High-Frequency Jet Ventilation in Anesthetized, Paralyzed Dogs and Cats Via Transtracheal and and Endotracheal Tube Routes

The ability of the SAV 6 high-frequency jet ventilator to effectively ventilate three anesthetized, paralyzed cats (3.2–4.2 kg), two small dogs (7.2 and 10.0 kg), six medium-sized dogs (20.5–25.0 kg), and three large dogs (36.0–43.0 kg) via a 14-gauge (dogs) or a 16-gauge (cats) catheter placed percutaneously into the trachea via the cricothyroid membrane or into a preplaced endotracheal tube was evaluated. The lowest driving pressure within the range of 0.25 to 2.0 kg/cm² (1 kg/cm²= 14.2 psi) and the highest cycle rate within the range of 60 to 240 per minute that would generate a PaCO₂ of 30 ± 3 mm Hg were determined.
All animals could be ventilated to a PaC0₂ of 30 ± 3 mm Hg by the endotracheal tube and transtracheal route, except the largest dogs, which couid be ventilated to an average PaC0₂ of 36 mm Hg by the transtracheal route. The transtracheal route consistently required higher driving pressures and lower cycle rates than did the endotracheal tube route. Cats could be ventilated with a driving pressure of 0.25 kg/cm²; small dogs could be ventilated with 0.5 to 1.0 kg/cm₂; medium-sized dogs with 1.0 to 1.5 kg/cm²; and large dogs with 1.5 to 2.0 kg/cm².
The SAV 6 high-frequency jet ventilator can effectively ventilate cats and dogs (7.2–43.0 kg) via a transtracheal catheter and an endotracheal tube.     

Hepatic Volume Measurements in Dogs with Extrahepatic Congenital Portosystemic Shunts before and after Surgical Attenuation

Background: In dogs with congenital portosystemic shunts (CPSS), the ability of the hypoplastic liver to grow is considered important for recovery after surgical shunt attenuation.
Objectives: This study investigated hepatic growth after extrahepatic shunt attenuation in dogs using magnetic resonance imaging (MRI) and computed tomography (CT).
Animals: Ten client-owned dogs with single extrahepatic CPSS.
Methods: Abdominal MRI, CT, or both were performed before and 8 days, 1, and 2 months after shunt attenuation. Liver volumes were calculated from the areas of the MRI or CT images.
Results: Before surgery, median liver volume was 18.2 cm³/kg body weight. Liver volume increased significantly after surgery. Growth was highest between days 0 and 8 and decreased afterward. Median liver volume was 28.8 cm³/kg at 2 months after attenuation. No significant differences in growth were found between dogs with complete or partial shunt closure or between dogs with complete or incomplete metabolic recovery. Volumes measured from consecutively performed MRI and CT images correlated well ( r = 0.980), but volumes from MRI images were significantly larger than volumes from CT images (6.8%; P = .008).
Conclusion and Clinical Importance: After shunt attenuation, rapid normalization of liver size was observed. Hepatic growth was not decreased in dogs after partial closure of CPSS or in dogs with subclinical, persistent shunting 2 months after surgery. CT is the preferred imaging method for volumetric estimation because of speed.     

High performance liquid chromatography and pharmacokinetics of the non-steroidal anti-inflammatory drug oxindanac in calves

A high-performance liquid chromatographic method for the determination of the non-steroidal anti-inflammatory drug, oxindanac, in calf plasma is described. Recoveries over the concentration range 0.3 75 to 62.5 μg/ml were 90.2–107.8% with interassay coefficients of variation of 2.1–22.3%. The limit of detection was estimated as 0.10 μg/ml and the limit of quantification calculated to be 0.24 pg/ml in a 1 ml plasma sample. This method was used to establish the pharmacokinetics following intravenous (i.v.), intramuscular (i.m.) and oral (p.o.) administration to calves of oxindanac at a dose rate of 2 mg/kg. The elimination t ¹/₂, was long ( t 1/2 21.2 h after i.v. injection) and absorption was rapid (t¹/_2B 0.072 h) and complete ( F > 100%) following i.m. administration. Bioavailability was incomplete ( F = 66.6%) following p.o. administration to calves that had been fed on milk, and Wagner-Nelson analysis revealed twoabsorption phases ( t ¹/₂'s 0.20 and 1.9 h). Oxindanac produced long-lasting inhibition of serum TxB₂ production, with mean k_max values (% inhibition) of 96.8, 94.1 and 81.3 following i.v., i.m. and p.0. administration, respectively. A single i.v. or i.m. injection of 2 mg/kg oxindanac will probably be active in calves for at least 36–48 h.     

