Noise-induced hearing loss (NIHL) has been reported in both people and canines and can raise the hearing threshold. In people, hearing protection devices (HPD's) are utilized to reduce the risk of hearing loss. In canines, HPD's have been developed, but none, to our knowledge, have been objectively tested to determine their ability to reduce incoming sound. We hypothesize that a canine hearing protection device (CHPD) will effectively protect hearing in canines by increasing hearing thresholds. Twenty-one apparently healthy canines between the ages of 4-69 months were anesthetized for routine surgical sterilization. Hearing thresholds were established using over-the-ear headphones (OTEH); starting at 70 dB nHL, sound was gradually diminished by 10 dB nHL until wave V was inapparent as recorded by BAER. Hearing thresholds were then established in the same patients while wearing CHPD. Median hearing thresholds for canines without the CHPD were 40 dB (range 5-70 dB) in the left ear and 50 dB (range 20-70 dB) in the right ear. Median hearing thresholds for canines with the CHPD were >70 dB AU (range 65-70 dB). Twenty out of twenty-one canines had hearing thresholds > 70 dB with the CHPD in place. The CHPD objectively increased the hearing threshold in canines, blocking sound of less than or equal to 70 dB nHL. This device could be utilized to lessen the likelihood of NIHL in canines.

This study evaluated electroencephalogram [EEG] and cardiovascular correlation of sevoflurane anesthesia in healthy beagle dogs at varying minimum alveolar concentration (MAC) multiples. Processed EEG indices (Patient State Index [PSI], burst suppression ratio [SR], and Spectral Edge Frequency [SEF95], cardiovascular parameters (mean blood pressure [MBP], heart rate [HR]), and responses to noxious (electrical) stimuli were recorded. Deep anesthesia (2.5x MAC) resulted in the lowest PSI and MBP values (13.5 ± 9.9, 42.2 ± 7.4 mmHg, respectively), the highest SR (52.7 ± 35.4%), and dominant burst suppression. Surgical anesthesia (1.5x MAC) was characterized by alpha/low beta waves and the absence of response to noxious stimuli. At 1x MAC (2.1%), PSI and MBP increased (41.9 ± 12.6, 119.9 ± 17.7, respectively) while SR decreased (7.1 ± 13%). A moderate PSI-MBP correlation (ρ = 0.48, p = 0.002) was observed. Recovery was acceptable or smooth in most dogs. These findings suggest that sevoflurane disrupts cortical communication, inducing anesthesia and antinociception and that real-time EEG monitoring may aid in titrating sevoflurane delivery in conjunction with MBP.

Objective:To evaluate the RNA and protein expression of hypoxia-inducible factor (HIF-1α) in canine urothelial carcinoma (UC) compared to normal canine urinary bladder tissue. Methods:Dogs with normal urinary bladder tissue were enrolled at the time of euthanasia with the tissue obtained via necropsy within 1 hour after death. The high-grade UC tissue was collected via necropsy or cystoscopically utilizing a resectoscope. Dogs in the UC group were excluded if they were treated with chemotherapy or radiation therapy prior to tissue collection. Immunohistochemistry was performed on all tissues to evaluate intracytoplasmic and intranuclear immunoreactivity of HIF-1α using a semiquantitative immunoreactivity score (IRS). Ribonucleic acid sequencing was also performed to evaluate the expression of HIF-1α in normal urinary bladders and canine UC. Results:10 dogs with high-grade UC and 10 dogs with normal urinary bladder tissue were enrolled. The median intracytoplasmic HIF-1α in the UC group was mild in intensity with a low percentage of positive cells (median IRS, 1; range, 0 to 2). The control dogs had similar intracytoplasmic HIF-1α expression (median IRS, 1; range, 0 to 1). The difference in RNA expression of HIF-1α between groups was not significant (1.3-fold change). Conclusions:This study did not identify any differential RNA or protein expression of HIF-1α between normal urinary bladder tissue and UC in dogs. Clinical Relevance:HIF-1α is not differentially expressed in canine UC, but further exploration is necessary to evaluate if other proteins associated with hypoxia and angiogenesis could play a role in tumor growth and chemotherapy resistance in canine UC.

