Age Dogs Research Articles

Estudo epidemiológico retrospectivo de cães portadores de ruptura do ligamento cruzado cranial: 323 casos (1999 a 2005)

O objetivo do presente trabalho foi caracterizar a população de cães portadores de ruptura do ligamento cruzado cranial (RLCC) para fatores considerados de risco como raça, idade, sexo e peso corporal. A base de dados consistiu de informações resgatadas de prontuários de 323 cães com diagnóstico de ruptura de ligamento cruzado cranial atendidos no Serviço de Cirurgia de Pequenos Animais do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo em um período de 7 anos (1999 a 2005). Os resultados mostraram que as raças de maior prevalência foram o Leonberger (100%), Cane Corso (66,7%), Dogue de Bordeau (50%), Starffordshire Terrier (40%) e o Chow Chow (36%), estando ainda o Rottweiler (11,6%) e o Labrador Retriever (8,1%) em 10º e 13º lugares, respectivamente. As idades de maior freqüência foram 2, 4, 3, 7 e 6 anos (média = 5,58 anos). Fêmeas (59,14%) foram mais acometidas do que machos (40,86%) e animais inteiros (76,15%) foram mais representativos do que animais castrados (17,76%). Quanto ao peso, entre 6 e 15 kg (32,82%) seguido por animais entre 36 e 45 kg (17,03%). Pode-se observar que os dados em nosso meio tendem a se assemelhar com a literatura estrangeira: ocorrência da RLCC em animais mais jovens de raças de grande porte e gigantes, o Rottweiler como uma raça em comum a fêmea é mais representativa do que o macho.

A longitudinal study of seroprevalence and seroconversion of Neospora caninum infection in dairy cattle in northeast Thailand

A long-term study was carried out in 11 dairy herds in the Khon Kaen province of northeast Thailand between August 2001 and November 2004. The objective was to investigate seroprevalence dynamics of Neospora caninum infection in the herds and to demonstrate patterns of seroconversion in individual cattle. Each herd was visited once a year, in total four times, and sera from cattle >3 months of age and farm dogs as well as a sample from the bulk milk were collected. All samples were analysed for presence of specific antibodies by an N. caninum iscom ELISA. The overall percentage of antibody-positive cattle was constant and varied only between 10 and 13% over the 4 years, but the variation in within-herd seroprevalence between herds was substantial. Two herds had ≥20% seropositive animals at all samplings and consistently high bulk milk OD, whereas two herds had no seropositive animal at the last two samplings and low bulk milk OD. Five herds had a decreasing trend of within-herd seroprevalence, whereas the remaining six herds had a higher portion of test-positive individuals at the end of the study. A total of 424 individuals were sampled more than once; 344 (81%) and 32 (8%) were consistently antibody-negative and antibody-positive, respectively. The proportions of animals that changed from being seronegative to seropositive and from being seropositive to seronegative between the years were 3.9–4.6% and 19–39%, respectively. Apparent vertical and horizontal transmission rates were 58% (95% CI; 44–71%) and 5% (95% CI; 3–7%), respectively. In conclusion, the overall percentage of N. caninum antibody-positive cattle was constant over the years, but the within-herd seroprevalence varied substantially between the herds. Seroconversions were likely to occur in individual cattle although most animals had consistent serological status throughout the study.

Mensuração de hormônios andrógenos, estrógeno, fosfatase ácida prostática (PAP) e antígeno prostático específico (PSA) em cães adultos com próstata normal e hiperplásica

As doenças prostáticas constituem um problema comum em cães adultos e idosos. Uma das afecções mais freqüentes é a hiperplasia prostática benigna (HPB) que, tanto no cão como no homem, está associada ao avanço da idade e ao desequilíbrio hormonal. No presente trabalho foram mensurados hormônios andrógenos, estrógeno, fosfatase ácida prostática (PAP) e antígeno prostático específico (PSA) de 37 cães com idade superior a três anos, em função do aspecto microscópico da próstata. Encontraram-se baixos níveis de estrógeno e altas concentrações de PSA nos animais com algum tipo de hiperplasia. Os valores de PAP sérico e urinário também foram maiores nos cães com hiperplasia.

The Earliest Ice Age Dogs: Evidence from Eliseevichi 1

The Earliest Ice Age Dogs: Evidence from Eliseevichi 1

Influence of age and body size on intestinal permeability and absorption in healthy dogs.

To evaluate effects of age and body size of dogs on intestinal permeability (unmediated diffusion) as measured by the ratio of urinary lactulose to L-rhamnose (L:R) and absorption (carrier-mediated transport) as measured by the ratio of urinary D-xylose to 3-O-methyl-D-glucose (X:MG) and to determine whether these variables correlated with fecal quality. 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. A solution that contained lactulose and rhamnose or xylose and 3-O-methyl-D-glucose was administered orally to dogs that were 12, 22, 36, and 60 weeks old. Urine was collected 6 hours later, and urinary L:R and X:MG were calculated. Fecal moisture and scoring were recorded during the same periods. Age and breed did not affect intestinal absorption, and we did not detect a relationship between X:MG and fecal variables. In contrast, we detected significant effects of age and body size on intestinal permeability. Puppies (12 weeks old) and large dogs had higher intestinal permeability than adult (60 weeks old) and small dogs. The increased intestinal permeability in large dogs was associated with lower fecal quality as indicated by the significant positive correlations between L:R and fecal moisture (r, 0.61) and L:R and fecal scores (r, 0.86) in adult dogs. These results indicate that age and body size should be considered when assessing intestinal permeability by use of the L:R urinary excretion test in dogs. High intestinal permeability could be a possible cause of poor fecal quality in large dogs.

