Respiratory alkalosis and primary hypocapnia in Labrador Retrievers participating in field trials in high-ambient-temperature conditions

Dog Handler Beliefs regarding Barriers and Facilitators to Canine Health Promotion and Injury Prevention in Swedish Working Dog Trials and Competitions

Dog trials and competitions involve various sport disciplines, e.g., obedience, agility, working dog trials and rally obedience. Dog handlers navigate their dogs through physically and mentally demanding tasks. The purpose of this study was to gain a better understanding of barriers and facilitators to canine health promotion and injury prevention described by dog handlers.

METHODS

Qualitative inductive content analysis was applied to systematically organize and interpret narrative data from 654 respondents' answers to open-ended questions in an anonymous online inquiry.

RESULTS

Two categories, with seven sub-categories, emerged from the analysis: (1) Challenges in applying the regulations in dog trials and competitions, and (2) Implementation of animal welfare and canine well-being approaches. Respondents described the challenges in applying regulations in dog trials and competitions and lack of scientific research as barriers to their intent to prevent injuries in their dogs. Implementation of animal welfare and canine well-being approaches were described as facilitators.

CONCLUSION

The findings imply that the stakeholders continuously need to work on bridging possible gaps between the canine welfare criteria and the scientific and empirical knowledge in canine sports and performance medicine.

The Effect of Two Acute Bouts of Exercise on Oxidative Stress, Hematological, and Biochemical Parameters, and Rectal Temperature in Trained Canicross Dogs

Canicross is a sport discipline that connects human and canine athletes in running. Changes in physiological, hematological, and biochemical parameters, and exercise-induced oxidative stress have not been thoroughly characterized in canicross dogs. The aim of our study was the assessment of the health status of trained canicross dogs that were subjected to two acute bouts of exercise with their owners during the training season. Health status was assessed by measuring the rectal temperature, hematological and biochemical parameters, as well as blood oxidative stress parameters (plasma malondialdehyde, lipid peroxidation marker; whole blood glutathione peroxidase and erythrocyte superoxide dismutase1, antioxidant enzymes) before and during a two-day canicross training session and after a 24-h rest period. Seven trained canicross dogs (three females/four males) aged 12–120 months were included in the study. Blood samples were collected before and immediately after the first acute bout of exercise (day 1), after the second acute bout of exercise (day 2), and after 24 h of rest (day 3). Rectal temperature was measured at the same time as blood sample collection. The majority of hematological and biochemical parameters remained within reference ranges at all sampling times. Rectal temperature was significantly higher after training on days 1 and 2 compared to resting temperature on day 3. Hematological parameters did not change significantly; however, there were significant differences in urea, creatinine, creatine kinase, and triglycerides between specific sampling times. Despite significant changes, these biochemical parameters remained within reference ranges. Significant changes in biochemical parameters seem to reflect the dogs' physiological response to each acute bout of exercise, considering all biochemical parameters and rectal temperature returned to pre-exercise values after a 24-h rest period (day 3). No significant differences in oxidative stress parameters were found between any sampling times. Relatively high erythrocyte superoxide dismutase1 activity at all sampling times may indicate that the canicross dogs are adapted to training by an increased expression of antioxidant enzymes. Based on our results, we can conclude that the trained canicross dogs included in our study were healthy, in good physical condition, and fit for the two acute bouts of field exercise.

A canine thermal model for simulating temperature responses of military working dogs