OBJECTIVE:To determine if oxidative stress induces phosphatidylserine (PS) externalization in canine erythrocytes and if exposure to antioxidants prevents such changes. METHODS:This was an in vitro, experimental study using 5 healthy, adult, purpose-bred research Beagles. Fresh EDTA-anticoagulated blood samples were collected from each dog, and erythrocytes were harvested. For objective 1, erythrocytes were exposed to the pro-oxidant agents tert-butyl hydroperoxide (TBHP) at 2, 3, or 4 mM or 2,2'-azobis(2-amidinopropane) dihydrochloride at 30, 40, or 50 mM. For objective 2, erythrocytes were exposed to 3 mM TBHP and the antioxidant N-acetylcysteine-amide (NACA) at various concentrations (0, 1, or 3 mM). Erythrocytes incubated with benzoylbenzoyl-ATP were used as positive control, whereas erythrocytes incubated with sodium chloride medium with 0.1% bovine serum albumin, DMSO, and NACA were used as negative controls. Erythrocytes were stained with allophycocyanin-conjugated Annexin V, and PS externalization was assessed by flow cytometry. The degree of PS externalization of each sample was recorded as median fluorescence intensity and percentage of PS positivity. RESULTS:TBHP at 3 and 4 mM caused increased PS externalization in canine erythrocytes. 2,2'-Azobis(2-amidinopropane) dihydrochloride at all concentrations caused increased PS externalization. N-acetylcysteine-amide at all concentrations prevented significant PS externalization measured by median fluorescence intensity and percentage of PS positivity from erythrocytes exposed to TBHP. CONCLUSIONS:Oxidative stress causes PS externalization in canine erythrocytes, and NACA ameliorates this effect. CLINICAL RELEVANCE:Future studies are needed to determine if increased PS externalization in erythrocytes occurs in dogs with immune-mediated hemolytic anemia and its role in promoting thromboembolism.

OBJECTIVE:To describe storage and oxidative lesions in canine packed red blood cells (pRBCs) during routine storage with additives, including saline, N-acetylcysteine (NAC), ascorbic acid (AA), and vitamin E analog (VE). DESIGN:Prospective, comparative study of canine pRBCs with or without antioxidant additives during routine 42-day storage. SETTING:University teaching hospital. ANIMALS:Nine leukoreduced units of canine pRBCs were aseptically separated into three aliquots (Groups 1, 2, and 3) on the same day as collection (day 0). All aliquots were shipped overnight and received by the investigators on day 1. INTERVENTIONS:Antioxidants (or control solution) were added on day 1, with three treatment groups that included saline (control, Group 1), NAC and AA (Group 2), and AA and a VE (Group 3). MEASUREMENTS AND MAIN RESULTS:Blood was collected from each aliquot on day 1, before the addition of antioxidants for baseline measurement of glutathione and intraerythrocytic reactive oxygen species (ROS). Additional samples were collected from each aliquot on days 7, 28, and 42. Type 3 fixed-effects tests were used to compare the impact of group and time on each measurement. All groups showed storage lesions and glutathione depletion by day 42 compared with baseline, regardless of the antioxidant additive. Intraerythrocytic ROS accumulation was lower in Group 3 (AA and a VE) compared with other groups at all time points after baseline (p < 0.0001). CONCLUSIONS:The addition of AA and a VE to canine pRBCs reduced ROS accumulation but did not prevent glutathione depletion during routine storage. Further studies using antioxidants as additives in canine pRBCs are warranted.

Introduction:Canine cutaneous adverse food reaction (CAFR) is a common disorder caused by abnormal and unwanted skin reactions to ingested dietary allergens. Whereas other forms of allergic dermatitis may require drug therapy, CAFR is best treated with dietary change. Therefore, early and accurate diagnosis and treatment of CAFR are critical. The gold standard test for CAFR is a 6-12 week elimination diet trial using limited and known hypoallergenic proteins. Method:A multicenter, triple-blinded, randomized, crossover prospective clinical study was conducted in dogs suspected to have cutaneous adverse food reaction. The study utilized a hydrolyzed salmon (HS) diet and a hydrolyzed poultry feather (HPF) diet in separate elimination diet trials to determine if the HS diet would be efficacious and well-tolerated, compared with the established HPF diet, to diagnose and treat CAFR. Results:Fifty-seven dogs were enrolled, and 47 dogs completed the study. HS was well-tolerated, similar to HPF. Pruritus scores during the initial elimination diet trial were reduced with both diets, and dermatitis severity scores during both diet trials were reduced with both diets in the 47 dogs diagnosed with either CAFR, CAFR with atopic dermatitis (AD), or AD. Over half of the subjects diagnosed with CAFR or CAFR with AD required >4 weeks to show PVAS score decreases ≥2 or any decrease in CADESI-4 score. Discussion:HS, like HPF, presents a valuable diagnostic and treatment tool for dogs suffering from CAFR. Both hydrolyzed diets tested also improved clinical signs in dogs diagnosed with AD and may be useful adjunctive tools in the management of canine AD.