Cystic Degeneration in Porcine Ovaries - First Communication: Morphology of Cystic Ovaries, Interpretation of the Results

Contents: The morphological appearance of ovarian structures in 79 sows with ovarian cysts was examined. Sixty sows had been culled due to sterility; 19 sows had been repeatedly investigated clinically before slaughter. It was found that cystic ovaries without corpora lutea (CL) had the largest diameter and volume (151.3 cm³), in comparison to both cystic ovaries with CL (85.7 cm³) and normalovaries (16.9 cm³). The number of cysts on ovaries without corpora lutea was approximately twice as high as on the ovaries with CL (23.3 vs 12.1 cystslsow; p < 0.001). A combined form of degeneration consisting of large (> 1.5 cm in diameter) and small (1.5 em in diameter) cysts was found in 63% of the animals, whereas degeneration with only small cysts occured in 8% of the cases. Dark CL, interpreted as being functional, were mainly present in animals with up to 10 cysts per sow (24 out of 27 sows, p < 0.001); pale CL, interpreted as being weakly functional, were mainly found on ovaries with more than 10 cysts (19 out of 23 sows; p < 0.001). Based on macroscopical differentiation cyclic activity was found to be dependent to the number of cysts. Regular or irregular estrous cycles were observed in oligocystic animals (10 cysts/animal) with functional CL (58%). Up to 75% of the animals with pale or absent CL showed no estrous activity.     

EFFECT OF WETNESS LEVEL ON THE SUITABILITY OF WET GAUZE AS A SUBSTITUTE FOR SUPERFLAB® AS A BOLUS MATERIAL FOR USE WITH 6 MV PHOTONS

Despite the availability of commercial tissue equivalent bolus material, wet gauze has an application in radiation therapy to provide superior conformance to irregular contours. Wet gauze bolus has the potential to reduce air gaps between the bolus and surface, which could decrease surface dose if sufficiently large to disrupt electronic equilibrium. Wet gauze bolus is often fabricated and wetness judged qualitatively. We assessed the effect of specific gauze wetness levels, quantified in terms of physical density, at various field sizes with respect to their effectiveness as bolus material compared with Superflab^®. For large fields, >7 × 7 cm² in this study, wet gauze sponges with a physical density of 1.02 g/cm³ performed essentially identical to Superflab^®; at a smaller field size the wet gauze was slightly less effective, likely due to the heterogeneity of the gauze-water matrix. Gauze that was wetter, with a physical density of 1.2 g/cm³, or less wet, with a physical density of 0.75 g/cm³ was not as effective either due to enhanced photon absorption in the wetter sponges, or less effective establishment of electronic equilibrium in the less wet sponges. The presence of an air gap under Superflab^® led to reduced surface dose, especially for small fields and large air gaps. Thus, if Superflab^® use leads to poor contact with the skin, wet gauze having a physical density of 1.02 g/cm³ can be used as a substitute. Judging the water content of wet gauze subjectively is not acceptable as over- or under wetness can lead to decreased effectiveness of the bolus material.     

Efficacy of 1.25% amitraz solution in the treatment of generalized demodicosis (eight cases) and sarcoptic mange (five cases) in dogs

Eight dogs with generalized demodicosis and five with sarcoptic mange were treated with 1.25% amitraz solution applied weekly and associated with an antidote treatment (atipamezol, 0.1 mg kg⁻¹ IM once: and yohimbine 0.1 mg kg⁻¹ once daily for 3 days, orally). Results of skin scrapings were used to determine whether therapy should be continued or stopped. The median number of treatments for demodicosis and sarcoptic mange was three (range 2–5) and two (range 1–3), respectively. Some side-effects were observed but all were stopped with antidote treatment; no failure or relapses occurred at 6–36 months after treatment.     

