A topographical analysis of the post-natal bone growth in the cochlea of the dog

The distribution of post-natal bone deposition was examined in the cochlea of 10-, 25-, 50- and 90-day-old dogs that had been intraperitoneally injected with tetracycline (20 mg/kg) five days before sacrifice. The temporal bones were embedded in methylmethacrylate and sectioned in a single mid-modiolar section 30 microns thick. The post-natal bone deposition occurs both on the periosteal surfaces and on the vascular canals of the endochondral layer until the age of 90 days. Scattered bone deposition is also shown on the endosteal layer of the three turns and on the spiral lamina until the age of 25 and 10 days respectively. The percentage extension of the osteogenetic fronts shows a higher value at the periosteal layer than at the endochondral or endosteal layers.

Use of the Wagner apparatus to lengthen the antebrachium of a growing dog

A six-month-old male golden retriever was presented with a shortened radius and ulna and valgus deformity of the carpus secondary to premature closure of the distal radial and ulnar physes. Osteotomies of the radius and ulna were performed and the antebrachium was lengthened over eight weeks using a Wagner apparatus. This external fixation distractor is used in humans for limb-lengthening procedures. In this case, it was used to correct the angular deformity and to lengthen the limb.

[Dependency on age of laboratory values in dogs and cats. 1. Enzyme activities in blood serum]

A significant dependency on the age of dogs can be observed in the following serum enzymes: AST, GLDH (low degree), SAP, GGT, and CK. In cats a dependancy on age can be seen in ALT, AST, SAP, LDH, alpha-HBDH, alpha-Amylase, Lipase, and CK. The differences between old and young animals are small in AST, GLDH, GGT, and LDH. Therefore, the differences are not important for routine diagnosis. Comparing ALT activities, lower values were found in kittens. Similar results were found in CK activities. On the other hand higher values of SAP can be seen in young than in adult individuals. In geriatric animals, diagnostically important changes of the enzyme activities examined in this study could not be found.

Morphological changes during ontogeny of the canine proximal colon

The development of the canine proximal colon from the completion of organogenesis through 43 days after birth was studied using light microscopy, immunofluorescence and electron microscopy. During this period the tunica muscularis increased in thickness from 42+/-6 microm in animals midway through the gestation period to 317+/-29 microm in animals 25-30 days old. This increase in thickness resulted from an increase in the number and size of smooth muscle cells in the circular and longitudinal muscle layers. The cross-sectional thickness of the circular muscle layer increased from 10+/-2 smooth muscle cells midway through the gestation period to 92+/-7 cells in animals 25-30 days old. The longitudinal layer increased in thickness from 1.5+/-1 cells in animals midway through the gestation period to 44+/-2 cells in animals 25-30 days old. Smooth muscle cells from both layers also increased in diameter and length. Ultrastructural and immunohistochemical studies suggested that many of the smooth muscle cells were undergoing development throughout the fetal period. Midway through the gestation period, the circular layer was positive for desmin-like immunoreactivity (D-LI), while both the circular and longitudinal layers were positive for vimentin-like immunoreactivity (V-LI). By birth, V-LI was suppressed in the circular and longitudinal layers, and both layers expressed D-LI. The enteric nervous system was already established midway through the gestation period, and submucosal and myenteric ganglia could be identified, although the chemical coding and mature morphology of neurons were incomplete. NADPH-diaphorase-positive neurons, indicating the expression of nitric oxide synthase, developed by the time of birth. Interstitial cells of Cajal (IC) could not clearly be identified midway through gestation, however, potential precursors to ICs were observed. Several classes of ICs were identifiable at birth.

