One strategy to address this potential problem would be referral to a board-certified veterinary nutritionist to ensure any home-prepared diet is complete and balanced. An alternative strategy could be to discuss with the owner their concerns with commercial pet foods. Collecting a comprehensive nutritional history is not only important for ensuring dietary needs are met, but the conversation could lead to discussion regarding perceived problems of commercial pet foods. The current study did not find the accompanying decrease in commercial diets that has been shown elsewhere with the vast majority of owners using a commercial diet for part or all of their dog’s foods. As our sample comprised dogs with a recent diagnosis of cancer, this might suggest that inclusion of home-prepared elements precedes the complete exclusion of commercial diets, and our survey was conducted too close to the time of diagnosis to find exclusion of commercial diets. However, for owners feeding a commercial diet both before and after diagnosis, nearly half stopped feeding the pre-cancer diagnosis diet. It is possible that our sample would ultimately have stayed on their second commercial diet, rather than eliminating commercial elements entirely. Among owners feeding commercial diets, we found a decrease in the use of grain-free foods, from 22% to 14% among all 128 respondents, after a cancer diagnosis. While this could seem contrary to the concerns of some owners regarding the role of carbohydrate in promoting cancer progression,possible benefits of the low carbohydrate approach have not been supported by any studies. Further,vertical grow cannabis designs grain-free diets can be lower, similar, or higher in carbohydrate content compared to other diet categories.
There has been considerable attention to the association between dilated cardiomyopathy in dogs and the use of grain-free diets,and both veterinarians and pet owners might have increased awareness of this issue. Regardless, given that more than 1 in 5 dogs in the present study were fed a grain-free diet before a cancer diagnosis, this data highlights the need for clinicians to discuss the risk of diet-associated DCM with all dog owners. The most common informational resource for diets and supplements was veterinarians, similar to previous studies for dogs.Veterinarians are a key resource for providing nutritional information, especially after a cancer diagnosis when veterinarians are actively involved with care, and around three quarters of pet owners believe a change is necessary.Additionally, as our data show, many dog owners do alter their dog’s diet. These findings underscore the importance of collecting and assessing a thorough diet history. This enables effective client counseling by the veterinary care team to help guide and ensure the safe use of diets, treats, and supplement products. Our study did not differentiate whether veterinary advice was taken from general practitioners, cancer-specialists, nutritionists, or elsewhere. Further specifying where owners receive information in a future study would be beneficial for understanding whose dietary advice pet owners value the most. To assess which factors were most likely to result in diet changes, we created a logit model. Our logit model showed that 1 predictor of owners making diet changes was median census tract income, which lowers the chance of diet change as tract income increases. This suggests that people in wealthier areas might be less likely to alter their dog’s diet in response to a diagnosis of cancer. Larger studies are warranted to confirm and further investigate this pattern. One limitation of the current study was only involving dogs referred to a single hospital’s oncology service. Coupled with time restrictions, this survey might not have recruited a large enough sample size to detect all of the patterns in nutritional alteration after a cancer diagnosis.
Furthermore, dog owners within the geographical area of the survey might not be representative of the greater population of dogs and owners. Additionally, dog owners visiting oncology services are a subset of the overall dog owner population, meaning these data can only apply to dogs with a recent cancer diagnosis presenting for evaluation by a specialist. Any owners that decided not to pursue a second opinion or further treatment would not have visited the oncology service, and because of treatment associated costs, respondents to this survey could have more disposable income. This study sought to capture a single snapshot in time, namely, when a dog initially presented to an oncology service. We do not know if this sample of dogs would have eventually shown similar or different patterns than other studies, such as exclusion of commercial diets and using social media groups for dietary and supplement recommendations. It is also possible that these owners would either revert to previously fed diets and supplements or make more extreme changes after treatment. Although we attempted to capture the time-point shortly after diagnosis, there was still a median delay of 61 days from diagnosis to survey. This is likely due the nature of online survey distributions, and the wait to get an oncology appointment which was exacerbated by the pandemic. Additionally, some dogs attempted cancer-related treatments elsewhere before presenting to the oncology service. As a result, some dogs were already undergoing or finished treatments at the time of taking the survey, some of which might have caused gastrointestinal issues before survey completion. Nonetheless, we feel that the time frame from diagnosis to survey enables us to capture additional nutritional changes beyond those simply because of an immediate medical need such as cancer and treatment related gastrointestinal signs.
