Polioencephalomyelopathy in a mixed breed dog resembling Leigh’s disease

A 14-month-old mixed-breed dog was presented with acute onset of exercise intolerance that quickly progressed to quadriparesis. Gross and microscopic autopsy findings indicated a type of degenerative polioencephalomyelopathy resembling subacute necrotizing encephalomyelopathy in dogs or Leigh’s disease in humans. This syndrome has previously been reported only in purebred dogs.     

Effects of sweet potato feathery mottle virus and sweet potato sunken vein virus on sweet potato yields and rates of reinfection of virus-Free planting material in Israel

Yield reductions ofca 50% or more were observed in field plots infected with both sweet potato feathery mottle virus (SPFMV) and sweet potato sunken vein virus (SPSVV) (‘complex’), compared with plots planted with virus-free propagation stocks. No yield reductions were observed in a plot planted with SPFMV-infected cuttings. In plots infected with SPSVV alone, no significant effect on tuber yields was observed in one year, whereas in the second year there was aca 30% reduction in yield compared with virus-free control plants. Reinfection in the field, in the absence of introduced infection sources, was observed only with SPSVV. However, natural spread resulted when SPFMV-infected source plants were introduced. This implies that aphid vectors were present during the growing season, but that SPFMV infection sources were absent from the area.     

MRI measurement of the canine auditory pathways and relationship with brainstem auditory evoked responses.

The objective of this study was to determine direct measurements of auditory pathways by magnetic resonance imaging (MRI) during the growth period of healthy Beagles, and to discover how canine brainstem auditory evoked response (BAER) latencies vary in relation to these MRI measurements. Eighty healthy Beagles were tested at eight, 16 and 52 weeks of age (stages 1, 2, 3, respectively) with BAER and brain MRI. The BAER interpeak latency (IPL) II-V and brain MRI neural generators of BAER waves II and V were identified. A linear distance was calculated in millimeters in order to determine the approximate length of auditory pathways. Sensory nerve conduction velocity (SNCV) of the auditory pathway between peak II and peak V was calculated for each group. A significant difference was observed between brain MRI distances among the three stages. Mean BAER IPL II-V were not significantly different between the three stages. The progressive growth of the skull and brain witnessed by the progressive increased distance of the MRI auditory pathways between peak II and peak V was not associated with a progressive maturation of the BAER IPL II-V. The SNCV of the auditory pathway between peak II and peak V was 6.14 m/sec for group 1; 6.76 m/sec for group 2; and 7.32 m/sec for group 3.     

The influence of severe prolonged exercise restriction on the mechanical and structural properties of bone in an avian model

Many studies have described the effects of exercise restriction on the mammalian skeleton. In particular, human and animal models have shown that reduction in weight bearing leads to generalised bone loss and deterioration of its mechanical properties. The aim of this study was to assess the effect of prolonged exercise restriction coupled with heavy calcium demands on the micro-structural, compositional and mechanical properties of the avian skeleton. The tibiae and humeri of 2-year-old laying hens housed in conventional caging (CC) and free-range (FR) housing systems were compared by mechanical testing and micro-computed tomography (μCT) scanning. Analyses of cortical, cancellous and medullary bone were performed.Mechanical testing revealed that the tibiae and humeri of birds from the FR group had superior mechanical properties relative to those of the CC group, and μCT scanning indicated larger cortical and lower medullary regions in FR group bones. Cancellous bone analysis revealed higher trabecular thickness and a higher bone volume fraction in the FR group, but no difference in mineral density. The biomechanical superiority of bones from the FR group was primarily due to structural rather than compositional differences, and this was reflected in both the cortical and cancellous components of the bones. The study demonstrated that prolonged exercise restriction in laying hens resulted in major structural and mechanical effects on the bird skeleton.     

Prior experience, antioxidants, and mitochondrial cofactors improve cognitive function in aged beagles

Results of this study support the free-radical theory of aging and demonstrated that providing higher levels of vitamin E in food resulted in higher serum vitamin E concentrations and improved performance on landmark-discrimination tasks in aged dogs. Factors other than vitamin E also contributed to the response but remain undefined.     

