MHC haplotype diversity in Icelandic horses determined by polymorphic microsatellites.

The Icelandic horse has been maintained as a closed population in its eponymous homeland for many generations, with no recorded introductions of new horses of any breed since the year 1000 CE. Here we determined the diversity of major histocompatibility complex (MHC) haplotypes in 156 Icelandic horses from two groups, based on a panel of 12 polymorphic intra-MHC microsatellites tested in families of various composition. We identified a total of 79 MHC haplotypes in these two groups, including one documented intra-MHC recombination event from a total of 147 observed meioses. None of these MHC haplotypes have been previously described in any other horse breed. Only one MHC homozygote was found in the entire population studied. These results indicate a very high level of MHC heterozygosity and haplotype diversity in the Icelandic horse. The environment in Iceland is remarkable for its lack of common agents of equine infectious disease, including equine herpesvirus type 1, influenza virus, and streptococcus equi. The driving forces for maintenance of MHC heterozygosity in Icelandic horses must thus be sought outside of these major horse pathogens. Based on our results, we propose that intra-MHC recombination may play a major role in the generation of novel haplotypes.

Lipemic uveitis and its etiologies in dogs: 75 cases.

OBJECTIVE: To describe clinical features of dogs with lipemic uveitis (LU). ANIMALS STUDIED: Seventy-five dogs (114 eyes) with LU. PROCEDURES: Medical records of dogs examined by the Cornell University ophthalmology service with a clinical diagnosis of LU between 2008 and 2017 were analyzed. Signalment and clinical case aspects, including concurrent ocular disease, systemic disease, and previous ophthalmic surgery, were recorded. RESULTS: Lipemic uveitis was diagnosed in 114 eyes of 75 dogs. The mean (±standard deviation) age of dogs was 9.0 years (±2.7 years). Miniature Schnauzers and Yorkshire Terriers were statistically overrepresented compared to the ophthalmology canine referral population. Lipemic flare varied in severity with loss of menace response due to markedly opaque flare seen in 15/114 eyes (13%). Two dogs developed LU after dietary indiscretion. Forty-nine eyes (43%) had concurrent ocular disease, most commonly keratoconjunctivitis sicca, ulcerative keratitis, and cataracts. Pseudophakia was present in 75/114 eyes (66%) and LU developed within 30 days of an intraocular surgical procedure in 63/114 eyes (55%). Hypertriglyceridemia was noted in 52 dogs of the 55 dogs tested (95%). Systemic disease affected 54/75 dogs (72%), of which diabetes mellitus, hyperadrenocorticism, and hypothyroidism were overrepresented compared to the referral population. Primary hyperlipidemia was identified in 12 dogs. Lipemic uveitis resolved at first reevaluation in 92/110 eyes (84%) and recurred in 6/114 eyes (5%) after complete resolution. CONCLUSIONS: Development of lipemic uveitis in dogs appears to require the combination of hyperlipidemia and uveitis. Systemic disease is commonly associated with LU in dogs.

Punctate retinal hemorrhage and its relation to ocular and systemic disease in dogs: 83 cases.

