Calculation of dose intensity and comparison of published methods using a cohort of canine T-cell lymphoma patients undergoing CHOP-based chemotherapy

Methods of calculating and reporting dose intensity (DI) of CHOP-based protocols in the veterinary literature vary. The goal of this retrospective study is to examine the prognostic significance of the average percentage of planned DI received in a cohort of canine T-cell lymphoma patients treated with a modified CHOP protocol with corresponding toxicity and efficacy data. Our data set of 40 dogs was analysed using various previously published methods for calculating DI. Median progression-free survival and overall survival were 91 and 196 days, respectively. Receiving a higher percentage of planned DI was not found to be associated with patient outcome. Outcomes remain poor for dogs with T-cell lymphoma treated with CHOP-based chemotherapy irrespective of received DI. Standard methods of DI calculation and reporting should be adopted in veterinary oncology to enable repeatable and rigorous comparisons of published chemotherapy protocols and to ascertain the potential prognostic relevance of DI in canine lymphoma patients.     

Image-based weed recognition and control: Can it select for crop mimicry?

As highly adaptable plants, weeds have evolved numerous mechanisms to evade control in agroecosystems. For example, reliance on herbicides has resulted in widespread evolution of resistance in many species. Minimising weed adaptation is a major driver for integrated weed management strategies. Crop mimicry is a notable example of weed adaptation, where weed species evolve to avoid control by mimicking aspects of the crop phenotype. Visual selection by hand weeding has been documented to select for crop mimics that are difficult to distinguish from the crop at the vegetative stage. With recent advancements in weed recognition technologies, image-based weed recognition for in-crop, site-specific weed control is on the cusp of becoming widely adopted. Whilst the control methods used in site-specific weed control will be varied (e.g., spot spraying or lasers), they will share weed recognition technology. Visual selection via image-based deep learning represents a selection pressure for weeds that can evade detection by mimicking crops. This mimicry may reduce weed recognition accuracy and thus weed control efficacy over time and result in difficult to manage mimetic weed phenotypes. Therefore, it is timely to explore the potential for selection of crop mimics by image-based weed recognition algorithms.     

Insecticide resistance management of Bemisia tabaci (Hemiptera: Aleyrodidae) in Australian cotton – pyriproxyfen,spirotetramat and buprofezin

BACKGROUND

Bemisia tabaci is a globally significant agricultural pest including in Australia, where it exhibits resistance to numerous insecticides. With a recent label change, buprofezin (group 16), is now used for whitefly management in Australia. This study investigated resistance to pyriproxyfen (group 7C), spirotetramat (group 23) and buprofezin using bioassays and available molecular markers.

RESULTS

Bioassay and selection testing of B. tabaci populations detected resistance to pyriproxyfen with resistance ratios ranging from 4.1 to 56. Resistance to spirotetramat was detected using bioassay, selection testing and sequencing techniques. In populations collected from cotton, the A2083V mutation was detected in three populations of 85 tested, at frequencies ≤4.1%, whereas in limited surveillance of populations from an intensive horticultural region the frequency was ≥75.8%. The baseline susceptibility of B. tabaci to buprofezin was determined from populations tested from 2019 to 2020, in which LC₅₀ values ranged from 0.61 to 10.75 mg L⁻¹. From the bioassay data, a discriminating dose of 200 mg L⁻¹ was developed. Recent surveillance of 16 populations detected no evidence of resistance with 100% mortality recorded at doses ≤32 mg L⁻¹. A cross-resistance study found no conclusive evidence of resistance to buprofezin in populations with high resistance to pyriproxyfen or spirotetramat.

CONCLUSIONS

In Australian cotton, B. tabaci pest management is challenged by ongoing resistance to pyriproxyfen, while resistance to spirotetramat is an emerging issue. The addition of buprofezin provides a new mode-of-action for whitefly pest management, which will strengthen the existing insecticide resistance management strategy. © 2023 Commonwealth of Australia. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Adverse effect of complete thoracic evacuation during chronic pneumothorax in a dog

OBJECTIVE: To describe an unusual response to evacuation of a chronic pneumothorax in a dog. CASE: Resolution of a pneumothorax is usually associated with lung expansion and a marked improvement in pulmonary function. In the case presented here, evacuation of a chronic pneumothorax improved oxygenation, but markedly impaired ventilation. CLINICAL RELEVANCE: This is a previously unreported complication associated with the treatment of pneumothorax in dogs. It suggests that in some cases of chronic pneumothorax, total evacuation of the pleural air pocket may improve oxygenation but ventilation deteriorates and increases PCO2, causing further complications.     

The effect of guaiphenesin on romifidine/ketamine anaesthesia in ponies

The purpose of this study was to investigate the effect of a single dose (50 mg/kg) of guaiphenesin on recumbency time, surgical conditions and the ‘quality’ of anaesthesia in ponies anaesthetised for castration. Sixteen ponies were sedated with romifidine 100 μg/kg and anaesthetised with ketamine (2.2 mg/kg). Ponies allocated to Group A received no treatment and those in Group B were given 50 mg/kg of a 15% guaiphenesin solution. Guaiphenesin was given as a rapid iv injection immediately after induction of anaesthesia. All ponies were subsequently castrated. The mean (± se) time of recumbency in Group A was 20.9 ± 1.37 min and in Group B 27.2 ± 2.1 min to (P<0.05). Subjective assessment scores for the quality of surgical conditions and anaesthesia itself were significantly greater (indicating better conditions) in ponies receiving guaiphenesin, although there was no difference between groups in the quality of recovery.     

Introgression of phenoxy herbicide resistance from Raphanus raphanistrum into Raphanus sativus

Phenoxy herbicides such as 2,4‐dichlorophenoxy acetic acid (2,4‐D) and 4‐chloro‐2‐methylphenoxy acetic acid (MCPA) are selective herbicides used extensively in agriculture for weed control. Wild radish (Raphanus raphanistrum) is a problem weed across the globe and heavily infests crop fields in Australia. Phenoxy herbicides are used to selectively control dicot weeds, including wild radish. As a result of selection, phenoxy‐resistant wild radish populations evolved in Western Australia. In this research, introgression of phenoxy resistance from wild radish to cultivated radish (Raphanus sativus) was investigated following classical breeding procedures. F₁ progeny were generated by crossing MCPA‐resistant R. raphanistrum and MCPA‐susceptible R. sativus. F₁ hybrids were screened for MCPA resistance. The MCPA‐resistant F₁ hybrids were used to produce three generations of backcross progeny. Genetic analyses of F₁ and backcross progeny demonstrated introgression of the MCPA‐resistant trait from wild radish to cultivated radish. Implications of phenoxy resistance introgression into cultivated radish include potential development of herbicide‐tolerant radish cultivars or other members of the Brassicaceae family.