Introduction
Usually, neonatal deaths occur as single incidents involving the death of one puppy, part of a litter or even whole litters, but the problem is not necessarily recurrent. With endemic herpesvirus infections or poor kennel hygiene the problem of neonatal deaths may recur. Prevention of disease in newborns is based on the principle of good management and care of the dam, hygienic measures in the delivery room and kennels, appropriate vaccine and deworming programmes and proper postnatal care of dam and puppies. The treatment of neonate puppies is a challenge, because diagnosis is often difficult, symptoms may be different to those of older young and adults and the drugs available for treatment may pose a risk to the newborn.
Causes of Neonate Problems
Non-infectious causes of puppy death during the first 3 weeks of life are often linked to problems developed while the foetus is in the uterus or problems associated with parturition. The most common problems during nursing and weaning that can cause neonatal disease include various bacterial and viral infectious diseases, as well as parasites. Parvovirus (CPV1) and canine herpesvirus are primary aetiological factors in puppy disease and death between the ages of 0 and 12 weeks. Escherichia coli, Staphylococcus spp. and Streptococcus spp. infections are also commonly associated with disease in newborn puppies. Foetal size and neonatal weight significantly influence survival rate. If the birth weight of individuals or all puppies is more than 25% below the average for the breed, survival rate is significantly reduced. In normally developing puppies the birthweight should double in 8-10 days. Hence, an increase in body weight of 15-20% per day is not unusual. Comparison with littermates is useful in these cases.
Fading puppy syndrome is characterised by a pattern of increasing weakness, failure to nurse, weight loss, hypothermia and death prior to weaning, usually within the first 2 weeks of life. It is now generally accepted that this is not a single disease entity, but rather that common clinical signs are caused by different underlying disease processes. There are no obvious clinical signs or pathological findings, such as poor mothering, mastitis, neonatal canine herpes infections or malformations. Fading puppies usually have a low birthweight, are restless and cry, often beginning shortly after birth. Normal puppies are quiet unless they are diverted from the mother and their littermates. Birth defects, which include both genetic as well as drug or environmental causes, account for a large number of fading puppies.
Do not forget the bitch, since her health is of utmost importance to the puppies. Preparturient disease of the dam may be a cause of neonatal disease and particularly serious conditions include hypoglycaemia/pregnancy toxaemia in the dam as well as postparturient hypocalcaemia (eclampsia), metritis and mastitis. Hence, when sick puppies are presented to the veterinary clinic the bitch as well as the puppies should undergo a thorough clinical examination.
Clinical Evaluation of the Puppy
A case history is the first step to diagnosis and disease management. Information is needed on age or time since birth, sex, breed, whether there are single pup or multiple pup problems, as well as the owner's observations on behaviour of the puppy (littermates) and dam. Additional information on the reproductive history of the mother as well as a description of the pregnancy and parturition may be important. Chronological occurrence of events may be significant, particularly when more than one puppy is affected. The well fed puppy should be silent and show an active sleep pattern. Constant crying indicates that the puppy is not receiving food or is chilled.
The physical examination itself should be carried out on a clean table within a warmed room or on a warm surface with a good light source and access to a magnification lamp if examining a very small neonate. A puppy has poor ability to maintain body temperature until approximately 4 weeks of age, and care should be taken to maintain a rectal temperature of at least 36°C. Hypothermia severely affects circulation, nursing ability and the ability to respond to infections.
When examining a newly born puppy one also needs to focus on the physiological changes that occur during parturition. Physical examination begins with inspection of the head area for evidence of physical trauma (bite wounds), dehydration, hair cover, condition and colour of skin and oral mucosa and footpads. A healthy neonate should be bright pink. The puppy's reaction to touch should be noted. Eyes and ears should be inspected for signs of infection or other lesions. In a neonate the eyes are closed until 12-14 days postpartum and the opening of the external ear canal occurs between 6 and 14 days postpartum.
