Diseases of Puppyhood
BY FRED LANTING AND LELAND CARMICHAEL, DVM, PhD, Prof. at Cornell.
Reprinted with permission from Fred Lanting and PureBred Dogs/American Kennel Gazette, August 1988; pp. 88-93. Copyright owner: Fred Lanting
Breeders’ responses to early puppy deaths vary. Some expend a great deal of effort, while others “let nature take its course” and stoically hope the next breeding will be more successful. Many have discovered that neonatal puppy mortality is preventable or call be reduced through scrupulous attention to prenatal and postnatal care. These breeders, who in the past may have accepted 20 to 25 percent mortality before weaning, have learned that such losses can be reduced dramatically by simple changes in management, including veterinary checkups.
Culling, or removal from participation of poor breeding stock is an important factor in reducing puppy losses. Both the bitch and the stud should be free of disease, which would include hereditary problems as well as acquired communicable disease. Of course, the bitch should be in good condition and free of parasites so she can easily handle the stresses of gestation, whelping, and care of her pups. Another factor is an appropriate environment for birth and development of the whelps. Relative quiet is recommended, at least until the puppies’ senses are fairly well developed. Cleanliness is essential, for disease obviously can be spread by cockroaches, rodents, and other vermin. Another part of good environmental management is regulation of temperature and humidity, especially in the first week after birth.
Despite remarkable progress during the past two decades in the areas of knowledge about infectious diseases of dogs and in strategies to control them (See the Sidebar, “Causes of Puppy Deaths”), there has been relatively little improvement in our understanding of the various causes of neonatal deaths. However, it has become clear that infectious diseases constitute only a small proportion of puppy death causes up to the time of weaning. Contagious diseases generally assume a prominent role only after that time when maternal antibody protection wanes. In this article, we will categorize puppy deaths into two broad areas: non-infectious and infectious causes, which roughly coincide with two time periods divided approximately by weaning at three to five weeks. Remember that there is some overlap in some of those given in the sidebar on the causes of puppy deaths, and that these percentages may arise partly from reports by people who had to make assumptions about the causes of death.
Non infectious Causes
The scientific Community has well established that there are significant physiological differences between neonatal and older pups or adults. Blood sugar, ability to regulate body temperature, and immunity or resistance to infection are among the differences to be appreciated when comparing puppies only three or four weeks apart in age. An understanding of these will lead to breeder management practices that will favor reduced death rates.
Causes of Puppy Deaths
It has been well established that there are significant physiological differences between very young pups and older dogs Differences such as immaturity in the regulation of body temperature, blood sugar and resistance to infection should be considered. Appreciation of these important differences between neonatal pups and puppies only 3 to 4 weeks old helps to explain why certain management practices lead to higher death rates while others greatly reduce mortality. —LEC & FLL
Trauma by bitch 13
“Disease” (sic) 10
“Weak pups” 5
Other (lactation failure, parasites, deformities…) 12
Source: J.F. Moiser, cited in Current Vet. Therapy VII, Kirk. ed. p.80 Saunders, Phila, 1977
The first three weeks of life are most critical. Approximately 75 percent of puppy deaths occur then, and the vast majority of these during the first week. Although the definitive cause of neonatal death is rarely determined, most seem to have a genetic, physiologic, or behavioral basis. In many cases the environment or the bitch’s psyche (temperament, mainly) is flawed. The principal causes include difficulties at time of whelping. There may be prolonged labor after which the bitch “gives up”; sometimes this is keyed to her lack of exercise prior to breeding and whelping, sometimes to too small a birth canal or pelvic opening often to not having been kept in good condition through vigorous exercise. Many breeds are selected for large heads and arrow hips because of fashion, but breeders of these usually are prepared for Cesarean section. Some brachycephalic breeds have individual pups with enlarged heads; many bitches in a breed where it is common to bear six to twelve smaller pups may have one or two abnormally large pups. Poor mothering is another principal cause of high mortality, so such bitches probably should not be bred again.