Intra-operative cisplatin for the treatment of canine extremity soft tissue sarcomas

Nineteen dogs with histologically confirmed soft tissue sarcomas of the extremities were treated with a combination of marginal surgery and intra-operative chemotherapy in the form of cisplatin in a biodegradable implant delivery system (Atrigel^®; Atrix Laboratories, Fort Collins, Co, USA). None of the dogs had evidence of metastasis at time of treatment. The median dose of cisplatin was 52.1 mg/m² (mean 55.4 mg/m², range 18.5–108.6 mg/m²). Wound complications were noted in 16 dogs (84.2%). Median follow-up time was 874 days (mean 777 days, range 125–1463 days). Nine dogs (47.3%) were alive at the time of analysis. Local recurrence occurred in three dogs (16.6%). The time to recurrence was 214, 264 and 874 days.     

CANINE ORAL NONTONSILLAR SQUAMOUS CELL CARCINOMA

The records of 33 dogs treated with radiation therapy for nontonsillar oral squamous cell carcinoma (SCC) were reviewed to determine which, if any, prognostic factors affected local tumor recurrence and survival. Information was collected on nine factors: age, sex, anatomic subsite, intraoral location, bone involvement, radiation dose, portal size, and tumor recurrence. Product limit survival estimates indicated than only anatomic subsite was significantly related to disease-free interval. Mean disease-free interval was 12.0, 3.4, and 1.8 months for maxilla, mandible, and soft tissue subsites, respectively. Four factors were significantly associated with survival. The intraoral location (listed in descending survival time: rostral > caudal > rostral and caudal), tumor recurrence (no > yes), relative portal size (less than 100 cm²/m² > greater than or equal to 100 cm²/m²), and age at diagnosis (less than or equal to 6 years > greater than 6 years) were of prognostic importance. Based on these data, a prospective randomized clinical trial for the treatment of nontonsillar oral SCC would be appropriate.     

Effects of Neodymium:Yttnum Aluminum Garnet Laser Irradiation on Endometrium and on Endometrial Cysts in Six Mares

Effects of neodymium:yttrium aluminum garnet (Nd:YAG) laser irradiation on equine endometrium were evaluated In vitro and in six mares with endometrial cysts. The Nd:YAG laser was applied to six endometrial sites, in each of five uterine specimens, with power densities of 5659 to 33,954 J/cm². Depth of tissue ablation was measured and graded on histologic sections of the tissue lesions. Power density had a significant effect on the depth of tissue ablation (p < .001). Grade 3 lesions (full-thickness ablation of the endometrium) were created with energy densities of 16,977 to 33,954 J/cm². Six mares had endometrial cysts treated by photoablation. Two of the four mares that were reproductively sound but barren, despite appropriate breeding, produced foals after treatment. One mare remained reproductively unsound after treatment, and another mare that was treated postpartum was bred successfully.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF PRESUMED NORMAL CANINE ABDOMINAL LYMPH NODES

Though identification of lymph nodes is essential in staging cancer patients, little has been reported about the CT features of canine abdominal lymph nodes. The purpose of this retrospective study was to describe the visibility, location, and characteristics of abdominal lymph nodes in abdominal CT studies of dogs considered unlikely to have lymphadenopathy. The relationship between the number of identified lymph nodes and intraabdominal fat ranking, body weight, and slice thickness was also investigated. A total of 19 dogs were included. At least two jejunal lymph nodes and both left and right medial iliac lymph nodes were identified in all dogs. Colic lymph nodes were not identified in any of the dogs. Visualization of all other lymph nodes varied. There were significantly more lymph nodes visible in dogs with more intraabdominal fat (P < 0.0001). No correlation between the number of identified lymph nodes and body weight (P = 0.64) or slice thickness (P = 0.76) was found. Though most of all identified lymph nodes had an elongated shape, a rounded shape was most common in splenic, pancreaticoduodenal, renal, ileocolic and caudal mesenteric lymph nodes. Most lymph nodes had a homogeneous structure before and following the intravenous administration of contrast medium. Some lymph nodes had a slightly irregular structure or were relatively more hyper attenuating in the periphery than centrally before and/or after contrast administration. Mean attenuation before contrast was 37 Hounsfield Units (HU) (range 20–52 HU), and 109 HU after contrast (range 36–223 HU). Findings indicated that the CT visibility, characteristics of different abdominal lymph nodes may be variable in dogs.     