Post natal development of canine caudal cervical vertebrae

The morphology and post natal ossification of the fifth, sixth and seventh cervical vertebrae of 51 crossbred puppies (aged from birth to 12 weeks) were examined grossly, histologically and radiographically. At birth there were two centres of ossification, one in the vertebral body and one in the base of each pedicle of the neural arch. By one month of age secondary centres of ossification were present in the cranial and caudal epiphyses of the vertebral body. By two months of age these epiphyseal centres began to show signs of closure. Endochondral ossification of the neural arch occurred from a single centre of ossification within each pedicle with bony fusion of the laminae occurring by one month of age. In addition the dimensions of the neural canal were measured. The difference between the caudal and cranial sagittal diameters of each vertebra was 1 mm or less. It was concluded that, after one month of age, the shape of the neural canal can be influenced only by changes within the physes between the vertebral body and the neural arch or by the remodelling of bone formed by intramembranous ossification.

[The effect of a different energy supply for growing Great Danes on the body mass and skeletal development. 3. Clinical picture and chemical studies of the skeleton]

In growth studies with young Great Danes (0-6 months old), the effects of ad libitum (nine animals) or restricted feed supply (70-80% of ad libitum supply; 17 dogs, 9 of them bearing additional weight loads, 15% of body weight attached to the shoulder) were investigated with regard to development of the skeleton and bone composition. Growth disturbances of the skeleton were seen in every group, but the incidence increased with ad libitum feeding. Fast growth led to the valgus syndrome in fore- and hindlimbs, while hyperextensions of the carpal joint were seen, independently of the growth intensity. Weight loading in connection with energy restriction could not reproduce the same effects as ad libitum feeding. The mineral and protein concentrations in the bones (related to fat-free dry matter) were not affected either by the different feeding levels or by the weight loading.

The role of perinatal care in development

The weanling puppy must be recognized as a product of numerous genetic, gestational, and environmental factors. There are several important transitional phases of early life. Each is influenced by preceding events and in turn influences subsequent development. The point at which the practicing clinician enters this continuum for given individuals largely is circumstantial. However, understanding the basic sequence of normal events, particularly those surrounding the pivotal neonatal period, can offer valuable insight and direction for treatment of individual animals. In addition, in those instances in which continued constructive contact with the breeder or kennel operator is possible, preventive or therapeutic management directed toward the appropriate stage of development ultimately can be rewarding for both client and veterinarian.

Age-related changes in ocular distances in normal eyes of Samoyeds

Ocular biometry, using A-scan ultrasonography and ultrasonographic pachymetry, was performed in 52 Samoyeds, 2 months to 13 years old, without intraocular or systemic diseases. Furthermore, the relative depth of the opening of the ciliary cleft was estimated from goniophotographs. The values were analyzed, and statistical models of changes in ocular distances with increasing age were identified. It was found that the changes in corneal thickness, axial anterior chamber depth, lens thickness, relative lens position, length of the vitreous body, and axial length could best be described by 1 of the 2 nonlinear models f(x) = alpha + beta/x + gamma x + epsilon and f(x) = alpha + beta/x + gamma log x + epsilon. The course began with a period of rapid increase, after which the ocular distance either increased at a progressively slower rate toward infinity (corneal and lens thickness) or to a finite limit (relative lens position and axial length), or ceased to grow and finally started to decrease toward minus infinity (axial anterior chamber depth and length of the vitreous body). However, suitable model for determining relative depth of the opening of the ciliary cleft could not be established. Results indicated that age-related changes, mainly in lens thickness, cause a shallow anterior chamber, and it was suggested that this may be of importance for development of a relative pupillary block and, thus, primary angle-closure glaucoma, at least in preconditioned eyes of Samoyeds.