Congenital (at time of birth) anomalies including stillbirth, runting, and other physical abnormalities may account for up to 40 percent of early pup deaths. Most of these defects are inherited, but some may result from prenatal infection such as in the case of the heart defect called myocarditis, which can result from parvovirus. Some of the more dramatic are isolated examples of congenital problems. One dog food manufacturer inadvertently added toxic doses of vitamin D, and the suspected cause of death initially was distemper; in another case, a mercury fungicide used to treat grain was responsible.
Warmth is vital to newborn puppies. Rectal temperatures do not reach ‘‘normal’’ (about 101 degrees F.) until puppies are about one month old when they more efficiently metabolize food. An ambient whelping box temperature of 85 90 degrees, with a relative humidity of 55 to 65 percent is desirable during the first week, though it can be lower if the dam is present to provide body heat and warm milk. Newborn pups generally do not recover from a few hours of chilling, so the mother’s instinctive reluctance to leave the nest for any substantial time or distance is naturally understandable. In the second and third weeks the temperature can be adjusted to 80 degrees in her absence, with further reduction to 75 degrees by the fourth week Chilling can occur at higher temperatures than you would find comfortable.
What are the best ways to supplement or take the place of the dam’s body heat to prevent chilling? Many breeders use a heat lamp for the few minutes that the bitch is outside relieving herself, but extended use of a lamp can bring about dehydration, especially in winter in a house that is not humidified. A puppy, which is about 80 percent water, can dehydrate rapidly; signs include rosy pink nose and feet pads and dry skin that does not “unfold” when pinched. Preferable is a heating pad on a low Setting and covered with a dish towel, or a hot water bottle that is renewed each time you remove the dam’s warmth. Keep the room fairly close to the ideal whelping box temperature for safety’s sake, especially for orphaned puppies.
Why is temperature so important that chilling ranks as the leading cause of early death? For one thing, there are biochemical regulatory processes that may not be efficient at lower temperatures, and pups are not able to reach a healthy 100 degrees minimum on their own until they are over three weeks old. More importantly, several studies indicate that the canine immune system does not function optimally until this body temperature is reached. Thus, infections which mature dogs are able to localize and withstand may become generalized in very young pups, affecting most of the body systems. The extent to which the immune system in neonatal pups is functionally immature is still unclear, and much has yet to be learned. It appears that proper immune function is related to the development of certain types of cells called lymphocytes, which are produced in the thymus gland and elsewhere, and circulate in the blood and lymph systems. There they do battle with foreign invaders such as microbes and other agents. A low body temperature inhibits cell division and proliferation of these infection fighters, and thus a chilled puppy may have inadequate defenses at the time they are most needed.
Practical implications of such research have not been fully explored, but we have already recognized that pups less than three or four weeks old may respond abnormally to modified live vaccines. Certain vaccines that are perfectly safe in older dogs may cause illness in very young, pups. For example, distemper virus vaccine may cause encephalitis in puppies under age four weeks. This has been seen most commonly in pups that were given combined vaccines of distemper and hepatitis (adenovirus type 1). In contrast, the type 2 (CAV 2 or simply A 2), which fully protects against hepatitis or the parvovirus (CPV) vaccines appear safe. Research at the University of Wisconsin suggests the combination of distemper and hepatitis (A 1) vaccines suppress the immune system more than when either virus is given alone. There is a need to more fully evaluate the safety and efficacy of combined vaccines, and the strains of viruses used, in young pups. This was demonstrated in a most unfortunate and dramatic manner when it was shown that a commercial live canine coronavirus vaccine caused encephalitis in most cases when it was used in combination with distemper virus vaccine. The offending vaccine was quickly withdrawn from the market.