A comparison of the various routes of administration of erythromycin in cattle

A comparison of i.v., i.m. and s.c. administration erythromycin base in polyethylene glycol at 15 mg/kg and 30 mg/kg body weight was carried out in beef-type calves of approximately 200 kg body weight. Additional evaluations were carried out with oral administration of erythromycin phosphate and erythromycin stearate. Absorption of erythromycin was very slow by both the i.m. and s.c. routes of administration with a K_ab of 0.0135 min^-1 and 0.0185 min^-1 for i.m. and 0.0032 min^-1 and 0.0074 min^-1 for s.c. at 15 mg/kg and 30 mg/kg, respectively. The bioavailability (32–42%) and peak serum concentrations were much lower with s.c. than with i.m. (60–65%) administration. The disposition of erythromycin administered i.v. appeared to be representative of dose-dependent kinetics rather than dose-independent first-order kinetics inasmuch as the elimination half-time ( t _1/2B) increased from 174.5 ± 13 min for the 15 mg/kg dosage to 239 ± 10.8 min with 30 mg/kg dosage. An acute apparent cardiovascular effect accompanied i.v. administration of erythromycin at 30 mg/kg dosage but not at 15 mg/kg. Severe diarrhea followed oral administration of either erythromycin phosphate or erythromycin stearate.     

Computed tomographic‐lymphography as a complementary technique for lymph node staging in dogs with malignant tumors of various sites

Locoregional lymph nodes are routinely examined in order to define the spatial extent of neoplastic disease. As draining patterns of certain tumor types can be divergent from expected anatomical distribution, it is critical to sample the lymph nodes truly representing the draining area. The aim of this bicenter prospective pilot study was to describe the technique of computed tomographic (CT)‐lymphography for primary draining lymph node mapping in tumor staging in dogs. Forty‐five dogs with macro‐ or microscopic tumors in specified localizations were evaluated. Depending on body weight, 0.8–2 ml contrast agent (iohexol) was injected into four quadrants around the tumor, and CT‐images were obtained at 1, 3, 6, 9, and 12 minutes post‐injection. Attenuation of chosen regions of interest (Hounsfield units (HU)) and patterns of enhancement were assessed for 284 lymph nodes in the precontrast study with median HUs of 31.1 (Interquartile range (IQR) = 18.4) and for 275 in the intravenous postcontrast study with 104.3 HU (IQR = 31.2) (paired Wilcoxon test, P < 0.001). In the CT‐lymphography study, 45 primary draining lymph nodes with a significantly higher median HU value of 348.5 (IQR = 591.4) (one‐sample t‐test, P < 0.001) were identified. Primary draining lymph nodes were found to be clearly visible after 1–3 minutes after local injection, often concurrent with a good visibility of the lymphatic vessel system. The herein described technique of peritumorally injected CT‐contrast agent followed by subsequent CT‐lymphography for primary draining lymph node mapping works well in a majority of cases in all investigated sites and warrants further validation for different tumor entities.     

A REVIEW OF SONOGRAPHIC IDENTIFICATION OF ABDOMINAL BLOOD VESSELS AND JUXTAVASCULAR ORGANS

Abdominal vasculature can be evaluated non-invasively using 2-D ultrasound imaging and Doppler ultrasonography.^5,6,12 The identification of abdominal vessels using ultrasound is based on knowledge of their normal location, appearance and relationship to specific organs. Because anatomic location of major abdominal vessels is fairly consistent, finding and following vessels is a useful aid when attempting to locate and evaluate juxta-vascular organs. Sonographic vascular evaluation may be beneficial in providing information regarding central cardiovascular abnormalities, detection of abnormalities involving the vessel interrogated, or detection of abnormalities of the parenchymal bed that the vessel supplies,^5–12 Knowledge of the location and appearance of the vessels is necessary for this information to be of diagnostic value.
In this paper, abdominal vessels in the dog are reviewed and a sonographic map of major abdominal vessels is described. This includes the sonographic appearance of the aorta, caudal vena cava, and portal vein, their major branches and their anatomic relationship with adjacent organs.
Identification of the medial iliac lymph nodes, mesenteric lymph nodes, abdominal esophagus, duodenum, spleen, kidneys, pancreas, adrenal glands and liver lobes are assisted by recognizing specific vascular landmarks. The locations and appearances of pertinent organs as pertains to abdominal vasculature (caudal vena cava and aorta) are described.     