Assessment of the nutritional adequacy of pet foods through the life cycle

Despite the lack of precise information on the requirements for many of the nutrients essential for cats and dogs and the paucity of information on the availability of nutrients in foods, many commercial diets support excellent growth, reproduction, and maintenance. However, these diets use empirical information that cannot be readily applied to the formulation of new diets. Progress in companion animal nutrition requires more precise information on requirements for various life stages (especially reproduction and maintenance), along with values for the bioavailability of nutrients in dietary ingredients. There is virtually no information on the bioavailability of nutrients for companion animals in many of the common dietary ingredients used in pet foods. These ingredients are generally byproducts of the meat, poultry and fishing industries, with the potential for wide variation in nutrient composition. Claims of nutritional adequacy of pet foods based on the current Association of American Feed Control Official (AAFCO) nutrient allowances ("profiles") do not give assurances of nutritional adequacy and will not until ingredients are analyzed and bioavailability values are incorporated. The AAFCO feeding test provides a superior method for assessing nutritional adequacy to the profile, although the current protocol has procedural and interpretative limitations.

Developmental changes in testicular luteinising hormone receptors and androgens in the dog

The changes with age in the levels of testicular luteinising hormone (LH) receptors in dogs, were correlated with plasma androgen concentrations and the effects of stimulation with human chorionic gonadotrophin (hCG). The presence of high-affinity binding sites for LH was demonstrated in the testes of all the animals studied, and the apparent affinity of the LH receptors did not change significantly with age. The total number of LH receptor sites per testis increased continuously with age and the growth of the testis. The major rise in the number of LH receptors occurred between six and 10 months of age, and coincided with the phase of rapid testicular growth. The concentrations of androstenedione, testosterone and 5 alpha-dihydrotesterone in plasma increased gradually until six months of age, and then increased rapidly with the increase in the number of testicular LH receptors. An increase in the concentrations of androgens in plasma was observed in response to stimulation with hCG after the number of testicular LH receptors began to increase progressively. The increase in the sensitivity of the dogs' gonads to LH could be responsible for the marked increase in the secretion of androgens which occurs during puberty in the male dog.

[Biochemical analysis in dogs of the beagle breed. 2. The content of Na, K, Ca, Mg, total P, Fe, Cu and Zn in tissue of fetuses and dogs of different ages]

In dog fetuses in the age of 45 and 55 days as well as in dogs in the age of one day, of 28 days, of 6 and of 18 months the content of minerals (Na, K, Ca, Mg, total-P), of Fe, of Cu and of Zn in different tissues (cerebrum, cerebellum, brain stem, lung, heart respectively left and right ventricle, liver, spleen, kidney respectively cortex and medulla, pancreas, M. biceps femoris and M. longissimus dorsi) was analysed. During the prenatal and postnatal development there are changes in the content of the mentioned elements in many tissues, that are necessary for the specialisation for certain functions.

Changes in histomorphometric values of iliac trabecular bone and serum biochemical constituents related to bone metabolism in beagle dogs during growth

Changes in histomorphometric values of iliac trabecular bone and serum biochemical constituents related to bone metabolism in normal beagle dogs during growth were examined. A total of 90 dogs (male; 46, female; 44) aged 3, 6, 9, 12 and 24 months, were used. Each dog was injected with tetracycline hydrochloride and calcein for double bone labeling in order to quantitatively measure dynamic as well as static parameters in bone histomorphometry and a part of the ilium was later removed. The measurements on cancellous bone areas of undecalcified iliac sections were performed with a semiautomatic image analyzer. There were no sex significant differences in histomorphometric values except for mineralization lag time at the age of 3 months. In the static parameters, bone volume and mean trabecular thickness increased from 3 to 9 months of age. Bone surface area and mean osteoid thickness increased up to 6 months. Osteoid volume and osteoid surface area decreased up to 6 months of age. As to the dynamic parameters, the mineral apposition and bone formation rates decreased from 3 to 12 months of age. Mineralization lag time increased from 3 to 9 months of age. However, high bone surface area values in both sexes and low osteoid thickness values in females were seen at the ages of 9 and 12 months. Low values of trabecular thickness in both sexes, osteoid thickness and mineralization lag time in males and mineral apposition rate in females were also noted at the age of 12 months. Serum total calcium did not show any specific tendency.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth and skeletal development in the dog in relation to nutrition; a review

