Management of medial luxation of the shoulder joint in toy-breed dogs using an antiluxation pin placed lateral to the supraspinatus muscle tendon: 20 limbs (2017-2022).

OBJECTIVE: To describe the clinical and diagnostic findings, surgical procedures, and clinical course of dogs with medial shoulder luxation (MSL) treated with a novel method using an antiluxation pin. ANIMALS: 18 client-owned toy-breed dogs (20 treated limbs). CLINICAL PRESENTATION: Toy-breed dogs with MSL were treated with the antiluxation pin (2017 to 2022). The collected data included signalment, cause of luxation, preoperative and follow-up clinical evaluations with lameness scores (LMS), and radiographic and/or CT findings. RESULTS: Toy Poodle was the most represented breed (17 of 18 dogs [94.4%]). The median age was 10 years. One of 18 dogs had a history of trauma. Medial luxation was confirmed in all limbs using radiography or palpation under general anesthesia. Reluxation occurred in 3 limbs at 1, 4, and 30 days after surgery, respectively. Of these 3 limbs, 1 limb underwent revision to replace the original pin and the other 2 limbs underwent no further treatment. One limb with persistent pain underwent 2 revision surgeries to adjust the pin orientation 30 and 72 days after the initial surgery. Eighteen limbs remained unluxated after the initial or revision surgery until the final follow-up (median, 18.5 months; range, 1 to 63 months). The LMS at the final follow-up for the 18 unluxated limbs (mean, 0.5) was significantly lower than the preoperative LMS (mean, 4.5) (P < .01). CLINICAL RELEVANCE: A novel method of the antiluxation pin provides an alternative surgical treatment for MSL in toy-breed dogs that is minimally invasive and technically simple.

Thoracic Vertebral Canal Stenosis and Vertebral Instability in a Young Minuet Cat.

This report describes a unique case of thoracic vertebral canal stenosis and vertebral instability in a 1 yr old Minuet cat. The cat presented with a history of chronic progressive nonambulatory paraparesis. Myelography with neutral and stress positions revealed dynamic compression at T1-4. Computed tomography and MRI revealed multiple sites of vertebral endplate osteolysis, adjacent bone sclerosis, intervertebral disk space narrowing, and spondylotic bridging within the cervical and cranial thoracic vertebral bodies and pedicles, particularly at C6-T4. The cat underwent a right-sided T1-4 hemilaminectomy and C7-T4 vertebral stabilization using positively threaded profile pins and polymethylmethacrylate. The cat fully recovered without any complication. The case highlights the potential for young cats, especially those with a chondrodysplastic condition, to develop vertebral canal stenosis and vertebral instability. The surgical treatment described herein resulted in an excellent outcome.

Alarm pheromone does not modulate 22-kHz calls in male rats.

Rats are known to emit a series of ultrasonic vocalizations, termed 22-kHz calls, when exposed to distressing stimuli. Pharmacological studies have indicated that anxiety mediates 22-kHz calls in distressed rats. We previously found that exposure to the rat alarm pheromone increases anxiety in rats. Therefore, we hypothesized that the alarm pheromone would increase 22-kHz calls in pheromone-exposed rats. Accordingly, we tested whether exposure to the alarm pheromone induced 22-kHz calls, as well as whether the alarm pheromone increased 22-kHz calls in response to an aversive conditioned stimulus (CS). Rats were first fear-conditioned to an auditory and contextual CS. On the following day, the rats were either exposed to the alarm pheromone or a control odor that was released from the neck region of odor-donor rats. Then, the rats were re-exposed to the aversive CS. The alarm pheromone neither induced 22-kHz calls nor increased 22-kHz calls in response to the aversive CS. In contrast, the control odor unexpectedly reduced the total number and duration of 22-kHz calls elicited by the aversive CS, as well as the duration of freezing. These results suggest that the alarm pheromone does not affect 22-kHz calls in rats. However, we may have found evidence for an appeasing olfactory signal, released from the neck region of odor-donor rats.