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The assessment of bird-based welfare indicators plays an important role in the evaluation of bird welfare. The aim of the study was to histologically validate a visual scoring system for hock burn in broilers and to detect threshold values of a visual score to define welfare-relevant alterations in terms of mild lesions or ulcers of the hock. We collected 200 hocks of 39- to 42-day-old Ross 308 broilers after the slaughter process. Each hock was scored visually ("macro scores" 0-4) and evaluated histologically ("micro scores" 0-3), with high scores representing more severe lesions. Although we found a tendency for higher micro scores with increasing macro scores, an exact allocation of macro to micro scores was not possible. For example, macro score 1 could represent micro scores 1, 2 and 3, whereas macro scores 3 and 4 always represented micro score 3 (ulcer). The conditional probability of certain micro scores for given macro scores was estimated using a multinomial logistic regression model. Ulcer showed the highest probability at macro score 1, whereas mild lesions were not found to have an estimated highest probability at any macro score. The depth of inflammation of hock burn lesions increased with increasing macro scores up to macro score 3 with an average depth of 1019 µm. Visually more severe and deeper lesions were also histologically rated with higher scores. Thus, considering limitations, the herein validated macroscopic assessment scheme for hock burn allows an estimation of histological alterations in hocks of broilers.

A retrospective study was conducted to evaluate degenerative joint disease (DJD) in captive waterfowl that died or were euthanized at Fresno's Chaffee Zoo in Fresno, California, USA from 2001 to 2005. Of these, 16 out of 33 birds (48%) had DJD in one or both stifle (femoral-tibiotarsal joint; n = 13), hock (tibiotarsal-tarsometatarsal joint; n = 4), or toe joints (n = 2), based on gross, histologic and/or radiographic confirmation. No joint disease was observed in any wings, nor were any infectious pathogens isolated from affected joints. Sixteen species of waterfowl were included (n = 1 to 5 per species), with an average age at death of 12.1 years and 11.3 years for waterfowl with, and without DJD, respectively. Neither age nor sex was associated with the presence of joint disease. Waterfowl housed in the Rainforest exhibit were more likely to be diagnosed with DJD compared with waterfowl housed in the duck pond exhibit, possibly due to the rough-textured concrete surfaces in the Rainforest exhibit. Further research involving a larger number of zoological collections and birds is necessary to gain a better understanding of risk factors in captive waterfowl.

Groups of eight 7-day-old Mycoplasma-free broiler chicks were inoculated with one of two strains of M. gallisepticum (MG/S6, MG/B31/85) or one of two strains of M. synoviae (MS/B31/88 and MS/B94/91) into the left hock joint. Controls were similarly inoculated with sterile mycoplasma broth. The birds were assessed at 2, 3, 4 and 5 weeks of age (1, 2, 3 and 4 weeks post-injection) for lameness and joint and limb lesions. At 5 weeks of age they were killed and examined for gross skeletal abnormalities and microscopic lesions of both hock joints. The in-contact controls showed no joint swelling or lameness. The mycoplasma did not apparently spread to cause gross pathology in the joints of in-contact control birds, or to other joints in a bird injected with mycoplasma. Each mycoplasma strain caused specific pathologies manifest as varying degrees of lameness, left hock joint swelling, bone deformity and differences in the severity of articular cartilage and chondrodystrophic growth plate pathology. Shortening and bowing of the right tibiotarsus in the birds injected with mycoplasma indicated unilateral increased limb loading contributing to bone deformity. Chondrodystrophy seen with three mycoplasmal strains may have contributed to bone deformity in these birds. Lameness appeared to be a consequence of either joint swelling and/or bone deformity resulting in mechanical dysfunction. The role of joint pain in the lameness was not determined.

One-day-old specific pathogen-free (SPF) light hybrid chicks were infected orally with an arthrotropic reovirus strain R2. At 2, 5, 8 and 10 weeks post infection (p.i.) birds were killed and tissues were taken from 7 sites in the leg for virus isolation and titration. Over the 10-week period the highest number of isolations was made from the hypo-tarsal sesamoid bone (89.7% of such specimens), followed in turn by digital flexor tendons (66.7%), articular cartilage at the hock (64.1%), gastrocnemius tendon (61.5%), head of the femur (56.4%), joint swab (30.8%) and synovial membrane at the hock (20.5%). Swabbing of the hock joint, although technically the simplest sampling method, was one of the least successful for virus recovery. Virus isolations from the articular cartilage at the hock gradually increased during the 10 weeks p.i. but decreased in the other tissues. Best correlations between the presence of gross tendon lesions and virus isolation were at 5 and 8 weeks p.i. With one exception, virus could always be recovered from specimens of hock articular cartilage which had gross lesions. For diagnostic purposes it is recommended that specimens from several birds in an infected flock, both with and without gross lesions, should be examined for virus, and the hypotarsal sesamoid bone and hock cartilage would be the tissues of choice.