Longitudinal growth of the appendicular skeleton in the growth plates and the adjacent metaphyseal area includes chondrocyte differentiation, proliferation, maturation, and hypertrophy in the physis and bone (re-) modelling in the metaphysis. The rate and extent of longitudinal growth are regulated by interactions between biomechanical factors and endogenous growth regulators, i.e., systemic endocrine factors, and local para or autocrine factors, that act on the growth plate chondrocytes. The most important endogenous regulators of growth and skeletal development are growth hormone (GH) and insulin-like growth factors (IGFs), and calciotropic hormones, i.e., parathyroid hormone (PTH), vitamin D (vitD), and calcitonin (CT). The biochemistry, synthesis, secretion, target organs, and effects of these endogenous factors are reviewed, and the calcium homeostatic mechanisms, dietary intake, bone turnover, and calcium excretion are discussed. Energy, protein, and calcium are nutritional factors of great importance to (skeletal) growth. The effects of low and high dietary intake of these nutrients are discussed, especially with reference to longitudinal growth and disturbances in endochondral ossification.

[Biochemical analyses in dogs of the beagle breed. 1. The content of DNA, RNA and protein in 13 tissues in ages from one day to 18 months]

In dogs of the race "beagle" in the age of one day, of 28 days as well as in that of 6 and 18 months the content of DNA, RNA and protein in 13 tissues was analysed. The wet weight:DNA-, the protein:DNA- and the RNA:DNA-ratios were calculated. The growth of the various tissues by hyperplasia and hypertrophy is described.

Analysis of physeal growth in dogs, using biplanar radiography

Biplanar radiography was used to study normal growth of the left and right radius in 5 Beagles and growth of the left radius alone in 15 additional Beagles. We explored the applicability of this radiographic method in veterinary medicine by measuring the contribution to total radius length from each growth plate. Spherical tantalum markers (0.5 mm) were embedded in the proximal epiphysis, diaphysis, and distal epiphysis of each dog's radius at 10 weeks of age. Simultaneous biplanar radiographic views were obtained every 4 weeks until skeletal maturity was documented. A three-dimensional coordinate system was constructed allowing for measurement of growth (in millimeters). Resolution of the measuring system was 0.074 mm. Mean +/- SEM length of the skeletally mature Beagle's radius, as measured from proximal epiphyseal bead to distal epiphyseal bead, was 95.33 +/- 1.07 mm. The percentage of contribution to the total radius length from the proximal and distal growth plates was 36.76 and 64.73%, respectively, with 95% confidence interval of 2.29%. The percentage of contribution to radius length from the distal radial growth plate increased for each consecutive time segment, with the distal radial physis contributing 61.75% from 10 to 14 weeks of age and increasing to 70.22% from 22 to 26 weeks of age. Significant growth was not observed after 26 weeks of age. The period of most rapid growth was between 10 and 14 weeks of age. Biplanar radiography was accurate and precise in quantifying the relative contribution of the proximal and distal growth plate to radius length in Beagles.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal development of semitendinosus muscle in the dog

In this study the differentiation of postnatal muscle fibres in dog semitendinosus muscle has been characterized. Several histochemical techniques for myosin ATPase and metabolic activity were used in animals aged between 1 day and 2 months. The results show that at birth there are two types of fibre, whose ATPase activity gradually changes during postnatal development, so that several types of fibre can be identified after 2 months. These finally become the four types of the adult: I, IIA, IIDog, IIC. The main conclusions of the study are that the use of mATPase techniques is appropriate for showing the differentiation between muscle fibres, even at early stages of postnatal development, and that the origin of the four different fibres of the adult can be traced back to early postnatal stages.