OBJECTIVE: To describe clinical aspects of dogs with punctate retinal hemorrhage (PRH). ANIMALS STUDIED: 83 dogs (119 eyes) with PRH. PROCEDURES: Medical records of dogs evaluated by the Cornell University ophthalmology service with a clinical diagnosis of PRH between 2006 and 2015 were reviewed. For this study, PRH was defined as retinal hemorrhages ≤ 1 optic disk diameter in size and dogs with other posterior segment ocular diseases were excluded. Signalment and clinical features of the dogs were recorded, including concurrent ocular and systemic diseases. RESULTS: Punctate retinal hemorrhage was identified in 119 eyes of 83 dogs. The mean (±standard deviation) age of dogs was 10.0 (±3.8) years. Mixed-breed dogs, Golden Retrievers, Jack Russell Terriers, and English Springer Spaniels were statistically overrepresented relative to the ophthalmology service canine referral population during the same period. Hemorrhages were found in all retinal locations and varied in number. Concurrent ocular disease was present in 78 eyes (66%) including keratoconjunctivitis sicca, uveitis, and cataracts. Fifty dogs (60%) suffered from concurrent systemic disease and diabetes mellitus, multiple myeloma, and systemic hypertension were statistically overrepresented in the PRH population. Less frequently, other serious systemic diseases were present in dogs with PRH including immune-mediated thrombocytopenia, leptospirosis, metastatic neoplasia, and thromboembolic disease. CONCLUSIONS: The risk of PRH in dogs may be increased by certain ocular and systemic diseases. As the presence of PRH can be associated with underlying systemic disease in dogs, it may prompt further clinical investigation and diagnostics.

Intracorneal stromal hemorrhage in dogs and its associations with ocular and systemic disease: 39 cases.

OBJECTIVE: To describe clinical features of dogs diagnosed with stromal intracorneal hemorrhage (ICH). ANIMALS STUDIED: Retrospective case series of 39 dogs (44 eyes) with ICH. PROCEDURES: Medical records of dogs evaluated by the Cornell University ophthalmology service were searched to identify animals with a clinical diagnosis of ICH between 2005 and 2014. Signalment and clinical details, including concurrent ocular disease, concurrent systemic disease, diagnostic tests performed, outcome of hemorrhage, presenting client complaint, and treatment, were recorded. RESULTS: Intracorneal hemorrhage was identified in 44 eyes of 39 dogs. The mean (±standard deviation) age of dogs was 11.5 years (±2.8 years). The Bichon Frise breed and older dogs were statistically over-represented relative to the entire ophthalmology service canine referral population during the same time period. Concurrent ocular disease was present in 40 eyes (91%) and included keratoconjunctivitis sicca, cataracts, and corneal ulcers. Twenty-three dogs (59%) suffered from concurrent systemic disease, most frequently diabetes mellitus, hyperadrenocorticism, hypothyroidism, and systemic hypertension. Less commonly, life-threatening systemic conditions were identified in dogs with ICH including immune-mediated hemolytic anemia, immune-mediated thrombocytopenia, metastatic neoplasia, and sepsis. Intracorneal hemorrhage was found in all corneal locations, and corneal vascularization was present in each affected eye. CONCLUSIONS: Intracorneal hemorrhage is an uncommon condition in dogs that occurs in association with corneal vascularization. The risk of ICH may be increased due to certain ocular and systemic diseases. Although uncommon, ICH may also be an ocular manifestation of severe immune-mediated, infectious, and neoplastic systemic diseases in dogs.

Effects of gabapentin and trazodone on electroretinographic responses in clinically normal dogs.

OBJECTIVE: To compare electroretinographic (ERG) responses obtained in dogs before and after oral administration of gabapentin, trazodone, and a combination of both medications. ANIMALS: 12 clinically normal dogs. PROCEDURES: A short-protocol ERG with 20 minutes of dark adaption was recorded for all dogs to establish baseline ERG responses. Dogs then received gabapentin (approx 30 mg/kg), trazadone (approx 20 mg/kg or approx 5 mg/kg), or a combination of gabapentin (approx 20 mg/kg) and trazodone (approx 5 mg/kg) orally, and the same ERG protocol was repeated 2 hours later. Dogs were given a washout period of at least 1 week between treatments. RESULTS: a-Wave amplitudes were significantly (P = 0.018) decreased after administration of the combination of gabapentin and trazodone. b-Wave amplitudes were significantly decreased after administration of the 20-mg/kg dose of trazodone (P = 0.006) and after administration of the combination of gabapentin and trazodone (P = 0.002). Heavier dogs that received higher total doses of trazodone had decreases in a-wave amplitude after administration of the 20-mg/kg dose of trazodone and in b-wave amplitude after administration of the 5-mg/kg dose of trazodone. CLINICAL RELEVANCE: High doses of trazodone and the combination of gabapentin and trazodone significantly decreased a-wave and b-wave amplitudes in clinically normal dogs. However, the effects on retinal responses had little clinical importance. Therefore, these medications can be used safely in a clinical setting; however, further studies are needed in dogs with retinal disease.

