Table of Contents and Abstracts

Our objective was to report the use of distraction osteogenesis at the site of angular limb deformity correction using external skeletal fixation for treatment of 1 femoral and 1 tibial angular limb deformity in 2 large-breed puppies. Medical records were reviewed from 2 dogs (a 7-month-old intact male golden retriever and a 4-month-old intact female German shepherd mixed breed) diagnosed with angular limb deformities and truncation of a pelvic limb. Surgical treatment consisted of neutral wedge ostectomy and distraction osteogenesis at the site of bone deformity with an external skeletal fixator (ESF). The surgical technique and postoperative period of distraction osteogenesis were reviewed along with postoperative complications and clinical outcomes after complete bone healing was evident radiographically.

Both dogs had adequate bone formation during distraction osteogenesis and the ESFs remained intact and structurally stable. At ESF removal, femoral length had increased 2.6 cm for Dog 1 and tibial length increased 3.88 cm for Dog 2, distal femoral valgus improved 16.3 degrees for Dog 1, and tibial procurvatum improved 19.5 degrees and distal tibial valgus improved 6.2 degrees for Dog 2. At the last follow-up examinations, 5 mo (Dog 1) and 3 mo (Dog 2) postoperatively, both dogs were ambulating without any visible lameness.

Key clinical message:
Acute angular correction and subsequent distraction osteogenesis at the site of bone deformity and corrective ostectomy using an ESF enabled successful treatment of femoral (Dog 1) and tibial (Dog 2) truncation and angulation in 2 large-breed puppies. Optimal deformity correction and lengthening were achieved through distraction osteogenesis at the site of neutral wedge ostectomy, minimizing soft tissue dissection and risk for potential complications that can occur with bifocal deformity correction (i.e., correction of the deformity at 1 osteotomy/ostectomy and correction of bone length at another, remote osteotomy).

A 2-year-old female Vietnamese potbellied pig was referred to the Large Animal Teaching Hospital at the Ontario Veterinary College for anoplasty and rectovaginal fistula repair. The presence of atresia ani and rectovaginal fistula had been previously diagnosed. Contrast radiography was used to confirm the diagnosis and determine the position of the fistula and terminal rectum. Under general anesthesia, the urethra was catheterized. An incision was made at the anatomic location of the anus, the rectovaginal fistula was isolated through deep dissection, and a Penrose drain was placed around it for caudal retraction. Transvaginal catheter placement through the fistula and into the rectum assisted with anatomic location. Once the urogenital and gastrointestinal tracts were clearly identified, the fistula was transected as close to the vaginal cavity as possible. The vaginal defect was sutured, and the fistula tract was mobilized 90° and sutured to the skin, creating the anal canal. Postoperative complications included constipation and cystitis. The gilt passed feces 5 d after surgery and was discharged on Day 11 of hospitalization. Normal urination and defecation were observed at the time, and fecal incontinence was resolved. Six months after surgical intervention, the gilt remained continent and no complications were reported.

Key clinical message:
Anoplasty and rectovaginal fistula repair were completed successfully in a gilt. Preservation of the fistula and its use during anal reconstruction may provide an internal anal sphincter and may be associated with improved continence.

A 5-month-old intact female Australian shepherd dog was referred to our clinic for neurologic signs including ataxia, a head tilt, and altered mentation following consumption of an unidentified rodenticide several days prior to developing clinical signs. A provisional diagnosis of bromethalin toxicosis had been made, given the neurologic signs seen and the general increased use of bromethalin-containing rodenticide products. However, on physical examination, the dog was noted to have scleral hemorrhage and bleeding at the venipuncture sites, which was inconsistent with bromethalin toxicosis. Coagulation testing was supportive of anticoagulant rodenticide toxicosis and the rodenticide was later identified as the first-generation anticoagulant rodenticide diphacinone. The neurologic signs seen were attributed to a coagulopathy causing multifocal hemorrhage into the central nervous system. Neurologic signs rapidly resolved following treatment with a frozen plasma transfusion and vitamin K₁. This atypical presentation of an anticoagulant rodenticide toxicosis highlights the need for accurate product identification, if available, and thorough patient examination and laboratory testing. An atypical presentation of anticoagulant rodenticide toxicosis should be considered when neurologic signs are present with clinical bleeding, especially if the type of rodenticide is unknown, or even if it was not thought to have an anticoagulant as the active ingredient.