Age-related plasma concentrations of growth hormone (GH) and insulin-like growth factor I(IGF-I) in Great Dane pups fed different dietary levels of protein

During a 20-week study, 17 Great Dane dogs, 7 weeks of age, were used to study the influence of 3 isoenergetic diets differing in dietary protein levels (i.e., 31.6%, 23.1%, and 14.6% on a dry matter basis) on body weight, growth in length, and age-related plasma GH and IGF levels. Significant differences occurred in weekly body weight gain of the high- and low- protein groups only in the fourth week of the study. There was a significant decrease in mean basal plasma GH values with time from 14.8 +/- 2.2, 13.7 +/- 2.2, and 14.3 +/- 2.2 micrograms/l in the second week to 2.3 +/- 1, 0.7 +/- 0.4, and 1.8 +/- 0.7 microgram/l in the last week of the study for the high-, normal- and low-protein groups, respectively. Differences among groups were not significant. There was a positive correlation between the decrease in weekly body weight gain and plasma GH concentration in all 3 groups. IGF-I concentrations in plasma did not change consistently with age and were not correlated with plasma GH values. Significant differences in plasma IGF-I concentrations were found between groups at 15 weeks of age. Preliminary results of measurements of IGF receptors in the membranes of growth plate cartilage of long bones of 5 dogs revealed that homologous displacement of 125I-labeled IGF-I binding resulted in similar curves. A single binding site for IGF-I was assumed. The large number of type II IGF receptors in 7 dogs suggests a key role for IGF-II in postnatal skeletal growth. The results of this study demonstrate for the first time that in Great Dane pups basal GH concentrations in plasma decrease between 7 and 27 weeks of age, parallel to the decrease in growth velocity, whereas the plasma IGF-I concentrations remain relatively high and unchanged. The slight but statistically significant effects of low-protein feeding on growth velocity and circulating concentrations of IGF-I indicate that a diet containing 14.6% protein on a dry matter basis (13% protein as metabolizable energy) is marginal for growing Great Dane pups between 7 and 17 weeks of age.

Effect of age on theophylline pharmacokinetics in dogs

Differences between neonatal and adult animals in their response to drugs can usually be attributed to altered disposition processes. Effect of age on the pharmacokinetics of theophylline was determined after IV administration of the drug to 10 groups of dogs at 1, 2, 3, 4, 8, 12, 16, 24, 52, and 104 weeks of age. Plasma theophylline concentration curves for all groups were adjusted to a biexponential kinetic, with rapid initial distribution phase and slower elimination phase. It also was noticed that young dogs have a slower elimination half-life (1 week old, t 1/2 beta = 987 minutes) than do older animals (8 weeks old, t 1/2 beta = 138 minutes). The values then plateaued until 16 weeks of age, increasing slightly at more advanced age (104 weeks old, t 1/2 beta = 282 minutes). A similar pattern was followed with respect to clearance (1-week-old pups, Cl = 1.17 ml/min/kg of body weight), which increased progressively to reach a value of 7.09 ml/min/kg at 16 weeks of age, then decreased to 3.5 ml/min/kg at 104 weeks of age. Volume of distribution beta, in relation to body weight, was not significantly different between age groups (between 1.2 and 1.6 L/kg; P < or = 0.03). Theophylline biotransformation mechanisms may be mainly responsible for Cl and t 1/2 beta variations. This leads us to suggest that quantitative and qualitative modifications in the P-450 mono-oxygenase system are responsible for the variations observed in pharmacokinetic variables of theophylline between dogs of different ages. These findings may have clinical relevance with regard to therapeutic range of theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in the level of plasma cortisol, progesterone and total testosterone in developing hairless dogs

Changes in the levels of plasma cortisol, progesterone and total testosterone were examined in developing hairless and haired dogs. Cortisol levels in the hairless dogs seemed to be higher than those in haired dogs within the age of 4-5 weeks. No apparent changes were seen in the level of plasma progesterone between the groups of hairless females and haired females. Total testosterone levels in hairless males showed to be significantly lower than those in haired males at the age of 13-21 weeks.