fellow judge in Pakistan, who is one of his country’s most notable breeders, wrote to me late in 2010 for advice. He related, “In my Labrador Retriever litter, I had a swimmer pup. I noticed it when the pup was about 16 days old. By three weeks, his hind legs would stretch back like a turtle and also go sideways. Front legs were OK and he could lift his chest and move with his front legs. He had a flattened chest. I tied his rear legs with an elastic ribbon, keeping it only as wide as his body. I made a loop around his neck also and tied [the cord running under the belly] to the elastic band joining the two hind legs. I did this to ensure the rear legs did not stretch back. Within three days, he started walking on his own (with elastic bands) and after another week started jumping around without any bands. Now he runs about and it is very difficult to spot it from his litter mates. His chest is absolutely normal. Litter is now five weeks old.
“After reading your article in detail, I want to know whether, in the swimmer puppies, the chest is flattened because of splayed legs or the legs are [spread out] because pups are born with flat chest. My other question is, will my pup have any after-effects later in life or will be normal?”
I told him this: “Ken, it is most widely believed (in the more knowledgeable veterinary and expert-breeder communities) that the problem is a congenital weakness that develops when the pup does not have the neurological stimulus (or muscle response) to control the early placement and use of limbs. Without this normal nerve development, the muscles are not ‘trained’ to respond when signals are sent from the brain or spinal cord. Apparently, the breeder’s act of positioning the limbs under the torso somehow allows this nerve impulse ‘send-and-response’ procedure to establish a ‘habit’ (which you could call the system’s development of ‘memory’). The later a breeder attempts to correct the problem, the less likely the pup will develop normally. The longer one waits to reposition and train the limbs, the more permanent will be the damaging effect on lungs and other internal organs. If ignored, apparently it will lead to death, although there are no reliable statistics. I have never heard of the problem resolving spontaneously — without human corrective intervention.
“In answer to the question of which came first, the chicken or the egg, I would say that the nervous system defect is the cause, and the flattening of the chest cavity is a result of this lack of stimulus to the limb muscles to move them under the body and push the torso up, sideways, and forward. I have not seen any study or testimonials as to ‘after-effects’ nor whether swimmer pups run in families. Until I see such a hint of familial relationship, I would guess it would be safe enough to breed dogs that were affected with this syndrome in the whelping box, but keep good records on future relatives’ puppies. It very well could be what many people call a “non-genetic” (but by which I personally mean low heritability) trait, one that is less influenced by genes and more influenced by environment — including the biochemical environment in the uterus.”
So, as in any abnormality whether very slight or more serious, the breeder needs to decide whether to try to eliminate or limit it, or to let it go and concentrate on more important things. In any case, it is a matter of ethics and good science to be diligent in keeping records on where swimming puppy littermates go and whether the condition appears again in those lines.
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