Further study is warranted into how specific treatments might result in changes to what owners feed their dogs. This study also tried to balance the quality and completeness of data obtained with respondents’ time and willingness to complete a lengthy survey. One concern was that adding too many questions would result in many owners not reaching the end of the survey. Since owners who made changes were asked additional questions, we felt these owners would disproportionately fail to reach the end of the survey, possibly skewing results. Another consideration in interpreting the results of this study was if owners who changed their dog’s diet or supplements could recall what was previously given. Based on initial piloting of the survey, some owners did not recall their dog’s previous diets and supplements and were frustrated by the survey. As a result, the survey program did not force a response for these questions. This was done to ensure owners who did not remember previous nutritional information would be able to complete the survey without guessing unknowns. While we feel this goal was achieved, it is also likely that some owners who remembered simply skipped past these questions for the sake of time. This study strived to be inclusive to all answers by providing text boxes, often referred to as “other” within the survey, if the owner felt the listed multiple-choice options for a question did not apply. However, as the owners largely filled out the survey online by themselves,vertical grow dry racks many either did not list what we were looking for, or possibly used the text box as an additional place to put information, rather than intending to respond with “other.” These factors limited the value of the free text responses, and we feel that studies in the future could avoid these issues by either limiting free text responses in favor of more comprehensive multiple-choice options or by administering the survey in person. Overall, many dog owners make alterations to diet or supplements after their dog has been diagnosed with cancer. Clinicians should counsel owners regarding cancer treatment and its relation to nutrition to assess the current diet and enable educated decisions for any changes. Topics of focus could include discussing owner concerns regarding commercial diets, formulation of home-prepared diets, and the use of certain herbal supplements, including mushrooms and CBD.Contrary to the hypothesis, medial temporal lobe structures were not significantly associated with odds of being impaired on recognition. Given the limited number of participants that were impaired on recognition, there may not have been enough power to detect an effect; however, the odds ratios were fairly close to 1 indicating the association was neither statistically nor clinically significant. Also contrary to the aim 1a hypothesis, a thinner pars opercularis, part of the prefrontal cortex, was significantly associated with greater odds of being impaired on recognition.
No other prefrontal regions or basal ganglia regions were significantly associated with odds of being impaired on recognition. Aim 1b examined the relationship between continuous delayed recall and the three regions of interest. Delayed recall was hypothesized to be more equally associated with all three regions, given that delayed recall deficits are observed in both aMCI/AD and HAND. Somewhat consistent with the hypothesis, thicker rostral middle frontal gyrus and pars opercularis were associated with better delayed recall. Examining laterality, these findings were somewhat more driven by the right. Additionally, thicker right pars triangularis was significantly associated with better delayed recall whereas the left pars triangularis was not. Contrary to the hypothesis, delayed recall was not significantly associated with the medial temporal lobe nor the basal ganglia. In post hoc analyses that excluded participants not on ART, or those with a detectable viral load or methamphetamine use disorder – a group of participants who are closer to those who are ideally treated in medical care – these associations held and thicker rostral middle frontal gyrus and pars opercularis were associated with better delayed recall and relationships were somewhat stronger within this subset of participants. It is important to note that given that delayed recall was examined continuously, this does not imply that these prefrontal regions are associated with delayed recall impairment, as that was not examined. Moreover, mean cortical thickness was included in the models as a covariate, so this means that this association is observed while accounting for average cortical thickness. Taken together, the finding that episodic memory was associated with some prefrontal structures may suggest that, at least in middle age, episodic memory performance is more likely related to frontally mediated etiologies, such as HIV, rather than early AD pathology. The inferior frontal gyrus, which includes the pars opercularis, pars triangularis, and pars orbitalis, as well as the middle frontal gyrus are not part of the medial limbic circuit implicated in memory formation, but they still contribute to memory deficits. The prefrontal cortex is of course associated with memory retrieval . Additionally, more recent models of memory formation stress the importance of the prefrontal cortex in memory formation given that there is some research to suggest that the prefrontal cortex aids in enabling long-term memory formation through connections with the anterior thalamic nuclei . Additionally, these more updated models of memory formation could account for why recognition was associated with prefrontal structures as well, although there could be several other explanations for this observed association. For example, recognition may also be associated with prefrontal structures due to poor initial encoding, which was not explicitly examined in these analyses. Nevertheless, functional MRI studies have shown alterations in prefrontal and hippo campal regions during memory tasks in PWH compared to controls further highlighting that prefrontal regions are implicated in memory in PWH . As highlighted in the introduction, HIV studies have found structural changes throughout the brain, including frontal regions, as compared to persons without HIV . Additionally, studies have demonstrated accelerated age-related atrophy or greater than expected “brain age” in middle-aged and older PWH compared to HIV-negative participants . For example, Milanini et al., 2019 found that, in a group of 19 participants with HAND who were on average 64 years old, HAND individuals showed faster atrophy in the cerebellum and frontal gray matter compared to HIV-negative controls. Additionally, Pfefferbaum et al., 2014 found accelerated changes in the frontal lobe, temporal pole, parietal lobe, and the thalamus in PWH compared to HIV-negative controls. Of these studies examining longitudinal brain changes, all found some involvement of the frontal lobe, but most studies did not examine the specific regions within frontal lobe that were driving these associations. Additionally, results from these studies were mixed as to if brain changes were associated with changes in cognition. Given that the current study only examines structural MRI at one time point, we cannot assume that there has been atrophy of the prefrontal cortex; however, given the literature demonstrates atrophic changes in PWH in the frontal lobe and accelerated aging in the frontal lobe, is possible that changes in the prefrontal cortex have occurred in this cohort and are contributing to the observed associations with memory.