Military working dogs (MWDs) are often required to operate in dangerous or extreme environments, to include hot and humid climate conditions. These scenarios can put MWD at significant risk of heat injury. To address this concern, a two-compartment (core, skin) rational thermophysiological model was developed to predict the temperature of a MWD during rest, exercise, and recovery. The Canine Thermal Model (CTM) uses inputs of MWD mass and length to determine a basal metabolic rate and body surface area. These calculations are used along with time series inputs of environmental conditions (air temperature, relative humidity, solar radiation and wind velocity) and level of metabolic intensity (MET) to predict MWD thermoregulatory responses. Default initial values of core and skin temperatures are set at neutral values representative of an average MWD; however, these can be adjusted to match known or expected individual temperatures. The rational principles of the CTM describe the heat exchange from the metabolic energy of the core compartment to the skin compartment by passive conduction as well as the application of an active control for skin blood flow and to tongue and lingual tissues. The CTM also mathematically describes heat loss directly to the environment via respiration, including panting. Thermal insulation properties of MWD fur are also used to influence heat loss from skin and gain from the environment. This paper describes the CTM in detail, outlining the equations used to calculate avenues of heat transfer (convective, conductive, radiative and evaporative), overall heat storage, and predicted responses of the MWD. Additionally, this paper outlines examples of how the CTM can be used to predict recovery from exertional heat strain, plan work/rest cycles, and estimate work duration to avoid overheating.

Predicting military working dog core temperature during exertional heat strain: Validation of a Canine Thermal Model

Military working dogs (MWDs) operate under a wide range of conditions, including hot environments. Predicting how long a MWD can safely work without overheating is important for both health and performance. A Canine Thermal Model (CTM) was developed to predict core temperature (Tc) of MWDs. The CTM calculates heat storage from the balance of heat production from metabolism and heat exchange with the environment. Inputs to the CTM are: meteorological conditions (ambient temperature, relative humidity, solar radiation and wind speed), physical characteristics of the dog (mass, length), and metabolic activity (MET level, estimated from accelerometer data). The CTM was validated against Tc measured in 23 MWDs during training sessions (11.6 ± 5.0 min (mean ± standard deviation), range 4-26 min) in October (24 °C, 52% RH), March (14 °C, 74% RH), or August (28 °C, 64% RH), and 24 kennel MWDs during a standard exercise walk (11.4 ± 3.3 min, range 5.6-18 min) in July (26 °C, 77% RH). The CTM was considered acceptable if predicted Tc was within ±0.5 °C of measured Tc at the end of exercise. Compared to Tc at the end of training sessions (39.8 ± 0.6 °C, range 38.4-41.1 °C) and exercise walks (40.0 ± 0.7 °C, range 38.9-41.4 °C), the CTM-predicted Tc was within ±0.5 °C for 71 of 84 cases (85%) and 19 of 24 cases (79%), respectively. The mean difference between CTM-predicted and measured final Tc during training was -0.04 ± 0.43 °C, with 80 of 84 cases (95%) within the range of ±2 SD (Bland Altman comparison). During exercise walks the mean difference was -0.15 °C ± 0.57, with 23 of 24 cases (96%) within ±2 SD. These results support the use of the CTM to predict Tc of MWDs for the types of physical activities described above.

Predicting recovery from exertional heat strain in military working dogs

A two-compartment (core, skin) rational Canine Thermal Model (CTM) of thermal-physiological responses was developed to predict the core temperature (Tc) of a military working dog (MWD) during recovery from exertional heat stress. Heat storage is represented as the balance among heat loss mechanisms, heat gain from the environment, and heat production from metabolism. Inputs to the CTM include environmental conditions (ambient temperature, relative humidity, solar radiation and wind speed), physical characteristics of the dog (weight, length), and metabolic rate. The CTM was validated against Tc of 16 MWDs measured in a previous study, where training was conducted in October (24 °C, 52% RH), March (14 °C, 74% RH), and August (28 °C, 64% RH). Measured and CTM-simulated Tc were compared at 5, 10, 15, 30 and 60 min post-exercise. The CTM was considered acceptable if it was within 0.5 °C of measured Tc for 80% of cases. This occurred in 92% of 37 cases after 30 min recovery, and 86% of 29 cases after 60 min. The mean difference between CTM-simulated and measured Tc was - 0.01 °C at 30 min recovery, with 2 of 37 cases falling outside the range of two standard deviations (Bland Altman comparison). After 60 min recovery the difference was 0.05 °C, with 4 of 29 cases outside the range of acceptance. The root mean squared deviation between CTM-simulated and measured Tc for all time points was 0.3 °C ± 0.3 °C. For comparison, the mean ± standard deviation of resting Tc was 38.2 °C ± 0.3 °C and at peak Tc was 39.4 °C ± 0.7 °C. For this population, the CTM is a valid method for simulating recovery from exertional heat stress. It can be used to develop work / rest cycles during activity in hot environments, and to compare rates of recovery across different environmental conditions.

