Long-term assessment of pancarpal arthrodesis performed on working dogs in New Zealand

AIM: To determine the outcomes following unilateral pancarpal arthrodesis (PCA) in working dogs in New Zealand, in terms of return to work and ability, as assessed by the owner. METHODS: Working dogs treated using unilateral PCA were identified by searching the medical records of the Massey University Veterinary Teaching Hospital (MUVTH) by diagnosis and breed code. Eight Heading dogs (working Collies) and four New Zealand Huntaways were identified with carpal pathology that had been treated by dorsal-plate application, bone-grafting, and casting. All dogs were actively in work on sheep or cattle farms at the time of injury. Case files and radiographs were retrospectively analysed, and the ability of the dog to work after surgery and owner satisfaction with the outcome were assessed using a questionnaire conducted at a mean follow-up interval of 5 years. RESULTS: Following arthrodesis, 6/12 (50%) dogs could perform duties as before surgery. A further four (33%) dogs could perform most former duties. Ten of the twelve owners were satisfied or very satisfied with resultant mobility and work performance of their dogs. Post-operative complications occurred in 50% of dogs, but in only one case affected the eventual outcome. Eleven owners felt surgical repair was worthwhile in a trained working dog. CONCLUSIONS: Unilateral PCA carries a good prognosis for working dogs in New Zealand to return to work, even on hill-country properties. CLINICAL RELEVANCE: This study may allow veterinarians to provide a more accurate prognosis for working dogs requiring PCA. Working dogs that have sustained severe carpal injury including hyper-extension injury, luxation and fracture, or dogs with crippling carpal osteoarthrosis (OA) can return to work after PCA.     

Complications following tarsal arthrodesis using bone plate fixation in dogs

OBJECTIVES: To report the complications encountered following tarsal arthrodesis surgery with bone plate fixation and describe the previously unreported complication of plantar necrosis. METHODS: Medical records of 40 dogs that had been treated by tarsal arthrodesis with bone plate fixation were reviewed to determine the major and minor complications and the associated risk factors. RESULTS: The major complication rate was 32.5 per cent and the minor complication rate was 42.5 per cent. Pantarsal arthrodeses had a higher major complication rate than partial tarsal arthrodeses. Plantar necrosis was the most common major complication and occurred in 15 per cent of cases. Plantar necrosis occurred more frequently when a bone plate was applied to the medial aspect of the hock, and only occurred in cases where tarsometatarsal joint arthrodesis was performed. CLINICAL SIGNIFICANCE: Plantar necrosis is a catastrophic complication that may be associated with injury to the dorsal pedal artery or perforating metatarsal artery. Application of a bone plate to the medial aspect of the hock should be performed with care during tarsal arthrodesis, particularly where the tarsometatarsal joint is debrided of cartilage. Strict attention to surgical technique and proper postoperative coaptation is critical to reduce the potential for complications with tarsal arthrodesis.     

Prospective evaluation of pancarpal arthrodesis for carpal injuries in working dogs in New Zealand,using dorsal hybrid plating

Abstract

AIM: To determine whether working dogs in New Zealand with carpal injuries and treated with unilateral pancarpal arthrodesis (PCA), using a dorsal hybrid-plating method, are able to return to satisfactory working ability.

METHODS: Fourteen working dogs presented to the Veterinary Specialist Group (VSG) and the Massey University Veterinary Teaching Hospital (MUVTH) with carpal injuries were prospectively treated using dorsal hybrid plating. Dogs were eligible if actively involved in farm, hunting or police work. Dogs had a standardised PCA surgical procedure performed, and similar instructions for post-operative care were provided. Dogs were re-evaluated clinically and radiographically at 6 weeks, 6 months, and 12 months after surgery. A questionnaire was completed by 12 owners, to assess each dog's working ability.

RESULTS: Twelve months following arthrodesis, 10/12 (83%) dogs could perform most or all duties normally. Eleven owners (92%) reported that the result of the surgery met their expectations, and nine owners (75%) were very satisfied with the outcome of the surgery. No owners were disappointed or very disappointed with the surgical outcome. Post-operative complications requiring surgical removal of the implant occurred in three (25%) dogs.

CONCLUSIONS: Unilateral PCA using a standardised surgical procedure and dorsal hybrid plating of carpal injuries has a good prognosis for working dogs in New Zealand to return to work.