The oral cavity should be inspected for signs of malformation, such as a cleft palate or lip. The skull should be checked for malformations, such as hydrocephalus. This condition is usually due to blockage of cerebrospinal fluid (CSF) outflow in the ventricles or in the subarachnoid space over the brain. Typically, congenital hydrocephalus is first diagnosed when the dog is a neonate or very young, usually less than 4 months of age. The head takes on a dome-shaped appearance and the skull bones at the top of the head fail to close. A soft spot may be noticed on the top of the head, which is a sign of an open fontanel. The affected dog may be blind, have seizures or have altered movements. A breed disposition exists in Yorkshire Terriers, Maltese Terriers, Pomeranians and Chihuahuas but can occur in any breeds.
Neurological examination may be difficult to perform in neonate puppies due to the immaturity of the nervous system. For instance, the newborn cannot voluntarily defecate or urinate, and stimulation by licking (dam) or stroking the lower abdomen with a cotton pad is necessary to elicit this reflex. The anogenital reflex is present at birth and disappears by 4 weeks of age. The suckling reflex is strong and present in the advanced foetus and the newborn puppy and disappears by 3 weeks after birth. The motor skills are poorly developed. Postural reactions (the puppy wants to turn around when put on its back) can be used to evaluate neurological function.
The rectum should be inspected for signs of occlusion. Additionally, it may be of interest to determine whether meconium is present, or if it has passed, i.e., if the puppy has ingested mother's milk (colostrum), and hence, has received sufficient amounts of maternal antibodies. The umbilical area should be inspected for evidence of infection, trauma or abnormalities of the abdominal wall. Auscultation with a paediatric chest pad (2 cm bell or 3 cm diaphragm) of the chest for heart rate (>220 beats/min) is valuable. A respiratory rate of 15-30 breaths/min is normal during the first 4 weeks of life. Heart rhythm is a regular sinus rhythm, with little or no variation in rhythm associated with breathing.
Treatment of the Dam and the Neonate
Milk replacement should not be fed to weak and chilled puppies, rather, an equal mixture of warm Ringers solution and 5% dextrose/water solution should be given parenterally or a warm nutrient electrolyte solution be given orally every 15-30 minutes until the puppy responds by suckling. If the stool is loose in consistency, a particular Lactobacillus paste ZooLac® Propaste (4.2 billion bacteria per ml) is very useful to normalise the stool and should also be first choice when the puppy has weaning diarrhoea. The normal dose for animals less than 10 kg body weight is 1 ml q12h for 3 days and it can be used even in very young puppies. If a puppy has not ingested colostrum, a dose of 150 ml/kg s.c. or intraperitoneally of adult dog serum to deprived puppies has been shown to produce serum IgG levels comparable with littermates that received colostrum.
Antibiotic therapy should be avoided in newborn puppies, but septic conditions warranting antibiotic use in the dam may arise in the postpartum period (mastitis, metritis). Analgesics may be indicated; nursing neonates appear to tolerate opioid analgesics in the dam. First-generation cephalosporins, such as cephalexin (10-20 mg/kg i.m., s.c., orally q8-12h) or cephazolin (20 mg/kg i.v. q8h) and β lactamase-resistant antibiotics flucloxacillin (15 mg/kg i.v, i.m, orally q6h) or β lactamase-susceptible penicillins combined with a β lactamase inhibitor, clavunalate) (Synolox® 14 mg/kg combined orally q8-12h) are advised and safe for the nursing neonates. Antibiotic therapy may be warranted until weaning, and can preclude further nursing if sensitivities force the choice of a drug potentially toxic to neonates. Nursing puppies should be hand-reared if the dam is seriously ill.
References
1. Davidson A. Husbandry and clinical management of the neonate to optimize survival. In: Proceedings of the 2nd EVSSAR/ESAVS Course: Reproduction in companion, exotic and laboratory animals, School of Veterinary Medicine Hannover, 2003; 19.1-19.6
2. Hoskins JD, Partington BP. Physical examination and diagnostic imaging procedures. In: Hoskins, JD. ed. Veterinary pediatrics. Dogs and cats from birth to six months (third edition). WB Saunders Company, Philadelphia, 2001; 1:1-34.
3. Mathews K. Analgesia of the pregnant, lactating and neonatal to pediatric dog. Journal of Veterinary Emergency and Clinical Care, 2005; 15: 273-284.