Evaluation of Three Hydration Strategies in Detection Dogs Working in a Hot Environment

Physical activity in hot environments can increase the risk of heat stress or heat stroke in dogs. Heat tolerance is influenced by acclimatization to the environment, physical fitness, and hydration state. Three common strategies to promote hydration in working dogs are free access to water (W), oral electrolyte solutions (OESs), and administration of subcutaneous fluids (SQs). None of these methods have been compared for safety or efficacy in a working environment. In a cross-over design, seven vehicle-screening canines were randomly assigned to each of the three hydration strategies during working shifts at the Sarita, TX checkpoint. Physical, behavioral, and biochemical parameters were collected before, during, and after a work shift (mean 5.7 ± 0.8 h). Dogs were given 10 mL/kg oral W, 10 mL/kg chicken flavored OES, or 15 mL/kg of SQs initially followed by controlled access to W or OES. The dogs drank 15.61 ± 4.47 mL/kg/h of W and OES when in the OES group, compared to 7.04 ± 3.42 and 5.56 ± 4.40 mL of W, for the W and SQ groups, respectively. The median environmental temperature was 84.8°F (29.3°C). The median humidity was 70%. Based on mixed effects linear modeling, dogs in the OES and SQ groups had significantly higher total CO₂, and lower packed cell volume and total plasma protein at the end of the day. Creatinine increased a small but significant amount in the SQ group and decreased in the OES group. Searching behaviors were independent of hydration strategy but highly related to the dog specific factors of sex, breed, and activity level. Under conditions of controlled activity in moderate heat and humidity, dogs accustomed to the work and the environment were more likely to increase fluid consumption and hydration when provided a flavored OES. Potential benefits of OES and SQ were indirect and no adverse effects were documented for any of the hydration strategies tested.

Environmental and Physiological Factors Associated With Stamina in Dogs Exercising in High Ambient Temperatures

This IACUC approved study was performed to evaluate the environmental, physiological, and hematological components that contribute to stamina following successive bouts of exercise that included searching (5-min), agility (5-min), and ball retrieve (<10-min). Regularly exercised dogs (N = 12) were evaluated on five separate occasions. The population consisted of eight males and four females ranging in age from 8 to 23 months, which included six Labrador retrievers, three German shepherds, and one each English springer spaniel, German wirehaired pointer, and Dutch shepherd. The exercise period was up to 30 min with 5 min of intermittent rest between the exercise bouts or until a designated trainer determined that the dog appeared fatigued (e.g., curled tongue while panting, seeking shade, or voluntary reluctance to retrieve). At the end of the exercise period, pulse rate (PR), core temperature, blood lactate, and venous blood gas were collected. The median outdoor temperature was 28.9°C (84°F) (IQR; 27.2–30°C/81–86°F) and median humidity was 47% (IQR; 40–57%). Median duration of exercise was 27 min (IQR; 25–29). No dog showed signs of heat stress that required medical intervention. The components used to measure stamina in this study were total activity, post-exercise core body temperature (CBT), and increase in CBT. When controlling for breed, total activity, as measured by omnidirectional accelerometer device, could be predicted from a linear combination of the independent variables: pre-exercise activity (p = 0.008), post-exercise activity (p < 0.001), outdoor temperature (p = 0.005), reduction in base excess in extracellular fluid compartment (BEecf) (p = 0.044), and decrease in TCO₂ (p = 0.005). When controlling for breed and sex, increase in CBT could be predicted from a linear combination of the independent variables: study day (p = 0.005), increase in PR (p < 0.001), increase in lactate (p = 0.001), reduction in BEecf (p = 0.031), increase in glucose (p = 0.044), increase in hematocrit (p = 0.032), and increase in hemoglobin (p = 0.038). This study suggests that the influence of outdoor temperature, pre- and post-exercise activity, and the metabolic parameters are important components of stamina associated with exertion.