CLINICAL RELEVANCE: These results may allow veterinarians to provide a more accurate prognosis to owners of working dogs that have debilitating carpal injury     

Severe carpal and tarsal shearing injuries treated with an immediate arthrodesis in seven dogs

The medical records of seven dogs with severe, grade 3, open shearing wounds of the carpus or tarsus that were treated with an immediate arthrodesis were reviewed. Six dogs were managed with a transarticular external skeletal fixator (ESF), and one dog was treated with plate fixation. The soft tissues were managed simultaneously along with the definitive joint stabilization in all cases. Minor complications occurred in four dogs: one dog that required a skin graft, one dog in which a skin graft was recommended but not performed, one dog in which a secondary skin closure was performed, and one dog in which a delayed cancellous bone graft was placed. Major complications occurred in three dogs: two dogs that required restabilization of the arthrodesis and one dog that required implant (i.e., plate) removal due to infection. All dogs healed with acceptable functional and cosmetic results. Further long-term evaluation of five dogs revealed that all but one dog had either excellent or good functional outcomes, and the remaining dog had a fair outcome. Similarly, five dogs had either excellent or good cosmetic outcomes, with the remaining dog having a fair outcome. All owners were very satisfied with the overall results. This clinical study demonstrated that an immediate, definitive management technique, in which bone fusion and wound management are undertaken as simultaneous objectives, is a viable technique of managing severe periarticular shearing injuries. Transarticular stabilization with an ESF is the technique recommended.     

Tarsometatarsal subluxation in dogs: partial arthrodesis by plate fixation

In a retrospective study of tarsometatarsal joint subluxation in eight dogs, secondary fractures were identified in six dogs, particularly of the fourth tarsal bone and the proximal fifth metatarsal bone. Common causes of tarsometatarsal joint injury included jumping or falling and direct trauma to the foot. Partial tarsal arthrodesis, with the use of bone-plate stabilization and cancellous bone grafting of joint spaces after removal of articular cartilage, led to progressive bone healing in all dogs. Implant breakage did not occur in any dog.     

The use of veterinary cuttable plates for carpal and tarsal arthrodesis in small dogs and cats

The objective of the study was to evaluate, retrospectively, carpal and tarsal arthrodesis in small dogs and cats by using veterinary cuttable plates in 6 animals and comparing those with arthrodesis stabilized with other implants in 9 animals. Veterinary cuttable plates were used for 1 pancarpal, 2 partial tarsal, and 3 pantarsal arthrodeses. Other implants were used to stabilize 1 pancarpal, 6 partial tarsal, and 2 pantarsal arthrodeses. In the veterinary cuttable plates group, complications included 2 cases with pressure sores and 1 case with screw loosening. One animal was lost to follow-up and 4 of the remaining 5 were always weight-bearing. In the other group, there were 2 cases with pressure sores, 1 case with dermatitis, and 2 cases with pin migration. Six out of 9 animals were always weight-bearing. The use of veterinary cuttable plates appears to be a suitable option with a good clinical outcome.     

Multifocal retinitis in New Zealand sheep dogs

Thirty-nine percent of 1,448 working sheep dogs were affected with varying degrees of multifocal retinal disease on ophthalmoscopic examination. Lesions consisted of localized areas of hyperreflexia in the tapetal fundus, often associated with hyperpigmentation. Severely affected animals had widespread hyperreflexia with retinal vascular attenuation. Only 6% of 125 New Zealand dogs raised in urban environment were similarly affected. Both eyes of 70 dogs from New Zealand were examined histologically. Forty-seven of 70 dogs had ocular inflammatory disease. Ten other dogs had noninflammatory eye disease, and 13 dogs had normal eyes. Histologically, eyes with inflammatory disease were divided into three categories: Dogs 3 years of age or less with active inflammatory disease of the retina, uvea, and vitreous. Four dogs in this group had migrating nematode larvae identified morphologically as genus Toxocara. Diffuse retinitis and retinal atrophy in conjunction with localized retinal necrosis and choroidal fibrosis. Dogs in this category were severely, clinically affected. Chronic, low-grade retinitis with variable retinal atrophy. Most dogs in this category were over 3 years of age, and many were visually functional. The existence of a definable spectrum of morphological changes associated with inflammation, suggests that Toxocara sp. ocular larva migrans may be the cause of a highly prevalent, potentially blinding syndrome of working sheep dogs in New Zealand.     

Granulomatous meningoencephalomyelitis of dogs in New Zealand

A progressive neurological disease affecting twenty-two young adult dogs of smaller breeds is reported. The disease was most often acute in onset and the neurological signs included cervical pain, seizures, behavioural changes, ataxia, head tilt, muscle tremor and paresis. The lesions were those of a disseminated granulomatous meningoencephalomyelitis in which perivascular cuffs of macrophages and lymphoid cells were the predominant finding. Severe lesions were most often seen in the cerebral white matter although the brain stem, mid-brain and spinal cord were also commonly affected.     

Partial tarsal arthrodesis and botulinum toxin A injection for correction of tarsal arthrogryposis in a cat

An 11-week-old, domestic shorthair cat was presented for evaluation of a congenital right tarsal deformity. The cat was non-weightbearing lame on the right hindlimb. There was severe tarsal hyperextension and concurrent spasticity/contracture/shortening of the gastrocnemius muscle-tendon. The cat was otherwise healthy. Radiographically there was luxation of the proximal intertarsal joint and talocrural hyperextension. Treatment with 10 mu/kg botulinum toxin A (Botox; Allergan) intramuscular injections directly into the gastrocnemius muscle and passive physiotherapy marginally improved the range of motion in the talocrural joint. Definitive surgical treatment with partial tarsal arthodesis produced an excellent clinical outcome. This case report demonstrates the successful treatment of a severe congenital tarsal abnormality and also documents the first clinical use of botulinum toxin in a feline patient.     