Short-, intermediate-, and long-term results for endoluminal stent placement in dogs with tracheal collapse.

OBJECTIVE To evaluate outcomes following endoluminal stent placement for treatment of tracheal collapse (TC) in dogs. DESIGN Retrospective case series with nested observational study. ANIMALS 75 dogs that underwent endoluminal placement of a self-expanding metallic stent to treat TC between September 2009 and August 2015. PROCEDURES Medical records were reviewed to collect data on dog characteristics, clinical signs, TC type, diagnostic test results, peri- and postoperative complications, and outcomes. Complication rates and survival times and rates were compared between various groups. RESULTS The 75 dogs received 119 stents (56% [42/75] received 1 stent and 44% [33/75] received ≥ 2 stents). Thirty-eight (51%) dogs had a malformation type of TC, and 37 (49%) had the traditional type. Ninety-three percent (70/75) of dogs survived to hospital discharge. Median survival time was 1,005 days. Improvement in goose-honking or raspy breathing (89% [42/47]) and dyspnea (84% [43/51]) was reported at final follow-up examination. Major complications requiring additional stent placement procedures occurred in 47% (33/70) of dogs over the follow-up period; stent fracture and tissue ingrowth were the most common types. Male dogs and younger dogs had a significantly longer survival time than other dogs. Mainstem bronchial collapse at the time of stent placement had no significant association with outcome. CONCLUSIONS AND CLINICAL RELEVANCE Endoluminal stent placement provided a high survival rate for dogs with TC, even those with severe clinical signs. This information, as well as the information on potential complications, should be useful for advising owners of affected dogs.

Correlations among tracheal dimensions, tracheal stent dimensions, and major complications after endoluminal stenting of tracheal collapse syndrome in dogs.

BACKGROUND: Endoluminal tracheal stenting can relieve signs associated with tracheal collapse syndrome (TCS) in dogs, but major complications can result. OBJECTIVE: To identify associations among tracheal dimensions, stent dimensions, and subsequent complications requiring additional stent placement after endoluminal stenting for TCS. ANIMALS: Fifty-two dogs from the hospital population. METHODS: Medical records of dogs that received an endoluminal self-expanding tracheal stent for TCS by the interventional radiology service between 2009 and 2014 were reviewed for relevant data. Signalment and clinical details, including tracheal collapse type, tracheal measurements, nominal stent dimensions, follow-up evaluation times, and stent complications, were recorded. RESULTS: Fifty-two dogs that received an endoluminal stent for TCS met the inclusion criteria. Major complications included stent fracture (13/52; 25%), obstructive tissue ingrowth (10/52; 19%), and progressive tracheal collapse (6/52; 12%). Natural tracheal taper (P = .04) and more stent diameter oversizing (P = .04) in the intrathoracic (IT) trachea were associated with caudodorsal stent fracture. Only stents with a 14-mm nominal diameter fractured. Progressive tracheal collapse was associated with smaller maximum tracheal diameters (P = .02). The majority of dogs with obstructive tissue ingrowth (7/10; 70%; P = .30) and all dogs with thoracic inlet fractures (3/3; 100%) had tracheal malformations. CONCLUSIONS AND CLINICAL IMPORTANCE: A higher taper in tracheal diameter may lead to increased risk of fracture in the IT location. Dogs with tracheal malformations may have higher risk for thoracic inlet fracture and development of obstructive tissue ingrowth. Clinicians should be aware of the possible risk factors for tracheal stent complications.