Exercise-induced hyperthermia syndrome (canine stress syndrome) in four related male English springer spaniels

OBJECTIVE

This retrospective study describes the signalment, clinical presentation, diagnostic findings, and mode of inheritance in four young male English springer spaniel dogs with presumptive canine stress syndrome.

MATERIALS AND METHODS

Appropriate cases were located through medical searches of medical records of two large private referral centers. Inclusion criteria comprised of English springer spaniel dogs with tachypnea and hyperthermia that subsequently developed weakness or collapse, with or without signs of hemorrhage, soon after a period of mild-to-moderate exercise. The pedigrees of the four affected dogs, as well as eleven related English springer spaniels, were then analyzed to determine a presumptive mode of genetic inheritance.

RESULTS

Four dogs met the inclusion criteria. All four were male, suggesting the possibility of a recessive sex-linked heritable disorder. Pedigree analysis suggests that more dogs may be potentially affected, although these dogs may have never had the concurrent triggering drug/activity/event to precipitate the clinical syndrome. There was complete resolution of clinical signs in three of the four dogs with aggressive symptomatic and supportive therapy, with one dog dying during treatment.

CONCLUSION

Dogs with canine stress syndrome have the potential for rapid recovery if treated aggressively and the complications of the disease (eg, coagulopathy) are anticipated. All four dogs were male, suggesting the possibility of a recessive sex-linked mode of inheritance. Further genetic analyses should be strongly considered by those involved with the English springer spaniel breed, either with a genome-wide association study using canine single-nucleotide polymorphism arrays or whole-genome sequencing of affected and closely related dogs.

Eye and Ear Temperature Using Infrared Thermography Are Related to Rectal Temperature in Dogs at Rest or With Exercise

Rectal body temperature (BT) has been documented in exercising dogs to monitor thermoregulation, heat stress risk, and performance during physical activity. Eye (BTeye) and ear (BTear) temperature measured with infrared thermography (IRT) were compared to rectal (BTrec) temperature as the reference method and assess alternative sites to track hyperthermia, possibly to establish BTeye IRT as a passive and non-contact method. BT measures were recorded at 09:00, 11:30, 12:30, and 02:30 from Labrador Retrievers (N = 16) and Beagles (N = 16) while sedentary and with 30-min play-exercise (pre- and 0, 15, 30-min post-exercise). Total exercise locomotor activity counts were recorded to compare relative intensity of play-exercise between breeds. BTrec, BTeye, and BTear were measured within 5 min of the target time. Each BT method was analyzed by analysis of variance for main effects of breed and time. Method differences were compared using Bland-Altman plots and linear regression. Sedentary BT differed by breed for BTrec (p < 0.0001), BTear (p < 0.0001), and BTeye (p = 0.06) with Labs having on average 0.3-0.8°C higher BT compared to Beagles. Readings also declined over time for BTeye (p < 0.0001) and BTear (p < 0.0001), but not for BTrec (p = 0.63) for both breeds. Total exercise (30-min) activity counts did not differ (p = 0.53) between breeds. Time and breed interaction was significant in response to exercise for both BTrec and BTear (p = 0.035 and p = 0.005, respectively), with a marginal interaction (p = 0.09) for BTeye. All the three methods detected hyperthermia with Labs having a higher increase compared to Beagles. Both BTear and BTeye were significantly (p < 0.0001) related to BTrec in all dogs with sedentary or exercise activity. The relationship between BTeye and BTrec improved when monitoring exercise hyperthermia (r = 0.674) versus measures at rest (r = 0.381), whereas BTear was significantly related to BTrec regardless of activity (r = 0.615-0.735). Although BT readings were significantly related, method bias (p < 0.02) was observed for BTeye to slightly underestimate BTrec, whereas no bias was observed between BTear and BTrec. This study demonstrates that IRT technology effectively measures both ear and eye temperature and enables effective monitoring of BT changes at rest, with exercise, and between breeds. However, ear, and not eye, temperature is a better reflection of rectal temperature.