Introduction:Measuring serum free thyroxine (fT4) concentration is recommended to distinguish hypothyroidism from nonthyroidal illness syndrome (NTIS) in dogs having a serum total thyroxine (TT4) concentration below the reference interval (RI). Serum fT4 concentration can be measured by equilibrium dialysis (fT4ED) or chemiluminescent immunoassay (fT4CLIA), neither of which have been extensively evaluated in known euthyroid dogs with NTIS. The objectives of this study were to: (1) determine agreement between fT4ED and fT4CLIA in serum samples from established euthyroid dogs with NTIS, (2) evaluate how frequently each fT4 assay is within the RI when the serum TT4 concentration is within and below the RI, and (3) evaluate concordant and discordant fT4ED and fT4CLIA results in dogs with a serum TT4 concentration below the RI. Methods:This retrospective study used 116 banked serum samples from 38 known euthyroid dogs with NTIS. On each sample, fT4ED and fT4CLIA were measured, and agreement assessed by a Bland-Altman plot. Using the hospital admission serum TT4 concentration, dogs were stratified into two groups: TT4 within the RI (n = 16) and TT4 below the RI (n = 22). The frequency that each fT4 assay was within the RI was calculated in both groups. In dogs having a serum TT4 concentration below the RI, concordant and discordant fT4 results were evaluated. Results:Assay comparison showed agreement, with no significant systematic or proportional bias. When the serum TT4 concentration was within the RI, fT4ED and fT4CLIA were within the RI in 100% (95% CI: 79.4-100%) and 94% (95% CI: 69.8-99.8%) of dogs, respectively; however, when the serum TT4 concentration was below the RI, fT4ED and fT4CLIA were within the RI in 41% (95% CI: 20.7-63.6%) and 45% (95% CI: 24.4-67.8%) of dogs, respectively. Concordant fT4ED and fT4CLIA were present in 77% (95% CI: 54.6-92.2%) of dogs with a serum TT4 concentration below the RI. Discussion:The fT4ED and fT4CLIA were regularly below the RI in dogs with NTIS and a serum TT4 concentration below the RI, potentially resulting in a misdiagnosis of hypothyroidism. This raises concerns about the ability of both fT4 assays to distinguish hypothyroidism from NTIS in this subset of dogs.

BACKGROUND:Meningoencephalitis of unknown origin (MUO) is a neuroinflammatory disease that is suspected to be immune-mediated. Vaccination and season inconsistently have been reported as risk factors for development of MUO in dogs, but limited prospectively collected data is available to evaluate these potential risk factors. OBJECTIVE:Prospectively evaluate the association between vaccination and season and the development of MUO in dogs. ANIMALS:A total of 172 client-owned dogs diagnosed with MUO. METHODS:Dogs were enrolled prospectively from August 2021 through July 2023. Signalment, body weight, vaccination history, and season of onset of neurologic signs were recorded. The incidence rate ratio (IRR) of MUO within various post-vaccination windows was statistically compared to a referent window of 451-560 days post-vaccination. The incidence rate (IR) of MUO in each season was compared statistically. RESULTS:Of dogs vaccinated within the previous 450 days, MUO IRR was highest in the first 0-45 days (IRR = 9.14; confidence interval [CI] = 4.04-20.71), followed by 46-90 days (IRR = 4.86; CI = 2.01-11.71) and 91-180 days (IRR = 4.86; CI = 2.15-10.96) post-vaccination compared to the 451-560 day post-vaccination referent window. The MUO IR was slightly more common in the spring (28.5%) and least common in the summer (19.8%). No significant difference in IR between seasons was identified. CONCLUSIONS AND CLINICAL IMPORTANCE:In dogs with potential vaccine-associated MUO, the highest risk to develop MUO may be in the first 45 days post-vaccination. A slowly developing immune response to vaccination over 3-6 months may occur in some dogs. There is no apparent association between season and the development of MUO.