Comparison of mesenteric lymphadenography performed via surgical and laparoscopic approaches in dogs

OBJECTIVE: To determine whether injection of a mesenteric lymph node with iodinated aqueous contrast medium results in radiographic delineation of the thoracic duct and its branches, ascertain the ideal interval between injection and radiographic imaging, and evaluate mesenteric lymphadenography performed via laparoscopic and surgical approaches in dogs. ANIMALS: 10 adult dogs. PROCEDURE: In each dog, a right paracostal laparotomy or a right laparoscopic approach was performed to identify a mesenteric lymph node for injection of an iodinated aqueous contrast agent (0.22 mL/kg [81.4 mg of iodine/kg]). Lateral radiographic views were obtained at 60, 120, 180, 240, and 300 seconds after injection. RESULTS: A mesenteric lymph node was identified and injected with contrast medium in each dog. Via paracostal laparotomy, lymph node injection resulted in successful lymphangiographic evaluation in 4 of 5 dogs, whereas via the laparoscopic approach, lymph node injection resulted in successful lymphangio-graphic evaluation in 2 of 5 dogs. In successful radiographic evaluations, injected lymph nodes, mesenteric lymphatics, and the thoracic duct and its branches were delineated. Radiographs obtained at 60 and 120 seconds after injection of contrast medium provided the most detail. CONCLUSIONS AND CLINICAL RELEVANCE: Injection of a mesenteric lymph node directly with contrast medium appears to be a feasible technique for delineation of the thoracic duct and its branches in dogs and might be useful in small animals in which mesenteric lymphatic catheterization can be difficult and lymphangiography is more likely to fail. Refinement of the laparoscopic technique may provide a minimally invasive approach to lymphadenography.     

Prothrombotic and Inflammatory Effects of Intravenous Administration of Human Immunoglobulin G in Dogs

Background: Intravenous administration of human immunoglobulin G (hIVIgG) has been suggested to potentiate thromboembolism in dogs, but supportive scientific reports are lacking.
Objectives: To determine if hIVIgG therapy promotes hypercoagulability and inflammation in dogs.
Animals: Twelve healthy Beagle dogs.
Methods: Prospective, experimental trial. An hIVIgG/saline solution was infused IV at 1 g/kg BW over 8 hours to 6 dogs, and physiological saline was infused to the other 6 dogs. Blood samples were drawn before, during, and after infusion for serial measurement of indicators of coagulation and inflammation. Data were analyzed by 2-way repeated measures analysis of variance.
Results: Dogs administered hIVIgG developed mildly decreased blood platelet concentrations without thrombocytopenia (median, 200 × 10³/μL; range, 150–302 × 10³/μL; P < .01), leukopenia (median, 3.5 × 10³/μL; range, 20–62 × 10³/μL; P < .001), and mildly increased plasma total protein concentrations (median, 6.3 g/dL; range, 5.6–6.7 g/dL; P < .001). Administration of hIVIgG was also associated with increases in fibrin/fibrinogen degradation products in all dogs (either 5 μg/mL or 10 μg/dL), thrombin-antithrombin III complexes (median, 7.2 ng/mL; range, 4.9–14.2 ng/mL; P < .001), and C-reactive protein concentrations (median, 2.5 mg/dL; range, 0.5–4.3 mg/dL; P < .01).
Conclusion and Clinical Importance: Administration of hIVIgG to dogs promotes hypercoagulability and an inflammatory state. This should be further evaluated and considered when using hIVIgG in dogs with IMHA or other prothrombotic conditions.     

Effect of nonessential amino acids on nitrogen retention in growing pigs fed on a protein-free diet supplemented with sulphur amino acids, threonine and tryptophan

Two N balance experiments were conducted on growing pigs to study the effect of essential and nonessential amino acids added to a protein-free diet on N retention. In Expt. 1, the addition of sulphur amino acids, threonine and tryptophan to a protein-free diet at levels two times the maintenance requirements reduced (p > 0.1) daily N loss from –131 to –108 mg/kg^0.75. A further addition of nonessential amino acids equivalent to 250 mg N/kg^0.75/d resulted in a marked increase (p < 0.01) in daily N retention to 28 mg/kg^0.75. In Expt. 2, nonessential amino acids were added to a protein-free diet supplemented with sulphur amino acids, threonine and tryptophan at levels corresponding to 100, 200 and 300 mg N/kg^0.75/d. N retention increased linearly as dietary nonessential N increased. The slope of the best-fit regression line indicated that the marginal efficiency of nonessential N utilization for protein accretion was 0.26. The results suggest that nonessential amino acids may be a limiting factor for the re-utilization of amino acids released by body protein breakdown or that they may serve as precursors for de novo synthesis of amino acids by gut microorganisms, thus contributing to the amino acid requirements of the pig.     