Serum biochemical, blood gas and antioxidant status in search and rescue dogs before and after simulated fieldwork

The aim of the study was to assess the physiological and antioxidant status before and after a 4 h search and rescue field exercise, with handlers, under warm-weather conditions performing activities compared to a control group of similarly trained dogs at rest. Serum chemistry demonstrated a decrease in serum sodium (Na) and potassium (K) in both exercising and control groups, however only Na was decreased significantly (P < 0.05) after exercise and hematocrits (HCTs) remained unchanged. The exercise group demonstrated significantly decreased serum phosphorus (P) and magnesium (Mg) compared to pre-exercise values, as did the control group (P < 0.025). There was also a significant increase in creatinine kinase concentrations in the exercise groups (P < 0.025). Serum non-esterified fatty acids were increased only in the exercise group after exercise, suggesting fat mobilization to produce energy. The mean total serum antioxidant potential in searching dogs was no different from the pre- and post-exercise values in the control dogs. Serum vitamin E concentrations did not differ between the two groups, with a decreasing trend in both groups. There was a modest decrease in serum uric acid in the control group, while there was a significant rise after exercise in the searching group (P < 0.01). Multiple changes in serum chemistry, HCTs and blood gases were documented in this study, and were similar to those observed after other endurance activities. The lack of hemoconcentration in this field search exercise suggested that even in extreme environmental conditions (heat and humidity), dogs with access to water do not experience significant dehydration or diminished antioxidant status.

Dog poisonings associated with a Microcystis aeruginosa bloom in the Netherlands

In early autumn 2011, three dogs died after they had been exposed to a Microcystis aeruginosa bloom on Lake Amstelmeer, The Netherlands. The cyanobacterial scum from the lake contained up to 5.27 × 10³μg g⁻¹ dry-weight microcystin, the vomit of one of the dogs contained on average 94 µg microcystin g⁻¹ dry-weight. In both cases, microcystin-LR was the most abundant variant. This is the first report of dog deaths associated with a Microcystis bloom and microcystin poisoning in The Netherlands.

The effect of agility exercise on eicosanoid excretion, oxidant status, and plasma lactate in dogs

Background

The objective was to determine the effects of agility exercise on dogs of different skill levels with respect to urinary eicosanoids, urinary 15F_2t-isoprostane (lipid peroxidation marker) and hematological/biochemical changes in plasma. Fifteen adult dogs had blood and urine samples obtained prior to, immediately and 4-hours following an agility exercise.

Results

Hematocrit, red blood cells (RBC), albumin, and hemoglobin increased following exercise, with greatest increases correlating to increased skill group (novice, intermediate, masters); at 4-hours post-exercise, hematocrit, RBC, and hemoglobin were decreased. Phosphorus increased following exercise with the greatest increase in novice and intermediates. Plasma lactate increased 3.6-fold in masters, 3.2-fold in intermediates, and 1.2-fold in novice dogs. Urine thromboxane B₂ (TXB2) more than tripled 4-hours post-exercise while 6-keto prostaglandin F_1α (PGF1α, prostacyclin metabolite), prostaglandin E₂ metabolites (13,14-dihydro-15-keto-prostaglandin A₂ and 13,14-dihydro-15-keto-prostaglandin E₂), and 13,14-dihydro-15-keto prostaglandin F_2α were unaffected as determined by a competitive enzyme immunoassay and standardized by division with urine creatinine. Urine 15F_2t-isoprostane increased insignificantly.

Conclusions

Alterations in the plasma post-exercise were likely due to hemoconcentration from insensible water loss, splenic contraction and sympathetic stimulation while 4-hours later autohemodilution reduced RBC parameters. Elevations in plasma lactate and urinary TXB2 correlated with advanced skill level/speed of the dogs.