OBJECTIVE To establish the lowest effective dose of commercially available nanoparticulate silver (AgNP) for antibacterial activity against Escherichia coli (E coli) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), in vitro, and to establish the effect of incorporating AgNP into carriers for sustained release on this antibacterial activity. SAMPLES Silver nanoparticle dispersion (0.02 mg/mL) composed of citrate-stabilized, spherical, 10 nm diameter nanoparticles in aqueous buffer. PROCEDURES E coli and MRSP were treated with 0.01 mg/mL AgNP. The highest concentration of bacteria where growth was inhibited by AgNP was selected for treatment with 0.01 mg/mL AgNP incorporated 3 carriers for sustained release: calcium sulfate hemihydrate (CSH) beads, poloxamer 407 gel, and gelatin sponge, respectively. The antibacterial activity of AgNP and AgNP incorporated into carriers for sustained release was compared with a mixed linear effects model. RESULTS AgNP inhibited bacterial growth at a concentration of 10 1 for MRSP and 10 3 for E coli. For MRSP, the treatment group was associated with bacterial growth ( P < .001) while the concentration of bacteria and time were not ( P = .292 and P = .289, respectively). For E coli, the treatment group and concentration of bacteria were associated with bacterial growth ( P < .001 and = .029, respectively) while time was not ( P = .095). Poloxamer 407 gel exerted standalone antibacterial activity against both species of bacteria; sponge and CSH beads did not. CLINICAL RELEVANCE AgNP has antibacterial activity against E coli and MRSP, which can be reduced when incorporated into carriers for sustained release. Poloxamer 407 gel alone and combined with AgNP exerts antibacterial activity against E coli and MRSP.

This study investigated the use of frontal electroencephalography (EEG) to monitor varying levels of isoflurane anesthesia in dogs. The patient state index (PSI), burst suppression ratio (SR), and waveforms, were continuously recorded while mean arterial blood pressure (MBP), heart rate, responses to electric stimuli, and subjective anesthetic “depth” were assessed every 3 min. At deep anesthesia (2.5× MAC − 3.2%), the PSI (6.5 ± 10.8) and MBP (45.6 ± 16.4 mmHg) were the lowest, and SR was the highest (78.3 ± 24.0%). At 1× MAC (1.3%), the PSI and MBP increased significantly to 47.8 ± 12.6 and 99.8 ± 13.2, respectively, and SR decreased to 0.5 ± 2.5%. The EEG was predominantly isoelectric at 2×–2.5× MAC, indicating unconsciousness and unresponsiveness. As anesthesia lightened, waveforms transitioned to flatter and faster activity patterns with a response to noxious stimuli, suggesting regained consciousness. The PSI and MBP exhibited a stronger correlation (ρ = 0.8098, p = 0.001) than the relationship of PSI with heart rate (ρ = −0.2089, p = 0.249). Five of the six dogs experienced rough recovery, possibly due to high SR and low MBP. These findings suggest that EEG monitoring in dogs can be a valuable tool for the real-time tracking of brain states and can be used to guide the management of isoflurane anesthesia.

Vaccination is a cornerstone of canine preventive healthcare and one of the most cost-effective ways of maintaining a dog's health, longevity, and quality of life. Canine vaccination also serves a public health function by forming a barrier against several zoonotic diseases affecting dogs and humans. Canine vaccines are broadly categorized as containing core and noncore immunizing antigens, with administration recommendations based on assessment of individual patient risk factors. The guidelines include a comprehensive table listing canine core and noncore vaccines and a recommended vaccination and revaccination schedule for each vaccine. The guidelines explain the relevance of different vaccine formulations, including those containing modified-live virus, inactivated, and recombinant immunizing agents. Factors that potentially affect vaccine efficacy are addressed, including the patient's prevaccination immune status and vaccine duration of immunity. Because animal shelters are one of the most challenging environments for prevention and control of infectious diseases, the guidelines also provide recommendations for vaccination of dogs presented at or housed in animal shelters, including the appropriate response to an infectious disease outbreak in the shelter setting. The guidelines explain how practitioners can interpret a patient's serological status, including maternally derived antibody titers, as indicators of immune status and suitability for vaccination. Other topics covered include factors associated with postvaccination adverse events, vaccine storage and handling to preserve product efficacy, interpreting product labeling to ensure proper vaccine use, and using client education and healthcare team training to raise awareness of the importance of vaccinations.