Key clinical message:
Given the change in commercially available rodenticide products, this case highlights the need for accurate product identification in cases of suspected toxicosis, and the variable clinical signs that can be seen following anticoagulant rodenticide toxicosis.

A 16-month-old neutered male domestic shorthair cat weighing 2.7 kg was referred for further evaluation of acute generalized muscle weakness and paraparesis after a long-standing history of polyuria-polydipsia. The diagnosis of hypodipsic/adipsic hypernatremia relied on the key findings of absent spontaneous drinking despite hypernatremia and a hyperosmolar state (444.8 mOsm/kg, reference interval 280 to 310 mOsm/kg). Brain MRI revealed severe multifocal anatomic anomalies of the rostral calvarium and the forebrain, suggestive of encephaloclastic porencephaly. Involvement of the thalamic and hypothalamic regions could have been responsible for the cat’s adipsic hypernatremia. The unique aspects of this case were the rare description of central nervous system disease leading to hypodipsia, and the history of chronic polydipsia before the acute onset of hypodipsia.

Key clinical message:
Multifocal abnormalities of the forebrain can present with polyuria-polydipsia syndrome, hypodipsia/adipsia, or both, depending on the stage of the disease. This likely happens when the hypothalamic and thalamic regions are affected, since they regulate antidiuretic hormone release and thirst, respectively.

Objective
To visually evaluate and morphometrically describe a sample of abnormal hooves from Sable Island horses that died between 2007 and 2013.

Animal
Equine.

Procedure
An opportunistic sample of 356 abnormal hooves from horses inhabiting Sable Island National Park Reserve (Canada) was collected postmortem between 2007 and 2013 from 101 Sable Island horses. These hooves were assessed for abnormalities in conformation through visual and morphometric evaluation.

Results
On visual and morphometric evaluation, 100% of horses (101/101) had abnormal hoof conformation when compared to a domestic horse hoof model. Specific abnormalities from visual evaluation included long heels (85%); medial, lateral, and dorsal flares (45, 78, and 46% of horses, respectively); and cracking (62%). Specific abnormalities determined from morphometry of the hooves included contracted heels (87%), hoof imbalances including mediolateral imbalance (61%), and hoof length greater than width (100%).

Conclusion
Sable Island horses had various hoof abnormalities such as hoof capsule flaring; long, contracted heels; and mediolateral imbalance. These abnormalities have been observed in other feral horse populations living on soft substrates. Given the potential impact of hoof abnormalities on the welfare status of the Sable Island horses, further studies are warranted, including estimation of the prevalence of hoof abnormalities and direct observation of horse gait and behavior.

Clinical relevance
The significance of the hoof abnormalities for the health of the Sable Island horses is difficult to determine but the issue highlights the importance of further study to investigate the impact on the horses’ welfare.

Objective
To describe producer attitudes toward antimicrobial use (AMU) and antimicrobial resistance (AMR), identify factors associated with attitudes, and inform stewardship initiatives.

Animal
Beef cattle, cow-calf.

Procedure
Cow-calf producers from the Canadian Cow-Calf Surveillance Network (C3SN) completed a survey (n = 146) on producers’ attitudes toward AMU, AMR, and impacts of recent regulatory changes requiring a prescription for the purchase of medically important antimicrobials (MIA).

Results
Most producers (78%, 114/146) reported being aware of initiatives to improve antimicrobial stewardship within the beef industry and 67% (97/146) indicated that AMR was a highly important issue to the industry and producers personally. Almost half of producers reported concerns that AMR development has impacted AMU decisions on their operations. Overall, veterinarians were producers’ primary source of information regarding AMU, including treatment protocols, stewardship programs, and regulatory changes. Following introduction of the 2018 prescription-only regulations, 95% (138/146) of producers reported no change in AMU on their operations. Similarly, 77% (112/146) of producers reported no change in antimicrobial product access, whereas 63% (91/146) reported no change in cost.