Five groups of light hybrid SPF chicks were inoculated at 1 day of age with different strains of Mycoplasma iowae via the right thoracic air sac and right foot pad. Control birds were inoculated with sterile mycoplasma broth at the same sites. The chicks were observed daily for clinical signs and at 3 and 6 weeks approximately half the birds in each group were killed for postmortem, histological and cultural examination. At 6 weeks serological studies were also carried out. Clinical signs were minimal although in three of the five infected groups there was impaired ability in some birds to flex the digits of the feet. On postmortem examination the most common finding was exudative tenosynovitis affecting the digital flexor tendons above and below the hock joint. Histological examination of such tendons revealed inflammatory changes with heterophil infiltration together with plasma cells and lymphoid foci. Some tendons exhibited sigmoid folding which was apparently associated with rupture of that tendon. M. iowae was reisolated from chicks in only three of the five infected groups and there was no obvious correlation with lesions. Rapid serum plate agglutination tests using an antigen made from the type strain gave one positive reaction out of 34 infected birds tested but an antigen prepared from another strain (serovar J DJA) gave 11 positive reactions.

The effect of breed of chicken on infection with an arthrotropic avian reovirus strain R2 was studied by oral or footpad inoculation of 1-day-old chicks of the following breeds: (1) specific pathogen-free (SPF) light-hybrid, (2) commercial White Leghorn egg-layer, and (3) commercial Ross I broiler, and observed to 12 weeks of age. Although most inoculated birds of all three breeds developed swelling of one or both legs below the hock joint at 3 to 4 weeks of age, gross lesions of tenosynovitis became progressively more severe and extended above the joints only in broilers, whereas in most orally-infected SPF and commercial light chickens gross lesions were intermittently severe and regressed with time. Cloacal virus shedding continued up to 2 weeks in the lighter breeds and 3 weeks after infection in broilers. From a small proportion of infected chickens, reovirus was also reisolated from heart, pancreas and caecal tonsils. In all breeds, the tissue in which virus persisted longest was the hock joint/tendon. There was a poor correlation between isolation of virus and the presence of gross lesions in chickens of 12 weeks of age, especially in broilers. Virus-neutralisation tests demonstrated that seroconversion in the lighter breeds occurred predominantly at 3 weeks and in broilers at 4 weeks after infection. In all three breeds the footpad infection gave significantly lower growth rates than were found in the control and oral-infection groups. Oral infection had no apparent effect on growth rates. The greater susceptibility of broilers to reovirus infection is discussed.

During the period 1959 to 1968 0.4% of ducks slaughtered in Denmark were condemned because they had arthritis. The condemnation rate due to arthritis decreased 2 years after compulsory measures to control salmonella infections were introduced and in the 10 years from 1969 to 1978 this condemnation rate was 0.12%. The condemnation rate due to arthritis was relatively high during the period 1961 to 1967. A positive correlation between the condemnation rate due to arthritis and the number of ducks slaughtered and the overall condemnation rate existed at this time. Seasonal variations in the condemnation rate due to arthritis were observed. Mallards were found to be less susceptible to arthritis than White Pekin and Muscovy ducks reared under the same conditions. The hock was most frequently affected (43%) with arthritis. In 37% of arthritic birds the knee was affected, hip and toe joints being affected in 18% and 1% of cases respectively. Wing joints were affected in less than 1% of cases. The national annual cost of arthritis from 1959-1968 was estimated at 207, 579 Danish crowns. In the subsequent 10 years the cost was only one third of this sum.

A group of light hybrid chicks was inoculated via the footpad at 1-day-old with an avian reovirus isolated from ruptured gastrocnemius tendons, and were housed with a similar number of uninoculated chicks (in-contacts) from the same hatch. Though all inoculated birds showed swellings of the injected leg after 7 days, lesions of tenosynovitis did not develop in the other leg or in either leg of in-contacts until they were 6- to 7-weeks-old. Lesions in leg tendons, and particularly the digital flexors, persisted in both inoculated and in-contact birds until the termination of the experiment at 33 weeks of age. Reovirus was recovered for varying periods from the trachea, intestine, hock and footpad of inoculated chickens commencing 1 week after infection, and from the same tissues of in-contacts but from 2 weeks, and generally for shorter periods. In both groups virus persisted for at least 13 weeks in the hock joint or surrounding tissues and cloacal swabs were positive between the 14th and 16th weeks after inoculation. Fluorescent antibody staining demonstrated penetration of the virus into the tendons. Precipitating antibodies to the reovirus were detectable in both groups between the 3rd and 24th weeks after infection.

Summary A virus was isolated from the diseased hock joints of turkeys suffering from infectious synovitis. Results in the agar gel precipitation test indicate that the virus is identical with tenosynovitis virus of chickens. Mycoplasma synoviae was also isolated from the hock of an afflicted bird during the same outbreak.

Summary Two adenoviruses isolated as the only viruses from the hock joints of chickens in outbreaks of tenosynovitis were tested for their ability to cause experimental tenosynovitis in chickens. It was previously shown that they were capable of growth in tendon organ cultures. One strain, designated 92, was used for infection of specific pathogen‐free light hybrid chicks either in ovo at 17 days incubation or at 1‐day‐old orally or via the footpad. It was also used for infection of commercial broiler chicks at 1‐day‐old via the oral or footpad routes. The other virus, strain PS, was similarly used for infection of broiler chicks via the same routes. In none of the experiments did clinical signs or lesions of tenosynovitis develop other than transient inflammatory changes in the tissues and there was no evidence of prolonged virus persistence in hock joints. Of the tissues examined for virus, persistence was greatest in the gut.