Progressive myelopathy and neuropathy in New Zealand Huntaway dogs

AIM: To investigate the nature and cause of a progressive ataxia in three 20-month-old Huntaway dogs that were litter mates. METHODS: Affected dogs were examined before they were humanely killed and submitted to necropsy. Selected formalin-fixed tissues were examined by light and electron microscopy. RESULTS: The lesions were those of axon and myelin degeneration within sensory, proprioceptive and motor tracts of the spinal cord and to a lesser degree some peripheral nerves. CONCLUSION: A progressive myelopathy and neuropathy, tentatively described as a central-peripheral distal axonopathy, was present in all 3 dogs. The cause was not determined but was likely to be either genetic or nutritional. CLINICAL RELEVANCE: In the early stages of this disease, careful examination may be necessary to distinguish the signs of ataxia from orthopaedic disease such as hip dysplasia. Affected animals are unlikely to be of use as working dogs.     

Giardia infection of cats and dogs in New Zealand

Giardia intestinalis is a pathogenic protozoan which infects humans and a wide range of animal hosts, including cats and dogs⁽¹⁾. However, the status of animals in New Zealand with respect to Giardia infection has not received much attention, so we undertook a preliminary study of cats and dogs in Palmerston North and Hamilton to determine the prevalence of infection, as indicated by the presence of cysts in faeces.     

Progressive myelopathy and neuropathy in New Zealand Huntaway dogs

Aim: To investigate the nature and cause of a progressive ataxia in three 20-month-old Huntaway dogs that were litter mates.

Methods: Affected dogs were examined before they were humanely killed and submitted to necropsy. Selected formalin-fixed tissues were examined by light and electron microscopy.

Results: The lesions were those of axon and myelin degeneration within sensory, proprioceptive and motor tracts of the spinal cord and to a lesser degree some peripheral nerves.

Conclusion: A progressive myelopathy and neuropathy, tentatively described as a central-peripheral distal axonopathy, was present in all 3 dogs.The cause was not determined but was likely to be either genetic or nutritional.

Clinical relevance: In the early stages of this disease, careful examination maybe necessary to distinguish the signs of ataxia from orthopaedic disease such as hip dysplasia. Affected animals are unlikely to be of use as working dogs.     

Observations on mortality of young dogs in New Zealand

Changes in the plasma concentrations of cortisol were recorded in 5–6 weeks-old lambs during the first 480 minutes after surgical castration and tailing in order to define the full post-treatment cortisol response and to determine whether or not the handling associated with repeated blood sampling delayed the return of cortisol concentrations to pretreatment values. Four groups of six or seven lambs were studied: One group was bled regularly throughout the 480 minutes of the study, and in the other three post-treatment blood sampling began at 90, 240 or 480 minutes. Plasma cortisol concentrations increased after treatment and returned to or approached pretreatment values by 480 minutes. No significant differences in mean cortisol concentrations were observed between the groups at any stage. It is concluded that the acute distress response of these lambs to surgical castration and tailing lasted about 8 hours and that repeated handling for blood sampling did not contribute significantly to this distress.     

Ability to work and owner satisfaction following surgical repair of common calcanean tendon injuries in working dogs in New Zealand

AIM: To report the long-term outcome (return to work and owner satisfaction) following surgical treatment of common calcanean tendon (Achilles tendon) injuries in working dogs in New Zealand. METHODS: Ten New Zealand Huntaway or Heading dogs (working Collies) with complete or partial tears of the common calcanean tendon, were treated using locking-loop suturing and casting, with (7) or without (3), a calcaneo-tibial screw. All dogs were actively in work on sheep or cattle farms at the time of injury, and return to work was the desired outcome. Ability to work and owner satisfaction were investigated using a telephone questionnaire at a mean followup interval of 14.6 months. RESULTS: Overall, 7/10 dogs returned to full or substantial levels of work. Post-operative complications occurred in two dogs that did not return to full or substantial levels of work. Moderate persistent lameness (score 3 on a scale of 0-5) was present in 2/7 dogs that returned to full or substantial levels of work, equating to a 71% good-to-excellent functional outcome within this group. Seven owners felt the financial investment in opting for surgical repair was worthwhile. A screw and cast method of rigid immobilisation was thought to be superior to casting alone. CONCLUSIONS: Surgical treatment of common calcanean tendon injury in working dogs carries a good prognosis if an appropriate tenorrhaphy technique is used and rigid immobilisation is achieved for 6 weeks. Care must be taken to limit post-operative complications. CLINICAL RELEVANCE: This study justifies the use of surgical repair of such injuries in the working dog even when return to work is the only acceptable outcome.