Evaluation of the urinary Cortisol: creatinine ratio in the diagnosis of hyperadrenocorticism in dogs

The diagnostic accuracy of the urinary cortisol:creatinine ratio (CCR), with the cortisol being measured by ELISA, was evaluated by subjecting data from 18 dogs with and 20 dogs without hyperadrenocorticism to recelver operating characteristic (ROC) curve analysis. The area under the ROC curve (W 0–93, SE_w 0–044) was much higher than 045, indicating that the CCR did distinguish between dogs with and without hyperadrenocorticism.A cutoff value of about 60 × 10^-6 was assoclated with the highest sensitivity (1.0)and speciflcity (0–85). At the disease prevalence rate of the present study (0 47), the positive and negative predictive values were 0–87 and 1.0, respectively. These numbers indicate that canine hyperadrenocorticism may be safely excluded when the CCR Is below 60 × 10^-6 but that a test of higher specificlty (eg, the ACTH stimulation test) should be used to confirm the diagnosis of canine hyperadrenocorticism when the CCR Is above 60 × 10^-6.     

Pretaping of the Aorta Prior to Patent Ductus Arteriosus Ligation

SURGICAL repair of the patent ductus arteriosus (PDA) is one of the most common cardiovascular procedures performed in veterinary and human medicine.^1–3 The techniques have been well documented and used successfully.^2–5     

The effect of pre-anaesthetic medication on the incidence of cardiac arrhythmias during halothane anaesthesia in cats

Objective To compare the incidence of arrhythmias in cats receiving either acepromazine or diazepam for pre-anaesthetic medication prior to halothane anaesthesia.
Study design A blinded, randomized clinical study.
Animals Forty-six healthy cats undergoing surgery.
Methods Animals were allocated to one of two groups for pre-anaesthetic medication. Group 1 received diazepam (0.2 mg kg⁻¹). Group 2 received acepromazine (0.02 mg kg⁻¹). The trial drug was administered intramuscularly in combination with buprenorphine (0.01 mg kg⁻¹) 30 minutes prior to induction of anaesthesia with propofol (approximately 5 mg kg⁻¹). Anaesthesia was maintained using halothane: delivered concentration was 1–2% carried in oxygen and nitrous oxide via an endotracheal tube attached to an Ayre's T-piece (with Jackson-Rees modification) breathing system. The incidence of cardiac arrhythmias was determined by continuously monitoring the electrocardiogram from the time of induction until recovery occurred. Demographical group characteristics were compared using analysis of variance. The incidence of cardiac arrhythmias was compared by the Chi squared test. Statistical significance was set at the 5% level.
Results The two groups were similar in weight, age, length and type of procedure undertaken. The incidence of arrhythmias was the same in each group (3/23 cases) ( p = 1.0).
Conclusions The incidence of cardiac arrhythmias in this study did not appear to be influenced by the nature of pre-anaesthetic medication.
Clinical relevance The incidence of cardiac arrhythmias under halothane anaesthesia was 13% in this study. Acepromazine did not appear to exert an anti-arrhythmic effect. This may not be the case in a larger scale study.     

Photodynamic therapy response in cats with cutaneous squamous cell carcinoma as a function of fluence

The response of advanced stage cutaneous squamous cell carcinomas (SCC) following treatment with photodynamic therapy (PDT) has been poor. It was the aim of this pilot study to determine whether an increase in the delivered fluence (i.e. energy density) would improve the duration of tumour remission in cats with advanced-stage SCC. Tumours were treated with aluminium phthalocyanine tetrasulphonate (AlPcS₄) PDT at a fluence of either 100 J cm⁻² or 200 J cm⁻² and tumour response was evaluated at regular intervals. Those feline tumours treated with a fluence of 100 J cm⁻² ( n = 8) had a significantly shorter median remission duration (69 days; range 0–619 days) than those feline tumours treated with 200 J cm⁻² ( n = 6; 522 days; range 151–1057 days). It is our conclusion that a fluence of 200 J cm⁻² is well tolerated and more effective when treating cats with advanced stage cutaneous SCC.