Outcomes of dogs undergoing limb amputation, owner satisfaction with limb amputation procedures, and owner perceptions regarding postsurgical adaptation: 64 cases (2005-2012).

OBJECTIVE: To evaluate outcomes of dogs and owner satisfaction and perception of their dogs' adaptation following amputation of a thoracic or pelvic limb. DESIGN: Retrospective case series. ANIMALS: 64 client-owned dogs. Procedures-Medical records of dogs that underwent limb amputation at a veterinary teaching hospital between 2005 and 2012 were reviewed. Signalment, body weight, and body condition scores at the time of amputation, dates of amputation and discharge from the hospital, whether a thoracic or pelvic limb was amputated, and reason for amputation were recorded. Histologic diagnosis and date of death were recorded if applicable. Owners were interviewed by telephone about their experience and interpretation of the dog's adaptation after surgery. Associations between perioperative variables and postoperative quality of life scores were investigated. RESULTS: 58 of 64 (91%) owners perceived no change in their dog's attitude after amputation; 56 (88%) reported complete or nearly complete return to preamputation quality of life, 50 (78%) indicated the dog's recovery and adaptation were better than expected, and 47 (73%) reported no change in the dog's recreational activities. Body condition scores and body weight at the time of amputation were negatively correlated with quality of life scores after surgery. Taking all factors into account, most (55/64 [86%]) respondents reported they would make the same decision regarding amputation again, and 4 (6%) indicated they would not; 5 (8%) were unsure. CONCLUSIONS AND CLINICAL RELEVANCE: This information may aid veterinarians in educating clients about adaptation potential of dogs following limb amputation and the need for postoperative weight control in such patients.

Description of the Anatomy, Surgical Technique, and Outcome of Hemipelvectomy in 4 Dogs and 5 Cats.

OBJECTIVE: To provide (1) a comprehensive description of hemipelvectomy; and (2) report clinical application and outcome of hemipelvectomy in dogs and cats. STUDY DESIGN: Descriptive report and retrospective case series. ANIMALS: Dogs (n = 4) and 5 cats. METHODS: Cadaveric dissection was performed for imaging purposes using 4 mixed breed dogs euthanatized for reasons unrelated to this study. Medical records (2005-2012) were reviewed for dogs and cats that had hemipelvectomy. Data collected included signalment, body weight, body condition score, clinical presentation, diagnostic imaging findings, location and extent of tumor, definitive diagnosis, use of adjuvant therapy, ability to ambulate postoperatively, complications, and survival. RESULTS: The most common indication for hemipelvectomy in cats was injection site sarcoma (ISS) and in dogs, osteosarcoma or peripheral nerve sheath tumor (PNST). Complete tumor excision was achieved in 6 (67%) cases. Incomplete excision occurred in 2 dogs with lumbosacral PNST and 1 cat having a 2nd surgery for ISS. Complications included intraoperative hemorrhage (n = 2), postoperative soft tissue infection (2), and discharge from the incision site (1). All but 1 animal were ambulatory at the time of discharge. Hospitalization ranged from 1-10 days (median, 4 days). Survival after surgery was individually assessed. CONCLUSION: With in-depth anatomic familiarity, hemipelvectomy can be successful for excision of neoplastic lesions of the proximal aspect of the pelvic limb, with only minor complications.

Learning confounds algometric assessment of mechanical thresholds in normal dogs.

OBJECTIVE: To perform algometric readings in normal dogs in a design that would assess possible confounding factors. STUDY DESIGN: Prospective study. ANIMALS: Skeletally mature spayed female, intact male and castrated male retriever or retriever mix dogs without orthopedic or neurologic disease (n = 19). METHODS: Twelve common surgical sites were selected for algometric pressure testing. Threshold response was defined as a conscious recognition of the stimulus, and recorded in Newtons. Sites were tested in the same order, and the testing sequence repeated 3 times on each side of the dog. Dogs were tested in the morning and evening of the same day and was repeated 10-14 days later, allowing 4 separate data collections for each dog. RESULTS: Data were analyzed using ANOVA or ANCOVA. When all the data were included in the analysis, dog (P < .0001), order (P < .0001), site (P < .0001), site order (P = .0217), time (P < .0001), day (P < .0001) and repetition (P < .0001) all significantly affected the algometer readings. When only the first reading for each site was included in the analysis, dog (P < .0001), site (P < .0001) and sex (P < .0001) all significantly affected algometer readings. CONCLUSION: These results suggest that learning occurred over repeated collection time points, with dogs anticipating the stimulus and reacting at lower thresholds.

Calvarial hyperostosis presenting as unilateral exophthalmos in a female English Springer Spaniel.