Abstract Rotational feeding has been suggested in recent years as a method for improving “food boredom” in dogs. Some owners choose to add diversity to the canine diet for enrichment and potential cognitive benefits. However, little data are available on effects of rotational feeding strategies to gastrointestinal health, gut metabolites, and potential impacts to fecal consistency. The objective of this study was to understand the impact of rotational ingredient exposure on the ability of the dog to withstand an abrupt dietary change based on fecal pH, fecal dysbiosis index (DI), fecal score, calprotectin, and C-reactive protein (CrP). Labrador retrievers [n = 16; 1 to 3 yr of age; body condition scores (BCS) = 5 to 6] enrolled in detection dog training and receiving daily conditioning (exercise), were used in a 120-d study investigating the effects of an abrupt diet change on dogs with and without novel ingredient exposures. Study participants were assigned to one of two treatment groups. Control dogs (CON) received the basal diet and treatment dogs (ROT) received the basal diet along with the addition of rotating supplemental ingredients (2.5% total daily DM intake) over 90 d including oatmeal, blueberries, pumpkin, beef liver, salmon, and rabbit. All dogs were acclimated to the basal diet for 30 d, after which dogs in both groups were exposed to an abrupt (untransitioned) diet change [two meals (am and pm feeding)] on d 0, d 45, and d 90. Morning fecal samples at each timepoint were collected for three consecutive days and analyzed for fecal pH, DI, and calprotectin. Blood samples were collected 6 h following the AM dietary challenge and were used to measure CrP. Statistical analysis was performed using PROC MIXED and significance was set at 5%. Rotational ingredient supplemental did not impact DI (P = 0.0844). Similarly, fecal pH and calprotectin were unaffected by the addition of rotating ingredients (P = 0.7243; P = 0.9356, respectively). Fecal scores did not change by period (P = 0.0768) or by treatment (P = 0.9002). Values for CrP demonstrated no treatment effect on acute phase response (P = 0.8022). Markers of gastrointestinal health remained consistent, and tolerant, of rapid dietary change in both treatment groups. These findings suggest that the inclusion of rotational dietary ingredients may be well tolerated in healthy active canines, thus allowing owners to safely introduce diverse ingredients (at low levels) to the diet of their dog with minimum risk to health challenges.

In both human and veterinary medicine, computed tomography (CT) volumetry provides a quantitative and accurate measure of liver volume. While CT volumetry is recognized as a useful method for assessing liver volume in dogs, a statistically significant reference interval for liver volume in dogs with no history of hepatic disease has not been reported. The purpose of the present study was to define a reference interval for liver volume with no history of hepatic disease using CT volumetry. Medical records from 2 June 2020 to 25 July 2022 were retrospectively reviewed, including 121 dogs that underwent abdominal CT scans and had no history of hepatic disease. Liver volumes were measured using CT volumetry and normalized by body weight. The median of normalized CT-based liver volume in 121 dogs was 22.2 cm3/kg. Based on these data, a weight-based reference interval lower limit of 11.1–15.5 (90% confidence interval [CI]) to an upper limit of 31.9–42.6 (90% CI) cm3/kg for CT-based liver volume was defined in dogs without hepatic disease. This study provides an accurate assessment of liver volume changes in dogs with various hepatic diseases.