Bacterial, Protozoan, and Viral
Microbial infections are generally thought of as being caused by bacteria, one celled “plants”, but don’t forget the one celled animals (motile) called protozoa. The plant/animal distinction is of minor practical import to the breeder except as it may influence treatment or prevention. The more common early bacterial problems include umbilical infections, generalized skin disease, and “puppy septicemia.” this latter term, as well as “acid milk” or “toxic milk” have obscure meanings, though they provide the breeder or clinician with convenient categories for illnesses whose exact cause has not been established.
Bacteria have often been blamed for “fading puppies” because they’ve been isolated from tissues of dead pups, but these bacteria are incidental in most cases, since microorganisms rapidly invade the blood and body tissues from the intestinal tract after death from any cause. Bacteria are rarely found if tissue cultures are prepared immediately after death. One other common bacterial attack, although it more often takes place about the time of weaning or later, is the secondary bacterial infection associated with coccidiosis, a protozoan organism.
Early infection may gain entry via the placenta or the umbilical cord, by mouth, or during passage through the birth canal. Lack of hygiene may contribute to umbilical infection with ensuing generalized septicemia and early death or polyarthritis. Much safety can be attained by frequently checking to see that umbilical cords are drying up normally. Most ill pups of the same age have similar clinical signs; too often they are found dead or dying, so autopsies are not performed as often as would be desirable for the best statistics. The most common bacteria which have been identified in dead neonates are E. coli, staphylococci, streptococci, and pseudomonas.
Nursing from bitches with mastitis or with teats contaminated by uterine discharge may produce a rapidly fatal gastroenteritis characterized by foamy vomitus and liquid feces. Such pups often exhibit severe abdominal pain, rapidly dehydrate from the diarrhea, and usually cry continuously. An entire litter may die. Antibiotic and fluids treatment are often futile. Some breeders refer to “toxic milk” in such cases, but it has not been established that the milk is abnormal, even though some veterinarians may attribute the illness to milk toxins, metritis, or failure of the uterus to involute properly. Whatever the cause really is, the pup cries, becomes bloated, has greenish diarrhea, and exhibits a red, swollen anus. You need not go so far as to “boil everything except the baby” to give it a germ-free, risk free environment, but cleanliness and care of your bitch before, during, and after pregnancy can help you avoid infections like these.
Infection of bitches with Brucella canis is associated with abortions in the last few weeks of gestation, early embryonic death, and occasionally death of whelps, though it is not a common factor in neonatal puppy death. Infected pups that survive often have retarded growth, and usually remain infected for months or years. Brucellosis is not widespread among breeders, but it is very difficult to get rid of once it gets into a kennel.
Pups with hemolytic streptococcal infections are initially vigorous and apparently healthy for the first day. Then they no longer suck avidly and they become weak and rapidly lose weight. These pups become progressively uncoordinated and develop tetanus like spasms, often showing an unnatural extension of the spine and forelimbs shortly before death. All pups in the litter might not be affected, and the bitch may produce healthy litters upon subsequent pregnancies. Since the same streptococci are commonly seen both in puppies and the dam’s vaginal swabs, antibiotic treatment of such bitches during the next pregnancy may be an effective preventive measure. Chronic uterine infection is insidious and clinical signs are not generally apparent to the owner of the bitch.
Toxoplasmosis is caused by a protozoan parasite that is spread primarily from its prime reservoir, the cat. Oocysts (“eggs”) in cat feces may infect rodents, man, and dogs, and you know how dogs are irresistibly drawn to litter boxes! Most infections are subclinical; that is, they produce no obviously identifiable signs of their presence or activity. If, however, an affected animal is immuno suppressed because of worms, injury, work, pregnancy, illness, or other stresses, toxoplasmosis can be manifested, even in prenatal and neonatal pups. Outbreaks in breeding kennels have been described wherein signs were abortions, stillbirths, and “fading pups”. Puppies that otherwise appeared healthy developed the symptoms and died between two weeks and three months of age. In some cases, symptoms resembled those of distemper, with central nervous system and ocular signs being common in chronically infected pups. Early diagnosis of toxoplasmosis and administration of specific anti-protozoan and antibacterial drugs can be successful, but prevention is difficult because the carriers (infected cats) are difficult to cure.