Safety of selamectin in dogs

Selamectin is a broad-spectrum avermectin endectocide for treatment and control of canine parasites. The objective of these studies was to evaluate the clinical safety of selamectin for topical use in dogs 6 weeks of age and older, including breeding animals, avermectin-sensitive Collies, and heartworm-positive animals. The margin of safety was evaluated in Beagles, which were 6 weeks old at study initiation. Reproductive, heartworm-positive, and oral safety studies were conducted in mature Beagles. Safety in Collies was evaluated in avermectin-sensitive, adult rough-coated Collies. Studies were designed to measure the safety of selamectin at the recommended dosage range of 6–12 mg kg −1 of body weight. Endpoints included clinical examinations, clinical pathology, gross and microscopic pathology, and reproductive indices. Selected variables in the margin of safety and reproductive safety studies were subjected to statistical analyses. Pups received large doses of selamectin at the beginning of the margin of safety study when they were 6 weeks of age and at their lowest body weight, yet displayed no clinical or pathologic evidence of toxicosis. Similarly, selamectin had no adverse effects on reproduction in adult male and female dogs. There were no adverse effects in avermectin-sensitive Collies or in heartworm-positive dogs. Oral administration of the topical formulation caused no adverse effects. Selamectin is safe for topical use on dogs at the recommended minimum dosage of 6 mg kg −1 (6–12 mg kg −1) monthly starting at 6 weeks of age, and including dogs of reproducing age, avermectin-sensitive Collies, and heartworm-positive dogs.

The Legacy of Iron Age Dogs and Livestock in Southern Africa

Histoire de l'expansion des chiens domestiques et des differentes especes representees dans les cheptels (âne, mouton et brebis, betail), vers le sud de l'Afrique depuis au moins le IIIe millenaire av. J.-C.

Comparison of Lung Carcinoma Incidence in Beagle Dogs Exposed to 239PuO2 as Young Adults or as Immature Dogs

Beagle dogs were exposed by inhalation either as immature ("3 months of age) or as young adult (" 13 months of age) dogs to monodisperse particles of 239PuO2. These particles are relatively insoluble in vivo and thus the majority of the radiation dose is delivered to the lung and associated tissues. As have been reported previously there were no apparent differences in lung retention associated with age at exposure. Time-dependent radiation doses to the lung, averaged over the total lung mass, were calculated to take into account the growing lung of the immature dog. There were 108 immature dogs exposed to a monodisperse 1.5 µm AMAD particles (74 survivors are 7-10 years after exposure) and 252 young adults dogs exposed to 0.75, 1.5 or 3.0 µm AMAD particles (52 survivors are 11-13 years after exposure). To date, 24 immature dogs have died with lung carcinomas at doses of 2.5 to 83 Gy and 104 young adult dogs have died with lung carcinomas at doses of 3.2 to 89 Gy. The lung carcinoma incidence rates for the two study groups were compared using a Cox proportional hazards model with a time-dependent dose. A common baseline incidence rate was used so that risks would be estimated relative to the same baseline. No statistically significant difference (P>0.30) was found between the immature and the young adult dogs in how their lung carcinoma incidence rates increased with radiation dose. This suggests that there is not a unique radiosensitivity attributable to alpha particle irradiation of a growing lung.

Cerebral Energy Metabolism and Oxygen State during Hypoxia in Neonate and Adult Dogs

The relationship between a noninvasive determination of relative oxygen saturation of Hb circulating in brain tissue (StO2) and energy metabolism was investigated with respect to age [dogs in three age groups (0 to 6-d-old, 7- to 21-d-old, and adults)] and to severity of brain hypoxia using double beam spectroscopy of Hb deoxygenation and nuclear magnetic resonance spectroscopy of energy metabolism. The in vivo oxy-Hb dissociation was determined from the relationship between StO2 curve in the adult dog brain and sagittal sinus oxygen partial pressure during graded hypoxemia and found to be sigmoidal with an oxygen dissociation constant of 26.6 mm Hg. This agreed with an in vitro determination for oxygen dissociation constant of 28.2 mm Hg in adult dog red cells. The arterial oxygen pressure at which brain StO2 was reduced by 50% was shifted toward the right with increasing age (22.2, 33.8, and 40.8 mm Hg, respectively). This correlated with an in vitro oxygen dissociation constant of red cell Hb of 17.0, 22.3, and 28.2 mm Hg in the three age groups, respectively. The phosphocreatine-inorganic phosphate ratio (PCr/Pi) was used to relate changes in cellular energy metabolism during hypoxia with changes in StO2. There was no change in PCr/Pi when StO2 had decreased to 50% of the control value. However, when the brain StO2 had decreased to between 7 and 15%, a reduction of PCr/Pi to 50% of the normoxic value occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal Development of Bile Secretory Physiology in the Dog