A 4-month-old intact female English Springer Spaniel presented to the University of Georgia Veterinary Teaching Hospital for evaluation of unilateral, progressive exophthalmos oculus sinister (OS) of 2 weeks' duration. Complete ophthalmic examination revealed moderate OS exophthalmos and lateral globe deviation. No other abnormalities were noted on physical or ophthalmic examination, ocular ultrasound, complete bloodwork, or thoracic radiography. Skull computed tomography (CT) revealed a large, focal, smoothly irregular, cavitated, expansile bony lesion involving the left caudal maxillary and left frontal bones. Biopsies, obtained through a frontal sinusotomy approach to preserve the left globe integrity, demonstrated normal reactive trabecular bone with locally extensive fibrosis. Calvarial hyperostosis was diagnosed based upon appearance on imaging, lesion unilaterality, absence of mandibular involvement, and histopathology. Six months after initial presentation, skull CT was repeated and marked reduction in the degree of frontal bone thickening was demonstrated with complete resolution of cavitations. There was marked clinical improvement with mild, nonpainful exophthalmos, and lateral globe deviation OS on ophthalmic examination. Eleven months after initial presentation, there was complete resolution of the frontal bone lesion with mild thickening of the left calvarial bones on repeat skull CT. There was no exophthalmos or globe deviation present on clinical ophthalmic examination. The proliferative osteopathic lesion was self-resolving with resolution of the exophthalmos and has not recurred to date. To the authors' knowledge, this is the first report of calvarial hyperostosis in a previously unreported breed presenting as unilateral exophthalmos.

A knockout mutation of a constitutive GPCR in Tetrahymena decreases both G-protein activity and chemoattraction.

Although G-protein coupled receptors (GPCRs) are a common element in many chemosensory transduction pathways in eukaryotic cells, no GPCR or regulated G-protein activity has yet been shown in any ciliate. To study the possible role for a GPCR in the chemoresponses of the ciliate Tetrahymena, we have generated a number of macronuclear gene knockouts of putative GPCRs found in the Tetrahymena Genome database. One of these knockout mutants, called G6, is a complete knockout of a gene that we call GPCR6 (TTHERM_00925490). Based on sequence comparisons, the Gpcr6p protein belongs to the Rhodopsin Family of GPCRs. Notably, Gpcr6p shares highest amino acid sequence homologies to GPCRs from Paramecium and several plants. One of the phenotypes of the G6 mutant is a decreased responsiveness to the depolarizing ions Ba²âº and K⁺, suggesting a decrease in basal excitability (decrease in Ca²âº channel activity). The other major phenotype of G6 is a loss of chemoattraction to lysophosphatidic acid (LPA) and proteose peptone (PP), two known chemoattractants in Tetrahymena. Using microsomal [³5S]GTPγS binding assays, we found that wild-type (CU427) have a prominent basal G-protein activity. This activity is decreased to the same level by pertussis toxin (a G-protein inhibitor), addition of chemoattractants, or the G6 mutant. Since the basal G-protein activity is decreased by the GPCR6 knockout, it is likely that this gene codes for a constitutively active GPCR in Tetrahymena. We propose that chemoattractants like LPA and PP cause attraction in Tetrahymena by decreasing the basal G-protein stimulating activity of Gpcr6p. This leads to decreased excitability in wild-type and longer runs of smooth forward swimming (less interrupted by direction changes) towards the attractant. Therefore, these attractants may work as inverse agonists through the constitutively active Gpcr6p coupled to a pertussis-sensitive G-protein.

Chemoattraction to lysophosphatidic acid does not require a change in membrane potential in Tetrahymena thermophila.

LPA (lysophosphatidic acid), a known chemoattractant for many types of eukaryotic cells, is also a reliable chemoattractant for Tetrahymena. Since LPA receptors are GPCRs (G-protein coupled receptors) in many cell types and several putative GPCR sequences can be found in the Tetrahymena Genome Database, we are interested to determine whether similar GPCR pathways can be used for chemosensory transduction in Tetrahymena. To confirm our procedures, we tested the known chemoattractant proteose peptone (at 1.0 mg/ml), which caused hyperpolarization and increased forward swimming speed in Tetrahymena, consistent with the current model for ciliate chemoattraction. Although 10 µM LPA did not produce these same responses, it was still an effective chemoattractant. PTX (pertussis toxin) blocked attraction to both of these compounds, suggesting a possible G-protein involvement in chemoattraction. Both of these chemoattractants also decreased the basal percent of cells showing direction changes [PDC (percent directional change)] and the duration of backward swimming in 0.5 mM Ba2+ (a general excitability assay). LPA probably causes chemoattraction in Tetrahymena by decreasing the basal PDC without changing either membrane potential or swim speed. Since a pertussis-sensitive G-protein might modulate the ciliate voltage-dependent Ca2+ channels, we propose that LPA acts through an uncharacterized GPCR to lower the PDC by decreasing cellular excitability. These combined behavioural and electrophysiological analyses support the novel hypothesis that chemoattraction to some attractants, like LPA, can occur without hyperpolarization and increased swim speed in Tetrahymena.