Coccidiosis is another protozoan disease but usually it only seriously affects pups immunosuppressed by worms or other parasites or stresses. Get rid of the roundworms, hookworms, fleas, and other adverse environment, and a healthy pup will probably not be bothered by coccidia. If you don’t, you could lose puppies to the combination. Secondary bacterial infection is as bad or worse than the coccidiosis itself, so a veterinarian may prescribe one drug for the former and Albon for the coccidia, or one drug for both, but again the value of proper management by the breeder is a major key to avoiding serious disease.
There are several viruses that may affect young puppies, but thanks to widespread vaccination, infectious canine hepatitis and distemper, which can infect the pregnant dam, have not been significant causes of neonatal mortality With good reason, parvovirus is the most frightening to breeders. Coronavirus has been found to be of very minor significance, and the vaccine to be not worth using. Although canine herpes virus is a common killer of younger pups, death is simple to prevent if you are knowledgeable and diligent. (See the category “control” in the sidebar, “Puppy Vital Signs, A Summary”) For some reason, young bitches are more likely to produce litters that suffer the effects of the canine herpes virus. Older bitches are more likely to lose their whelps for a variety of other reasons.
Healthy newborn puppies are a delight to behold. They are warm, with good muscle tone, skin elasticity, and pink mucus membranes. Their principal activity is sleeping, which may sound like a paradox if you consider sleep to be a period of inactivity. Sleep of newborns is marked normally by twitching, and this continues (though to a decreasing degree) as the pup grows; you may face trouble if activated sleep is not evident. When awakened, healthy pups suckle vigorously. For the most part they are quiet unless separated from the dam and littermates. Birth weight should double in about ten days. If your pups don’t fit this pattern, turn to experienced breeders and your veterinarian for advice. If you have properly prepared for whelping by gaining an understanding of the birth process and the management of common emergencies with the help of these people, you can probably keep your litters of newborn pups alive and healthy.
PUPPY VIRAL DISEASES — A SUMMARY
Symptoms (1st two weeks) heart (myocarditis): stops nursing, gasps for breath, dies.
(Later weeks) enteritis: severe vomiting, mucoid diarrhea may become bloody; dehydration.
Most dangerous age 5 6 weeks to 4 months, depending on when maternal antibodies “wear off” and pup can respond to vaccine.
Transmission Direct contact with feces produced between 5th and 6th day of infection; hands, feet, clothing, utensils (contamination can last weeks or months). Highly contagious. Most cases occur in breeding kennels or are carried home by dog show exhibitors, visitors to other dogs’ homes and yards.
Prognosis Grave; very high risk. Kennel rates may be 50 percent typically, litter mortality death risk rates up to 100 percent.
Vaccine Immunity/Protection Good, once maternal antibodies no longer protect. Vaccination is not immunization.
Control Annual boosters, clean environment; change shoes and wash hands if coming home to unprotected pups after possible exposure at shows etc.
Symptoms Fetal death, mummified fetus; Neonates: general illness, dull, cease nursing, cry incessantly; all organs affected, speckled kidneys at autopsy. (3rd week and later): mild infections of vagina, prepuce, & upper respiratory tract.
Most dangerous age First three four weeks—(most deaths between 9 14 days age)
Transmission At birth: from saliva or vaginal discharge of dams infected up to 3 weeks before whelping. Nasal, in reactivated, “dormant” carriers.
Prognosis Very high in first couple weeks, lower in next week or two. Always and only a risk if pups are chilled.
Vaccine Immunity/Protection Most adults have been infected by one year; inactive virus in nerve cells may be “awakened” during stresses. No vaccine.
Control Avoid chilling of pups (see text)