To determine whether bile formation in the dog is an immature process at birth, several determinants of bile secretion were studied in anesthetized, bile duct‐cannulated puppies of 0–42 days of age and adult dogs. Basal canalicular bile flow rate, estimated by 14C‐erythritol biliary clearance, averaged 0.182 μl/min/g liver in 0–3 day‐old puppies and increased to 0.324 and 0.461 μl/min/g in puppies 7–21 and 28–42 days of age, respectively. The latter two values were not significantly different from that observed in adult dogs (0.348 μl/min/g). This age‐related increase in canalicular bile flow could be accounted for primarily by an increase in bile acid independent bile flow (0.103, 0.277, 0.375, and 0.252 μl/min/g in 0–3, 7–21, and 28–42 day‐old puppies and adult dogs, respectively). Calculated ductular bile water reabsorption (14C‐erythritol biliary clearance‐bile flow) was virtually absent in 0–3 day‐old puppies (0.005 μl/min/g), and averaged 0.017 and 0.092 μl/min/g in puppies of 7–21 and 28–42 days of age, respectively. In adult dogs, ductular bile water reabsorption was 0.132 μl/min/g. These functional deficiencies of the newborn dog were associated with an increased biliary permeability to 3H‐inulin which could not be accounted for solely by an increased solute diffusion due to the lower rate of canalicular bile flow. Administration of taurocholate up to 2000 nmol/min/kg produced in all animals a similar increase in canalicular bile flow and bile acid excretion, and was not associated with changes in ductular bile water reabsorption rate. These findings are interpreted to indicate that, in the dog, bile secretory function is immature at birth and develops during postnatal life.

Postnatal development of bile secretory physiology in the dog.

To determine whether bile formation in the dog is an immature process at birth, several determinants of bile secretion were studied in anesthetized, bile duct-cannulated puppies of 0-42 days of age and adult dogs. Basal canalicular bile flow rate, estimated by 14C-erythritol biliary clearance, averaged 0.182 microliter/min/g liver in 0-3 day-old puppies and increased to 0.324 and 0.461 microliter/min/g in puppies 7-21 and 28-42 days of age, respectively. The latter two values were not significantly different from that observed in adult dogs (0.348 microliter/min/g). This age-related increase in canalicular bile flow could be accounted for primarily by an increase in bile acid independent bile flow (0.103, 0.277, 0.375, and 0.252 microliter/min/g in 0-3, 7-21, and 28-42 day-old puppies and adult dogs, respectively). Calculated ductular bile water reabsorption (14C-erythritol biliary clearance-bile flow) was virtually absent in 0-3 day-old puppies (0.005 microliter/min/g), and averaged 0.017 and 0.092 microliter/min/g in puppies of 7-21 and 28-42 days of age, respectively. In adult dogs, ductular bile water reabsorption was 0.132 microliter/min/g. These functional deficiencies of the newborn dog were associated with an increased biliary permeability to 3H-inulin which could not be accounted for solely by an increased solute diffusion due to the lower rate of canalicular bile flow. Administration of taurocholate up to 2000 nmol/min/kg produced in all animals a similar increase in canalicular bile flow and bile acid excretion, and was not associated with changes in ductular bile water reabsorption rate. These findings are interpreted to indicate that, in the dog, bile secretory function is immature at birth and develops during postnatal life.

The acute oral toxicity of the anticoagulant brodifacoum to dogs

Abstract The oral toxicity of an anticoagulant, brodifacoum, was tested with dogs of mixed breed, age, and sex. In the first trial using 20 dogs, predominantly under 2 years old, an acute oral LD50 of 1.09 kg kg−1 (95% confidence limits, 0.49–2.42 kg kg−) was derived. In the second trial with 59 mixed age dogs an acute oral LD50 of 3.56 mg kg−1 (2.13–6.03 mg kg−1) resulted. No significant differences as a result of age or sex were found.

Metabolic factors in the development of homeothermy in dogs.

Dogs from 1 to 25 days of age were exposed to air temperatures of 5, 23 and 30°C and their oxygen consumption measured in a closed calorimeter. Animals 1–5 days old had a rise of 20–25% in metabolic rate, but rectal temperature fell, when they were exposed to 5 or 23°C. At 11–21 days of age dogs exposed to 5°C had a rise of about 75% in metabolic rate, but rectal temperature fell several degrees in 1 hour. In dogs 21–25 days of age metabolic rate increased about 75% at air temperatures of 5°C and rectal temperature fell only about 1°C. Under the same conditions a trained adult dog had a rise of 80% in metabolic rate, and no fall in rectal temperature. Since heat production in 2- to 3-week-old dogs was increased to about the same extent as in the adult on cold exposure, it was assumed that heat conservation lagged behind heat production in the development of homeothermy.