Conclusion
Most producers reported little change in access to antimicrobials and in AMU following the introduction of regulations requiring a prescription for MIA.

Clinical relevance
Producers rely on veterinarians as their primary source of information regarding antimicrobial regulations and AMU. It is therefore important for veterinarians to understand their role as educators for beef cow-calf producers. Ultimately, veterinarians and producers need to work together to ensure that the health and welfare of animals are protected while using antimicrobials in a responsible manner.

Background
Metabolic acidosis (MA) is the most common acid-base disorder reported in horses with colitis but its association with survival is yet to be determined.

Objective
Investigate the types of MA in horses with colitis to determine effects of various anions on fatality rates.

Animals and procedures
We studied 158 horses with colitis. Horses were classified into 4 groups depending on the anion contributing to MA: i) no MA, ii) lactic acidosis (LA), iii) unmeasured strong ion (USI) acidosis, and iv) hyperchloremic acidosis (HA).

Results
Sixty percent (95/158) of horses had no MA, 22% (34/158) had LA, 12% (19/158) had HA, and 6% (10/158) had USI acidosis. The fatality rate of horses without MA was 20% (20/95), whereas the rates for those with LA, USI, and HA were 53% (18/34), 30% (3/10), and 16% (3/19), respectively. Horses with LA were more likely to die or be euthanized than horses without MA (OR: 4.2, 95% CI: 1.83 to 9.72, P < 0.001) and HA (OR: 5.9, 95% CI: 1.47 to 24.4, P < 0.01).

Conclusion and clinical relevance
Lactic acidosis was the most common type of MA in horses with colitis, and it was associated with non-survival.

Objective
Corticosteroids are indicated to treat many feline diseases. However, side effects are a limiting factor in their use. The most concerning side effects are steroid-induced diabetes mellitus (SI-DM) and steroid-induced congestive heart failure (SI-CHF). This study aims to determine the incidences of these diseases in a large population of domestic cats seen at a privately-owned, feline-only practice.

Animals
Cats in the study were client-owned patients of Alamo Feline Health Center in San Antonio, Texas. Control cats (controls) were examined as part of their routine health care.

Procedures
The records of 732 cats that received methylprednisolone acetate (MPA) for various clinical indications were reviewed to determine how many developed SI-DM and SI-CHF. A similar record review of 310 controls was made to determine the incidence of spontaneous diabetes mellitus (Sp-DM) and spontaneous congestive heart failure (Sp-CHF). Control cats never received any oral or injectable corticosteroids.

Results
Of the cats that received MPA, 28 developed SI-DM (3.83%) and 6 developed SI-CHF (0.82%). Of the controls, 22 developed Sp-DM (7.10%) and 6 developed Sp-CHF (1.90%).

Conclusion
The incidences of developing SI-DM and SI-CHF were 3.83% and 0.82%, respectively; and the risk was not increased even when repeated doses of MPA were given.

Clinical relevance
The authors consider the risk-benefit ratio sufficient to justify the use of MPA when it is indicated, especially if another drug cannot be substituted with the same therapeutic results.

Opioid analgesics are routinely used during the perioperative period, to provide analgesia and reduce anesthetics doses required to maintain a surgical plane of anesthesia in companion animals. Acting on receptors in the brain, spinal cord, and peripheral nervous system, opioids provide reliable and consistent analgesia; however, they are not without adverse effects. Methadone, a mu agonist opioid analgesic, was recently licensed for veterinary use in Canada. In addition to its action on opioid receptors, methadone contributes to analgesia through other pathways, including inhibition of N-methyl-D-aspartate (NMDA) receptors. It has physiologic effects similar to other mu opioid agents, but fewer adverse gastrointestinal effects. This review discusses methadone’s mechanism of action, pharmacologic characteristics, and clinical effects in dogs and cats. Current recommendations for using methadone in companion animals are also provided.