BACKGROUND:The prognosis of individual dogs with meningoencephalomyelitis of unknown etiology (MUE) remains difficult to predict. MUE cases with no lesions detected by magnetic resonance imaging (MRI) occur, but it is unknown whether this finding is associated with prognosis. HYPOTHESIS:MUE cases without detectable lesions on MRI have a better outcome than cases with detectable lesions. ANIMALS:Study included 73 client-owned dogs with MUE presenting to Purdue University Veterinary Hospital from 2010 to 2020. METHODS:Retrospective study. Dogs with a clinical diagnosis of MUE were identified by medical record search. MRI reports were reviewed for presence or absence of lesions consistent with MUE. Clinical findings at presentation, treatment, disease-specific survival, and outcomes including rates of remission and relapse were compared between cases with normal MRI or abnormal MRI. RESULTS:Overall, 54 dogs (74%) were classified as abnormal MRI, and 19 dogs (26%) were classified as normal MRI cases. Death caused by MUE occurred in 1/19 (5%) normal MRI dogs and 18/54 (33%) abnormal MRI dogs (P = .016). Median survival was >107 months in both groups, but survival was significantly longer in the normal MRI group (P = .019). On multivariate analysis, abnormal MRI was significantly related to death (hazard ratio, 7.71; 95% confidence interval 1.03-58.00, P = .0470), whereas significant relationships with death were not identified for either the use of secondary immunosuppressive medications or cerebrospinal fluid nucleated cell count. CONCLUSIONS:MUE dogs with no detectable lesions on MRI have reduced disease-related death compared with dogs with abnormal MRI. The presence or absence of MRI lesions in MUE dogs is prognostically relevant.

OBJECTIVE The objectives were to (1) compare the impact of preoperative fluid resuscitation on anesthetic parameters and in- terventions and (2) assess the impact of preoperative resuscitation duration on the integrity of intestinal tissue and postoperative complications in dogs with gastrointestinal foreign body obstruction. METHODS Medical records from 1 academic hospital were reviewed for 297 client-owned dogs that underwent gastrointestinal foreign body obstruction surgery between May 2017 and August 2022. Data collected included the following: signalment, preoperative fluid resuscitation, surgical findings, anesthetic parameters and interventions, postoperative complications, and timing of the first meal. Variables for preoperative length of fluid resuscitation (hours), total preoperative fluid bolus (mL/kg), and preoperative fluid rate (mL/kg/d) were changed to categorical variables. As- sociations between anesthetic interventions, postoperative outcomes, preoperative fluid resuscitation length, and total fluid bolus were assessed with ordered logistic regression. RESULTS Shorter preoperative fluid resuscitation length was associated with higher anesthetic fluid rates (P = .033) and fluid boluses performed (P = .023). Increased total volume of preoperative fluid boluses was associated with anesthetic synthetic colloid use (P = .028). There was insufficient evidence to claim an association between the impact of preopera- tive fluid resuscitation length and intestinal wall compromise (perforation, P = .912; enterectomy performed, P = .711). CONCLUSIONS Shorter preoperative fluid resuscitation was associated with increased anesthetic fluid interventions but not the need for more complex surgeries. CLINICAL RELEVANCE Longer fluid resuscitation periods are associated with fewer anesthetic interventions in dogs.

Objective: To describe fluid dispersal and retrieval patterns in an infusion-retrieval system across various configurations and locations in a cadaveric canine model. Study design: Cadaveric study. Animals: Four large breed canines. Methods: Four full-thickness wounds (10 x 10 cm) were created bilaterally in four canine cadavers (shoulder, thorax, flank, and thigh). A wound infusion catheter and active suction drain were placed in four configurations (diagonal, opposite, parallel, and perpendicular) and the incisions were closed. Diluted methylene blue was instilled, allowed to dwell for 10 min, and quantified after retrieval. A 14 x 14 cm full-thickness skin segment, including the initial 10 x 10 cm wound, was removed. Images of the removed skin and cadaver wound bed were taken to calculate surface area (SA) and to evaluate fluid dispersion. A mixed-effects linear regression model was used for statistical analysis. Results: Fluid retrieval did not differ by configuration (p = .92) or location (p = .32), although the perpendicular configuration resulted in the highest retrieval (11.35 +/- 6.1 mL) (56.8 +/- 30% volume instilled) and the flank location resulted in the lowest (7.2 +/- 6.4 mL) (35.9 +/- 32% volume instilled). Configuration influenced SA coverage of the wound bed (p < .01), whereas location did not (p = .10). The parallel configuration had the greatest SA coverage (83.4 +/- 11.6%). No difference existed for leakage of methylene blue (MB) beyond the borders for configuration (p = .74) or location (p = .10). Conclusion: The parallel configuration maximized the fluid dispersion within the cadaveric wound bed in comparison with other configurations (p < .01). Clinical significance: An infusion-retrieval system could be considered during wound closure to administer topical solutions and remove excess free fluid.