A novel cognitive palatability assessment protocol for dogs

Assessment of canine palatability is important for both the pet food and pharmaceutical industries; however, the current palatability assessment protocols are limited in their utility. The most common technique, the two-pan test, does not control for the satiating effects of food and may not be useful for long-term palatability analysis because nutritional or caloric characteristics of the diets may interfere with the results. Furthermore, the large quantities of foods consumed may be detrimental to the health of animals that do not self-limit their food intake. The purpose of this study was to determine whether a cognitive protocol could be used to determine food palatability in dogs. Five beagle dogs were trained on a three-choice object-discrimination learning task. After establishing object preferences, the preferred object was associated with no reward, a second object was associated with the dog's normal laboratory diet (Purina Agribrands Canine Lab Chow No. 5006; Agribrands Purina Canada, Inc., Woodstock, ON, Canada), and the third object was associated with a commercial (Hill's P/D; Hill's Pet Nutrition Inc., Topeka, KS) diet. In the discrimination-training phase, dogs were trained until they learned to avoid the no-reward object. They were subsequently given an additional 20 test sessions, which were used to determine food preference. In the reversal phase, which involved reversal learning, the object-food associations were modified, such that the object that was previously associated with Hill's P/D diet was now associated with the normal laboratory diet and vice versa. Once the dogs learned to avoid the no-reward object, they were tested for an additional 20 sessions. All subjects learned to avoid the no-reward object during the initial learning, and the number of choices to the object associated with the Hill's P/D diet was greater than the number of choices to the objects associated with the dry laboratory diet (P < 0.05) and no reward (P < 0.05), indicating a strong preference for the Hill's P/D diet. The object preferences were reversed in only three of five dogs when the food-choice associations were reversed, although the two phases did not differ significantly from one another. The protocol in the present study provides a robust measure of food palatability and circumvents many of the limitations associated with other palatability assessment techniques. The present protocol should be useful as a replacement or adjunct to other tests of palatability, but requires further validation by comparing the assessment of more similar and novel foods directly with other palatability tests.     

Characterizing behavioral sleep using actigraphy in adult dogs of various ages fed once or twice daily

Adult dogs possess strong diurnal locomotor activity/rest rhythms, and sleep/wake patterns have been characterized. However, behavioral sleep/wake data are lacking related to aging and daily feeding pattern. Three groups (young adults [Y], 1.5–4.5 years; middle-aged adults [M], 7–9 years; and senior, 11–14 years) of beagles (N = 48) wore the Actiwatch activity monitoring system (Respironics Co., Inc., Bend, OR) for 3 days while housed indoors with 12-hour light/dark schedule and fed once or twice daily. Actiware-Rhythm software (version 5.52; Respironics Co., Inc., Bend, OR) was used to estimate behavioral sleep or wake from locomotor activity data. All dogs demonstrated diurnal sleeping patterns. Total wake minutes during the light phase declined with age (P < 0.05) and differed by 7.7% and 10.2% for middle-aged adults and seniors, respectively, compared with young adults. Further analysis revealed that increased light phase nap bouts (P < 0.008), not increased nap duration, caused this decline. Total sleep minutes during the night increased with age, as middle-aged adults and seniors slept at least 38 (P = 0.01) more minutes than young adults. Increased sleep time at night resulted from a longer sleep interval duration (P = 0.05), delayed morning activity onset time (P = 0.02), and marginally fewer waking bouts (P = 0.07). Independent of age, twice-daily feeding significantly influenced daytime sleeping patterns but did not affect total minutes recorded as sleep during the day. Interestingly, napping bouts decreased significantly (P = 0.01) and napping duration increased (P = 0.0001) when fed twice-daily. Twice-daily feeding was also associated with earlier sleep onset time at night and onset of morning activity, as well as shortened sleep interval. Clear changes in behavioral sleep patterns were observed with age and daily feeding schedule.