The assessment of liver size is usually performed using radiography in dogs. However, due to wide variations in patients’ sizes and body conformations, accurate diagnosis of hepatomegaly or microhepatia is difficult. Computed tomographic (CT) volumetry can quantitatively and accurately measure liver volume. However, a reliable method for the standardization or normalization of volume in dogs without hepatic disease using CT has not yet been established. The purpose of this study was to assess seven different anatomic measures for normalizing liver volume in dogs and determine the tentative range of liver volume in dogs without hepatic disease. We retrospectively searched medical records from 1 January 2017 through to 1 June 2020 and included dogs with abdominal computed tomography without hepatic disease. The liver volume, lengths of four vertebrae (T11, T12, L2, L3), diameter of the abdominal aorta, body weight, and body condition scores (BCSs) of the dogs were recorded. Forty-one client-owned dogs without evidence of hepatic disease were included. The CT-derived liver volume was 813.8 ± 326.5 cm3 (mean ± SD). Body weight was determined to be the most reliable single-variable method for normalizing liver volume, with a raw CT-derived liver-volume-to-body-weight ratio of 22.1 cm3/kg (95% CI: 12.9–31.3 cm3/kg) and regression prediction model of volume = 19 × BWkg + 97. However, a better normalizing factor would likely be provided by the fat-free mass if it can be accurately measured.

This study aimed to assess the impact of dexmedetomidine constant rate infusion (CRI) on key parameters in dogs. Six dogs received a 60 µg/kg/h dexmedetomidine infusion over 10 min, followed by three 15 min decremental CRIs (3, 2, and 1 µg/kg/h). A subsequent reversal phase employed 600 µg/kg/h atipamezole over 5 min. Continuous electroencephalogram (EEG) assessment, and cardiorespiratory and analgesia monitoring (every 3 min) were conducted, including analgesia evaluation through responses to electric stimulation. Dexmedetomidine induced profound sedation, evidenced by lateral recumbency and immobility. Patient State Index (PSI) decreased from awake (90.4 ± 4.3) to Phase 1 (50.9 ± 30.7), maintaining sedation (29.0 ± 18.1 to 33.1 ± 19.1 in Phases 2–4). Bradycardia (37.8 ± 3.5 bpm, lowest at Phase 3) and hypertension (133.7 ± 17.0 mmHg, highest at Phase 1) were observed, with minimal analgesia. Atipamezole promptly reversed sedation, restoring cognitive function (tail wagging behavior), and normalizing cardiovascular parameters. During atipamezole CRI, the EEG exhibited a transition from delta waves to alpha and low beta waves. This transition was observed alongside gradual increases in PSI and electromyographic activities. Additionally, spindle activities disappeared during this process. This study’s results suggest potential clinical utility for EEG-guided dexmedetomidine sedation with reversal using atipamezole, warranting further investigation.

CTHV is a non-invasive and accurate method for assessing liver volume in dogs. CTHV has not been studied in each type of extrahepatic PSS in dogs. This study aimed to use CTHV to compare liver volumes in dogs with different types of PSSs that had been confirmed by computed tomography angiography. Dogs with PSSs were retrospectively included and categorized into IH, EHPC, EHPA, or EHPP shunt groups. Manual CTHV was performed, and the normalized liver volume (nLV) and the difference in nLV from the estimated liver volume calculated based on body weight (LV%diff) was calculated. The study included 57 dogs: 20 IH, 21 EHPC, 9 EHPA, and 7 EHPP. The median nLV (cm3/kg) and LV%diff (%) for each group were as follows: IH 17.3 (−40.4%); EHPC 16.9 (−60.3%); EHPA 15.1 (−56.7%); and EHPP 17.2 (−59.2%), respectively. There were no significant differences in nLV among the PSS types. However, LV%diff was significantly more pronounced in the EHPC and EHPA groups compared with the IH group. Additionally, smaller dogs exhibited more severe microhepatia, with a significant positive correlation between LV%diff and body weight (p < 0.01). These findings suggest that microhepatia severity varies by shunt type and is more severe in smaller dogs, highlighting the need for further research to understand the underlying mechanisms.